Introduction: Deep medial parieto-occipital arteriovenous malformations (AVMs) and cerebral cavernous malformations (CCMs) are traditionally resected through an ipsilateral posterior interhemispheric approach (IPIA), which creates a deep, perpendicular perspective with limited access to the lateral margins of the lesion. The contralateral posterior interhemispheric approach (CPIA) flips the positioning, with the midline positioned horizontally for gravity retraction, but with the AVM on the upside and the approach from the contralateral, dependent side.
Methods: Retrospective review of pre- and postoperative clinical and radiographic data was performed in 8 patients operated with a CPIA.
Results: Three AVMs and four CCMs were resected using the CPIA, with an average nidus size of 2.3 cm and CCM diameter of 1.7 cm. All lesions were resected completely, as confirmed by postoperative catheter angiography or magnetic resonance imaging. All patients had good neurological outcomes, with either stable or improved mRS at LFU.
Conclusions: The CPIA is a safe alternative approach to the IPIA for deep medial parieto-occipital vascular malformations that extend 2 cm or more off the midline. Contralaterality and gravity retraction optimize the interhemispheric corridor, the surgical trajectory to the lesion, and the visualization of the lateral margin, without resection or retraction of adjacent normal cortex. Although the falx is a physical barrier to lesion access, it stabilizes the ipsilateral hemisphere while gravity delivers the dissected lesion through the transfalcine window. Patient positioning, CSF drainage, venous preservation, and meticulous dissection of the deep margins are critical to the safety of this approach.
Patient Care: Gravity retraction in combination with a contralateral approach prevents resection or retraction of adjacent normal cortex
Learning Objectives: gravity retraction using a contralateral approach optimize the interhemispheric corridor, the surgical trajectory to the lesion, and the visualization of the lateral margin, without resection or retraction of adjacent normal cortex