Presented to the 53rd Annual Meeting of the American Epilepsy Society, December 1999

Cognitive Decline after Epilepsy Surgery in Cryptogenic Temporal Lobe Epilepsy

Daniela N Minecan, Wassim Nasreddine, Gus Buchtel, Linda Selwa, Erasmo Passaro, Donald Ross, Ahmad Beydoun, University of Michigan, Ann Arbor, MI

Introduction: Post-operative cognitive decline is a potential complication of anterior temporal lobectomy (ATL) in patients with Temporal Lobe Epilepsy (TLE). We compared the post-operative change in Verbal IQ (VIQ)and Performance IQ (PIQ) in patients with cryptogenic temporal lobe epilepsy (normal. MRI) (CTLE) to those with mesial temporal sclerosis (MTS).

Methods: We included all patients who underwent anterior temporal lobectomy and who had pre and post-operative neuropsychological testing (2 mo-1 year). Patients with MRI lesions other than Mesial temporal lobe sclerosis were excluded. We divided patients into dominant (DATL) and nondominant hemisphere (NDATL) anterior temporal lobectomy groups according to language dominance as determined by the Wada Test. Each group was subdivided into Cryptogenic temporal lobe epilepsy (CTLE) and Mesial temporal lobe sclerosis (MTLE). We defined DVIQ = (pre-operative VIQ) - (post-operative VIQ) and DPIQ = (pre-operative PIQ) - (post-operative PIQ).

Results: 74 patients (M/F 33/46) with a mean age of 38 years were included.

Dominant temporal lobectomy: 38 patients underwent dominant temporal lobectomy: 14 had Cryptogenic temporal lobe epilepsy and 24 has mesial temporal lobe sclerosis. The mean pre-op VIQ and PIQ were 88 and 94 respectively in Cryptogenic temporal lobe epilepsy patients, and 85 and 91 in mesial temporal lobe sclerosis patients. The mean DVIQ was larger in Cryptogenic temporal lobe epilepsy compared to Mesial temporal lobe sclerosis (4.0 vs 0.25, p = 0.018). Three Cryptogenic temporal lobe epilepsy and no Mesial temporal lobe sclerosis patients had a DVIQ of at least 10 (p=0.043, Fisher test). The mean DPIQ was not different between Cryptogenic temporal lobe epilepsy and Mesial temporal lobe sclerosis (0.57 vs 0.38, p > 0.1).

Non-dominant temporal lobectomy: 41 patients underwent non-dominant anterior temporal lobectomy: 20 had Cryptogenic temporal lobe epilepsy and 21 Mesial temporal lobe sclerosis. The mean pre-op VIQ and PIQ were 89 and 94 respectively in Cryptogenic temporal lobe epilepsy patients, and 92 and 94 respectively in Mesial temporal lobe sclerosis patients. The mean DVIQ was larger in Cryptogenic temporal lobe epilepsy compared to Mesial temporal lobe sclerosis (1.65 vs -2.7, p = 0.005). The mean DPIQ was not different between the Cryptogenic temporal lobe epilepsy and the Mesial temporal lobe sclerosis groups (1.2 vs 3.9, p > 0.1).

Conclusions: Patients with Cryptogenic temporal lobe epilepsy have a significant decline in VIQ after dominant and nondominant anterior temporal lobectomy compared to patients with Mesial temporal lobe sclerosis. 21.4% of patients with Cryptogenic temporal lobe epilepsy had a clinically significant decline in VIQ (>10) after dominant hemisphere anterior temporal lobectomy.


http://www.umich.edu/~gusb/minecan.aes.1999.html