A case of shunt responsive tremor due to normal pressure hydrocephalus

Hydrocephalus refers to an abnormal accumulation of cerebral spinal fluid (CSF) within the brain resulting in enlarged ventricles and subsequent distortion of periventricular structures [1], while normal pressure hydrocephalus (NPH) is a specific form of communicating hydrocephalus where intra-ventricular CSF pressure remains in the normal range. As only a small disparity in pressure between the ventricles and surrounding subarachnoid space are needed to trigger absorption of interstitial fluid, ventricular enlargement still occurs in this condition [2], which is typically accompanied by symptoms of gait disturbance, urinary incontinence and cognitive impairment [3]. Although a number of movement disorders have been described in patients with hydrocephalus [4], the occurrence of tremor is a rare finding, which has consequently received very little attention in the literature and warrants further investigation. Here we present a case of an appendicular, predominantly lower-limb tremor occurring in a patient with concomitant idiopathic NPH, which demonstrated a marked reduction in amplitude following the insertion of a ventriculo-peritoneal shunt. The potential mechanisms underlying this clinical presentation are also discussed.