Introduction: The treatment of Idiopathic Normal Pressure Hydrocephalus (INPH) entails the placement of a valve regulated CSF shunt system. The use of a Differential Pressure or Flow Regulated valve system is optional. Data regarding the efficacy of flow related devices in INPH is sparse and generally inferred. Our primary goal was to objectively evaluate the clinical outcomes in 13 patients with INPH treated with a (Integra) Low Flow Valve (LFV) at six months and one year. Secondary objectives include an analysis of the incidence of shunt related complications.

Methods: This prospective study involves the use of a (LFV) system in thirteen patients admitted to the Florida Hospital NPH Program for a trial of three day lumbar drainage with pre and post drainage Neuropsychological testing, gait assessment, and imaging studies. Repeat testing was performed at six months and one year post implantation of a LFV(I) system.

Results: Statistically significant improvements in gait assessment were noted at six months and one year (Berg and Timed Walking Test). A statistically significant difference was not observed with regards to neuropsychological assessment. One patient required proximal shunt revision for malposition of the ventricular catheter.

Conclusions: The use of the Low Flow Valve System (Integra) in patients with INPH appears to have validity. Although a definite trend towards improvement in their neuropsychological assessment was noted, the small size of the cohort may have contributed to the lack of statistical significance. Hydrodynamic shunt related complications (subdural hematomas, obstruction) were not seen. Patient satisfaction was high.

Patient Care: Differential Pressure Valves are noted for complications related to overdrainage, underdrainage, and frequent adjustments (Programmable). The use of a Flow Regulated Valve System appears to significantly reduce or abolish these occurrences.

Learning Objectives: 1. Flow regulated valve systems may be recommended for treatment of Normal Pressure Hydrocephalus. 2. Shunt related complications in the treatment of Normal Pressure Hydrocephalus may be reduced by the use of Flow Regulated Valve systems.

References: Phillippe Decq, M.D., Jean-Luc Barat, M.D. et al. Shunt failure in adult hydrocephalus: Flow-controlled shunt versus differential pressure shunts- A cooperative study in 289 patients. Surgical Neurology 43:333-339, 1995. Hanlow, Patrick W., et al. Treatment of hydrocephalus determined by the European Orbis Sigma Valve II survey: a multicenter prospective 5-year shunt survival study in children and adults whom a flow-regularing shunt was used. J Neurosurg 99: 52-57, 2003. Zemack M.D., Goran, et al. Adjustable Valves in noraml-pressure hydrocephalus: A retrospective study of 218 patients. Neurosurgery 51:1392-1402, 2002.