Hydrocephalus (HCP)

Definition

• increased CSF volume

Etiology

• obstruction to CSF flow

• decreased CSF absorption

• increased CSF production (rarely) – e.g. choroid plexus papilloma (0.4-1% of intracranial tumours)

Epidemiology

• estimated prevalence 1-1.5%; incidence of congenital hydrocephalus ~1-2/1000 live births

Classification

Clinical Features

acute hydrocephalus

• signs and symptoms of acute elevated ICP

• impaired upward gaze ("sunset eyes") and/or CN VI palsy

chronic/gradual onset hydrocephalus (i.e. NPH)

• gradual onset of classic triad (синдром Хакима Адамса) developing over weeks or months

  • pressure of ventricle on LE motor fibers → gait disturbance (ataxia and apraxia usually initial symptoms)

  • pressure on cortical bowel/bladder center → urinary incontinence

  • pressure on frontal lobes → dementia

• CSF pressure can be measured within clinically "normal" range

Investigations

• CT/MRI (periventricular lucency suggests raised CSF pressure)

• ultrasound (through anterior fontanelle in infants)

• ICP monitoring (e.g. LP) may be used to investigate NPH, test response to shunting (lumbar tap test)

• radionuclide cisternography can test CSF flow and absorption rate (unreliable)

• β-2 transferrin assay to test for the presence of CSF leak

Treatment

• ventricular drainage

• surgical removal of obstruction (if possible) or excision of choroid plexus papilloma

• shunts

  • ventriculoperitoneal (VP): most common

  • Ventriculopleural

  • ventriculo-atrial (VA): relatively increased risk of infections, shunt emboli

  • lumboperitoneal: for communicating hydrocephalus and pseudotumour cerebri

• third ventriculostomy (for obstructive hydrocephalus) via ventriculoscopy

• LPs for transient hydrocephalus (e.g. SAH), IVH in premature infants, etc.