Cerebrospinal fluid hydromechanics in adult patients with benign noncommunicating hydrocephalus: one-hour test shunting and balanced cerebrospinal fluid infusion test to select patients for intracranial bypass operation.

Cerebrospinal fluid (CSF) pressure and absorption were determined in 12 patients with benign noncommunicating hydrocephalus. An extracorporeal communication of plastic tubing between the ventricular system and the lumbar subarachnoid space was established to imitate the hydromechanical condition after an intracranial bypass operation. This extracorporeal shunt, which in effect was an externalized Torkildsen shunt, served first as a test shunt for 1 hour and then as a route for the constant rate CSF infusion test. The total CSF absorptive capacity was thus determined under a condition of balanced CSF pressure between the proximal and distal compartment. Four patients, whose tests showed normal CSF pressure and absorption, were selected for intracranial bypass operation. Follow-up examination showed a normal clinical condition, reduction of the ventricular system, normal CSF pressure, and normal CSF absorption in all 4 patients. The other 8 patients, whose tests indicated impaired CSF absorption, were treated by ventriculoatrial shunting. The tests were valid in selecting patients for intracranial bypass operation.