Long‐Term Outcome of Functional Hemispherectomy in Two Cases of Diffuse Cortical Dysplasia of One Hemisphere

Purpse: Patients with diffuse cortical dysplasia in one cerebral cortex, such as those with cortical hemihypertrophy, are well known to have intractable epileptic seizures and severe developmental delay of mental state and motor skills. We previously reported that the region of cortical dysplasia shows the histologic characteristics of neuronal hyperactivity with impaired γ-aminobutyric acid (GABA)-mediated transmission. Resections of one hemisphere have historically been performed to control such epileptic seizures, although often they also cause severe complications such as massive bleeding and hydrocephalus. To decrease the severity and incidence of such complications, a procedure known as modified hemispherectomy was recently developed. We performed functional hemispherectomies on two cases of intractable epilepsy caused by unilateral cortical dysplasia. The purpose of this study was to evaluate the long-term clinical effects of this surgery for epileptic seizure, including the effects on mental state and motor skills. Patients and Methods: Case 1 was a 4-year-old boy whose epilepsy first occurred 2 weeks after birth. The seizures were focal motor seizures and secondarily generalized seizures, which began from the region of the right face. The seizures occurred >l00 times every day and sometimes involved the pharyngeal region, leading to apneic episodes. The patient was severely retarded and had no head control, could not respond to his name being called, and could not track movements visually. Case 2 was a 2–year 10–month-old boy, whose epilepsy appeared at birth and whose seizures were simple motor and secondarily generalized seizures occumng 20–50 times a day. He was a floppy infant, could not sit, could crawl only on his elbows, and could not speak. The epileptic seizures of both cases were intractable to any anticonvulsant therapy. Case 1 had unilateral cortical hypertrophy of left hemisphere on magnetic resonance imaging (MRI), and case 2 had a large cortical hyperplasia occupying almost two thirds of the left hemisphere. The epileptic seizures were confirmed to originate from the region of the cortical dysplasia by both ictal and interictal physiological examinations, including EEG and single-photon-emission computed tomography (SPECT). Functional hemispherectomy with resection of the parietal cortex and fiber disconnection was performed in case 1. Case 2 received a modified hemispherectomy. which involved only a fiber-disconnection procedure, and was originally developed by Simizu. The clinical effects of the surgical treatment were evaluated in both cases with regard to epileptic seizures and mental and motor development. The follow-up period was 3.5 years in case 1, and 1.5 years in case 2. Results: Unfortunately, case 1 had a massive intracranial hemorrhage and hydrocephalus shortly after the operation. Thereafter, however, he became stable and could eat, respond to stimuli, such as the voice of his mother, and follow movements visually. His epileptic seizures disappeared after treatment with only phenytoin (PHT). In case 2, the seizures disappeared completely with no anticonvulsant therapy from the day of the operation. His right hemiplegia recovered remarkably, and he can now stand and walk, and he can use his right fingers. He can speak, sing a song, and seems happy. Although soon after operation, he was almost completely deaf in the right ear, he can now respond even to a whisper. Conclusions: Because patients with diffuse cortical dysplasia often have severe epileptic seizures and developmental delays, surgical treatment should be considered to control the epilepsy and allow developmental “catch-up”, and should be performed, if necessary, as soon as possible after determining its intractability to anticonvulsant medication.