In Reply: Contralateral Anterior Interhemispheric Approach to Medial Frontal Arteriovenous Malformations: Surgical Technique and Results.

Abstract

Background Medial frontal arteriovenous malformations (AVMs) require opening the interhemispheric fissure and are traditionally accessed through an ipsilateral anterior interhemispheric approach (IAIA). The contralateral anterior interhemispheric approach (CAIA) flips the positioning with the midline still positioned horizontally for gravity retraction, but with the AVM on the upside and the approach from the contralateral, dependent side. Objective To determine whether the perpendicular angle of attack associated with the IAIA converts to a more favorable parallel angle of attack with the CAIA. Methods The CAIA was used in 6 patients with medial frontal AVMs. Patients and AVM characteristics, as well as pre- and postoperative clinical and radiographic data, were reviewed retrospectively. Results Four patients presented with unruptured AVMs, with 5 AVMs in the dominant, left hemisphere. The lateral margin was off-midline in all cases, and average nidus size was 2.3 cm. All AVMs were resected completely, as confirmed by postoperative catheter angiography. All patients had good neurological outcomes, with either stable or improved modified Rankin Scores at last follow-up. Conclusions This study demonstrates that the CAIA is a safe alternative to the IAIA for medial frontal AVMs that extend 2 cm or more off-midline into the deep frontal white matter. The CAIA aligns the axis of the AVM nidus parallel to the exposure trajectory, brings its margins in view for circumferential dissection, allows gravity to deliver the nidus into the interhemispheric fissure, and facilitates exposure of the lateral margin for the final dissection, all without resecting or retracting adjacent normal cortex.