[Arachnoid cyst of the middle cranial fossa with extraocular muscle paresis: case report].

Arachnoid cysts in the middle cranial fossa usually present with skull deformity, intracranial hypertension, epilepsy, focal symptoms and delayed mental development. Some cases, however, have neither symptoms nor signs. We have encountered a patient with an arachnoid cyst of the middle cranial fossa with extraocular muscle paresis and who was treated with cyst wall fenestration with good results. An 11-year-old boy presenting with double vision was diagnosed as having an arachnoid cyst in the middle cranial fossa with extraocular muscle paresis. He had no signs of increased intracranial pressure. This patient underwent a cyst membranectomy. Postoperatively this symptom rapidly subsided. Double vision disappeared two months postoperatively. To our knowledge, if those cases associated with increased intracranial pressure signs are excluded, this is the first case reported so far of a middle cranial fossa arachnoid cyst with extraocular muscle paresis. This report illustrates that extraocular muscle paresis can be caused by an arachnoid cyst in the middle cranial fossa and that knowledge of this could be helpful in its early diagnosis and treatment.