Remitting sixth nerve palsy in skull base tumors.

OBJECTIVE

Spontaneous recovery of a sixth nerve palsy is thought to rule out a neoplastic origin. We reviewed cases of sixth nerve palsy that improved without treatment but that ultimately proved to be caused by a tumor at the base of the skull.

DESIGN

Case series.

SETTING

Hospital-based, neuro-ophthalmology referral practice.

PATIENTS: Seven patients with an age range from 7 to 61 years had sixth nerve palsy secondary to a slow-growing neoplasm at the skull base.

MAIN OUTCOME MEASURES: Return of lateral rectus function and resolution of diplopia without intervention.

RESULTS

Seven patients with sixth nerve palsy caused by skull base tumors experienced spontaneous improvement of their deficit. Recovery time ranged from 1 week to 18 months. No patient was diabetic or had evidence of vascular disease. In one patient, the palsy improved once prior to becoming a fixed deficit, and spontaneous improvement occurred on two to five occasions in the other patients.

CONCLUSION

Spontaneous recovery of a sixth nerve palsy can occur in the presence of an extramedullary compression by a tumor at the base of the brain. Possible mechanisms for recovery include remyelination, axonal regeneration, relief of transient compression (eg, resorption of hemorrhage), restoration of impaired blood flow, slippage of a nerve previously stretched over the tumor, or immune responses to the tumor.