Left Transsylvian-Transinsular Approach for Radiation-Induced Cavernous Malformation: 3-Dimensional Operative Video

De novo cavernous malformation (CM) formation after radiation therapy for brain tumors is well known, but CM formation adjacent to a radiosurgically treated arteriovenous malformation (AVM) is rare.1 This video demonstrates the microsurgical resection of a de novo CM adjacent to a previously treated high-grade AVM and clipping of a middle cerebral artery (MCA) aneurysm. A 70-yr-old male with history of radiosurgery for AVM presented with aphasia and confusion. Preoperative angiography showed complete occlusion of the AVM. MRI showed multiple cystic lesions suspicious for radiation-induced necrosis and CM. IRB approval and patient consent was obtained. A pterional craniotomy was performed with transsylvian exposure of the insula. The radiated feeding arteries were followed to the occluded AVM nidus. A CM was noted deep to this candelabra of the MCA vessels, which were mobilized to access and resect the CM. A small incision was made in this insular cortex underneath the malformation circumferentially freeing it of adhesions. The sclerotic AVM nidus was circumferentially dissected and removed en bloc. Thorough exploration of the resection cavity revealed no residual CM or AVM nidus. Attention was then turned to the M2-MCA bifurcation aneurysm, which was occluded with a straight clip. Postoperative imaging confirmed complete CM resection. The patient recovered from his aphasia. This case demonstrates the management of a radiation-induced de novo CM following treatment of a high-grade AVM. Radiographic follow-up for radiosurgically treated AVM is needed to rule out long-term complications. Bleeding from a de novo CM mimics bleeding from residual AVM nidus, requiring careful angiographic evaluation.

Transsylvian-Transinsular Approach for an Insular Cavernous Malformation Resection: 3-Dimensional Operative Video

Surgical resection of insular lesions is challenging due to their proximity to critical neurovascular structures such as the middle cerebral arteries (MCA), Sylvian veins, thalamus, internal capsule (IC), and lenticulostriate arteries. A surgical series using the transsylvian-transinsular approach to treat cerebrovascular pathologies reported ∼5% permanent neurological morbidity.1,2 This case demonstrates the utility of this approach for resecting an insular cavernous malformation (CM). A 25-yr-old female presented with an acute-onset right homonymous hemianopsia. Neuroimaging revealed a large left insular CM, adjacent to the posterior limb of IC. After obtaining IRB approval and patient consent, a left pterional craniotomy with a wide distal Sylvian fissure split was completed. Using neuronavigation, an insular entry point was chosen for corticectomy. The CM was opened with subsequent hematoma evacuation and intracapsular resection technique. Inspection of the cavity revealed remnants anteromedially near the IC, which were removed meticulously, mobilizing the CM away from the IC. Postoperative MRI demonstrated gross total resection of the CM. The patient was discharged home on postoperative day 5 with persistent homonymous hemianopia. This case describes the use of a transsylvian-transinsular approach to access deep lesions with the shortest surgical distance and minimal cortical transgression. A wide Sylvian fissure split exposes the M2 MCA and accesses a safe insular zone, keeping the most eloquent structures deep to the lesion in the surgical corridor. This approach can safely expose vascular pathologies in the insular region without the risk of injury to overlying eloquent frontal and temporal lobes, even in the dominant hemisphere.

Cavernomas and Arteriovenous Malformations in the Mesial Temporal Region: Microsurgical Anatomy and Approaches

BACKGROUND: The mesial temporal region (MTR) is located deep in the temporal lobe and it is surrounded by important vascular and nervous structures that should be preserved during surgery. OBJECTIVE: To describe microsurgical anatomy and approaches to the MTR in relation to cavernomas and arteriovenous malformations (AVMs). METHODS: Five formalin-fixed and red silicone-embedded heads of adult cadavers were used for this study. Between January 2003 and June 2014, 7 patients with cavernomas and 6 patients with AVMs in the MTR underwent surgery. RESULTS: The MTR of the cadavers was divided into 3 areas: anterior, middle, and posterior. Of the 7 patients with MTR cavernomas, 4 were located anteriorly, 2 were located medially, and 1 was located posteriorly. Of the 6 patients with MTR AVMs, 3 were located in the anterior sector, 2 in the middle sector, and 1 in the posterior sector. For the anterior portion of the MTR, a transsylvian-transinsular approach was used; for the middle portion of the MTR, a transtemporal approach was used (anterior temporal lobectomy); and for the posterior portion of the MTR, a supracerebellar-transtentorial approach was used. CONCLUSION: Dividing the MTR into 3 regions allows us to adapt the approach to lesion location. Thus, the anterior sector can be approached via the sylvian fissure, the middle sector can be approached transtemporally, and the posterior sector can be approached via the supracerebellar approach.