Background and objective: Hemispherotomy surgery in adults is shrouded in doubts regarding the functional outcome. The age at surgery alone should not be the deciding factor for surgery. Language paradigms were used in functional magnetic resonance imaging (fMRI) to confirm the role played by the age at the onset of seizures to predict the postoperative functional outcome. The objective of the study was to formulate an optimal strategy for patient selection for the left-sided hemispherotomy in adults, based on functional outcome analysis.
Materials and methods: A retrospective analysis of 20 participants (age at surgery 1-26 years) who underwent left hemispherotomy (over a 5-year period) was conducted. The language and motor functional assessments of 18 participants (13 pediatric and five adult participants; attrition of participants- two) were recorded at presentation and during follow-up visits. After approval was obtained from the Institutional Ethics Committee, 13 cooperative participants (eight pediatric and five adult participants) underwent language fMRI. Motor fMRI with both active and passive paradigms was done in 16 participants.
Results: All 18 participants with a mean follow-up of 24 months had class I seizure-free outcome. Of these 18, five were adults (mean age = 21 years, range: 18-22 years) and 13 were in the pediatric age group (mean age = 8 years, range: 2-15 years). Postoperatively, four adults retained both verbal fluency and language comprehension at a mean follow-up period of 38 months (range: 24-48 months). Their pre- and post-op language fMRI showed word generation and regional activations for semantic comprehension in the right hemisphere. The motor area activations were seen in the right hemisphere in two and in the left hemisphere in two participants. Among the pediatric participants, four (group I [n = 4/13]) who had good language outcome showed activations in the right hemisphere. In two participants (group II [n = 2/13]) who deteriorated postoperatively, the activations were in the left hemisphere. Five participants (group III [n = 5/13]) who retained the telegraphic language postoperatively had bilateral activations of semantic comprehension areas in fMRI. All 13 pediatric participants had motor area activations seen in the left hemisphere, similar to controls.
Conclusion: Left hemispherotomy can be advised to adults with comparably good postoperative language and motor outcome as in the pediatric age group, provided the weakness is acquired perinatally or below the age of 7 years. The fMRI is a valuable tool to aid in patient selection.
Keywords: Epilepsy; fMRI; hemispherotomy; language; plasticity.