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.