Neurophysiologic and neuroradiologic features of intractable epilepsy after traumatic brain injury in adults

Background: There is controversy regarding the precise mechanism by which e pilepsy results after traumatic brain injury (TBI). Previous reports have s uggested that mesial temporal lobe epilepsy may result from TBI only in you ng children, while neocortical epilepsy arises from TBI in later life. Thes e conclusions were based on surgical series and may be biased because of pa tient selection. Objective: To determine the frequency of mesial temporal lobe as opposed to neocortical epilepsy in patients with intractable epilepsy resulting from TBI after the age of 10 years. Patients and Methods: We identified 23 patients with intractable epilepsy w ho had TBI after the age of 10 years, preceding the onset of epilepsy. Pati ents were studied by simultaneous videotape and scalp electroencephalograph ic recording of typical seizures; magnetic resonance imaging; neuropsycholo gic studies; and, when appropriate, intracarotid amobarbital testing. Two p atients underwent anterior temporal lobectomies. Results: Of the 23 patients, 8 (35%) had mesial temporal lobe epilepsy, bas ed on the finding of hippocampal sclerosis on a magnetic resonance imaging scan, consistent interictal and ictal electroencephalographic recordings, e vidence of temporal lobe dysfunction on neuropsychologic testing, and chara cteristic seizure semiology. Two of these patients underwent anterior tempo ral lobectomies with clinical benefit, and hippocampal sclerosis was confir med pathologically. In 2 cases, patients were not treated surgically becaus e of bilateral temporal lobe dysfunction noted on intracarotid amobarbital testing. Eleven patients had neocortical epilepsy; 1 had primary generalize d epilepsy; and, in 3, the site of seizure onset was not localized. Conclusions: Mesial temporal lobe epilepsy can result from TBI in adolescen ts and adults as well as in children, and can often be bilateral and associ ated with multifocal injury. This information may be useful in developing p rophylactic therapy for posttraumatic epilepsy.