Asynchronous pentobarbital-induced burst suppression with corpus callosum hemorrhage

OBJECTIVE: We describe the electroencephalographic (EEG) findings in a 9-year-old girl, who presented with generalized tonic-clonic status epilepticus requiring pentobarbital anesthesia, and correlate these findings with clinicoradiologic evidence of a ruptured AVM with hemorrhage into the body of the corpus callosum. METHODS: EEG analysis accompanied by clinical assessment, CT and MRI scans, and cerebral angiography were performed. RESULTS: With pentobarbital coma, the EEG showed burst suppression with prominent interhemispheric asynchrony. Suppression epochs >2 s in duration and with amplitude <20 microV in all channels were identified. In 12 min of the EEG analyzed, 6 unilateral and 20 bilateral epochs occurred. Of the 20 bilateral suppression epochs, interhemispheric asynchrony of >1 s was noted at onset for 5 epochs and at offset for one. Chi-square analysis revealed an equal tendency for unilateral suppressions to occur over either hemisphere, and for suppression in one hemisphere to begin before the other. CONCLUSIONS: We conclude that the corpus callosum plays a critical role in interhemispheric synchronization of cortical neuronal electrical activity and propose that: (1) normally, the corpus callosum modulates interhemispheric synchronization of cortical inhibition; and (2) with corpus callosal disruption, cortical areas are 'released' from such synchronization.