Ahmad Hafez1,2, Kunal P Raygor1, Michael T Lawton1. 1. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California. 2. Department of Neurosurgery, Helsinki University Central Hospital, Helsinki, Finland.
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.
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.