Transcondylar Approach for Resection of Medullary Cavernous Malformation: 2-Dimensional Operative Video

Cavernous malformations located within the brainstem present with a high rate of neurological symptoms and carry a more aggressive course in both pediatric and adult populations.1,2 Cavernomas within the medulla are the rarest form, representing only 5% of all brainstem lesions.3 Repeated hemorrhage of brainstem cavernomas is associated with significant and cumulative neurological deficits and thus requires treatment.4 Microsurgical resection has become the optimal mode of treatment with the aim of resecting the live malformation and not merely the multiaged, organized hematoma.4 This is best achieved by approaching the cavernoma at the location where it projects to the surface and entering the lesion through a safe brainstem anatomic zone. For ventrally located lesions in the medulla, a transcondylar skull base approach provides a direct trajectory to the entry zone through a short surgical distance without the need to manipulate or retract neurovascular structures.5-8 Neuronavigation and intraoperative neurophysiological monitoring of somatosensory evoked potential, motor, and lower cranial nerves are adjuncts to increase patient safety. Radiosurgery for the treatment of brainstem cavernous malformations has been proposed; however, it demonstrates high risk and variable and often poor response rates.9 We present a surgical video demonstrating the transcondylar approach and resection of a medullary cavernoma in a 54-yr-old woman who has had multiple known prior hemorrhages and presented with a new onset of facial numbness and weakness, ataxia, and left body sensory loss. The patient consented to surgery and to photograph publication. Images at 1:28, 1:43 (left), 2:02 from Al-Mefty O, Operative Atlas of Meningiomas, © LWW, 1997,5 with permission. Images at 1:43 (right) from Arnautovic et al,8 with permission from JNSPG.

Endoscope-assisted far-lateral transcondylar approach for craniocervical junction chordomas: a retrospective case series and cadaveric dissection

OBJECTIVE Craniocervical junction (CCJ) chordomas are a neurosurgical challenge because of their deep localization, lateral extension, bone destruction, and tight relationship with the vertebral artery and lower cranial nerves. In this study, the authors present their surgical experience with the endoscope-assisted far-lateral transcondylar approach (EA-FLTA) for the treatment of CCJ chordomas, highlighting the advantages of this corridor and the integration of the endoscope to reach the anterior aspect and contralateral side of the CCJ and the possibility of performing occipitocervical fusion (OCF) during the same stage of surgery. METHODS Nine consecutive cases of CCJ chordomas treated with the EA-FLTA between 2013 and 2020 were retrospectively reviewed. Preoperative characteristics, surgical technique, postoperative results, and clinical outcome were analyzed. A cadaveric dissection was also performed to clarify the anatomical landmarks. RESULTS The male/female ratio was 1.25, and the median age was 36 years (range 14–53 years). In 6 patients (66.7%), the lesion showed a bilateral extension, and 7 patients (77.8%) had an intradural extension. The vertebral artery was encased in 5 patients. Gross-total resection was achieved in 5 patients (55.6%), near-total resection in 3 (33.3%), and subtotal resection 1 (11.1%). In 5 cases, the OCF was performed in the same stage after tumor removal. Neither approach-related complications nor complications related to tumor resection occurred. During follow-up (median 18 months, range 5–48 months), 1 patient, who had already undergone treatment and radiotherapy at another institution and had an aggressive tumor (Ki-67 index of 20%), showed tumor recurrence at 12 months. CONCLUSIONS The EA-FLTA provides a safe and effective corridor to resect extensive and complex CCJ chordomas, allowing the surgeon to reach the anterior, lateral, and posterior portions of the tumor, and to treat CCJ instability in a single stage.

C1-2 cyst presenting with syringobulbia: a case report

Extradural atlantoaxial cysts are typically related to C1-2 degeneration. Intradural cysts may cause secondary syringobulbia depending on the size and cerebrospinal fluid flow obstruction. However, medullary syrinxes have not been previously described with extradural cysts. Treatment of symptomatic lesions involves surgical resection, often via a far-lateral approach, with consideration of fusion if C1-2 instability is present. We present a case of an extradural C1-2 cyst with intradural extension causing syringobulbia. Effective surgical resection was accomplished via a far-lateral, partial transcondylar approach without fusion. It is important to recognize that cysts of extradural origin may exhibit intradural extension and compress critical neurovascular structures.

Morphology and morphometric study of occipital condyles

Introduction: The occipital condyles are undersurface protruberances of the occipital bone in vertebrates, which articulate with the superior facets of the atlas vertebra. The condyles are oval or reniform in shape, and their anterior extremities directed forward and medially and are closer together than the posterior end. Aim: The aim of the study is to provide important anatomical parameters for lateral transcondylar approach. Materials and Methods: 200 occipital condyles in 100 dry human skulls ( 73 males and 27 females) were studied. The measured parameters included length, width, height, shape, anterior and posterior intercondylar distance, distance between basion and opesthion, distance from anterior tip of the condyle to the basion and opestion and distance from posterior tip to the basion and opesthion. Measurements were made using Vernier Callipers. Results: The mean length, width and height of the occipital condyles in males is greater than females. The anterior intercondylar distance is more in females whereas posterior intercondylar distance is more in males. The mean distance from basion to opesthion / anteroposteriordiamerer of foramen magnum is more in males than in females. The mean distance between the anterior tip of occipital condyles to basion is more in females than in males on both the sides. Conclusion: The knowledge of condylar anatomy helps the surgeon in making important decisions regarding extent and direction of condylar drilling and minimizing injury and retraction of neural structures. KEY WORDS: Occipital Condyles, Foramen Magnum, Intercondylar distance, Basion, Opesthion.

Far-Lateral Transcondylar Approach to a Right Cervicomedullary Dural Arteriovenous Fistula of the Posterior Fossa

Objectives Dural arteriovenous fistulas (DAVFs) at the cervicomedullary junction are uncommon and often accompanied by subarachnoid hemorrhage (SAH). We aim to illustrate in detail the microsurgical procedure for treating a DAVF located at the cervicomedullary junction. Design We present a two-dimensional operative video that includes clinical history, preoperative imaging, surgical strategy, still images with labels, clinical course, and postoperative imaging. Setting The microsurgery was performed at an academic medical center. Participant The patient is a 55-year-old female who presented with SAH, acute onset headache, nausea, and vomiting. Angiography demonstrated right vertebral artery vasospasm and a persistent arteriovenous shunt at the cervicomedullary junction supplied by small perforating arteries of the right vertebrobasilar junction (Fig. 1). Main Outcome Measures The patient was placed in the park-bench position with the head turned to the contralateral side. A hockey stick incision was made, followed by a right-side far-lateral transcondylar approach. Indocynanine green videoangiography was performed to help identify the areas of arteriovenous shunting. Multiple clips were placed to interrupt vessels that corresponded to arterial feeders at the level of the C1 and C2 nerve root sleeves (Fig. 2). The dura was closed in a water tight fashion and the posterior fossa was reconstructed with a titanium mesh. Results Postoperative imaging showed no evidence of continued arteriovenous shunting. The patient was discharged in good clinical condition with an uneventful postoperative course. Conclusion A deep understanding of the microsurgical vascular anatomy is necessary for successful occlusion of a cervicomedullary DAVF.The link to the video can be found at: https://youtu.be/-LfOcNB05BY.

Far Lateral Transcondylar Approach for Anterior Foramen Magnum Lesions

Objective: To study the efficacy and safety of far-lateral transcondylar approach for anterior foramen magnum lesions with early experience at our Institute. Material and Methods: We treated six patients, with lesion anterior to the foramen magnum and posterior to the brainstem and cervical cord in a period of 2 years, March 2017 to March 2018.Initial assessment was made by history and examination followed by CT scan and contrast MRI. All were treated using far-lateral transcondylar approach. Result: Among six patients, there were two were male and four were female. Three of these patients had a meningioma while two patients had neurofibromas and one clival chordoma. Total excision was achieved in five neoplastic cases, while subtotal excision was done in one case. There were no fresh postoperative deficits in any of the other patients. One patient had an unexplained sudden cardiorespiratory arrest 18h after the surgery and succumbed. One patient had cerebrospinal fluid (CSF) discharge from the wound, which was satisfactorily managed by lumber CSF drainage. Conclusion: This approach provides an excellent approach to lesions located anterior to foramen magnum posterior to the brainstem and upper cervical cord. Gross total excision of these benign and malignant lesions is safely possible through this approach. Keywords: Craniovertebral Junction, Far-Lateral Transcondylar Approach, Anterior Foramen Magnum, Brain Stem, Chordoma.