The Occipital Transtentorial Approach for Superior Vermian and Superomedial Cerebellar Arteriovenous Malformations: Advantages, Limitations, and Options

Introduction: Arteriovenous malformations (AVMs) of the superior vermis and superomedial cerebellum are uncommon lesions. They have been approached through various routes including the subtemporal transtentorial, suboccipital supracerebellar infratentorial, and occipital interhemispheric transtentorial (OITT). We review the advantages and limitations of the OITT route for such AVMs and discuss therapeutic options.

Methods: Case series was reviewed of superior vermian and superomedial cerebellar AVMs that were approached via the OITT route. The key aspects of the OITT approach specific to the treatment of these AVMs are summarized.

Results: The exposure from the posterior incisura to the torcular herophili provides a view of the SCAs, the nidus, and the draining veins, which can be managed sequentially. In circumstances when the AVM extends well beyond midline to the contralateral side, deep to the ventricles, caudally to the cerebellar tonsils, and/or is vascularized by caudal branches of the SCAs, AICA, and/or PICA feeders, or has an aneurysm on any of these feeding arteries, then the OITT alone may not be appropriate. Preoperative embolization can target contralateral, deep, or caudal feeders or aneurysms, potentially rendering the OITT a favorable route. The OITT can also be combined with other approaches for AVMs that extend caudally with multiple feeders.

Conclusion: The OITT approach is a valuable approach for specific superior vermian and superomedial cerebellar AVMs and should be part of the surgical armamentarium of vascular surgeons. Detailed assessment of angiographic features may, however, preclude its safety as a unique treatment plan and therapeutic options should then be considered.