Abstracts

Up to 5% of patients with multiple sclerosis have concurrent epilepsy. This is a higher prevalence than the general population. We describe a patient with MS and intractable epilepsy who benefited from epilepsy surgery, highlighting some important issues in treating this dual disorder. Our patient was a 50 year-old right handed woman with MS and intractable epilepsy. She had been treated with multiple AEDs without success and continued to have frequent clusters of generalized tonic-clonic seizures followed by protracted periods of poor cognition making it impossible for her to function independently. Her MRI showed extensive plaques throughout the brain, including both temporal lobes. Volumetric MRI revealed marked right hippocampal atrophy. PET showed diffuse hypometabolism. Video EEG monitoring showed almost equal right and left medial temporal onset seizures. Bilateral temporal lobe depth electrodes showed 7/8 clinical seizures from the left hippocampus and 28/32 subclinical seizures from the right hippocampus. Those that started on the right and spread to the left became clinically evident. Those that remained on the right, and did not spread, were subclinical. The patient subsequently had a right temporal lobectomy with intraoperative electrocorticography. The electrocorticography revealed frequent interictal spiking over the lateral temporal neocortex. Postoperatively, she developed a superior quandrantanopia, visual processing problems, and continued to have nocturnal seizures at the same rate. Addition of levetiracetam to her phenytoin resulted in a cessation of all clinical seizures. She has remained seizure free for over two and a half years and can live independently. Neuropathological examination showed hippocampal sclerosis (grade 4/5) and severe demyelination in the neocortex underlying electrode locations that were silent during electrocorticography. Temporal neocortex underlying electrodes that showed frequent interictal spiking did not show demyelination. This carefully-studied patient with both MS and epilepsy raises important issues in the surgical management of these patients. First, patients with intractable epilepsy and MS can benefit from epilepsy surgery. Second, diffuse demyelination makes it difficult to localize seizure foci with conventional imaging tools. Third, epilepsy sugery can produce unexpected deficits, such as her visual processing problems. Fourth, extremely frequent epileptiform activity was seen overlying regions of relatively normal neocortex, but not over adjacent, demyelinated neocortex. This suggests a neocortical model of epileptogenesis in multiple sclerosis due to nearby demyelination or inflammation. Fifth, this patient[apos]s epileptogenic process seemed to exhibit an interaction between medial and lateral temperal structures, in that she had marked HS as well as an actively spiking lateral temporal neocortex, which was adjacent to areas of demyelination.