Transsylvian keyhole functional hemispherectomy

OBJECTIVE: To describe the technical steps, advantages, and limitations of a quicker, minimal-exposure, functional hemispherectomy procedure developed from a hemispherical deafferentation technique previously described. METHODS: The surgical approach using the transsylvian/transsulcal passage t o the ventricular system, with the anatomic orientation points and key feat ures for planning of the small trepanation, is described. Through a linear incision, a craniotomy (4 x 4 to 4 x 5 cm) is placed over the sylvian fissu re. Transsylvian exposure of the circular sulcus allows transcortical expos ure of the entire ventricular system, from the frontal horn to the temporal horn encircling the insular cortex. The frontobasal and mesial white matte r is disconnected via the intraventricular approach, with a callosotomy. An amygdalohippocampectomy completes the dissection. The experience with 20 p atients who were treated using the transsylvian keyhole hemispherectomy tec hnique is summarized. RESULTS: The operation time was significantly shorter (mean, 3.6 h) than wi th the Rasmussen technique (mean, 6.3 h) and 25% shorter than with the tran scortical perisylvian technique (mean, 4.9 h). The proportion of patients r equiring blood replacements was lower (15 versus 58%), as was the mean amou nt of transfused blood. The mean follow-up period was 46 months; 88% of pat ients were in Engel Outcome Class I, 6% in Class III, and 6% in Class IV. CONCLUSION: The transsylvian keyhole procedure has been demonstrated to fur ther reduce operation time and the need for blood replacement. It is most e asily performed in cases with enlarged ventricles or perinatal ischemic cys ts and is not recommended for hemimegalencephaly. The immediate seizure rel ief was satisfying. This minimal-exposure approach seems to be a satisfying alternative among possible functional hemispherectomy procedures.