Transient Abducens Nerve Palsy Following Radiofrequency Rhizotomy for Multiple Sclerosis-Associated Trigeminal Neuralgia
Shearwood McClelland III M.D., Christopher D. Roark M.D., Stephen J. Haines M.D.
Department of Neurosurgery, University of Minnesota Medical School, Minneapolis, MN
Percutaneous radiofrequency rhizotomy (PRFR) for medically intractable trigeminal neuralgia (TN) is well-established, with efficacy ranging from 80-100% for TN associated with multiple sclerosis (MS). Although previous reports of PRFR have revealed morbidity along the trigeminal nerve (corneal reflex pathology, anesthesia dolorosa) related to the destructive nature of the procedure, the occurrence of abducens nerve palsy (ANP) has yet to be reported in this patient population. We present a report of ANP associated with PRFR for MS-associated TN.
A 59-year-old man with a known history of MS presented with a six-year history of intense lancinating facial pain in the distribution of the maxillary (V2) and ophthalmic (V1) divisions of the left trigeminal nerve increasingly refractory to optimal medical management. Because MRI revealed no intracranial pathology or vascular compression of the trigeminal nerve, he was recommended for PRFR. The probe was gradually advanced into the skull through the foramen ovale toward the left trigeminal nerve under continual C-arm fluoroscopic guidance, after which a single lesion at 60 degrees for 60 seconds was made for sufficient lesioning of the appropriate pain fibers.
Postoperatively, neurological examination revealed persistent left lateral gaze impairment, consistent with a left ANP. CT revealed no intracranial pathology explaining the new-onset deficit. Due to this finding and his otherwise normal neurological exam, the patient was managed with reassurance and serial outpatient follow-up. The ANP spontaneously resolved 5 months later, with the patient continuing to experience significant reduction of his TN following PRFR.
In this report of abducens nerve palsy following PRFR for MS-associated TN, our findings indicate that ophthalmic involvement of TN is a risk factor, and that in the setting of negative brain imaging and an otherwise normal neurological examination, reassurance and meticulous outpatient follow-up are appropriate and sufficient management modalities for this condition.
Trigeminal Neuralgia, Multiple Sclerosis, Percutaneous Radiofrequency Rhizotomy, Abducens Nerve