Memory, executive function and language function are similarly impaired in both temporal and extra temporal refractory epilepsy-A prospective study

Cognitive impairment has long been recognized as a co-morbidity or sequel to refractory epilepsy. This study was conducted to evaluate the degree and selectivity of involvement of memory, language and executive functions performance among patients with temporal (TLE) versus extratemporal epilepsy (ETLE).

We prospectively enrolled adolescent and adult patients with medically refractory focal epilepsy, who had undergone pre-surgical evaluation. Language, memory and executive function assessment was done using Western Aphasia Battery, PGI memory scale and battery of four executive function tests (trail making test A & B, digit symbol test, Stroop Task and verbal fluency test), respectively.

Among102 patients enrolled (TLE-59, ETLE-43), mean age of patients 23.0 4± 8.3 years, 83 (82%) had impairment of more than one cognitive domain and 21 (21%) had all three domains involved. Severely impaired memory scores were found in 8.6% patients with MTLE-HS, 8% of the rest of the patients with TLE and 7% patients with ETLE. The differences in the mean scores were also not found statistically significant (p=0.669). Naming impairment was the most common language abnormality, although all aphasia subscores were similar for the ETLE and TLE groups. Executive function impairment was the most common cognitive domain affected. Overall performance on executive function tests was found impaired in almost all patients of both groups without any significant inter-group difference, except on Trail-A test, which revealed better results in patients with mTLE-HS as compared to all other sub-groups.

Our study shows that impairment of memory, language and executive function is common among patients with drug refractory epilepsy. The most prevalent impairment is in executive function. There is no significant difference in the degree, prevalence or selectivity of impairment in either of the three domains, between the TLE versus ETLE groups.