Introduction: Insular cavernous malformations(CM)are rare, as are giant CMs. Insular vasculature, deep structures, and traversing fibers make surgical resection challenging.

Methods: We performed a retrospective, IRB-approved, study of patients harboring giant insular CMs from1991-2014. We defined giant insular CM as those >3.5cm in diameter arising from or rupturing through insular cortex. Primary outcome measures included morbidity and epilepsy outcomes. Secondary outcomes included demographics, CM characteristics, and surgical details.

Results: Five patients met inclusion criteria. Ages ranged from 14-56. Four(80%) presented with seizures(including2-partial and2-generalized), and one with refractory headaches. Sizes ranged from 3.5-4.3cm and all were associated with a DVA. One patient had familial CMs and two had multiple CMs. Fronto-temporal craniotomies with stereotactic image guidance were used, with additional Functional-MRI and DTI in 2 cases. Transcortical approaches were utilized in 2; sylvian fissure dissection was otherwise utilized. Gross total resection was achieved in all cases and complete resection of hemosiderin stained cortex was undertaken in 2. Post-Operative morbidity included hemiparesis in2/5, anomia in one, and one epidural hematoma. At most recent follow-up(mean-11months), one had persistent hemiparesis and one had developed thalamic pain syndrome. Seizure frequency reduction was seen in all patients, with 3/5 off of anti-epileptics entirely and 2 patients on reduced doses.

Conclusions: Giant insular CMs have higher surgical risk than other supratentorial CMs and this may be related to CM size. Most giant insular CMs present with seizures, which can be improved by surgery.

Patient Care: It will improve the safety of patients undergoing cavernous malformation surgery.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of pre operative planning for insular and giant CMs

References: 1. Potts MB, Chang EF, Young WL, Lawton MT: Transsylvian-transinsular approaches to the insula and basal ganglia: operative techniques and results with vascular lesions. Neurosurgery 70:824-834; discussion 834, 2012. 2. Tirakotai W, Sure U, Benes L, Krischek B, Bien S, Bertalanffy H: Image-guided transsylvian, transinsular approach for insular cavernous angiomas. Neurosurgery 61:423-430; discussion 430-421, 2007.