Beneficial effect of siphoning in treatment of adult hydrocephalus [see comments]

Source: Archives of Neurology 1999 Oct;56(10):1224-1229.
Author: Bergsneider M, Peacock WJ, Mazziotta JC, Becker DP.
PubMed ID: 10520938

Abstract:
OBJECTIVE: To increase awareness about the treatment of adult patients with shunt-nonresponsive hydrocephalus--a state characterized by marked ventriculomegaly, low intracranial pressure, and a patent cerebrospinal fluid diversionary shunt. DESIGN: Retrospective analysis of hospital and outpatient records. PATIENTS: Four patients with symptomatic ventriculomegaly and patent ventriculoperitoneal shunts treated with a protocol of progressive ventricular hypotension induced by external cerebrospinal fluid drainage. RESULTS: Severe clinical manifestations exhibited by the patients, including parkinsonian features, Parinaud syndrome, and extensor posturing, completely reversed once a normalization of ventricular size was achieved. External ventricular drainage pressures as low as -30 cm H2O were required to reduce ventricular size. All patients finally received a shunt incorporating a standard medium differential pressure valve with no antisiphon device. CONCLUSIONS: Shunt siphoning may be an essential mechanism by which cerebrospinal fluid shunting is effective in many patients with adult hydrocephalus. Cerebrospinal fluid shunts that contain an antisiphon device are ineffective in these patients, despite the attainment of 'physiologic' intracranial pressures. Based on reported experimental and clinical evidence, it seems that the cause of this condition may be related to abnormally high intracranial compliance