Coma due to meteorism and increased intra-abdominal pressure subsequent to ventriculoperitoneal shunt dysfunction

Abstract

In October, 2005, a 76-year-old woman was admitted to the emergency room with subacute loss of consciousness. She had a history of hydrocephalus and had undergone ventriculo-peritoneal shunt surgery at the age of 53 years. On admission she presented with stupor and appropriate responses on painful stimuli. Her abdomen was distended. She had a 1-week history of severe constipation and recent onset of oliguria. CT scan of the head showed a distinct hydrocephalic ventricular system; this was more prominent than seen on her last available CT scans from 1998 (fi gure A). Radiography of the abdomen showed severe meteorism with huge bowel dilatation (fi gure B). We ruled out mechanical dysfunction of the shunt system. After releasing 50 ml of cerebrospinal fl uid (CSF) from the shunt reservoir, our patient gradually became more alert. Diagnostic work-up, including CT scan of the abdomen, revealed diverticulitis of the colon as the cause of the meteorism. She was treated conservatively, including the use of simeticone and amidotrizoic acid for meteorism and constipation, and her state of consciousness normalised over the next 2 days. There was no need for shunt revision and her consciousness was completely normal within 3 days. During follow-up over 11 months until September, 2006, there was no other episode of shunt malfunction and she remained generally well. A diff erence in pressure between the intracranial space and the peritoneal cavity is necessary for ventriculoperitoneal shunts to allow CSF fl ow between these two compartments. This pressure gradient leads to drainage of the CSF from the ventricular system to the peritoneal cavity. The fl ow rate is controlled by the shunt valve. Changes in this pressure gradient have been reported in pregnant women. Shunt malfunction with symptoms of increased intracranial pressure during pregnancy, especially in the third trimester, is a well known condition. Spontaneous improvement usually occurs usually postpartum. When the increased intra-abdominal pressure overcomes the pressure diff erences required for adequate CSF fl ow, symptoms of hydrocephalus become apparent, and coma can occur. Similarly, as in pregnancy, constipation and meteorism may aff ect distal fl ow by obstruction of the catheter outlets by distended bowel. Because increased intra-abdominal pressure is a well known cause of renal dysfunction, the transient oliguria experienced by our patient during the period of extensive meteorism is not surprising. During treatment of a gastroenterological disease in patients with a ventriculoperitoneal shunt, special attention should be given to the intra-abdominal pressure and level of consciousness. Although shunt dysfunction due to raised intra-abdominal pressure is well recognised in pregnancy and in paediatric neurosurgery, it should be considered in cases of elderly hydrocephalic patients with dysfunctional CSF shunts. With the increase in life expectancy we are seeing, such occurrences may be more likely in the future. Management of such patients requires team-work across the specialities, including emergency medicine, gastroenterology, and neurosurgery.