Acute lumbar intervertebral disc prolapse: a ... bra1 disc prolapse precipitated by the lithotomy position ... concussion and are reversible, complete recovery.
British Journal of Obstetrics and Gynaecology December 2000, Vol107, pp. 1519-1521
CASE REPORTS
Acute lumbar intervertebral disc prolapse: a complication of the lithotomy position Kishor Choudhari Consultant (Neurosurgery), *Yasbasbri Choudhari Specialist Registrar (Obstetrics and Gynaecology), Thomas Fannin Consultant (Neurosurgery) Department of Neurosurgery, Royal Victoria Hospital, Belfast; *Department of Obstetrics and Gynaecology, Ulster Hospital, Dundonald, Belfast
Introduction Neurovascular complications of the lithotomy position are rare. We report a case of an acute lumbar intervertebra1 disc prolapse precipitated by the lithotomy position for a vaginal hysterectomy.
Case report A 36 year old woman underwent a vaginal hysterectomy in the lithotomy position under general anaesthesia. She had been perfectly fit and healthy prior to undergoing surgery. The procedure was uneventful. Post-operatively she woke up with severe backache and bilateral sciatica radiating to the lateral aspects of both legs. The straight-leg-raising test was restricted to 40 degrees on the left and 60 degrees on right. There was subtle weakness of the dorsiflexors of feet and she had transient numbness on the lateral aspect of her left leg. Her ankle reflexes were diminished on both sides. She had loss of lumbar lordosis with spasm of her spinal extensor muscles. A clinical diagnosis of acute lumbar intervertebral disc prolapse was made. Initially she was treated conservatively with bed rest, analgesics, physiotherapy and local analgesic injections, without any benefit. Computed tomography of her lumbosacral spine revealed an acute central disc prolapse at the L4/5 level superimposed on a mild degree of congenital spinal stenosis (Fig. 1). After failure of conservative treatment she underwent L4/5 microdiscectomy with significant relief of her symptoms.
Discussion Post-operative backache is a common problem. The aetiology of post-operative backache is uncertain and Correspondence: Mr K. A. Choudhari, Department of Neurosurgery, Royal Victoria Hospital, Belfast BT12 6BA, UK. 0 RCOG 2000 British Journal of Obstetrics and Gynaecology
probably involves many factors. Surgical positioning plays an important part in its development. Although a cause and effect relationship has not yet been fully established, the lithotomy position is often implicated'. Lithotomy is the commonly used position in various gynaecological, colorectal and urological procedures. It provides maximum access to the pelvic organs, and allows the surgeon to work below and inside the leg without having thigh, knee, and foot interfere with his activities. It also allows the surgeon to be comfortable and the scrub nurse to have a clear view of the field. Apart from common backache that is usually selflimiting, a variety of neurovascular complications have been reported following procedures in the lithotomy position. Vascular complications include the compartmental syndrome and thromboembolism2. Common neurological complications described are f e m ~ r a l -sciatic6v7 ~, and peronea18neuropathies. These peripheral neuropathies are usually stretch injuries resulting in various neurological deficits. Fortunately, they are usually due to neuropraxia caused by axonal concussion and are reversible, complete recovery within six to eight weeks being the rule. In our case, however, instead of the more commonly seen neural stretch injury, the lithotomy position precipitated an acute disc prolapse. Relentless progression of the woman's symptoms despite early recognition and appropriate conservative measures warranted neurosurgical intervention. Acute disc prolapse is an extremely rare complication of the lithotomy position. Two possible mechanisms can be postulated. First, a congenitally narrow spinal canal, hitherto asymptomatic, was inherently more vulnerable to the manipulations involved in the lithotomy position, resulting in a symptomatic disc protrusion. Flexion and abduction at the hips and flexion at the knees in the supine posture during lithotomy can be likened to similar joint movements in the erect posture encountered during the lifting of a heavy weight, which is known to be the 1519
1520 CASE
REPORTS
Fig. 1. Axial CT scan image through L4-5level showing canal stenosis and a broad disc bulge (black arrow) compressing the disc.
commonest single precipitating factor for acute disc prolapse. However, because the force applied in the former is considerably less, only rarely is disc prolapse precipitated by the lithotomy position. Another mechanism seems more likely. It is known that upper and lower parts of lumbosacral plexuses can be stretched between their respective origins and exits, beneath the inguinal ligament the greater sciatic foramen, respectively, by hyperabduction of the hip9. It is reported that simultaneous hip flexion and knee extension can stretch the sciatic nerve by approximately 1.5 inches7. In this case the spinal canal was already compromised due to congenital stenosis. The nerve roots were slightly stretched over the existing mild disc bulge and were still asymptomatic. By placing the woman in the lithotomy position, flexion and hyper-abduction of the hips made the stretching of the lumbosacral nerveroots worse, and converted an occult pre-existing asymptomatic disc bulge into a frank disc prolapse with intractable sciatica and sensory-motor deficits. It is well known that patients with spinal stenosis are more susceptible to symptomatic disc prolapse with relatively minor provocation. Considering the infrequency and sporadic occurrence of lumbosacral plexus or sciatic nerve injuries in the lithotomy position, an underlying predisposing factor must be present in most patients. It is not possible to screen for asymptomatic stenosis of the spinal canal. Unlike this patient, the majority of patients have chronic low backache or neurogenic claudications. Compared with the reversible nerve stretch injuries affecting peripheral nerves more distally, acute disc prolapse with severe sciatica can have prolonged and debilitating neurological effects. When stenosis is complicated
with sudden disc protrusion, the pain may be so intense with relative paucity of physical signs that the individual may be suspected of being hysterical'". Considering the number of gynaecological, urological and colorectal procedures performed in the lithotomy position, the incidence of either neuropraxic or discogenic sciatic neuropathy is extremely low. Before computed tomography became available McQuarrie et aL7reported sustained S1 nerve root compression due to a prolapsed disc following vaginal hysterectomy. In the last two decades, even with advanced neuro-imaging and neuro-physiological tests, post-operative disc prolapse is a rare diagnosis, although post-operative backache is common. Due to the rarity of this complication, the diagnosis can be easily missed. Prevention of the neurological neural complications of the lithotomy position requires pre-operative detection and recognition of predisposing factors. A history of backache or any other neurological disorder should be evaluated pre-operatively. Other metabolic conditions such as diabetes mellitus may cause peripheral neuropathy making the nerves more vulnerable to mechanical injury. In susceptible individuals general anaesthesia may be preferred to spinal or epidural anaesthesia so as to minimise interference with the back. Brown and Elman" have shown that the incidence of backache increases with the duration of surgery. Patients undergoing longer operations are more prone to develop complications of the lithotomy position. It is important that during positioning two assistants raise and lower both legs gently and simultaneously. O'Donovan et al.l 2 recommend use of an inflatable wedge to support the lumbosacral curve and to maintain normal lordosis. Severe post-operative backache or persistent sciatica, restricted straight-legraising, motor signs, sensory deficits or diminished reflexes following any operation in the lithotomy position warrant an urgent neurosurgical opinion and further investigations in the form of computed tomography or magnetic resonance imaging and nerve conduction studies. Primary neuropraxia is the commonest neurological complication of the lithotomy position and is usually reversible with conservative measures alone. Timely surgical decompression of trapped nerve roots by microdiscectomy in cases of prolapsed intervertebral disc results in immediate neurological improvement and prevention of permanent disability. References 1 Clarke AM, Stillwell S, Patterson ME, Getty CJ. Role of surgical position in the development of postoperative low back pain. J Spinal Disord 1993; 6: 238-241. 2 Angermeier KW, Jordan GH. Complications of exaggerated lithotomy position: a review of 177 cases. J Urol 1994; 151: 866-868. 3 Tondare AS, Nadkami AV, Sathe CH, Dave VB. Femoral neuropathy: a complication of lithotomy position under spinal anaesthesia. Report of three cases. Can Anaesth Soc J 1983: 30: 84-86.
0 RCOG 2000 Br J Obstet Gynaecol 107,1519-1521
C A S E REPORTS
4 Gombar KK, Gombar S, Singh B, Sangwan SS, Siwach RC. Femoral 5
6 7 8
neuropathy: a complication of the lithotomy position. Reg Aneszh 1992; 17:306208. Roblee MA. Femoral neuropathy from the lithotomy position: case report and new leg holder for prevention. Am J Obsret Gynecol1967; 97:871-872. Batres F, Barclay DL. Sciatic nerve injury during gynaecologic procedures using the lithotomy position. Obstet Gynecoll983; 62: 92-94. McQuanie HG, Harris JW,Ellsworth HS, Stone RA, Anderson AE. Sciatic neuropathy complicating vaginal hysterectomy. Am J Obstet Gynecoll972; 113:223-232. Liu YH, Wang JJ, Chang CF. Common peroneal nerve palsy following a surgical procedure-a case report. Acta Anaesthesiol Sin 1999; 3 7 101-103.
0 RCOG 2000 Br J Obstet Gynaecol 107,1519-1521
1521
9 Flanagan WF, Webster GD, Brown MW, Massey EW. Lumbosacral plexus stretch injury following the use of the modified lithotomy position. J Urol1985; 134: 567-568. 10 Epstein NE, Epstein JA, Carras R et al. Far lateral lumbar disc hemiation and associated structural abnormalities: an evaluation in 60 patients of the comparative value of CT, MRI,and myelo-CT in diagnosis and management. Spine 1990; 15: 534-539. 11 Brown EM, Elman DS. Postoperativebackache.Anuesrh Analg 1961; 40: 683. 12 O’Donovan N, Healy TEG, Faragher EB, Wilkins RG, Hamilton AA. Postoperative backache: the use of an inflatable wedge. Br JAnaesth 1986 58: 28CL283. Accepted 2 August 2000
