A historical perspective: Stereotactic lesions for the treatment of epilepsy

PURPOSE Most deep brain stimulation targets for movement disorders were derived from effective ablative surgery targets. Similarly effective lesion targets for epilepsy control may help refine brain stimulation targeting for epilepsy. A literature review of past stereotactic lesions for epilepsy treatment was performed to provide historical context and possible anatomical guidance for current and future attempts at controlling epilepsy with electrical stimulation. This work was undertaken to provide insights for electrical stimulation targets in epilepsy treatment based on outcomes from previous ablative therapies. METHODS A MEDLINE search was conducted for studies with the words "stereotactic surgery" and "epilepsy." Post-operative results for 619 patients with stereotactic brain lesions targeting various anatomical foci were standardized using a modified Engel scale (1 'free of seizures' to 3 'no significant improvement'). Each individual patient was entered into a database as a unique data point. RESULTS There was a statistically significant difference in reported seizure control among the different procedures and seizure types. The procedures that produced the best seizure control outcomes were the hippocampectomy, pallido - amygdalotomy, and amygdalohippocampectomy. Simple partial motor and combined generalized tonic clonic with complex partial seizure types demonstrated the best outcomes following surgery; complex partial and generalized tonic had the worst outcomes. CONCLUSIONS The results of this study demonstrate the location of brain lesions has a significant effect on seizure control. Thus, future research designed to optimize brain stimulation targets for epilepsy control may be informed by previous ablative outcomes.