Subdural effusion usually occurs in infants as a complication of pyogenic meningitis. The usual site is frontal or parietal region.
The effusion is generally small. Such small effusions may be multiple and, as a rule, clear spontaneously.
Large effusions are likely to cause raised intracranial pressure and interfere with recovery from meningitis.
Manifestations include persistent fever, vomiting, convulsions, irritability or drowsiness, tense and bulging anterior fontanel and progressively increasing hydrocephalus in a case of pyogenic meningitis on adequate therapy. CSF usually continues to be abnormal. Skull sutures may be separated. Increased transillumination of head may be observed.
Once the existence of subdural effusion is suspected, a subdural tap should immediately be done.
Treatment consists in tapping a large effusion daily or on alternate days. Its persistence beyond 2 weeks, despite such taps, is an indication for surgical drainage after craniotomy.