Asynchronous pentobarbital-induced burst suppression with corpus callosum hemorrhage

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.

EEG analysis accompanied by clinical assessment, CT and MRI scans, and cerebral angiography were performed.

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.

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.