Idiopathic normal pressure hydrocephalus

Hydrocephalus can present with acute or chronic symptoms at any age. Obstructive and communicating hydrocephalus are the two main types. In adults, the most common form of the latter is normal pressure hydrocephalus (NPH) with a mean age at onset of about 70 years, equally common in both sexes. This review will focus on the idiopathic variant of the disease (INPH), the typical features of which are imbalance, gait disturbance, urinary symptoms, and cognitive decline. Although the treatment is surgical, by placing a cerebrospinal fluid (CSF) shunt, neurologists are essential for diagnosing patients with gait disturbance and/or ventriculomegaly, for preoperative selection of shunt candidates, and to optimise the CSF shunt system postoperatively. Very little is known about the incidence and prevalence of INPH. In a door to door survey in people older than 65 years, 0.7% of the population had Parkinson’s disease and 0.4% NPH.1 In Sweden, between three and six shunt operations in adults per 100 000 inhabitants are done every year at the six neurosurgical centres, about 30% of which are for INPH and 20% for secondary NPH.2 The pre- and postoperative investigation of INPH is the fourth most common diagnosis after stroke, epilepsy, and headache at the neurology inpatient service at our hospital. There are few neurological conditions where treatment has such a large impact on outcome as INPH. The patients are elderly and even a small improvement in their gait or activities of daily living has the potential to substantially increase their independence. In most countries hydrocephalus is considered a “neurosurgical problem” without any need to consult the neurologist. But we believe that a multidisciplinary approach with the neurologist and neurosurgeon in fruitful cooperation is what is needed. An important issue for the general neurologist is the evaluation of patients referred because of gait …