Endoscopic Endonasal Transclival Odontoidectomy for Basilar Invagination: Operative Video and Technical Nuances.

Basilar invagination is a congenital or acquired craniovertebral junction abnormality where the tip of the odontoid process projects through the foramen magnum which can cause severe symptomatic compression of the brainstem and spinal cord. If left untreated, patients can develop progressive quadriparesis. Traditionally, basilar invagination can be treated with cervical traction and posterior stabilization. However, in irreducible cases, anterior decompression via a transoral or endonasal approach may be necessary. In this operative video, we demonstrate an endoscopic endonasal transclival approach for odontoidectomy to successfully treat a 37-year-old female with severe basilar invagination causing symptomatic compression on the cervicomedullary junction resulting in unsteady gait and motor weakness. The patient had Klippel-Feil syndrome where the C1 arch was assimilated to the foramen magnum and transclival drilling was needed to adequately access the odontoid process for removal. A second-stage posterior occipitocervical stabilization and fusion was performed the following day. Immediate postoperative imaging showed excellent decompression of the cervicomedullary junction. Postoperatively, the patient had significant improvement in gait and motor strength in all extremities, and was ambulating independently without assistance at 1 year after surgery. The endoscopic endonasal transclival odontoidectomy is a useful strategy to treat severe irreducible basilar invagination causing symptomatic neural compression. The surgical technique and nuances are described in a step-by-step fashion in this illustrative operative video. The link to the video can be found at: https://youtu.be/HL4K7KqJEJM.

Far Lateral Transcondylar Transtubercular Approach for Microsurgical Resection of Foramen Magnum Meningioma: Operative Video and Technical Nuances.

Surgical access to the ventral foramen magnum remains a technical challenge. With large lesions in this region compressing the brainstem and distorting the regional neurovascular relationships, formulating a surgical plan and its appropriate execution have crucial importance in achieving favorable outcomes. While the endoscopic endonasal approaches have gained increasing attention to access the clivus and the ventral brainstem, foramen magnum meningiomas are still preferred to be removed via an approach that obviates a trajectory through the nasopharyngeal mucosa. Therefore, the far lateral approach remains one of the most practical approaches for these challenging lesions. This operative video demonstrates the use of the far lateral transcondylar transtubercular approach to remove a large meningioma in the ventral foramen magnum in a 63-year-old male with progressive cervical myelopathy, presenting as spastic quadriparesis without any cranial nerve abnormality. Using a right-sided far lateral transcondylar transtubercular approach, the meningioma was exposed within the cerebellomedullary gutter engulfing the vertebral artery and distorting the course of the adjacent cranial nerves. Using the different corridors identified between the vertebral artery, spinal accessory, vagus, and hypoglossal nerves, multiple angles of attacks to the tumor were established and utilized to resect the lesion. A gross total resection was achieved and the patient was neurologically intact without any neurological deficits. This video demonstrates the importance of understanding the intricacies of neurovascular anatomy of the cervicomedullary region (i.e., the various triangles formed between these structures), and the effective use of these corridors to safely and efficiently remove a challenging ventral foramen magnum meningioma with neurovascular involvement, while preserving cranial nerve function. The surgical technique and nuances are described in a step-by-step fashion in this illustrative operative video. The link to the video can be found at: https://youtu.be/s1dFhuaRSt8 .

Translabyrinthine Approach for Resection of Large Cystic Acoustic Neuroma: Operative Video and Technical Nuances of Subperineural Dissection for Facial Nerve Preservation.

The translabyrinthine approach is advantageous for the resection of large acoustic neuromas compressing the brainstem when hearing loss is nonserviceable. This approach provides wide access through the presigmoid corridor without prolonged cerebellar retraction. Early identification of the facial nerve at the fundus is also achieved. In this operative video atlas manuscript, the authors demonstrate a step-by-step technique for microsurgical resection of a large cystic acoustic neuroma via a translabyrinthine approach. The nuances of microsurgical and skull base technique are illustrated including performing extracapsular dissection of the tumor while maintaining a subperineural plane of dissection to preserve the facial nerve. This strategy maximizes the extent of removal while preserving facial nerve function. A microscopic remnant of tumor was left adherent to the perineurium. A near-total resection of the tumor was achieved and the facial nerve stimulated briskly at low thresholds. Other than preexisting hearing loss, the patient was neurologically intact with normal facial nerve function postoperatively. In summary, the translabyrinthine approach and the use of subperineural dissection are important strategies in the armamentarium for surgical management of large acoustic neuromas while preserving facial nerve function. The link to the video can be found at: https://youtu.be/zld2cSP8fb8 .

Retrosigmoid Transmeatal Approach for Resection of Acoustic Neuroma: Operative Video and Technical Nuances of Subperineural Dissection for Facial Nerve Preservation.

The retrosigmoid (suboccipital) approach is the workhorse for most acoustic neuromas in the cerebellopontine angle. In this operative video atlas manuscript, the authors demonstrate the nuances of the subperineural dissection technique for microsurgical resection of an acoustic neuroma via the retrosigmoid transmeatal approach. The plane is developed by separating the perineurium of the vestibular nerve away from the tumor capsule. This perineurium provides a protective layer between the tumor capsule and the facial nerve which serves as a buffer to avoid direct dissection and potential trauma to the facial nerve. Using this technique during extracapsular tumor dissection helps to maximize the extent of tumor removal while preserving facial nerve function. A gross total resection of the tumor was achieved, and the patient exhibited normal facial nerve function ( Fig. 1 ). In summary, the retrosigmoid transmeatal approach with the use of subperineural dissection are important strategies in the armamentarium for surgical management of acoustic neuromas with the goal of maximizing tumor removal and preserving facial nerve function ( Fig. 2 ). The link to the video can be found at: https://youtu.be/L3lPtSvJt60 .

Retrosigmoid Suprameatal Approach for Resection of Petrotentorial Cerebellopontine Angle Meningioma: Operative Video and Technical Nuances.

Meningiomas are the second most common tumor to arise in the cerebellopontine angle. In this operative video atlas manuscript, the authors demonstrate a step-by-step technique for microsurgical resection of a petrotentorial meningioma in the cerebellopontine angle via a retrosigmoid suprameatal approach. Drilling of the hyperostotic suprameatal tubercle was necessary to gain access to the dural origin and anterior petrosal extent of the tumor. The nuances of microsurgical and skull base technique are illustrated including microsurgical dissection of the tumor away from the brainstem and neurovascular structures, facial nerve preservation, and fat graft-assisted Medpor Titan reconstruction to prevent cerebrospinal fluid leakage. A gross total resection was achieved, and the patient was neurologically intact. In summary, the retrosigmoid suprameatal approach is an important strategy in the armamentarium for surgical management of petrotentorial meningiomas in the cerebellopontine angle. The link to the video can be found at: https://youtu.be/kwQP6BSYK7U .

Combined Petrosal Approach for Resection of Petroclival Meningioma with Endoscopic Assistance: Operative Video and Technical Nuances.

Petroclival meningiomas are formidable lesions due to their deep location in the skull base and proximity to critical neurovascular structures. The combined petrosal approach, comprised of an anterior petrosectomy and posterior retrolabyrinthine petrosectomy, allows for both supra- and infratentorial exposure of the tumor in the petroclival region while potentially preserving hearing function ( Fig. 1 ). In this operative video atlas manuscript, the authors demonstrate a step-by-step technique for microsurgical resection of a petroclival meningioma via the combined petrosal approach. The nuances of microsurgical and skull base technique are illustrated including drilling of the petrous bone, transecting the tentorium, resection of the tumor, and multilayered reconstruction of the dural defect. The combined petrosal approach allows for multiple angles of attack including both subtemporal and presigmoid corridors. In summary, the combined petrosal approach with endoscopic assistance is an important strategy in the armamentarium for surgical resection of petroclival meningiomas ( Fig. 2 ). The link to the video can be found at: https://youtu.be/ipZb9kHcP2g .

Endoscopic-Assisted Microvascular Decompression of Ectatic Vertebral Artery for Hemifacial Spasm: Operative Video and Technical Nuances.

In this operative video atlas manuscript, the authors demonstrate the operative nuances and surgical technique for endoscopic-assisted microvascular decompression of a large ectatic vertebral artery causing hemifacial spasm. A retrosigmoid approach was performed and a large ectatic vertebral artery was transposed away from the root exit zone of cranial nerve VII ( Fig. 1 ). The lateral spread response disappeared, signifying adequate decompression of the facial nerve ( Fig. 2 ). The use of endoscopic-assistance during the microsurgical decompression was very useful to confirm the origin and also the resolution of neurovascular conflict. Postoperatively, the patient experienced immediate resolution of hemifacial spasm with normal facial nerve and hearing function. Written consent was obtained from the patient to publish videos, photographs, and images from the surgery. The link to the video can be found at: https://youtu.be/RlMz44uCDCw .

Microsurgical resection of brainstem cervicomedullary ganglioglioma: operative video and technique of creating a surgical pseudoplane for near-total resection.

Cervicomedullary gangliogliomas are rare low-grade neoplasms of the brainstem. They can be challenging lesions to resect due to the eloquent location in the brainstem. In some instances, the absence of a clear surgical plane between the tumor and normal neural tissue can prohibit a complete resection. Therefore, it is important to leave a thin rim of residual tumor at the tumor-brainstem interface in order to avoid irreversible neurological injury. In this operative video, the authors demonstrate the technique to develop a surgical pseudoplane using sharp microdissection for a cervicomedullary brainstem ganglioglioma without a clear interface between the tumor and normal neural tissue. This strategy allowed for radical near-total resection of the tumor, thereby maximizing the extent of removal while preserving neurological function. Postoperatively, the patient had normal neurological function and returned to work without any disability. In summary, due to the lack of a clear surgical dissection plane, a pseudoplane near the surgical interface can be performed using sharp dissection to facilitate radical near-total resection. The video can be found here: https://youtu.be/biD4G1Hh0yk.

Telovelar approach for microsurgical resection of fourth ventricular subependymoma arising from rhomboid fossa: operative video and technical nuances.

Fourth ventricular tumors have traditionally been removed via transvermian approaches, which can result in potential dysequilibrium and mutism. The telovelar approach is an excellent alternative to widely expose fourth ventricular tumors without transgressing the cerebellar vermis. This is achieved by opening the cerebellomedullary fissure and incising the tela choroidea and inferior medullary velum, which form the lower half of the roof of the fourth ventricle. In this operative video manuscript, the authors demonstrate microsurgical resection of a fourth ventricular subependymoma arising from the rhomboid fossa via the telovelar approach. The key technical nuance in this video is to demonstrate a gentle and safe technique to identify a dissectable plane to peel the tumor off of the rhomboid fossa using a microspreading technique with fine micro-bayonetted forceps. A gross-total resection was achieved, and the patient was neurologically intact. The video can be found here: https://youtu.be/ZEHHbUGb9zk.

Combined petrosal approach for resection of recurrent brainstem cavernous malformation: operative video and technical nuances.

Brainstem cavernous malformations are formidable lesions because of their eloquent location and propensity for bleeding resulting in neurological impairment. The surgical management can be challenging due to their deep location around critical neurovascular structures. In this operative video manuscript, the authors demonstrate resection of a large recurrent pontine cavernous malformation with an exophytic component in the cerebellopontine angle via a combined petrosal approach. Both anterior and posterior (retrolabyrinthine) petrosectomies were performed to allow multi-corridor access to the lesion. Due to excessive scar formation from prior surgeries, sharp dissection was paramount to create dissection planes around the lesion. This video atlas demonstrates the operative technique and surgical nuances of the skull base approach, safe resection of the malformation through the operative corridor, gentle handling of the neurovascular structures and a multi-layered reconstruction technique to prevent cerebrospinal fluid leakage. The use of endoscopic-assisted microsurgery of the brainstem is also demonstrated. A gross total resection was achieved, and the patient improved neurologically. In summary, the combined petrosal approach with endoscopic assistance is an important strategy in the armamentarium for the surgical management of brainstem cavernous malformations. The video can be found here: https://youtu.be/oAETW6tVc_Y.