Surgical Treatment of Mesial Temporal Lobe Epilepsy in a Patient with Neurofibromatosis Type 1
A 32-year-old lady had developed seizures 5 years before visiting our hospital. She was a right handed postgraduate student. Her mom reported that she fumbled her fingers and showed lip smacking during her seizures and did not respond to questions. She reported only one episode of secondarily generalized seizures, which occurred before taking any antiepileptic drugs. The auras were the most frequently abdominal, but rarely vertiginous or psychic. The initial brain MRI had showed unusual multifocal lesions. Stereotaxic biopsy did not confirm the etiologic diagnosis.\nAfter the biopsy, she had been transferred and followed-up at our epilepsy outpatient clinic for seizure control. On family history, her grandmother had seizures. Physical examination showed apparent axillary pigmentation and freckling, seven café-au-lait spots which are more than 15 mm on back. Neurological examination, including visual, and auditory and somatosensory systems, did not reveal any focal deficit. Serial brain MRI showed multifocal lesions in right temporal area, left tectum, right cerebellar peduncle thalamus, basal ganglion, and intraventricular cyst in left trigon of the ventricle (). Those lesions were well localized and not enhanced, and were not accompanied by surrounding edema, which were compatible with CNS hamartomas. The right mesial temporal area showed increased signal changes and increased volume, prominently in the head of hippocampus. The volumetric study of hippocampi demonstrated that the total volume of right hippocampus was slightly bigger than that of left hippocampus [right hippocampus: 4,105 mm3 (normal range: 2,563–4,195 mm3), left hippocampus 3,659 mm3 (normal range: 2,476–3,973 mm3)]. The difference of right to left hippocampal volume was 446.14 mm3, which was in the normal range (−38.3–531.3 mm3). Those lesions were suggestive of multifocal infiltrative glioma, pleomorphic xanthoastrocytoma with multifocal involvement, other CNS lymphoma, vasculitis, and etc. However the enhanced MRI demonstrated multiple small lesions mainly in the scalp areas, indicating neurofibromas in skin, even though those lesions did not show clinical features (). Those skin manifestations and scalp MRI findings suggested neurofibromatosis type 1.\nAfter the polytherapy of antiepileptic drugs, the intensity of her seizures was milder, but the frequency of her seizures was not changed. During the hospital course, she had simple partial seizures monthly and, complex partial seizures twice per year, when she had been on oxcarbazepine 1,500 mg, topiramate 400 mg, levetiracetam 3,000 mg, clobazam 10 mg, and pregabalin 150 mg per day.\nIntellectual assessment revealed that the score of full scale IQ was 85, that of verbal IQ score 87, and that of performance IQ 84 which was estimated to be between 14.2–19.2 percentile. Her neuropsychological tests showed diffuse cerebral dysfunction. Beck’s depression inventory score was normal.\nFor treating intractable seizures and obtaining the pathologic tissues, presurgical evaluation of epilepsy surgery was performed, including video-EEG monitoring, Wada test, and detailed neuro-imaging studies.\nShe underwent three day video-EEG monitoring. During the stay, 10 complex partial seizures and 1 simple partial seizure were recorded. The one simple partial seizure was only abdominal aura. The complex partial seizures were consisted of abdominal aura, lip smacking, leaning backward, often with right or both hand fumbling, but, not accompanied by generalized seizures.\nThe interictal epileptiform discharges were frequently seen on right mid-temporal area about once per minute. The 11 ictal epileptiform discharges started with semi-rhythmic theta waves in right temporal area, and then delta waves in the same area, spreading into whole leads ().\nShe underwent ictal and interictal 99m-Tc HMPAO SPECT. The radiotracer for ictal SPECT was injected at 40 seconds from the onset of 102 second duration habitual complex partial seizure. The hyperperfusion was localized to right anterior mesial temporal area. Interictal SPECT, taken after 24 hour seizure freedom, showed focal hypoperfusion in right mesial temporal area. Subtracted ictal SPECT co-registered to MRI demonstrated definitely hyperperfused areas in right mesial temporal regions, which are concordant to the localization of ictal EEG onset (). Other lesions did not show any perfusion changes in SPECT studies. Brain 18F-FDG PET showed right temporal hypometabolism. Other brain and scalp lesions, which were confirmed on brain MRI, did not reveal any metabolic changes in PET study. Wada test demonstrated that her left hemisphere were both dominant for speech and memory, predicting good surgical outcome of right anteromesiotemporal resection.\nAfter the removal of right anteromesial temporal area, her seizures became free. The pathologic tests showed mild neuronal loss at hippocampus, and dysplastic changes in the specimen of lesion tissue without any evidence of neoplasm.