Preservation of Memory Despite Unresected Contralateral Hippocampal Volume Loss After Resection of Hippocampal Sclerosis in Seizure-Free Patients

Objective To determine postoperative long-term changes of hippocampal volume (HV) correlating with cognitive functions in patients who underwent surgery for hippocampal sclerosis with postoperative freedom from seizures. Methods We studied 1.5T magnetic resonance imaging before and after surgery in 24 patients (mean ± SD age, 36.9 ± 11.0 years) with hippocampal sclerosis. We performed serial magnetic resonance imaging at 6 months to 1 year, 1–2 years, 2–3 years, and 3–5 years postoperatively. We compared HVs of 24 patients with HVs of 14 age-matched control subjects. We analyzed correlations between consecutive HVs and seizure duration and age at surgery. We compared consecutive changes in HVs between dominant and nondominant hemispheres with concurrent cognitive functions. Results Preoperative HVs of unresected contralateral hippocampus were significantly smaller than HVs of control subjects (P Conclusions In seizure-free patients after hippocampal sclerosis resection , unresected contralateral HV significantly declined with older age at surgery. Visual memory was preserved regardless of side and volume loss. Despite significantly reduced HVs, verbal memory was preserved with the unresected contralateral dominant hippocampus. Earlier surgical intervention may have lower potential risk for memory decline secondary to postoperative HV loss.