Facial nerve palsy-an unusual complication after evacuation of a subdural haematoma or hygroma in children.

OBJECTIVE: This paper reports and discusses on the possible etiology of postoperative contralateral facial nerve palsy after uneventful evacuation of a subdural haematoma or hygroma after mild head trauma in two children with pre-existing middle cranial fossa subarachnoid cysts.
RESULTS: Two 14- and 15-year-old boys had prolonged headaches after mild head injuries. CT showed a right-sided middle cranial fossa arachnoid cyst in each patient. In one patient, an ipsilateral subdural haematoma was identified, and in the other, bilateral hygromas were identified. Exacerbation of symptoms required emergency evacuation of the subdural haematoma in the first child, and bilateral external drainage of the hygroma in the other child. In both children the late postoperative period was complicated by peripheral facial nerve palsies contralateral to the arachnoid cyst.
CONCLUSION: Facial nerve palsy may be a complication of hygroma or haematoma drainage. The etiology is not clear; traction of the facial nerve due to displacement of the brainstem may be the most likely explanation.