Basilar decompression via a far lateral transcondylar approach

Acta Neurochirurgica (2022) 164:2563–2572

Treatments for symptomatic or unstable basilar invagination (BI) include posterior decompression, distraction/ fusion, trans-nasal or trans-oral anterior decompression, and combined techniques, with the need for occipitocervical fusion based on the degree of craniocervical instability. Variations of the far lateral transcondylar approach are described in limited case series for BI, but have not been widely applied.

Methods A single-institution, retrospective review of consecutive patients undergoing a far lateral transcondylar approach for odontoidectomy (± resection of the inferior clivus) followed by occipitocervical fusion over a 6-year period (1/1/2016 to 12/31/2021) is performed. Detailed technical notes are combined with images from cadaveric dissections and patient surgeries to illustrate our technique using a lateral retroauricular incision.

Results Nine patients were identified (3 males, 6 females; mean age 40.2 ± 19.6 years). All patients had congenital or acquired BI causing neurologic deficits. There were no major neurologic or wound-healing complications. 9/9 patients (100%) experienced improvement in preoperative symptoms.

Conclusions The far lateral transcondylar approach provides a direct corridor for ventral brainstem decompression in patients with symptomatic BI. A comprehensive knowledge of craniovertebral junction anatomy is critical to the safe performance of this surgery, especially when using a lateral retroauricular incision.

Management of Anterolateral Foramen Magnum Meningiomas: Surgical Vs Conservative Decision Making

Neurosurgery 67[ONS Suppl 1]:ons00-ons00, 2010. DOI: 10.1227/01.NEU.0000382971.63877.DD

Anterolateral meningiomas of the foramen magnum (FMMs) represent a neurosurgical challenge because they grow in close contact with osteoarticular, nervous, and vascular structures that cannot be sacrificed or retracted. OBJECTIVE: To evaluate our strategy and results in 26 patients with FMMs and analyze factors affecting the decision-making process, resection, and outcome. METHODS: Among 26 consecutive symptomatic FMM (10 anterior, 16 lateral) patients (16 women, 10 men, ages 28-82 years), 4 older than 70 years of age were untreated. Twentytwo were operated on using a posterolateral approach, with the vertebral artery transposed in 19 and the occipital condyle drilled in 10. We analyzed the characteristics and outcome of untreated cases, the utility of THE occipital condyle drilled, the difficulties of microdissection, morbidity and total removal rates, the outcome of tumor residues, and the literature on radiosurgery. RESULTS: Three of 4 untreated patients remained clinically stable at 2 to 5 years. After systematic vertebral artery medial transposition and occipital condyle drilled in 6 cases, our technique evolved with experience in the next 16 (vertebral artery transposed in 13 of 16; occipital condyle drilled in 4 of 13) for dissecting anteriorly beyond midline (anterior FMMs). Retrocondylar access was sufficient for lateral FMMs. Tumors were totally removed in 16 of 22 (73%). One patient died, and 4 had permanent deficits. Follow-up of more than 5 years in 12 patients showed no C0-1 instability, and slight increase of tumor residue size 7 years after surgery. In the literature, 15 FMMs treated with radiosurgery are reported, 13 at diagnosis and 2 at recurrence, with short-term clinical and radiological safety and efficacy. CONCLUSION:We currently recommend (1) aiming for subtotal removal in difficult cases, (2) remaining conservative in asymptomatic or elderly patients with mild symptoms, and (3) considering radiosurgery at diagnosis for small (<30 mm) symptomatic FMMs or as an adjunct for evolving residues/recurrences in poor candidates for resection.