Background   

Idiopathic normal pressure hydrocephalus (iNPH) is a potentially treatable dementia and gait disorder with abnormal CSF dynamics.

Objective   

To investigate and characterize the changes in motor symptoms and CT and MRI features of iNPH before and after a shunt operation using specific evaluation criteria.

Methods   

We studied 17 definitive iNPH patients, diagnosed according to the clinical guidelines of both the Japanese Society of NPH and the International NPH Consultant Group, with ventricular enlargement (Evan’s index > 0.3) and narrowed CSF spaces at the high convexity on CT scan and /or MRI. The pre- and post-operative evaluation criteria for the gait and motor disturbances included the Japanese NPH Grading Scale-Revised (JNPHGSR), the Timed “Up and Go” test and the motor sections of the Unified Parkinson Disease Rating Scale. For cognitive impairments, the JNPHGSR, Mini Mental State Examination, Frontal Assessment Battery and Trail Making Test were used. White matter lesions were rated from the CT and/or MRI using a validated visual rating scale.

Results   

All patients showed specific CT and MRI findings, consisting of diffusely-dilated Sylvian fissure, as well as narrowed CSF space at the high convexity. Fifteen patients (88 %) showed white matter lesions on their CT or MRI images. These signs were ameliorated in all patients after the shunt operation. Evan’s index and the mean total scores on the visual scale for white matter lesions also improved significantly. Clinically, the patients had frequent parkinsonism (71 %), but relatively few had a history of either small-vessel diseases (29 %), hypertension (41 %) or diabetes (35 %). All patients showed gait disturbances, and these symptoms, including postural instability and body bradykinesia, improved significantly after the operation. Over half also showed signs of cognitive impairment and urinary incontinence, and all such symptoms and signs improved significantly.

Conclusion   

iNPH often appears as a shunt-responsive type of parkinsonism and reversible white matter lesions among the geriatric population.