B. Types and causes of hydrocephalus.
- 1. Noncommunicating hydrocephalus (obstruction between lateral
ventricles and lumbar subarachnoid space) - obstruction may occur at any
location, but tends to occur most commonly at sites of normal narrowing:
- a. Obstruction at foramen of Monro
- 1. colloid cyst of third ventricle
- b. Obstruction at aqueduct of Sylvius
- 1. congenital malformations
- 2. acquired disease, e.g. stenosis due to gliosis, ependymitis or glioma
- c. Obstruction at foramina of Luschka and Magendie
- 1. basal leptomeningitis (acquired) - usually caused by granulomatous
inflammatory processes (e.g., TB, fungal infections)
- 2. Communicating hydrocephalus (lateral ventricles and lumbar
space communicate)
a. obstructive:
- 1. impairment of CSF reabsorption due to leptomeningitis, subarachnoid
hemorrhage or cerebral venous thrombosis
- b. nonobstructive (rare)
- 1. overproduction of cerebrospinal fluid, e.g. by papilloma of choroid
plexus or ependymoma of cauda equina
- 2. decreased absorption of cerebrospinal fluid