Chronic Traumatic Encephalopathy Uncommon in Treatment-Refractory Epilepsy

Chronic traumatic encephalopathy (CTE) is relatively uncommon in young adult patients undergoing surgical treatment for drug-resistant focal epilepsy, according to the results of a small retrospective observational study conducted at the Mayo Clinic in Rochester, Minnesota, and published in Neurology.

A total of 10 patients who had undergone epilepsy surgery were randomly selected for this investigation. Of the participants, 5 underwent temporal lobe resections and 5 underwent frontal lobe focal cortical resections. All patients were between 18 and 45 years of age, underwent a preoperative neuropsychological assessment, and had a 1-year postoperative follow-up. In all participants, microscopic sections from resections were examined for the presence of CTE with the use of standard stains and antibodies to tau (clone AT8).

Median patient age at resection was 32.5 years (range, 23-43 years). The median duration of seizures prior to surgery was 23.5 years (range, 3-8 years). Of the 10 patients, 1 experienced focal impaired awareness seizures, 2 had tonic-clonic seizures, and 7 experienced both types of seizures. Only 1 of the 10 patients had a history of status epilepticus. The frequency of the patients’ seizures ranged from 2 to 3 per day to 1 to 2 per year.

Overall, 2 patients reported experiencing mild concussions prior to seizure onset, 6 had documented “head trauma” related to seizures, and 2 had no history of head injury. Preoperative neuropsychological testing revealed mild to moderate cognitive impairment in 8 patients. Pathologic examination of 1 of these patients with reduced cognitive performance revealed tau deposition. Overall, 9 of the 10 patients displayed no evidence of CTE.

The researchers concluded that the results of this study warrant additional investigation to define the relative importance of tau accumulation in young adult patients with drug-resistant focal epilepsy and cognitive decline. Larger, longer-term prospective studies are needed to determine the prevalence of CTE in younger patients with epilepsy and to help establish any possible relationship between pathologic findings and cognitive defects.

Reference

Jones AL, Britton JW, Blessing MM, Parisi JE, Cascino GD. Chronic traumatic encephalopathy in an epilepsy surgery cohort: clinical and pathologic findings [published online January 10, 2018]. Neurology. doi: 10.1212/WNL.0000000000004927