CALLOSOTOMY FOR INTRACTABLE EPILEPSY FROM BIHEMISPHERIC CORTICAL DYSPLASIAS

Four patients suffering for severe drug-resistant epilepsy from bihemi spheric cortical dysplasias underwent anterior callosotomy. One of the se patients also presented mental retardation of mild degree associate d with the epileptic syndrome. There were no operative complications i n this series. Clinical signs of interhemispheric disconnection were n ot detectable postoperatively. Twenty-eight to 53 months after surgery , the generalized seizures were completely suppressed in 2 cases, and were reduced by 89-97% in frequency in the other 2 cases. Partial seiz ures were less affected by callosotomy being reduced by 14-87%. In an additional fifth case of intractable epilepsy from bihemispheric corti cal dysplasias with associated severe mental retardation operated upon elsewhere for callosotomy and followed at our institution, the outcom e for seizures was completely unsatisfactory. Neurophysiological studi es revealed that the interhemispheric transfer (IHT) of visuo-motor re sponses was functionally impaired after callosotomy only in one patien t who harboured bilateral cortical dysplasias in the occipital lobes. This malformation might affect the pattern of axonal projection to the posterior portion of the corpus callosum which is considered of cruci al importance for the integration of crossed visuo-motor responses. Fr om this paper the following conclusions can be drawn: a) epileptic pat ients with severe drug-resistant epilepsy due to bihemispheric cortica l dysplasias are good candidates for callosotomy, b) one-stage extensi ve anterior callosotomy sparing the splenium is the procedure of choic e, c) associated severe mental retardation seems to contra-indicate ca llosotomy, d) the neurophysiological study of the IHT can yield inform ation on the functional status of the corpus callosum.