Neurology — NPH Shunt Surgery

Idiopathic normal pressure hydrocephalus (iNPH) is a potentially reversible cause of dementia in older adults, characterized by the classic Hakim-Adams triad of gait disturbance, cognitive impairment, and urinary incontinence with ventriculomegaly on neuroimaging despite normal CSF opening pressure. Disease prevalence rises markedly above age 65 and is often under-diagnosed.

Diagnostic workup includes brain MRI demonstrating disproportionately enlarged subarachnoid space hydrocephalus (DESH), Evans index above 0.3, callosal angle below 90 degrees, and tight high convexity. Functional confirmation requires positive response to large-volume lumbar puncture (40-50 mL CSF removal), 72-hour external lumbar drainage, or measured CSF dynamics with intracranial compliance testing.

Programmable ventriculoperitoneal shunting with adjustable valve and anti-siphon device is the standard treatment, providing improvement in gait in 75-80 percent and cognition in 40-60 percent of well-selected patients. Common complications include subdural hematoma, shunt infection (3-5 percent), and over-drainage symptoms requiring valve adjustment. Multidisciplinary assessment by neurology, neurosurgery, and neuropsychology is essential before and after surgery.