Bilateral hippocampal atrophy - Consequences to verbal memory following temporal lobectomy

Background: Bilateral hippocampal damage is a risk factor for memory declin e after anterior temporal lobectomy (ATL) Objective: To investigate verbal memory outcome in patients with temporal lobe epilepsy (TLE) with either un ilateral or bilateral hippocampal atrophy as measured by MRL Methods: The a uthors selected 60 patients with TLE who had undergone ATL (left = 31, righ t = 29). They determined normalized MRI hippocampal volumes by cursor traci ng 1.5-mm slices from three-dimensional MRI acquisition. Hippocampal volume s were defined as atrophic if the volumes were below 2 SD for control subje cts. Bilateral hippocampal atrophy was present in 10 patients with left TLE and 11 patients with right TLE. The authors assessed acquisition, retrieva l, and recognition components of verbal memory both before and after ATL. R esults: Groups did not differ across age, education, intelligence, age at s eizure onset, or seizure duration. Seizure-free rates after ATL were 70%, o r higher for all groups. Before surgery, patients with left TLE displayed w orse verbal acquisition performance compared with patients with right TLE. Patients with left TLE with bilateral hippocampal volume loss displayed the lowest performance across all three memory components. After surgery, both groups of patients with left TLE exhibited worse verbal memory outcome com pared with patients with right TLE. Bilateral hippocampal atrophy did not w orsen outcome in the patients with right TLE. A higher proportion of patien ts with left TLE with bilateral hippocampal atrophy experienced memory decl ine compared with the other TLE groups. Conclusion: Bilateral hippocampal a trophy in the presence of left TLE is associated with worse verbal memory b efore and after ATL compared with patients with unilateral hippocampal volu me loss or right TLE with bilateral hippocampal volume loss.