Recurrent and self-remitting sixth cranial nerve palsy: pathophysiological insight from skull base chondrosarcoma

Palsy of the abducens nerve is a neurological sign that has a wide range of causes due to the nerve's extreme vulnerability. Need of immediate neuroimaging is a matter of debate in the literature, despite the risks of delaying the diagnosis of a skull base tumor. The authors present 2 cases of skull base tumors in which the patients presented with recurrent and self-remitting episodes of sixth cranial nerve palsy (SCNP). In both cases the clinical history exceeded 1 year. In a 17-year-old boy the diagnosis was made because of the onset of headache when the tumor reached a very large size. In a 12-year-old boy the tumor was incidentally diagnosed when it was still small. In both patients surgery was performed and the postoperative course was uneventful. Pathological diagnosis of the tumor was consistent with that of a chondrosarcoma in both cases. Recurrent self-remitting episodes of SCNP, resembling transitory ischemic attacks, may be the presenting sign of a skull base tumor due to the anatomical relationships of these lesions with the petroclival segment of the sixth cranial nerve. Physicians should promptly recommend neuroimaging studies if SCNP presents with this peculiar course.