Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH), also termed symptomatic hydrocephalus, may cause dementia in up to 6% of patients (2) and thus not infrequently enters the differential diagnosis of dementia. The diagnosis and treatment of NPH are problematic. The cardinal symptoms (gait difficulty, cognitive decline, and incontinence of urine) are not pathognomonic for the diagnosis, commonly occur in the elderly (3-5), and may be caused by multiple disease processes. Cerebral ventricle size increases with age (6) and in common dementing illnesses such as Alzheimer’s disease (AD) (7), so that ventriculomegaly is frequent in an older population. Current diagnostic tests for NPH give both false positive and false negative results. Its surgical treatment carries important short and long term risks. Finally, the cause or pathogenesis of many NPH cases is unknown. This chapter will address the reasons why the diagnosis is difficult as well as the differential diagnosis, features of the history, examination, and neuropsychological assessment in NPH that may help clinicians with management. It also will discuss the radiological evaluation, including computed tomography (CT), magnetic resonance imaging (MRI), cisternography and single photon emission tomography (SPET), and special testing including lumbar puncture (LP), continuous cerebrospinal fluid (CSF) drainage, CSF absorption tests, and CSF pressure monitoring.