Hydrocefalus

Hydrocefalus is a condition characterized by an abnormal accumulation of cerebrospinal fluid (CSF) within the brain’s ventricles or the subarachnoid spaces, typically due to an imbalance between CSF production and absorption. The resulting ventricular enlargement can raise intracranial pressure and compress brain tissue. It may be present at birth or develop later, and it can follow an acute, subacute, or chronic course.

Types of hydrocefalus include obstructive (non-communicating) hydrocephalus, where a blockage within the ventricular system impedes CSF flow, and communicating hydrocephalus, in which CSF absorption at the arachnoid granulations is impaired. Normal pressure hydrocephalus (NPH) occurs mainly in older adults and features enlarged ventricles with symptoms of gait disturbance, cognitive change, and urinary problems; hydrocephalus ex vacuo reflects brain atrophy with secondary ventricular enlargement rather than excess CSF.

Causes include congenital malformations such as aqueductal stenosis, intraventricular or subarachnoid hemorrhage, meningitis or other CNS infections, brain tumors, trauma, and post-surgical scarring. Premature birth and neonatal complications increase risk, as do conditions that disrupt CSF dynamics.

Symptoms vary by age. In infants, rapid head growth, a bulging fontanelle, poor feeding, vomiting, and irritability may be seen. In older children and adults, headaches, nausea, cognitive decline, gait disturbance, and urinary incontinence are common; the classic triad for NPH comprises gait disturbance, dementia, and urinary urgency.

Diagnosis relies on clinical assessment and imaging, typically CT or MRI showing ventricular enlargement; the Evans index is a common quantitative measure. Treatment usually involves CSF diversion, most often ventriculoperitoneal shunt placement, or, in selected obstructive cases, endoscopic third ventriculostomy. Prognosis improves with timely treatment, but shunt-related complications and infections can occur.