[Drilling of the subarcuate fossa to release the anterior inferior cerebellar artery in a surgery of a vestibular Schwannoma]. / Fresado de la fosa subarcuata para liberar la arteria cerebelosa anteroinferior en una cirugía de un Schwannoma vestibular.

INTRODUCTION: A retrosigmoid suboccipital approach is the route most commonly utilized to resect vestibular schwannomas (VS). However, the anterior inferior cerebellar artery (AICA) usually runs adjacent to internal auditory canal nerves, and its course may severely impede total tumor resection. CASE REPORT: A 38-year-old male patient presented with presumed grade T3B VS, diagnosed by magnetic resonance imaging (MRI). Surgery was performed using a retrosigmoid approach, during which the AICA was identified to be completely covered by dural and bone tissue. Further drilling in the subarcuate fossa was necessary to release the AICI, allowing for total gross resection of the VS. No neurological deficits were observed postoperatively. DISCUSSION: On rare occasions, the AICA has been described fixed to the dura and/or embedded within subarcuate fossal bone, thereby preventing removal of the intra-canalicular portion of the VS and, hence, total resection. However, AICA release adds to the risk of vascular injury. CONCLUSION: Injury to the AICA may cause high morbidity in patients with a VS. Neurosurgeons must be able to recognize and deal with certain anatomical configurations that place patients at particularly high risk.

Transzygomatic approach plus mini-peeling of middle fossa for devascularization of sphenoid wing meningiomas. Technical note.

BACKGROUND: Sphenoid wing meningiomas account for 20% of supratentorial meningiomas. The main supply of these tumors is provided by branches of the middle and accessory meningeal arteries. Surgical resection of meningiomas requires early tumor devascularization. Our objective is to present the role of transzygomatic approach plus mini-peeling of the anterior third of the middle fossa in the extradural identification and coagulation of branches of middle and accessory meningeal arteries involved in tumor supply. METHODS: Ten formalin-fixed, silicone-injected cadaveric heads were used. On each side a transzygomatic approach plus mini-peeling of the anterior third of the middle fossa was performed. Between 2005 and 2017, the authors applied this technique for the resection of sphenoid wing meningiomas in 28 patients. RESULTS: The mean age of patients was 54 years. Thirteen tumors could be classified as medial-third type, 6 as middle-third type, and 4 tumors were lateral-third type. Five tumors represented combined types. Of these, 3 tumors involved the medial and middle-third of the sphenoid wing and 2 involved the entire wing. Surgical resection was classified as Simpson I/II in 24 patients (86%). There were no permanent deficits or postoperative mortality. CONCLUSIONS: The transzygomatic approach combined with mini-peeling of the anterior third of the middle fossa is effective in allowing early devascularization of sphenoid wing meningiomas. These maneuvers are particularly important during resection of large tumors.

The Nuchal Lines as Anatomic Landmarks to Dissect the Muscles in the Far Lateral Approach.

BACKGROUND: A critical step in the far lateral approach (FLA) is exposure of the V3 segment of the vertebral artery, located deep in the suboccipital triangle (SOT). Safe exposure of the SOT is achieved by means of a plane-by-plane dissection, which carries the risk of devascularization. A suitable alternative is to lift a cutaneous muscle flap including the 3 first muscle planes and leave the deepest plane (SOT) attached to the skull base. To achieve this, it is necessary to have superficial anatomic landmarks to help identify the cleavage site. We describe the use of the nuchal lines as a safe, effective, and reproducible method to dissect the muscles to expose the SOT and vertebral artery. METHODS: Eight adult cadaveric heads, fixed with formaldehyde and injected, were studied. On both sides, FLA was simulated by using the nuchal lines as anatomic landmarks to expose the SOT. This technique was later applied on 10 patients requiring FLA. RESULTS: Anatomic dissections confirmed identification, by means of the nuchal lines, of a cleavage site, which made it possible to separate the deepest muscle plane from the rest of the flap. This technique was successfully applied in 10 patients undergoing FLA. CONCLUSIONS: The nuchal lines allow dissection of muscles in 2 groups, one superficial and the other deep (SOT), which remains attached to the skull base. The V3 segment of the vertebral artery is easily exposed.

Microsurgical Anatomy of the Interfascial Vein. Its Significance in the Interfascial Dissection of the Pterional Approach.

BACKGROUND: The pterional approach (PA), together with its variants, is still one of the most common methods used by surgeons to reach the anterior and middle cranial base. A highly important technical detail during a PA is the preservation of the frontotemporal branch of the facial nerve, which can be achieved through an interfascial dissection. OBJECTIVE: To describe the anatomy of the interfascial vein (IFV), highlighting its recognition as a significant anatomic reference to perform an interfascial dissection (IFD). METHODS: Eight adult cadaveric heads, fixed with formaldehyde and injected with colored silicone, were studied. In 6 heads, an IFD was performed, simulating a PA. In the 2 remaining heads, the IFV was dissected. In addition, an IFD was performed in 10 patients, studying the IFV anatomy. RESULTS: In the 6 cadaveric heads in which the PA with an IFD was performed, and in the 10 patients who underwent a PA with an IFD, the IFV was found. If the interfascial space is divided into thirds, in all cases, the IFV was located within the middle third of the interfascial fat pad. On the 2 cadaveric heads in which the IFV was anatomically dissected, the IFV was also located within the middle third of the interfascial space. CONCLUSION: Recognizing the IFV in the interfascial space is of great help as an anatomic landmark to confirm that one is actually between both layers of the superficial temporal fascia.