Aug 9, 1994 - INTRODUCTION. Munchausen syndrome is a cluster of psychiatric and .... patients with Korsakoff's syndrome, however, have not shown any ...
BRIEF REPORTS
Tc-99m HMPAO Brain SPECT Scanning in Munchausen Syndrome James M Mountz, MD, PhD', Pamela E Parker, MD2, Hong-Gang Liu, MS',Terny W Bentley, MD3, Duncan W Lill, MD1, Georg Deutsch, PhD4 'Division of Nuclear Medicine, Department of Radiology, University of Alabama at Birmningham, Birmingham, Alabama, USA 2Department of Psychiatry, University of Alabama, Tuscaloosa, Alabama, USA 3Department of Psychiatry, University of Alabama at Birmingham, Birmingham, Alabama, USA 4Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA Submitted: August 9, 1994 Accepted: May 9, 1995
Regional cerebral blood flow was studied in a patient with Munchausen syndrome using high resolution Tc-99m HMPAO SPECT. The scan demonstrated marked hyperperfusion of the right hemithalamus. The cranial CT scan was normal. The abnormal right hemithalamic blood flow is discussed in relation to the hypothesized neuropathy of this disorder.
Key Words: thalamus, rCBF, brain, Tc-99m HMPAO, SPECT, Munchausen INTRODUCTION
Munchausen syndrome is a cluster of psychiatric and behavioral symptoms meeting the DSM-III-R (American Psychiatric Association 1987) criteria for a factitious disorder. Factitious disorders are characterized by intentional production or feigning of physical or psychological symptoms, a psychological need to assume the sick role, and the absence of secondary gain from the behavior. Munchausen syndrome is further characterized by features of chronic lying, pseudologia fantastica, wandering, and the use of aliases. Munchausen syndrome is a medical conundrum of untold proportions due to the difficulty of diagnosis, the complexity
ofmedical and psychiatric treatment, and legal ramifications. Failure to diagnose the disorder can result in inappropriately spent medical time and cost. The proposed etiologies of Munchausen syndrome include biological and psychological abnormalities, none of which has been consistently found in this disease. The possibility that right hemispheric central nervous system dysfunction is involved in the pathogenesis of Munchausen syndrome has been suggested by Pankratz (1987) but a specific cortical or subcortical region has not been established. To further define the underlying functional brain abnormality in Munchausen syndrome, a functional brain scan was perAddress reprint requests to: Dr James M Mountz, Associate Professor of Radiology, Division of Nuclear Medicine, University formed to evaluate the regional cerebral blood flow (rCBF) of Alabama at Birmingham, 619 19th Street South, Birmingham, using Tc-99m Hexamethylpropyleneamine Oxime (Tc-99m Alabama 35294 USA. HMPAO) SPECT. This is the first published report of JPsychialry Neurosci, VoL 21, No. 1, 1996 49
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Figure 1. Brain SPECT scan illustrating the regional cerebral blood flow in the case of Munchausen syndrome. There is hyperperfusion of the right hemithalamus (see arrowhead).
Munchausen syndrome investigated by high resolution rCBF brain SPECT. Case report A 51-year-old Caucasian female with multiple entries into the medical system with factitious illness was evaluated. Her history included features of pseudoseizures, extensive lying, pseudologia fantastica, use of aliases, petty theft, and incarceration. Although she claimed to be left-handed, observation supported the conclusion that she was predominantly righthanded. An electroencephalogram and a CT scan of her head were interpreted as normal. An MMPI and Million testing batteries revealed depression, hysteria, and antisocial features. Two attempts with amytal interview were unsuccessful because the patient continued to give false information up to the point of total sedation. The Halsted-Reitan batteries revealed only malingering. At the time of the brain SPECT scan, the patient had not received psychotropic medication for 8 months. Although the patient had a prior history of barbiturate abuse, no evidence of this abuse was found 1 year prior to SPECT. Psychological examination revealed signs that the patient was suicidally depressed and had fictitious ideation. Additional details of this patient's clinical picture have been reported elsewhere (Parker 1993).
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approximately 8 mm full width at halfmaximum. The matrix size is 128 x 128 yielding a pixel size of 1.96 mm. Oblique reconstruction resulted in transverse sections precisely aligned parallel to and serially above the canthomeatal (CM) line as determined by a standard reference system method (Mountz et al 1994). Image reconstruction and analysis was performed using the ADAC Pegasys analysis and workstation computer. Cortical circumferential profiles were obtained by delineating an annular ring of cortex 1.56 cm (8 pixels) wide; the perimeter of this annulus was defined by a pixel threshold value of 50% of the average pixel value for the entire slice under analysis. Individual cortical regions were then created by subdividing this annulus into 12 sectors of equal angle (Mountz et al 1994). This division yielded a total of 36 cortical regions in transverse sections at levels 3.5 cm, 5.5 cm and 7.5 cm above the orbitomeatal line (OM) line. The hemithalamic and caudate tracer uptake activity was determined by superimposing the anatomic boundary from CT to the corresponding location on the Tc-99m HMPAO brain SPECT scan section (Mountz et al 1994). Individual cortical regions were analyzed using a circumferential profile analysis technique for comparing average counts per pixel in each region relative to the cerebellar uptake (cortical-to-cerebellar ratios) (Mountz et al 1994). The basal ganglia was analyzed by comparing caudate and hemithalamic rCBF average counts per pixel relative to the cerebellum. Data were compared to age- and sex-matched normals (n = 10, average age ± 1 sd = 52.6 ± 6 years) (Mountz et al 1992). RESULTS
The cortical-to-cerebellar ratio was within 1 sd of normal controls for all 36 cortical circumferential regions analyzed. Both caudate head nuclei had region to cerebellar ratios within 1 sd of normal controls. There was, however, marked increase in uptake in the right hemithalamus as shown by the Tc-99m HMPAO brain SPECT scan section in Figure 1. Figure 2 shows the Tc-99m HMPAO brain SPECT scan section through the level of the hemithalami (as superimposed from the CT scan) illustrating the regions of interest used to obtain the hemithalamic values of Tc-99m HMPAO uptake. The right hemithalamic-to-cerebellar ratio was equal to 1.14, and the left hemithalamic-to-cerebellar ratio was equal to 0.92; (normal for both right and left hemithalami 1 ± sd = 0.96 ± 0.05) (Mountz et al 1992). The right:left hemithalamic uptake ratio was equal to 1.24 (normal ± 1 METHODS sd = 1.01 ± 0.06) (Mountz et al 1992). The cranial computthe iv after was A brain SPECT scan injection erized tomography (CT) scan was normal (see Figure 3). performed of a dim conditions the under HMPAO Tc-99m of 20 mCi and quiet room, with eyes closed in a resting state. The scans DISCUSSION were acquired on the ADAC (ADAC Laboratories; Milpitas, A number of psychological explanations have been sugCA) dual-head Genesys gamma camera equipped with high resolution collimators yielding image resolution of gested for pathological lying, pseudologia fantastica,
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Brain SPECT scanning in Munchausen syndrome
Figure 2. Brain SPECT scan section through the level of the hemithalami showing the regions of interest used to semiquantify hemithalamic values of Tc-99m HMPAO uptake.
Munchausen syndrome, and other similar disorders that include misrepresentation ofthe truth. These explanations have been reviewed by Ford et al (1988). In one explanation, the superego is constrained or under-developed, allowing for fabrication and lying, interwoven with truth, to provide a mechanism for accomplishing one's objectives. Another explanation is that pathological lying may result from
Figure 3. Cranial CT scan section through the hemithalami. The CT section is normal and demonstrates that the morphologic structure of the hemithalami is normal bilaterally.
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idealization ofthe selffor purposes of enhancing self-esteem. Lack of tolerance of anxiety may result in pressure to lie immediately rather than suffer by contemplating the relative merits of a truthful response (Snyder 1986). Similarly, Kemberg (1975) has suggested that projection identification influences these patients to lie rapidly, as a result of lack of impulse control (Kernberg 1975). Given that all brain activity relies on the circuitry ofneural pathways, this study attempts to look more closely at the functional and anatomical levels for clues to etiology, assessment and treatment. The biological findings associated with lying have also been reviewed (Ford et al 1988). The observation and studies of confabulation in the setting ofalcoholism and Korsakoffs syndrome make a major contribution to this literature. Confabulation is thought to be associated with memory deficits and frontal lobe dysfunction; abnormalities of the nondominant speech area may also play a role. SPECT scanning of patients with Korsakoff's syndrome, however, have not shown any specific thalamic lesions (Hunter 1990; Hunter et al 1989). The possibility that right hemispheric central nervous system dysfunction is involved in the pathogenesis of Munchausen syndrome has been suggested by Pankratz (1987). An abnormal MRI of a patient with Munchausen syndrome found disseminated white matter abnormalities, but the patient was not available for further evaluation of central nervous system disease (Fenelon et al 1991). In a patient with pathological lying, but without the other symptoms of Munchausen syndrome, abnormal and asymmetric hemithalamic regional blood flow has been demonstrated using Tc-99m HMPAO single photon emission computed tomography (Modell et al 1992). This case of Munchausen syndrome resembles the report of pathological lying in that some of the clinical symptoms have similarities, and the functional imaging studies of both patients reveal abnormalities in the right hemithalamus. In pathologic lying there is low rCBF to the right hemithalamus and, therefore, an abnormally low right:left hemithalamic asymmetry. In Munchausen syndrome there is increased rCBF to the right hemithalamus and, therefore, an abnormally high right:left hemithalamic asymmetry. The diverse function ofthe thalamus, and the difference in the nature of these 2 diseases may account for the absolute rCBF abnormality of the right hemithalamus with differences in rCBF asymmetry in both diseases. It should be recalled that the thalamus has extremely diverse and complex functions that extend well beyond its classically described roles in the somatosensory motor system. The anterior and dorsal medial nuclei, for example, have extensive connections with various regions of the limbic system and appear to be involved in the modulation of arousal, the encoding of new information, memory retrieval and sequencing, and emotional responsiveness to external
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stimuli (Armstrong 1990; Jones 1985). Therefore, integration of interoseptive and sensory information with higher cortical functions by the thalamus permits appropriate interpretation and subsequent processing of these incoming stimuli. In pathologic lying there is the tendency to lie impulsively, which has been reported to be associated with decreased activity of the right hemithalamus (Modell et al 1992). This state has been hypothesized to arise either from subnormal afferent activity to this region or from abnormal neuronal connections or cellular groupings within the hemithalamus itself, resulting in the finding of hypoperfusion (Modell et al 1992). The particular emphasis on a dramatic presentation in Munchausen syndrome is somewhat contary to the impulsivity of pathologic lying, and possibly requires more cognitive deliberation which may be inconsistent with subnormal right hemithalamic activity. The study of a larger series of both patients with Munchausen syndrome and patients with pathologic lying will clarify whether or not there is a consistent abnormality of the right hemithalamus, and by what mechanism the asymmetry in hemithalamic uptake is related to these disorders. CONCLUSION Tc-99m HMPAO brain SPECT scanning is a readily available technique to study the functional status of the brain in various psychiatric disorders. The abnormal uptake in the right hemithalamus seen in pathologic lying and now in Munchausen syndrome suggests that the right hemithalamus may play an important role in the manifestation of these syndromes. Additional Tc-99m HMPAO brain SPECT studies will be required to determine whether or not the finding ofabnormal thalamic rCBF is representative of Munchausen syndrome.
REFERENCES
American Psychiatric Association. 1987. Diagnostic and statistical manual of mental disorders. 3rd ed, rev (DSM-IIIR). Washington DC: American Psychiatric Association.
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Armstrong E. 1990. Limbic thalamus: anterior and medial dorsal nuclei. In: Paxinos G, editor. The human nervous system. San Diego CA: Academic Press. pp 469-479. Fenelon G, Mahieux F, Roullet E, Guillard A. 1991. Munchausen syndrome and abnormalities on magnetic resonance imaging of the brain. Br Med J 302:966-967. Ford CV, King BH, Hollender MH. 1988. Lies and liars. Psychiatric aspects of prevarication. Am J Psychiatry 145:554-562. Hunter R. 1990. Frontal metabolic deficits in Korsakoff's syndrome. Br J Psychiatry 157:454-455. Hunter R, McLuskie R, Wyper D, Patterson J, Christie JE, Brook DN, McCullough J, Fink G, Goodwin GM. 1989. The pattern of function-related regional cerebral blood flow investigated by single photon emission tomography with Tc-99m-HMPAO in patients with pre-senile Alzheimer's disease and Korsakoffs psychosis. Psychol Med 19:847-855. Jones EG. 1985. The thalamus. New York: Plenum Press. pp 87-149, 607-697. Kernberg 0. 1975. Borderline conditions and pathological narcissism. New York: Jason Aronson. Modell JG, Mountz JM, Ford CV. 1992. Pathol6gical lying associated with thalamic dysfunction demonstrated by Tc-99m-HMPAO single photon emission computed tomography. J Neuropsychiatry Clin Neurosci 4:442-446. Mountz JM, Deutsch G, Kuzniecky R, Rosenfeld SS. 1994. Brain SPECT. 1994 Update. In: Freeman LM, editor. Nuclear medical annual 1994. New York: Raven Press. pp 1-54. Mountz JM, Modell JG, Deutsch G, Harris JM. 1992. Within subject test:re-test r-CBF variability using Tc-99mHMPAO brain SPECT. J Nucl Med 33:826. Mountz JM, Wilson MW, Wolff CG, Deutsch G, Harris JM. 1994. Validation of a reference method for correlation of anatomic and functional brain images. Comput Med Imag Graph 18:163-174. Pankratz LL. 1987. Cerebral dysfunction in the Munchausen syndrome. Hillside J Clin Psychiatry 9:195-205. Parker PE. 1993. A case report of Munchausen syndrome with mixed psychological features. Psychosomatics 4:360-364. Snyder S. 1986. Pseudologia fantastica in the borderline patient. Am J Psychiatry 143:1287-1289.
