Asymptomatic schwannoma of the oculomotor nerve: case report.

Intracranial oculomotor schwannoma without neurofibromatosis is rare and is usually symptomatic. Only one case of asymptomatic oculomotor schwannoma has been previously reported. We present a case of intracranial oculomotor schwannoma which caused no signs or symptoms. Microsurgical resection of this tumour resulted in oculomotor palsy. We reviewed 7 reported cases and the findings indicated that radical removal of the tumour invariably caused or worsened the oculomotor palsy. The reason why the tumour caused no symptoms in this case was unclear. However, improvements in diagnostic methods such as magnetic resonance imaging (MRI) may increase the detection of such asymptomatic cases. Indications for surgical treatment should be established.