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Voice and Speech Characteristics of Persons With Parkinson’s Disease Pre- and Post-Pallidotomy Surgery: Preliminary Findings Geralyn M. Schulz Teri Peterson Christine M. Sapienza Department of Communication Sciences and Disorders University of Florida Gainesville

Melvin Greer Department of Neurology Health Science Center University of Florida Gainesville

William Friedman Department of Neurosurgery Health Science Center University of Florida Gainesville

Pallidotomy surgery, lesioning the globus pallidus internal, has been performed to alleviate Parkinsonian symptoms and drug-induced dyskinesias. Improvements in limb motor function have been reported in recent years following pallidotomy surgery. The purpose of this preliminary study was to determine the effect of pallidotomy surgery on select voice and speech characteristics of 6 patients with Parkinson’s disease. Acoustic measures were analyzed pre-pallidotomy surgery and again at 3 months following surgery. Preliminary findings indicated that all participants demonstrated positive changes in at least one acoustic measure; 2 of the participants consistently demonstrated positive changes in phonatory and articulatory measures, whereas 3 participants did not consistently demonstrate positive changes postsurgery. The results are discussed relative to the differential effects observed across participants. KEY WORDS: Parkinson’s disease, surgical treatment, treatment outcome, acoustic analyses, voice and speech

T

he characteristic movement abnormalities observed in Parkinson’s disease (PD)—resting tremor, rigidity, bradykinesia, hypokinesia, akinesia, and postural abnormalities—are caused by nigrostriatal dopamine deficiency (Marsden, 1994). Treatment for PD has centered on pharmacological therapies, especially those that increase production or mimic the actions of dopamine, such as levadopa (L-Dopa), and artificial dopamine agonists, such as bromocriptine and pergolide. Symptom improvement usually follows administration of these drugs, particularly for reductions in bradykinesia, rigidity, and tremor. These benefits, however, are often accompanied by early side effects of nausea and hypotension; and, over time, the extended use of these drugs can cause dyskinetic and dystonic movements and drug-dose related fluctuations, the “on-off” phenomenon (Marsden, 1994). In addition to these problems, the drugs can cause confusion, dementia, hallucinations, and delusions (Calne, 1995). Research has focused on finding more effective and enduring treatments for this disease and has (re)turned to various surgical techniques, such as fetal-tissue implantation, thalamotomy, chronic deep brain stimulation to the thalamus and palladium, and pallidotomy (Krauss & Jankovic, 1996). Thalamotomy and pallidotomy were widely used treatment techniques before the development of LDopa (Goetz & Diederich, 1996). Thalamotomy interrupts the increased

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excitatory outflow from the thalamus, whereas pallidotomy interrupts the increased inhibitory outflow from the globus pallidus. Both surgical techniques attempt to restore the balance of excitation and inhibition in basal ganglia and thalamic circuits (Marsden & Obeso, 1994). Pallidotomy surgery, a stereotactic surgical technique, was first performed by Myers in the 1930s (Myers, 1940). Pallidotomy became a popular procedure during the 1950s, with the anterodorsal part of the pallidum as the primary target (Narabyashi & Okuma, 1953). However, the results of pallidotomy were mixed; long-lasting improvement was reported for rigidity only; tremor and hypokinesia did not improve. When the target was moved to the posteroventral part of the pallidum, successful improvements were observed in tremor, rigidity, and bradykinesia that lasted from 1 to 5 years (Svennilson, Torvik, Lowe, & Leskell, 1960). Despite these reports of significant symptom relief, treatment for PD was centered on administration of L-Dopa from the 1960s to the late 1980s. Posteroventral pallidotomy surgery was revived during the late 1980s (Laitinen, Bergenheim, & Hariz, 1992a, 1992b). The vast majority (92%) of patients experienced relief from rigidity and hypokinesia for up to 6 years after surgery (Laitinen et al., 1992a, 1992b). Additionally, tremor was completely or nearly eliminated in 81% of the patients; L-dopa-induced dyskinesias and muscle pain were greatly reduced and gait improved. Problems in the long-term use of drugs and the reported success of pallidotomy caused a resurgence of interest in the procedure. Several groups of researchers reported marked improvement in limb motor symptoms in patients with PD using posteroventral pallidotomy. Iacono and his colleagues (Iacono, Lonser, & Morenski, 1994) reported significant improvement in motor function as measured by the Unified Parkinson’s Disease Rating Scale (UPDRS) and the Hoehn and Yahr staging scale (Hoehn & Yahr, 1967). All contralateral improvements and significant ipsilateral improvements surpassed the patients’ best response to medication and exceeded the best results of fetal graft (Iacono, Lonser, Mandybur et al., 1994). Bilateral pallidotomies have also proved beneficial in patients with PD who have significant disabling levadopa-induced dyskinesias (Iacono, Lonser, & Yamada, 1994). Symptom relief with globus pallidus internus (GPi) pallidotomy appears to be greatest for akinetic movement abnormalities (bradykinesia, hypokinesia, rigidity, and gait freezing) and for eliminating drug-induced dyskinesias (Baron et al., 1996; Dogali et al., 1995; Lozano et al., 1995). Symptom relief is due to reductions in the excessive inhibitory GABAergic outflow from GPi, which then disinhibits the ventral lateral thalamus, which disinhibits cortical motor areas and the pedunculopontine nucleus. The

pedunculopontine nucleus is known to have powerful influences on posture, postural stability, and locomotion (Iacono, Lonser, & Morenski, 1994; Sterio et al., 1994). Positron emission tomography (PET) studies following pallidotomy confirmed an increase in metabolic activity in primary motor, supplementary motor, and premotor cortical areas that receive projections from ventrolateral thalamus (Eidelberg et al., 1996; Grafton, Waters, Sutton, Lew, & Couldwell, 1995). Furthermore, a decline in thalamic metabolism was found to be significantly correlated with improvement in contralateral limb motor performance (Eidelberg et al., 1996). Not all researchers agree that pallidotomy results in dramatic improvements in motor control. Several studies found significant improvement only for druginduced dyskinesias but reported that overall functional improvement was not remarkable (Friedman et al., 1996; Sutton et al., 1995). Furthermore, complications have occurred following surgery that include visual field deficits due to proximity of the GPi to the optic tract, hemiparesis due to proximity of the GPi to the internal capsule, and internal hemorrhaging (Dogali et al., 1995). The reported incidences of these complications appear to be minimal (Dogali et al., 1995; Iacono, Lonser, & Morenski, 1994; Sutton et al., 1995). Despite the resurgence of interest in surgical interventions for PD, the vast majority of patients continue to be managed successfully neuropharmacologically. Given that approximately 60% to 80% of individuals with PD have motor speech disturbances (Mutch, Strudwick, Roy, & Downie, 1986), it is of significant clinical and theoretical interest to ascertain the functional effects of pallidotomy surgery on voice and speech. Phonatory deficits including reduced vocal loudness, pitch deviations, reduced stress, and harsh and/or breathy voice are commonly observed in PD (Darley, Aronson, & Brown, 1969; Fox & Ramig, 1997; Hanson, Gerratt, & Ward, 1984; Perez, Ramig, Smith, & Dromey, 1996). Individuals with PD also exhibit articulatory deficits including imprecise articulation, dysdiadochokinesis, variable speech rate, and reduced overall speech adequacy (Ackermann & Zeigler, 1991; Canter, 1965; Connor, Ludlow, & Schulz, 1989; Logemann, Fisher, Boshes, & Blonsky, 1978). The effects of neuropharmocological and neurosurgical treatments in individuals with PD suggest that these treatments can differentially affect voice, speech, and limb motor systems. Electrical stimulation or ablation of thalamic nuclei reduces or abolishes tremor and rigidity, but speech symptoms can develop following these procedures (Cooper, 1961; Stracciari, Guarino, Cirignotta, & Pazzaglia, 1993). L-Dopa alleviates limb motor symptoms, yet phonatory and respiratory symptom alleviation have not been observed (Daniels, Oates, Phyland, Feiglin, & Hughes, 1996; Larson, Ramig, &

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Scherer, 1994; Solomon & Hixon, 1993). Likewise, limb motor function improves following fetal dopamine transplantation (Freed et al., 1992), but voice and speech do not appear to be systematically influenced by this surgery (Baker, Ramig, Johnson, & Freed, 1997). Little objective data regarding voice and speech functions has been obtained from patients who have had pallidotomy surgery. Although several studies have suggested that voice and/or speech may be improved in some patients following pallidotomy (Buck & Cooper, 1956; Laitinen et al., 1992a; Sutton et al., 1995), others have reported voice and/or speech disorders, including transient facial paresis, presumably due to the proximity of GPi to the internal capsule (Laitinen et al., 1992b; Lozano et al., 1995). More recently, Barlow and his colleagues (Barlow, Iacono, Paseman, Biswas, & D’Antonio, 1998) reported on labial force production and stability and aerodynamics following bilateral pallidotomy. They found that 45% to 55% of their 11 subjects had significantly reduced labial force instability and peak and average rate of labial force recruitment during nonspeech tasks. Additionally, some of their subjects exhibited translaryngeal airflow and intraoral pressures that were more like those of control subjects during syllable repetitions. Interestingly, the distribution of voice onset times (VOT) remained unchanged in one of the patients. They concluded that bilateral pallidotomy might reflect a “global rescaling of neural inputs or concomitant adjustments in muscle stiffness among muscle subsystems of the vocal tract” (Barlow et al., 1998, p. 150). Given these findings, examination of acoustic, respiratory, and laryngeal changes that occur following pallidotomy is necessary to determine the efficacy of this procedure and to aid in determining the role of basal ganglia in speech motor control. This study examined specific acoustic phonatory and articulatory characteristics of a group of patients with PD undergoing unilateral pallidotomy. Patients were tested presurgery and at 3 months following pallidotomy. Voice and speech changes were assessed within individual patients because there was a wide range of motor and speech impairment in these patients presurgically. It was hypothesized that reduction of muscular rigidity, hypokinesia, and tremor (found in limb studies of post-pallidotomy patients) would cause changes in the phonatory and articulatory acoustic characteristics examined. This hypothesis was based on the cortical-basal ganglia motor control circuit, which has been shown to be critically involved in regulating and controlling both limb and speech movements. This circuit encompasses primary and secondary motor cortices, supplemental motor cortex, thalamus, and basal ganglia. Neuronal activity in the supplemental motor cortex has been recorded before both voluntary speech and limb movements (Deecke, Kornhuber, Lang, Lang, & Schreiber, 1985). Additionally, a somatotopic representation for the 1178

arms, legs, and face has been identified throughout this circuit (Alexander, DeLong, & Crutcher, 1992). Finally, damage to these areas causes both limb and speech movement abnormalities, such as occurs in PD. Given these cortical-basal ganglia circuit considerations, it was hypothesized that pallidotomy surgery would similarly affect phonatory, articulatory, and limb motor systems. The primary purpose of this preliminary study was to determine the effect of pallidotomy surgery on voice and speech production in 6 individuals with PD. Acoustic measures of phonation and articulation were used to assess aspects of voice and speech production that are frequently impaired in PD (Baker et al., 1997). A second purpose of this study was to determine whether any changes observed postsurgery brought the participants’ voice and speech measures within published normative ranges.

Method Participants Six persons with idiopathic PD were studied. Three men between the ages of 59 and 72 years and three women between the ages of 53 and 70 years were referred from an ongoing pallidotomy program at the University of Florida Health Science Center. These individuals expressed an interest in pallidotomy surgery and met surgical criteria set and determined by the Departments of Neurology and Neurosurgery at the University of Florida. Criteria included severe functional disability despite pharmacological treatment, disabling side effects of treatment such as medication-induced dyskinesia and/or fluctuating “on-off” phenomena, and the absence of severe depression or dementia. Years post-disease-onset ranged from 5 to 17 years. Before surgery, all 6 participants experienced bradykinesia, 5 experienced dyskinesia, and 3 experienced tremor by their report and the presurgery neurological report. All participants were seen for the voice and speech recording at the same time of day pre- and postsurgery to control the timing of their medications relative to the recording. Medications were kept constant pre- and postsurgery, but in two cases (P3 and P6) the neurologist slightly reduced Sinemet doses following surgery. Each participant received unilateral pallidotomy surgery. Standard stereotaxic pallidotomy surgical procedures were employed (refer to Laitinen, 1994; Laitinen et al., 1992a). Three participants had pallidotomy surgery on the left (2 men, 1 woman) and 3 on the right (1 man and 2 women). No surgical complications were reported. Neurologic and medical characteristics of the participants are summarized in Table 1. The overall severity of hypokinetic dysarthria before surgery was rated by the first author as moderate

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Table 1. Participant characteristics, motor symptoms, and medications pre- and post-pallidotomy surgery.

Participant

Sex/Age

Yrs disease

Motor presurgery

P1

F/70

6

Bradykinesia Dyskinesia

P2

M/59

12

P3

M/65

P4

Surgery side

Medications presurgery

Medications postsurgery

Left

Sinemet CR 50/100x2 Sinemet 25/100x4 Ambica Glaucoma drops

Sinemet CR 50/100x2 Sinemet 25/100x4 Ambica Glaucoma drops

Bradykinesia Tremor

Left

Sinemet 25/250x3 Valium 5mg

Sinemet 25/250x3 Valium 5mg

17

Bradykinesia Dyskinesia Tremor

Right

Sinemet 10/100(L)x10 Permax 1mgx3 Artane 2mgx3

Sinemet 25/100x4 Permax 1mgx3 Artane 2mgx3

F/53

14

Bradykinesia Dyskinesia Tremor

Right

Sinemet CR 25/250x4

Sinemet 25/100x5 Sinemet CR 50/200x1

P5

M/72

5

Bradykinesia Dyskinesia

Left

Sinemet 25/100x4 Amatadine x2 Relafin 500mgx1 Lynoxin .25mgx1

Sinemet 25/100x4 Amatadine x 2 Relafin 500mgx1 Lynoxin .25mgx1

P6

F/58

11

Bradykinesia Dyskinesia

Right

Sinemet 25/100x4 Sinemet CR 25/250x1 Eldepryl x 2 Verapamil x 1 Prednisone, Zantac Letensin

Sinemet 25/100x5 Eldepryl x 2 Verapamil x 1 Prednisone, Zantac Letensin

Note. Motor symptoms and medications pre- and postsurgery as reported by the patient.

for 4 and mild for 2 of the participants. The conversational speech sample was taken from the conversation portion of the pre- and postsurgery recording sessions. Approximately 3 to 5 minutes of conversation was elicited regarding the participant’s family, specifically their children and grandchildren. Therefore, the number of utterances on which the rating was based varied per participant. The severity rating was not based on any one characteristic but on the combination of several of the most deviant speech dimensions noted by Darley, Aronson, and Brown (1969). These included reduced volume, monopitch, monoloudness, imprecise articulation, and variable rate. An examination of the oral motor mechanism revealed that all participants exhibited labial and/or lingual weakness, and 4 demonstrated reduced range of motion of the articulators during nonspeech tasks. Table 2 summarizes voice, speech, and nasoendoscopy ratings.

Procedures For the voice and speech tasks, all participants were seated in a quiet, sound-treated room and were recorded once before surgery and again at approximately 3 months after surgery. The use of multiple baselines to

establish a background level of variability against which to measure postsurgical changes is probably the best research design for this study’s purposes (Ventry & Schiavetti, 1986). However, this was not feasible in the clinical setting in which the data were collected. Participants came to the University of Florida Health Science Center from great distances, and within a 2-day period all of their medical evaluations were completed by several research groups, each of which was allotted a strict amount of time to collect data. Participants traveled and lodged at their own expense and were not compensated for their participation in any of the research. Each participant went through the following protocol in the same order: interview, oral motor mechanism examination, acoustic recording, and fiberoptic nasoendoscopy with video stroboscopy when possible. The acoustic recording incorporated a voice and speech protocol that included three maximum sustained /i/ phonations at the participants’ comfortable effort level and repetitions of the syllables /pa/, /ta/, /ka/, and /pataka/ at the participants’ normal rate on one breath. The extended vowel phonations preceded the syllable repetitions for all participants. Care was taken to elicit a similar effort level from all participants by providing the same instructions for each participant. Other speech Schulz et al.: Voice and Speech Following Pallidotomy

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Table 2. Pre- and post-pallidotomy clinical impressions of dysarthria severity, oral motor, and fiberoptic nasoendoscopic findings rated by first author. Presurgery ratings Participant

Dysarthria

Oral motor

P1

Moderate

òROMa Lingual weakness

P2

Moderate

P3

Postsurgery ratings Nasoendoscopic

Nasoendoscopic

Dysarthria

Oral motor

Lxb tremor Glottal gap

Moderate

òROM Lingual weakness Labial weakness

Not possible

Masked face òROM Lingual weakness Labial weakness

Lx tremor Glottal gap

Moderate

òROM Lingual weakness

Glottal gap

Moderate

Masked face òROM, Labial weakness Lingual weakness

Arytenoid tremor Glottal gap

Moderate

òROM Lingual weakness Labial weakness

Not possible

P4

Moderate

Masked face, òROM Lingual weakness Labial weakness

No tremor Glottal gap

Mild

Masked face òROM Lingual weakness Labial weakness

Not possible

P5

Mild

Lingual weakness

Glottal gap

Mild

òROM masked face

Lx tremor Glottal gap

P6

Mild

Lingual weakness Labial weakness Mild tremor

Glottal gap

Mild

òROM Mild tremor

VF tremor Glottal gap

Note. ò indicates reduced, and ñ indicates increase. a “ROM” is range of motion. b “Lx” is laryngeal.

tasks that were recorded pre- and postsurgery included reading, picture descriptions, and conversation. These tasks will be part of a separate analysis and report. Acoustic signals were recorded onto a Sony Digital Audio Tapedeck (model 690) using an amplified (model DBX 707) headmount microphone placed 4 cm from the participant’s mouth. This constant mouth-to-microphone distance was maintained in all recordings for all participants. Fiberoptic nasoendoscopy with video stroboscopy was performed presurgery following the acoustic recording to determine overall glottal configuration and presence of laryngeal or vocal fold tremor. A medial glottal gap was evident for all 6 participants before surgery. Three participants also had this procedure postsurgery, and all evidenced a similar medial glottal gap. Table 2 summarizes these findings.

Measurements The measures used to assess the effects of pallidotomy surgery on phonation and speech included the phonatory variables of fundamental frequency (F0) and sound pressure level (SPL) and the speech acoustic variables of 1180

extended vowel duration (EVD), syllable repetition vowel duration (SVD), voice onset time (VOT), and syllables per second (SPS). The phonatory variables provided a measure of the perceptual correlates of pitch (F0) and loudness (SPL), both of which are deviant in individuals with PD (Darley et al., 1969). Articulatory acoustic variables provided information on vocal tract movement dynamics and timing (EVD, SVD, SPS) as well as orolaryngeal coordination (VOT) and have been used to assess the efficacy of other treatments for PD (Abramson, 1977; Baker et al., 1997; Klatt, 1975).

Data Analysis Tape-recorded samples of the participant’s speech were analyzed using the Computerized Speech Laboratory (CSL) program (Kay Elemetrics, Version 3.0) to measure F0, EVD, SVD, VOT, and SPS. Relative change in SPL pre- to postsurgery was measured using the CSpeech software program (version 4.0, Milenkovic, 1989). The Multidimensional Voice Program software program in CSL calculated the average fundamental frequency over each entire extended /i/ phonation. The

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other phonatory variable, relative change in SPL, was calculated as the RMS over the entire length for each extended /i/ phonation and from a 200-ms midportion of the voicing segment in each of 10 /pa/, /ta/, and /ka/ syllable repetitions. All of the articulatory acoustic variables were analyzed using CSL. The duration from the onset to the offset of regular periodic striations in the acoustic waveform for each extended vowel phonation was defined as EVD. The interval between the onset of the stop burst to the onset of regular periodic striations in the acoustic signal was defined as VOT. The interval from the onset of these regular periodic striations to their offset for the /pa/, /ta/, and /ka/ syllable repetitions was defined as SVD. The number of repetitions per second for each syllable and the combined /pataka/ was calculated as SPS.

Measurement Reliability To evaluate intrameasurer reliability for temporal articulatory acoustic measures, 10% of the samples were remeasured. The original measurements differed on average by 4 ms from the repeated measurements. The Pearson Product Moment Correlation for the temporal articulatory acoustic measures was 0.99, with p ≤ 0.001. To evaluate the intrameasurer reliability for the relative change in SPL, one subject was chosen at random and the relative change in SPL was remeasured for all /i/ phonations and for the /pa/ syllable repetitions. The average difference between the first and second measure was 0.246 dB. The Pearson Product Moment Correlation for the relative change in SPL was 0.84, with p ≤ 0.001.

Statistical Design Three methods were used to determine whether there were changes observed postsurgery. A meaningful postsurgery change was defined as a change in two of the three measures. This criterion was established to ensure that a change was not due to random variability in patient performance. Comparisons were made of each individual’s pre- to postsurgical means to determine whether differences existed in the phonatory and articulatory acoustic measures. Pre- and postsurgical means were used to determine potential changes due to the small sample size, the relative heterogeneity of the group, and the irreversible nature of the surgery (Baker et al., 1997; Kratochwill & Levin, 1992). A change by method one was considered substantial if the postpallidotomy mean exceeded the pre-pallidotomy mean by ±1 standard deviation (SD). A ±1 SD difference was chosen for several reasons; it is comparable to a large effect size (Cohen, 1988), it defines the variability of normal aged participants for some of the phonatory and acoustic articulatory measures used in this study (Ramig

& Ringel, 1983; Weismer, 1984), and it has been used in this population to describe meaningful differences preto post-fetal-cell transplant surgery (Baker et al., 1997). The SD was calculated for all voice and speech measures except SPS, which was measured once per /pa/, /ta/, /ka/, and /pataka/ repetition. Methods two and three were used to assess any changes postsurgery in relation to the stability of the participant’s performance. These methods were necessary because of the impossibility of gathering multiple baselines for each participant against which to assess post-surgery changes. These methods were used to demonstrate the stability of the participant’s performance and the effect of the surgery. Method two compared the difference in pre- to postsurgery SDs to the difference in pre- to postsurgery means. If the difference in the means exceeded the difference in the SDs by a factor of 3, the difference observed postsurgery was considered a function of the surgery and not due to random variability in participant performance. In Method three, the difference in pre- to postsurgery means was divided by the presurgery SD. This puts the performance into a “Standard Effect Size” (Minium, 1978). If the Standard Effect Size is 1, then the difference in the means equals the presurgery SD, and therefore the postsurgery change would not represent a meaningful change in the measurement. If the Standard Effect Size is larger than 2.5, then one can again be reasonably assured that the difference observed postsurgery was a function of the surgery and not due to random variability in participant performance. For the syllable repetition measure, because there was only one repetetion per participant, the first method of determining a meaningful change was whether or not the participant’s score increased, and the second method was whether the participant’s score increased by 0.5 syllables or more per second. A meaningful change for this measure was defined as a change measured by both methods.

Results Phonatory Measures Figure 1 displays the means for the phonatory measure of F0 pre- to postsurgery for each participant and also includes data from published control values taken from extended /a/ phonations of subjects 60 to 69 years old for comparison (Muller, Sweeney, & Baribeau, 1984). As can be seen in Table 3, the post-surgery F0 means of two participants (P1 and P3) were the same as their presurgery F0 means by all three methods. The postsurgery F0 mean for one participant (P2) was lower than his presurgery mean by all three methods. This change brought this participant closer to, but not within, the control range. Three participants (P4, P5, and P6) had

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Figure 1. Fundamental frequency (hertz) pre- and post-pallidotomy surgery; female participants on the left side of the figure and male participants on the right. Control range (control mean ± 1 SD) is also indicated by horizontal lines for comparison. These data were taken from extended /a/ phonations of subjects 60 to 69 years of age (Muller, Sweeney, & Baribeau, 1984).

in SPL postsurgery by all three methods, and one participant (P4) demonstrated consistently positive changes in SPL for the vowel task but not for the syllable-repetition tasks.

Articulatory Acoustic Measures Extended vowel duration (EVD) demonstrated the most consistent pre- to postsurgery differences across participants (see Figure 3 and Table 5). Five of the 6 participants (P1, P2, P3, P4, and P5) had greater EVDs by two or more methods, and P6 had shorter EVDs by all three methods postsurgery compared to presurgery. All participants had postsurgery EVDs that were within or above the average for non-brain-damaged, age-matched peers (Kreul, 1972). Figure 4 and Table 6 present the participants’ syllable vowel durations (SVD) pre- to postsurgery. Two participants (P5 and P6) had meaningfully shorter and one (P2) had consistently longer SVDs postsurgery than presurgery. Participants P1, P3, and P4 did not demonstrate consistently notable changes in SVD postsurgery. Participants P4, P5, and P6 all had postsurgery SVDs that were closer to the control range (Luce & CharlesLuce, 1985).

higher postsurgery than presurgery F0 means by at least two of the methods used to assess meaningful change. These changes brought the F0 of two participants (P4 and P6) further from the control range. Figure 2 shows the results for the relative change in SPL across the extended vowel and syllable-repetition tasks. For both the extended vowel and syllablerepetition tasks, three participant’s (P1, P2, and P3) postsurgery changes in SPL means were consistently negative by all three methods (Table 4). Two participants (P5 and P6) demonstrated consistently positive changes

Overall, postsurgery voice onset time (VOT) measures did not demonstrate meaningful changes as compared to presurgery VOT measures (Figure 5 and Table 7). Three participants (P3, P5, and P6) did not demonstrate any meaningful VOT differences postsurgery. Two participants (P1 and P4) did demonstrate meaningful

Table 3. Fundamental frequency (Hz) summary.

Measure Pre-Sx M (SD) Post-Sx M (SD) Pre-Sx M re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 11 Method 22 Method 33

Participant 1 (F)

Participant 2 (M)

Participant 3 (M)

Participant 4 (F)

Participant 5 (M)

Participant 6 (F)

227.72 (8.00) 222.85 (3.25)

195.37 (1.80) 157.51 (4.07)

122.31 (8.55) 114.93 (1.95)

240.19 (8.03) 271.96 (3.09)

118.47 (0.61) 125.10 (6.87)

211.17 (3.36) 234.18 (9.50)

Higher

Higher

Within

Higher

Within

Within

Same = = =

Closer ↓ ↓ ↓

Same = = =

Farther ↑ ↑ ↑

Same ↑ = ↑

Farther ↑ ↑ ↑

Note. Consistently positive results are italicized. a Presurgery mean relative to Control Range = Where the individual participant’s mean score fell in relation to the range (mean ± 1 SD) reported for control group. b Pre- to postsurgery mean relative to Control Range = Whether the participant’s mean change brought his or her score Closer to or Farther from the Control Range, or whether the participant’s mean stayed the Same; Female Control mean (and SD) = 179 (27.7) Hz; Male Control mean (and SD) = 118 (15.83) Hz (Muller et al., 1984). 1 Method 1 = Meaningful change if the participant’s post mean score differed from the pre mean by more than one SD. 2 Method 2 = Meaningful change if the participant’s post mean score differed from three times the pre SD. 3 Method 3 = Meaningful change if the participant’s effect size (mean difference pre- to postsurgery divided by the presurgery SD) was greater than ±2.5.

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Figure 2. The relative change in sound pressure level (dB SPL) pre- to post-pallidotomy surgery. A. The relative change in SPL for /i/. B. The relative change in SPL for /pa/. C. The relative change in SPL for /ta/. D. The relative change in SPL for /ka/.

negative differences in VOT postsurgery for some syllables, and none of the meaningful differences brought the postsurgery VOT values closer to the control range reported in the literature (Caruso & Burton, 1987). The results for single-syllable repetitions (SPS) are presented in Figure 6 and Table 8. Two participants (P4 and P6) demonstrated positive meaningful changes in all three syllables, and one (P5) demonstrated positive meaningful changes in two of the three syllables. All of these postsurgery positive changes brought the repetition rates postsurgery closer to or within the control range (Ptacek, Sander, Maloney, & Jackson, 1966). For the combined syllable repetition (/pataka/), none of the participants demonstrated positive meaningful changes postsurgery. For the combined syllables, the number of postsurgery SPS produced by each participant was lower than the number of SPS reported in the literature for age-matched control subjects (Ptacek et al., 1966).

Summary of Findings Table 9 summarizes the changes post-pallidotomy surgery for all tasks for each participant. Directional changes that indicate a consistent positive improvement

(improvement by two or more methods) are shown by a plus sign, directional changes that indicate a decline in function are shown by a minus sign, and those that did not change appreciably are indicated by an equal sign. These indications of changes are independent of the directional changes in the raw data depicted in Tables 3 through 8; that is, an increase in a measure may signify a decline in the function assessed by that measure. For example, an increase in syllable vowel duration for P2 in Table 6 is depicted by a minus sign in Table 9 because such an increase signifies a decline in acoustic articulatory function. The letters that follow the directional changes in Table 9 indicate whether the postsurgery change has brought the participant’s score “Within” the published control range (indicated by a “W”), whether the postsurgery score was “Above” (“A”) or whether the postsurgery score remained “Below” (“B”) the published control range.

Discussion The primary purpose of this preliminary study was to determine the effect of pallidotomy surgery on select Schulz et al.: Voice and Speech Following Pallidotomy

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Table 4. Relative change in sound pressure level (dB SPL). Measure

Vowel

/pa/

/ta/

/ka/

54.47 (2.23) 43.17 (10.40) –11.30 ↓ = ↓

54.92 (2.11) 43.69 (10.61) –11.23 ↓ = ↓

53.16 (4.04) 46.75 (2.66) –6.41 ↓ ↓ =

51.26 (12.89) 44.67 (8.21) –6.59 ↓ = =

64.49 (1.01) 53.98 (0.91) –10.51 ↓ ↓ ↓

61.50 (1.50) 46.91 (16.17) –14.14 ↓ = ↓

45.87 (3.39) 47.36 (2.60) 1.49 ↑ = =

45.71 (4.43) 47.02 (1.90) 1.31 ↑ = =

40.92 (1.65) 50.90 (2.01) 10.64 ↑ ↑ ↑

40.79 (2.44) 50.47 (0.46) 10.18 ↑ ↑ ↑

51.42 (0.76) 53.61 (0.68) 2.20 ↑ ↑ ↑

51.92 (1.30) 55.90 (0.35) 3.17 ↑ ↑ =

Participant 1 Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

56.94 (0.13) 43.61 (0.37) –13.33 ↓ ↓ ↓

57.01 (2.67) 46.45 (4.05) –10.56 ↓ ↓ ↓

Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

56.95 (1.39) 51.93 (2.21) –5.02 ↓ ↓ ↓

53.51 (2.19) 46.56 (2.78) –6.95 ↓ ↓ ↓

Participant 2

Participant 3 Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

65.17 (3.88) 46.91 (2.10) –18.26 ↓ ↓ ↓

63.44 (0.79) 52.27 (0.72) –11.17 ↓ ↓ ↓ Participant 4

Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

43.87 (0.99) 47.34 (0.20) 3.47 ↑ ↑ ↑

47.95 (0.99) 48.14 (1.02) 0.19 = = = Participant 5

Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

38.15 (0.58) 52.74 (1.25) 14.59 ↑ ↑ ↑

40.64 (1.27) 52.36 (0.38) 11.72 ↑ ↑ ↑

Pre-Sx M (SD) Post-Sx M (SD) Relative change Method 1 Method 2 Method 3

51.60 (0.50) 56.39 (1.48) 4.88 ↑ ↑ ↑

53.90 (1.97) 54.54 (1.55) 1.45 ↑ ↑ =

Participant 6

Note. See Table 3 for explanation of Methods 1–3.

voice and speech characteristics of 6 patients with PD. Because these data are preliminary, the following discussion represents tentative interpretations of the results. An inspection of Table 9 reveals that the surgical effects were not uniform across the 6 participants. Two of the 1184

participants (P5 and P6) had more positive changes in phonatory measures (indicated by the number of “+” signs in their columns for F0 and SPL), and 3 had negative phonatory changes (P1, P2, and P3, indicated by “–” signs in their columns for SPL). Three participants had positive

Journal of Speech, Language, and Hearing Research • Vol. 42 • 1176–1194 • October 1999

Figure 3. Extended vowel durations (in seconds) pre- and postpallidotomy surgery. For comparison purposes, the range (control mean ± 1 SD) for extended vowel durations from non-braindamaged, age-matched peers are shown (Ptacek, Sander, Maloney, & Jackson, 1966).

observation may negate a significant change in neuromuscular control parameters, at least at the level of the larynx. There are two factors that contribute to an increase in SPL: laryngeal and respiratory (Stathopoulos & Sapienza, 1993). Future studies of patients undergoing pallidotomy may reveal neuromuscular control changes via electromyography at the laryngeal level or at the respiratory level. It is noteworthy that Barlow and his collegues (Barlow et al., 1998) observed changes in laryngeal airway resistance in several participants following bilateral pallidotomy, suggestive of changes in neuromuscular control at the level of the larynx in some of the participants. Future studies may reveal the similarities and/or differences in neuromuscular control following uni- versus bilateral pallidotomy. The second purpose of this study was to determine whether any changes observed postsurgery brought the participants’ voice and speech measures within published normative ranges. Table 9 indicates whether postsurgery changes in voice and speech measures were within (W), above (A), or below (B) the published normative range. Although some participant’s positive scores postsurgery brought the measure within the normative range (e.g., EVD for P1, P2, P3, and P4), the majority of positive postsurgery changes were still outside published control ranges. This suggests that positive changes observed postsurgery did not normalize these phonatory and acoustic articulatory functions.

acoustic articulatory changes post-pallidotomy surgery (P4, P5, and P6). Considering all of the voice and speech results, P5 and P6 had the most beneficial changes in phonatory and articulatory acoustic measures following pallidotomy surgery. Participants P1, P2, and P3 had the fewest positive changes following pallidotomy surgery. It is difficult to determine whether the observed improvements occurred as a function of the surgical procedure because the performance of the 6 participants was not similar pre- to postsurgery. For example, changes in relative SPL postsurgery in the 2 participants who consistently demonstrated meaningful changes may reflect changes to underlying neuromuscular control parameters, such as those involving the larynx and/or the respiratory system. However, in these 2 participants, nasoendoscopic examinations were possible, and the presence of a glottal gap remained postsurgery (see Table 2). This

There are neurophysiologic and neuroanatomic differences in sensorimotor organization of voice and speech that may account for the differential involvement of these systems and may also account for the differential effects of treatment in individuals with PD. Several researchers have noted that the basal ganglia have the same somatotopic organization observed in the sensorimotor cortex (Alexander & Delong, 1985; Alexander,

Table 5. Extended vowel duration (seconds) summary. Measure Pre-Sx M (SD) Post-Sx M (SD) Pre-Sx M re Control Rangea Pre- to Post Sx M re Control Rangeb Method 1 Method 2 Method 3

Participant 1

Participant 2

Participant 3

Participant 4

Participant 5

Participant 6

8.21 (2.11) 11.88 (1.17)

8.15 (0.82) 10.77 (4.00)

10.78 (0.63) 12.79 (2.76)

5.54 (0.29) 7.85 (0.26)

16.57 (4.63) 32.36 (4.58)

18.30 (1.61) 15.31 (2.25)

Within

Within

Within

Lower

Within

Within

Within ↑ ↑ =

Within ↑ = ↑

Within ↑ = ↑

Within ↑ ↑ ↑

Farther ↑ ↑ ↑

Within ↓ ↓ ↓

Note. See Table 3 for explanation of Methods 1–3. a Presurgery mean relative to Control Range = Where the individual participant’s mean score fell in relation to the range (M =16.8 ± 8.35) reported for control group (Kreul, 1972). b Pre- to postsurgery mean relative to Control Range = Whether the participant’s mean change brought his or her score Closer to or Farther from the Control Range or whether the participant’s mean stayed the Same.

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Figure 4. Syllable vowel durations (in milliseconds) pre- and postpost-pallidotomy surgery. For comparison purposes, the range (control mean ± 1 SD) for syllable vowel durations from non-braindamaged, age-matched peers are shown (Luce & Charles-Luce, 1985). A. Extended vowel durations for /pa/. B. Extended vowel durations for /ta/. C. Extended vowel durations for /ka/.

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Figure 5. Voice onset time (in milliseconds) pre- and postpallidotomy surgery. For comparison purposes, the range (control mean ± 1 SD) for voice onset time from non-brain-damaged, agematched peers are shown (Caruso & Burton, 1987). A. Voice onset time for /pa/. B. Voice onset time for /ta/. C. Voice onset time for /ka/.

Journal of Speech, Language, and Hearing Research • Vol. 42 • 1176–1194 • October 1999

Table 6. Syllable vowel duration (milliseconds) summary. Measure

/pa/

/ta/

/ka/

Participant 1 Pre-Sx M (SD) 162.3 (17.9) Post-Sx M (SD) 176.2 (33.1) Pre-Sx M re Control Rangea Longer Pre- to Post-Sx M re Control Rangeb Same Method 1 = Method 2 = Method 3 =

192.0 (31.2) 183.7 (43.8)

187.0 (30.5) 150.9 (30.3)

Within

Longer

Same = = =

Within = = =

/ta/

/ka/

Pre-Sx M (SD) 372.3 (83.5) 390.3 (105.9) 371.3 (119.0) Post-Sx M (SD) 276.3 (25.4) 298.5 (46.0) 311.5 (36.3) Pre-Sx M re Control Rangea Longer Longer Longer Pre- to Post-Sx M re Control Rangeb Closer Closer Closer Method 1 ↓ = = Method 2 = = = Method 3 = = = Participant 5

187.5 (65.3) 335.0 (89.8)

211.3 (37.5) 436.8 (88.2)

Within

Longer

Farther ↑ ↑ =

Farther ↑ ↑ ↑

Participant 3 Pre-Sx M (SD) 128.4 (31.7) 139.2 (21.4) Post-Sx M (SD) Pre-Sx M re Control Rangea Within Pre- to Post-Sx M re Control Rangeb Same Method 1 = Method 2 = Method 3 =

/pa/ Participant 4

Participant 2 Pre-Sx M (SD) 186.1 (42.4) Post-Sx M (SD) 293.4 (26.8) Pre-Sx M re Longer Control Rangea Pre- to Post-Sx M re Control Rangeb Farther Method 1 ↑ Method 2 ↑ Method 3 ↑

Measure

Pre-Sx M (SD) 308.0 (49.8) Post-Sx M (SD) 243.7 (33.6) Pre-Sx M re Longer Control Rangea Pre- to Post-Sx M re Closer Control Rangeb Method 1 ↓ Method 2 ↓ Method 3 =

316.2 (28.8) 195.0 (23.3)

300.7 (61.1) 191.9 (42.8)

Longer

Longer

Closer ↓ ↓ ↓

Closer ↓ ↓ =

Participant 6

154.6 (31.0) 114.2 (21.8)

119.9 (38.9) 122.4 (40.3)

Within

Within

Farther ↓ ↓ =

Same = = =

Pre-Sx M (SD) 345.4 (64.9) 207.4 (15.3) Post-Sx M (SD) Pre-Sx M re Control Rangea Longer Pre- to Post-Sx M re Control Rangeb Closer Method 1 ↓ Method 2 = Method 3 =

323.9 (49.5) 198.6 (20.2)

354.9 (27.3) 223.4 (16.5)

Longer

Longer

Closer ↓ ↓ ↓

Closer ↓ ↓ ↓

Note. See Table 3 for explanation of Methods 1–3. a Presurgery mean relative to Control Range = Where the individual participant’s mean score fell in relation to the range (mean ± 1 SD) reported for control group (Luce & Charles-Luce, 1985); for /pa/ = 139.6 (13.4), for /ta/ = 164.0 (27.4), for /ka/ = 152.8 (27.9). b Pre- to postsurgery mean relative to Control Range = Whether the participant’s mean change brought his or her score Closer to or Farther from the Control Range or whether the participant’s mean stayed the Same.

Delong, & Strick, 1986; Crutcher & Delong, 1984). In particular, separate neural substrates exist in the putamen and globus pallidus subserving “leg,” “arm,” and “face” functions (Crutcher & Delong, 1984). Differential levels of impairment in voice/speech and motor functions may result from possible differential involvement of these separate neural substrates. Additionally, various forms of treatment, including pallidotomy surgery, may differentially affect these separate neural substrates, thus producing differential treatment effects observed in this and other studies.

means were not meaningfully different from their presurgery means (Tables 7 and 9). It is interesting to note in this regard that Barlow and his collegues (Barlow et al., 1998) did find changes in aerodynamic measures during /pa/ syllable repetitions in some patients following bilateral pallidotomy surgery. They suggested that these changes were reflective of an improvement in the dynamics of burst release and laryngeal engagement. However, they also noted that, at least in one patient, the distribution of VOT values did not change following bilateral pallidotomy.

Orolaryngeal coordination did not appear to significantly change by the present measures in this group of participants with PD following unilateral pallidotomy surgery. The majority of participants’ postsurgery VOT

Further, the pallidotomy surgery may have more beneficial effects on simple motor tasks than on more complex motor tasks requiring the coordination of several articulators. More consistent positive changes were Schulz et al.: Voice and Speech Following Pallidotomy

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Table 7. Voice onset time (milliseconds) summary. Measure

/pa/

/ta/

/ka/

Measure

50.33 (12.2) 58.47 (28.7)

57.33 (9.9) 26.62 (23.1)

Within

Shorter

Same = = =

Farther ↓ = ↓

Pre-Sx M (SD) 64.46 (37.4) Post-Sx M (SD) 33.91 (9.8) Pre-Sx M Re Control Rangea Within Pre- to Post-Sx M re Control Rangeb Farther Method 1 ↓ Method 2 ↓ Method 3 =

Participant 2 Pre-Sx M (SD) 39.75 (17.9) Post-Sx M (SD) 62.08 (36.0) Pre-Sx M Re Within Control Rangea Pre- to Post-Sx M re Control Rangeb Same Method 1 ↑ Method 2 = Method 3 =

/ka/

55.80 (13.9) 42.00 (15.5)

67.90 (20.3) 47.70 (8.0)

Within

Within

Farther = = =

Farther ↓ = ↓

Participant 5

84.35 (28.9) 63.40 (29.9)

50.07 (15.2) 111.6 (26.7)

Within

Shorter

Same = ↓ =

Longer ↑ ↑ ↑

Pre-Sx M (SD) 63.46 (37.4) Post-Sx M (SD) 33.91 (9.8) Pre-Sx M Re Within Control Rangea Pre- to Post-Sx M re Control Rangeb Farther Method 1 ↓ Method 2 = Method 3 =

59.67 (12.1) 55.05 (14.1)

67.12 (26.6) 47.33 (14.4)

Within

Within

Same = = =

Farther = = =

Participant 6

Participant 3 Pre-Sx M (SD) Post-Sx M (SD) Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2 Method 3

/ta/

Participant 4

Participant 1 Pre-Sx M (SD) 71.33 (23.5) Post-Sx M (SD) 34.58 (16.0) Pre-Sx M Re Control Rangea Within Pre- to Post-Sx M re Control Rangeb Farther Method 1 ↓ Method 2 ↓ Method 3 =

/pa/

17.68 (7.1) 11.73 (5.3)

16.14 (2.9) 14.20 (3.2)

28.82 (6.4) 27.31 (7.5)

Shorter

Shorter

Shorter

Farther = = =

Same = ↓ =

Same = = =

Pre-Sx M (SD) 48.61 (24.3) 24.14 (9.3) Post-Sx M (SD) Pre-Sx M Re Control Rangea Within Pre- to Post-Sx M re Control Rangeb Farther Method 1 = Method 2 = Method 3 =

20.31 (8.1) 29.26 (14.5)

35.28 (10.1) 30.79 (14.9)

Shorter

Shorter

Same = = =

Same = = =

Note. See Table 3 for explanation of Methods 1–3. a Presurgery mean relative to Control Range = Where the individual participant’s mean score fell in relation to the range (mean ± 1 SD) reported for control group (Caruso & Burton, 1987); for /pa/ = 62.5 (25), for /ta/ = 71.9 (19.4), for /ka/ = 74.8 (16). b Pre- to postsurgery mean relative to Control Range = Whether the participant’s mean change brought his or her score Closer to or Farther from the Control Range or whether the participant’s mean stayed the Same.

observed for measures reflecting the “simple” motor responses (single syllable repetition) than for the measures reflecting more complex coordination (multiple syllable repetition). This could be a reflection of the effects of task complexity on the performance of persons with PD. It has been shown that as movement complexity increases, either for limb movements or speech movements, movement control decreases (Connor & Abbs, 1991; Phillips, Mueller, & Stelmach, 1989). It may be that the physiologic changes that occur with pallidotomy surgery in some individuals with PD are sufficient to modify motor control for simple movements but are insufficient to modify complex multi-articulate movements. Similar suggestions regarding the effects of fetal-cell transplantation have been made (Baker et al., 1997). 1188

Many surgery- and participant-related factors could have affected the results of the pallidotomy surgery. These factors may account for the differential effects on voice and speech systems and the differential effects on individuals. There are reports in the literature to suggest that surgery-related factors, such as the exact site and volume of lesion, have an effect on the outcome of the surgery in terms of subjective motor performance ratings (dyskinesia, tremor, rigidity, bradykinesia, gait) (Lehman, Mezrich, Sage, & Goldbe, 1994). However, other reports suggested that neither the site nor the size of a lesion showed a clear correlation with subjective clinical motor performance following surgery (Hariz, 1990). Although the exact site and volume of the lesions made in these 6 individuals were not assessed

Journal of Speech, Language, and Hearing Research • Vol. 42 • 1176–1194 • October 1999

Figure 6. Syllables per second pre- and post-pallidotomy surgery. For comparison purposes, the range (control mean ± 1 SD) for syllable vowel durations from non-brain-damaged, age-matched peers are shown (Ptacek, Sander, Maloney, & Jackson, 1966). A. Syllables per second for /pa/. B. Syllables per second for /ta/. C. Syllables per second for /ka/. D. Syllables per second for /pataka/.

postsurgery by MRI or CT scans, the lesions were all placed via standard stereotactic means, and lesion site was verified by electrical stimulation before lesion induction. Nevertheless, lesion site and volume were no doubt at least slightly different for each of these 6 individuals, and this must be taken into consideration in light of the differential outcomes across and within individuals. Participant-related differences such as presurgery level of impairment might account for the differential participant effect observed in this study. Two participants who evidenced the most consistent beneficial voice and speech results following pallidotomy surgery (P5 and P6) were also judged by the first author to have a mild hypokinetic dysarthria (see Table 2). The other participants were all judged to have a moderate hypokinetic dysarthria presurgery. This rating did not change postsurgery, except for P4 who was judged to have a mild hypokinetic dysarthria postsurgery. The 3 participants who were judged to have a moderate

hypokinetic dysarthria (P1, P2, and P3) were also the 3 participants who had fewer positive changes postsurgery. It is possible that the participants who had more mild dysarthria symptoms were also those individuals who had less damage to those areas of the basal ganglia sensorimotor control circuits involved in oral facial functions, thus increasing the chances to observe improvements postsurgery. This tentative explanation would, of course, require a larger sample with greater numbers of participants in each severity category to be confirmed. It does not appear from this limited sample that the participants’ age, the number of years post-diseaseonset, nor any slight change in medication affected the results of the surgery. The 2 participants who demonstrated the most improvement differed in age and in the number of years that they reported having PD (see Table 1). Likewise, the other participants also varied in their age and in the number of years they reported having PD. The only 2 participants who reported a slight Schulz et al.: Voice and Speech Following Pallidotomy

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Table 8. Syllables per second summary. Measure

/pa/

/ta/

/ka/

/pataka/

3.20 2.69 Below Farther ↓ =

2.69 2.99 Below Closer ↑ =

1.91 1.78 Below Same = =

2.79 1.82 Below Farther ↓ =

2.68 1.32 Below Farther ↓ =

1.23 1.24 Below Farther = =

3.50 6.33 Below Above ↑ ↑

4.19 4.57 Within Same ↑ =

1.81 2.25 Below Closer ↑ =

1.78 2.50 Below Closer ↑ ↑

1.73 2.43 Below Closer ↑ ↑

1.38 1.84 Below Closer ↑ =

2.12 2.65 Below Closer ↑ =

1.98 2.95 Below Closer ↑ ↑

1.61 1.38 Below Farther ↓ =

2.00 3.13 Below Closer ↑ ↑

2.13 3.08 Below Within ↑ ↑

2.09 1.89 Below Farther ↓ =

Participant 1 Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

2.74 3.09 Below Closer ↑ =

Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

2.94 2.08 Below Farther ↓ =

Participant 2

Participant 3 Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

3.57 3.77 Below Closer = = Participant 4

Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

1.90 2.58 Below Closer ↑ ↑ Participant 5

Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

2.05 2.95 Below Closer ↑ ↑

Pre-Sx M Post-Sx M Pre-Sx M Re Control Rangea Pre- to Post-Sx M re Control Rangeb Method 1 Method 2

2.06 3.09 Below Closer ↑ ↑

Participant 6

Note. See Table 3 for explanation of Methods 1 and 2. a Presurgery mean relative to Control Range = Where the individual participant’s mean score fell in relation to the range (mean ± 1 SD) reported for Control group (Ptacek et al., 1966); for /pa/ = 5.2 (1.2), for /ta/ = 5.05 (1.05), for /ka/ = 4.65 (1.05), for /pataka/ = 4.0 (1.3). b Pre- to postsurgery mean relative to Control Range = Whether the participant’s mean change brought his or her score Closer to or Farther from the Control Range or whether the participant’s mean stayed the Same.

1190

Journal of Speech, Language, and Hearing Research • Vol. 42 • 1176–1194 • October 1999

Table 9. Summary of the pre- to post-pallidotomy surgery results. Measure

Participant 1

Participant 2

Participant 3

Participant 4

Participant 5

Participant 6

=/A

+/A

=/W

–/A

–/W

–/A

–/B –/B –/B –/B

–/B –/B –/B =/B

–/B –/B –/B –/B

+/B =/B =/B =/B

+/B +/A +/A +/A

+/B +/B +/B +/B

+/W

+/W

+/W

+/W

+/A

–/W

SVD /pa/ /ta/ /ka/

=/A =/W =/W

–/A –/A –/A

=/W –/B =/W

=/A =/A =/A

+/A +/A +/A

=/A +/A +/A

VOT /pa/ /ta/ /ka/

–/B =/W –/B

=/W =/W +/A

=/B =/B =/B

–/B =/B –/B

=/B =/B =/B

=/B =/B =/B

SPS /pa/ /ta/ /ka/ /pataka/

=/B =/B =/B =/B

=/B =/B =/B =/B

=/B +/A =/W =/B

+/B +/B +/B =/B

+/B =/B +/B =/B

+/B +/B +/B =/B

F0 SPL V’s /pa/ /ta/ /ka/ EVD

Note. A “+” indicates a meaningful positive change post pallidotomy (measured by two or more methods), a “–” indicates a meaningful negative change post pallidotomy (measured by two or more methods), and a “=” indicates no change post pallidotomy; a “W” indicates Within the published Control Range postsurgery, a “B” indicates Below the published Control Range postsurgery, and an “A” indicates Above the published Control Range postsurgery.

change in Sinemet dose postsurgery were P3 and P6, and each of them slightly reduced their dose postsurgery. The reduction in the amount of Sinemet they were taking postsurgery was not of a significant magnitude, and previous research has demonstrated that medication effects on speech are not significant in individuals with PD (Daniels et al., 1996; Larson et al., 1994; Solomon & Hixon, 1993). These 2 participants had differential responses to the surgery (see Table 9); nevertheless, the possibility does exist that any changes seen in these participants could be due to the slight differences in postsurgery Sinemet doses. Finally, the lack of consistent results across participants could have been due to the particular stimuli and/ or measures chosen to gauge the effects of pallidotomy surgery. One study did report changes in labial force parameters and aerodynamic measures but noted no change in perceived intelligibility nor in the one acoustic measure reported (Barlow et al., 1998). The purpose of the present study was to report preliminary findings from a subset of total data collected. Extended vowel productions and diadochokinetic tasks have been proven to be sensitive indicators of hypokinetic dysarthria (e.g., Canter, 1963). However, other measures will provide

additional information regarding the effects of pallidotomy surgery on voice and speech production. Although these preliminary data cannot support a general conclusion regarding voice and speech characteristics of Parkinson’s patients following unilateral pallidotomy surgery, the findings do demonstrate that pallidotomy surgery provides some benefit to some patients. This outcome supports the need for future studies with larger numbers of patients to determine the full scope of voice and speech functions following this theraputic approach. Future studies should use multiple baseline and multiple follow-up evaluations whenever possible to ensure the stability of the measures employed. If future results follow these preliminary trends, it may be that patients with mild hypokinetic dysarthria experience greater benefit from unilateral pallidotomy surgery than patients with more moderate hypokinetic dysarthria. Future research should include greater numbers of participants with a greater range of hypokinetic dysarthria severity and a greater number of tasks, including perceptual ratings, by which to assess the effects of surgery. The possible difference between unilateral and bilateral pallidotomy surgery on voice and speech characteristics also needs to be systematically Schulz et al.: Voice and Speech Following Pallidotomy

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investigated. The present results support the possibility that pallidotomy surgery may have beneficial effects on voice and speech in persons with PD.

Acknowledgments The authors wish to thank the participants in this study. The pallidotomy program at the University of Florida Health Science Center is supported in part through the generosity of the National Parkinson Foundation. We thank the Associate Editor, Michael Cannito, and three anonymous reviewers for their comments on earlier drafts of the paper.

References Abramson, A. S. (1977). Laryngeal timing in consonant distinctions. Phonetica, 34, 295–303.

Canter, G. J. (1965). Speech characteristics of patients with Parkinson’s disease: II. Physiological support for speech. Journal of Speech and Hearing Disorders, 30, 44–49. Caruso, A., & Burton, E.(1987). Temporal acoustic measures of dysarthria associated with ALS. Journal of Speech and Hearing Research, 30, 80–87. Cohen, J. (1988) Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale, NJ: Lawrence Erlbaum Associates. Connor, N. P., & Abbs, J. H. (1991). Task-dependent variations in Parkinsonian motor impairments. Brain, 114, 321–332. Connor, N. P., Ludlow, C. L., & Schulz, G. M. (1989). Stop consonant production in isolated and repeated syllables in Parkinson’s disease. Neuropsychologia, 27, 829–838. Cooper, I. S. (1961). Parkinsonism: Its medical and surgical therapy. Springfield, IL: Charles C. Thomas.

Ackermann, H., & Ziegler, W. (1991). Articulatory deficits in Parkinsonian dysarthria: An acoustic analysis. Journal of Neurology, Neuroscience, and Psychiatry, 54, 1093–1098.

Crutcher, M. D., & DeLong, M. R. (1984). Single cell studies in the primate putamen, II: Relations to direction of movement and pattern of muscular activity. Experimental Brain Research, 53, 244–258.

Alexander, G. E., & Delong, M. R. (1985). Microstimulation of the primate neostriatum, I: Physiological properties of striatal microexcitable zones. Journal of Neurophysiology, 53, 1401–1416.

Daniels, N., Oates, J., Phyland, D., Feiglin, A., & Hughes, A. J. (1996). Vocal characteristics and respose to levadopa in PD. Movement Disorders, 11, 117.

Alexander, G. E., DeLong, M. R., & Crutcher, M. D. (1992). Do cortical and basal ganglionic motor areas use “motor programs” to control movement? Behavioral and Brain Sciences, 15, 656–665. Alexander, G. E., DeLong, M. R., & Strick, P. L. (1986). Parallel organization of functionally segregated circuits linking basal ganglia and cortex. Annual Review of Neuroscience, 9, 357–381. Baker, K. K., Ramig, L. O., Johnson, A. B., & Freed, C. R. (1997). Preliminary voice and speech analysis following fetal dopamine transplants in five individuals with Parkinson’s disease. Journal of Speech, Language, and Hearing Research, 40, 615–626. Barlow, S. M., Iacono, R. P., Paseman, L. A., Biswas, A., & D’Antonio, L. (1998). The effects of posteroventral pallidotomy on force and speech aerodynamics in Parkinson’s disease. In M. Cannito, K. Yorkston, & D. Beukelman (Eds.), Neuromotor speech disorders: Nature, assessment and management (pp. 117–156). Baltimore: Brookes. Baron, M. S., Vitek, J. L., Bakay, R. A. E., Green, J., Kaneoke, Y., Hashimoto, T., Turner, R. S., Woodard, J. L., Cole, S. A., McDonald, W. M., & DeLong, M. R. (1996). Treatment of advanced Parkinson’s disease by posterior GPi Pallidotomy: 1-year results of a pilot study. Annals of Neurology, 40, 355–366. Buck, J. F., & Cooper, I. S. (1956). Speech problems in Parkinsonian patients undergoing anterior choroidal artery occlusion or chemopallidectomy. Journal of the American Geriatric Society, 4, 1285–1290. Calne, D. B. (1995, Jan. 15). Diagnosis and treatment of Parkinson’s disease. Hospital Practice, 83–89. Canter, G. J. (1963). Speech characteristics of patients with Parkinson’s disease: I. Intensity, pitch and duration. Journal of Speech and Hearing Disorders, 28, 221–229.

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Darley, F. L., Aronson, A. E., & Brown, J. R. (1969). Differential diagnostic patterns of dysarthria. Journal of Speech and Hearing Research, 12, 246–269. Deecke, L., Kornhuber, H. H., Lang, W., Lang, M., & Schreiber, H. (1985). Timing function of the frontal cortex in sequential motor and learning tasks. Human Neurobiology, 4, 143–154. Dogali, M., Fazzini, E., Kolodny, E., Eidelberg, D., Sterio, D., Devinsky, O., & Beric, A. (1995). Stereotactic ventral pallidotomy for Parkinson’s disease. Neurology, 45, 753–761. Eidelberg, D., Moeller, J. R., Ishikawa, T., Dhawan, V., Spetsieris, P., Silbersweig, D., Stern, E., Woods, R. P., Fazzini, E., Dogali, M. & Beric, A. (1996). Regional metabolic correlates of surgical outcome following unilateral pallidotomy for Parkinson’s disease. Annals of Neurology, 39, 450–459. Freed, C. R., Breeze, R. E., Rosenberg, N. L., Schneck, S. A., Kreik, E., Qi, J. X., Lone, T., Zhang, Y. B., Snyder, J. A., Wells, T. H., Ramig, L. O., Thompson, L., Mazziotta, J. C., Huang, S. C., Grafton, S. T., Brooks, D., Sawle, G., Schroter, G., & Ansari, A. A. (1992). Survival of implanted fetal dopamine cells and neurologic improvement 12 to 46 months after transplantation for Parkinson’s disease. New England Journal of Medicine, 327, 1549–1555. Friedman, J. H., Epstein, M., Sanes, J. N., Lieberman, P., Cullen, K., Lindquist, C., & Daamen, M. (1996). Gamma knife pallidotomy in advanced Parkinson’s disease. Annals of Neurology, 39, 535–538. Fox, C., & Ramig, L. O. (1997). Vocal sound pressure level and self-perception of speech and voice in men and women with idiopathic Parkinson disease. American Journal of Speech-Language Pathology, 6(2), 85–94. Goetz, C. G., & Diederich, N. J. (1996). There is a renaissance of interest in pallidotomy for Parkinson’s

Journal of Speech, Language, and Hearing Research • Vol. 42 • 1176–1194 • October 1999

disease. Nature Medicine, 2, 510–514. Grafton, S. T., Waters, C., Sutton, J., Lew, M. F., & Couldwell, W. (1995). Pallidotomy increases activity of motor association cortex in Parkinson’s disease: A positron emission tomographic study. Annals of Neurology, 37, 776–783. Hanson, D. G., Gerratt, B. R., & Ward, P. H. (1984). Cinegraphic observations of laryngeal function in Parkinson’s disease. Laryngoscope, 94, 3, 348–353. Hariz, M. I. (1990). Correlation between clinical outcome and size and site of the lesion in computed tomography guided thalamotomy and pallidotomy. Stereotactic Functional Neurosurgery, 54/55, 172–185. Hoehn, M., & Yahr, M. (1967). Parkinsonism: Onset, progression and mortality. Neurology, 17, 427. Iacono, R. P., Lonser, R. R., Mandybur, G., Morenski, J. D., Yamada, S., & Shima, F. (1994). Stereotactic pallidotomy results for Parkinson’s exceed those of fetal graft. The American Surgeon, 60, 777–782. Iacono, R. P., Lonser, R., & Morenski, J. D. (1994). Movement disorders: Stereotactic surgery for Parkinson’s disease. Movement Disorders, 9, 470–473.

patients. Journal of Speech and Hearing Disorders, 18, 47–57. Lozano, A. M., Lang, A. E., Galvez-Jimenez, N., Miyasaki, J., Duff, J., Hutchinson, W. D., & Dostrovsky, J. O. (1995). Effect of Gpi pallidotomy on motor function in Parkinson’s disease. The Lancet, 346, 1383–1387. Luce, P. A., & Charles-Luce, J. (1985). Contextual effects on vowel duration, closure duration, and the consonant/ vowel ratio in speech production. Journal of the Acoustical Society of America, 78, 1949–1957. Marsden, C. D. (1994). Parkinson’s disease. Journal of Neurology, Neurosurgery, and Psychiatry, 57, 672–681. Marsden, C. D., & Obeso, J. A. (1994). The functions of the basal ganglia and the paradox of stereotaxic surgery in Parkinson’s disease. Brain, 117, 877–897. Milenkovic, P. (1989). Cspeech 4.0 [computer software]. University of Wisconsin–Madison. Minium, E. W. (1978). Statistical reasoning in psychology and education (2nd ed.). New York: John Wiley and Sons. Muller, P. B., Sweeney, R. J., & Baribeau, L. J. (1984). Acoustic and morphologic study of the senescent voice. Ear, Nose and Throat Journal, 63, 71–75.

Iacono, R. P., Lonser, R. R., & Yamada, S. (1994). Contemporaneous bilateral postero-ventral pallidotomy for early onset “juvenile type” Parkinson’s disease. Case report. Acta Neurochirurgica, 131, 247–252.

Mutch, W. J., Strudwick, A., Roy, S. K., & Downie, A. W. (1986). Parkinson’s disease: Disability review and management. British Medical Journal, 293, 675–677.

Klatt, D. H. (1975). Voice onset time, frication and aspiration in word initial consonant clusters. Journal of Speech and Hearing Research, 18, 686–706.

Myers, R. (1940). Surgical procedure for postencephalic tremor, with notes on the physiology of pre-motor fibers. Archives of Neurologic Psychiatry, 44, 455–459.

Kratochwill, T., & Levin, J. R. (1992). Single-case research design and analysis: New directions for psychology and education. Hillsdale, NJ: Lawrence Erlbaum Associates.

Narabyashi, H., & Okuma, T. (1953). Procaine-oil blocking of the globus pallidus for the treatment of rigidity and tremor of parkinsonism. Proceedings of the Japanese Academy, 29, 134–137.

Krauss, J. K., & Jankovic, J. (1996). Surgical treatment of Parkinson’s disease. American Family Physician, 54, 1621–1629. Kreul, E. J. (1972). Neuromuscular control examination (NMC) for Parkinsonism: Vowel prolongations and diadochokinetic and reading rates. Journal of Speech and Hearing Research, 15, 72-83. Laitinen, L. V. (1994). Ventroposterolateral pallidotomy. Sterotactic Functional Neurosurgery, 62, 41–52. Laitinen, L. V., Bergenheim, A. T., & Hariz, M. I. (1992a). Leksell’s posteroventral pallidotomy in the treatment of Parkinson’s disease. Journal of Neurosurgery, 76, 53-61. Laitinen, L. V., Bergenheim, A. T., & Hariz, M. I. (1992b). Ventroposterolateral pallidotomy can abolish all Parkinsonian symptoms. Stereotactic Functional Neurosurgery, 58, 14–21. Larson, K. K., Ramig, L. O., & Scherer, R. S. (1994). Acoustic and glottographic voice analysis during drugrelated fluctuations in Parkinson’s disease. Journal of Medical Speech-Language Pathology, 2, 228–239. Lehman, R. M., Mezrich, R., Sage, J., & Goldbe, L. (1994). Peri- and postoperative magnetic resonance imaging localization of pallidotomy. Stereotactic Functional Neurosurgery, 62, 61–70. Logemann, J. A., Fisher, H. B., Boshes, B., & Blonsky, E. R. (1978). Frequency and cooccurrence of vocal tract dysfunctions in the speech of a large sample of Parkinson’s

Perez, K., Ramig, L. O., Smith, M., & Dromey, C. (1996). The Parkinson larynx: Tremor & videostroboscopic findings. Journal of Voice, 10, 354–361. Phillips, J. G., Mueller, F., & Stelmach, G. E. (1989). Movement disorders and the neural basis of motor control. In S. Wallace (Ed.), Perspectives on the coordination of movement (pp. 367–417). Amsterdam: North Holland. Ptacek, P. H., Sander, E. K., Maloney, W. H., & Jackson, C. C. R. (1966). Phonatory and related changes with advanced age. Journal of Speech and Hearing Research, 9, 353–360. Ramig, L. O., & Ringel, R. (1983). Effects of physiologic aging on selected acoustic characteristics of voice. Journal of Speech and Hearing Research, 26, 22–30. Solomon, N. P., & Hixon, T. J. (1993). Speech breathing in Parkinson’s disease. Journal of Speech and Hearing Research, 36, 294–310. Stathopoulos, E. T., & Sapienza, C. M. (1993). Respiratory and laryngeal function of women and men during vocal intensity variation. Journal of Speech and Hearing Research, 36, 64–75. Sterio, D., Beric, A., Dogali, M., Fazzini, E., Alfaro, G., & Devinsky, O. (1994). Neurophysiological properties of pallidal neurons in Parkinson’s disease. Annals of Neurology, 35, 586–591. Stracciari, A., Guarino, M., Cirignotta, F., & Pazzaglia, Schulz et al.: Voice and Speech Following Pallidotomy

1193

P. (1993). Development of palilalia after stereotaxic thalamotomy in Parkinson’s disease. European Neurology, 33, 275–276. Sutton, J. P., Couldwell, W., Lew, M. F., Mallory, L., Grafton, S., DeGiorgio, C., Welsh, M., Apuzzo, M. L. J., Ahmadi, J., & Waters, C. H. (1995). Ventroposterior medial pallidotomy in patients with advanced Parkinson’s disease. Neurosurgery, 36, 1112–1116. Svennilson, E., Torvic, A., Lowe, R., & Leskell, L. (1960). Treatment of parkinsonism by stereotactic thermolesions in the pallidal region. A clinical evaluation of 81 cases. Acta Psychiatrica Neurologica Scandinavia, 35, 358–377. Ventry, I. M., & Schiavetti, N. (1986). Evaluating research in speech pathology and audiology (2nd ed.). New York: MacMillan Publishing Co.

1194

Weismer, G. (1984). Acoustic descriptions of dysarthric speech: Perceptual correlates and physiologic inferences. In J. C. Rosenbek (Ed.), Current view of dysarthria: Nature, assessment and treatment (Seminars in Speech and Language, pp. 293-314). New York: Thieme Stratton. Received November 18, 1998 Accepted April 20, 1999 Contact author: Geralyn M. Schulz, PhD, Department of Communication Sciences and Disorders, University of Florida, PO Box 117420, Gainesville, FL 32611-7420. Email: [email protected]

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