Hydrocephalus: obliterated perimesencephalic cisterns and the danger of sudden death.

OBJECTIVE: We reported a possible risk factor which could identify patients with chronic hydrocephalus who are risk for sudden death.

METHODS: A retrospective review of medical records and computed tomographic (CT) scans was conducted on three patients with chronic hydrocephalus who suffered acute cardiorespiratory arrest without those signs which are normally associated with a progressive worsening of hydrocephalus.

RESULTS: All three of these patients were awake and communicative shortly before the life threatening or terminal event. All had experienced some recent worsening of neurologic signs or symptoms, but none had shown a progressive impairment of consciousness or major neurologic decline ordinarily associated with life threatening elevation of intracranial pressure. Absence of the perimesencephalic cisterns on head CT scans done prior to or just after the life threatening event was the only new radiologic finding common to all these patients.

CONCLUSIONS: The absence of the perimesencephalic cisterns in an awake and alert patient with severe hydrocephalus indicates that the patient may be at risk for neurogenic cardiorespiratory failure. In such cases, (especially when there has been a recent, albeit mild, change in neurologic signs or symptoms), the neurologist should urge emergency ventriculostomy or shunting for the hydrocephalus.