Characteristics and surgical outcomes for medial temporal post-traumatic epilepsy

A common post-traumatic location of epileptogenesis is the medial temporal lobe despite evidence of associated diffuse or remote cerebral injury. We undertook a review of post-traumatic medial temporal lobe epilepsy (MTLE) patients as part of an overall post-traumatic epilepsy population to assess the extent of cerebral injury sustained by this subpopulation and to establish whether surgical outcome differed from that of a non-traumatically-induced epilepsy population. A retrospective review of 57 patients operated for post-traumatic epilepsy (PTE) over a 10-year period (1993-2003) was undertaken with particular attention to those undergoing medial temporal resection. Preoperative magnetic resonance imaging (MRI) was assessed for the type and location of abnormalities. Postoperative outcomes were compared with those of patients with MTLE of non-traumatic origin operated by the same surgeon. Of the 57 patients operated, 30 cases underwent medial temporal lobe resection. The most common mechanism of injury was blunt trauma attributable to motor vehicle accidents with imaging abnormalities characterized by medial temporal sclerosis (MTS; 16 cases), T2/FLAIR hyperintensities (nine cases), periventricular gliosis (seven cases), diffuse cerebral atrophy (five cases) and focal encephalomalacia (three cases). Six patients had normal MRI studies. No significant differences in postoperative outcomes were found between post- and non-traumatic MTLE epilepsy groups. The presence of histopathological change in the medial temporal lobe varied greatly and provided no indication of a favourable postoperative outcome. Patients with post-traumatic medial temporal lobe epilepsy respond favourably to surgical treatment. In the case of medial temporal sclerosis, there is substantial variation of histopathological findings which correlate poorly with current imaging applications. The favourable outcomes obtained following surgery in this group attest to a commonality with other risk factors in the genesis of epilepsy in this location.