Changes in Central Auditory Processing in Patients with Mesial Temporal Lobe Epilepsy after Anterior Temporal Lobectomy with Amygdalohippocampectomy

Background and Purpose This study aimed to determine the effects of anterior temporal lobectomy with amygdalohippocampectomy (ATL-AH) on central auditory processing (CAP) in patients with mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS), and to identify factors that may contribute to the postoperative worsening of CAP. Methods Frequency-pattern, duration-pattern, and dichotic tests were performed before and after epilepsy surgery in 22 patients with normal hearing according to pure-tone audiometry. Results No significant difference in CAP scores was detected between pre- and postoperative tests, but there was a strong association between surgery in the language-dominant temporal lobe and postoperative worsening in the non-dominant-side dichotic test (p<0.05). The probability of a decreased performance in a non-dominant-side dichotic test after surgery was 7.5-fold greater in patients who underwent surgery on the dominant temporal lobe compared with the nondominant temporal lobe. No significant association of postoperative worsening in CAP with the verbal, nonverbal intelligence quotient, or right- or left-side lobectomy was noted. Conclusions These results suggest that ATL-AH on the dominant side in patients with mTLE-HS worsens the CAP ability in the non-dominant-side dichotic test.