Left hippocampectomy in an epilepsy patient with right hemisphere language dominance

Abstract

Background: The left hippocampus is believed to play an important role in memory function. Thus, left hippocampectomy should be carefully performed. However, the left hippocampus may be less important for memory in patients with right hemisphere language dominance. We performed left hippocampectomy in a patient with epilepsy and right hemisphere language dominance. Here we present the findings of our functional mapping and examine the relationship between memory and language dominance. Methods: The patient was a 32-year-old left-handed female implanted with subdural electrocorticography (ECoG) grids over both hemispheres to locate the epilepsy focus. Language dominance was determined by the Wada test. Functional localizations were identified with ECoG and electrocortical stimulation (ECS) mapping. The Wechsler Memory Scale-Revised (WMS-R) was used to evaluate the patient’s memory before and after surgery. Results: The epilepsy focus was located in the left mesial temporal lobe and hippocampus. The Wada test revealed right hemisphere language dominance. High gamma activity (HGA) mapping was consistent with ECS mapping in that both showed language-related activity in the right precentral gyrus. The WMS-R revealed improved memory after left hippocampectomy, without neurological deficits. The patient fully recovered without further epileptic seizures. Conclusion: Left hippocampectomy in a patient with epilepsy and right hemisphere language dominance did not cause memory dysfunction. Thus, memory function is possibly related to the language-dominant hemisphere. Furthermore, preoperative mapping and determining a patient’s language dominance can help to preserve language and memory in epilepsy surgery.

Keywords

• memory
• hippocampectomy
• language dominance
• electrocorticogram
• high gamma activity