Long term follow-up after multiple hippocampal transection (MHT)

PURPOSE Multiple hippocampal transection (MHT) is a new surgical procedure which disrupts seizure propagation within the hippocampus without impairing verbal memory or the loss of stem cells. Since there are very few papers on this procedure, the authors are presenting their long term results to increase the database on this procedure. METHOD Long term outcome in 15 consecutive patients who had MHT for unlilateral temporal lobe epilepsy, had intra-operative electro-corticography (ECoG) and have a minimum follow-up of at least 2 years is presented. The male/female ratio is 2/1; follow-up is 24-60 months (median of 41 months); and ages between 25 and 60 years. All patients had multiple subpial transection (MST) on the neocortex and MHT on the hippocampus. Amygdalectomy was done if seizure focus was present in the amygdala (10 patients). Temporal tip (1.5-2.5 cm in length) was resected (11 patients) when it was resistant to MST, based on intraoperative EEG recordings. RESULTS There was no permanent neurological complication. Fourteen patients (94.7%) are seizure free (Engel's Class I) and 1 (5.3%) has rare seizures (Class II). Neuropsychological studies showed that verbal memory was preserved. CONCLUSION The results show that the seizure outcome with MHT is equal or better than those reported with standard temporal lobectomy. Furthermore verbal memory is preserved. The study also shows that intraoperative ECoG is important in order to conclude adequacy of the procedure. Based on the result of this study the authors feel that this procedure needs to be persued as an alternate to hippocampectomy.