CSF drainage ameliorates the motor deficit in normal pressure hydrocephalus: evidence from the analysis of grasping movements.

Apart from the classic triad of hypokinetic gait disorder, cognitive dysfunction and urinary incontinence, the clinical spectrum of normal pressure hydrocephalus has been found to affect the upper limbs. It is unclear if the motor deficit of hand and arm movements improves with CSF evacuation. The present study was designed to quantitatively assess the effect of CSF evacuation on the hypokinesia of grasping movements in normal pressure hydrocephalus. Eight subjects with normal pressure hydrocephalus grasped to lift an instrumented object prior to and following evacuation of 40 ml CSF. The build-up of fingertip forces and the kinematics of the lifting movement were slower for patients compared with healthy controls. Patients also generated excessive grasping forces when lifting and holding the object stationary prior to and following CSF evacuation. CSF evacuation significantly improved the gait disorder, the cognitive impairment and the urinary incontinence in normal pressure hydrocephalus. CSF evacuation accelerated the lifting movement and reduced the grip force overshoot. These data suggest that the measurement of grasping forces may provide an additional test to quantify the clinical response to CSF tapping in normal pressure hydrocephalus.