Precision Surgery for a Complex Foramen Magnum Meningioma
A skull base meningioma was compressing the brainstem and upper cervical spinal cord in one of the most anatomically demanding regions of the nervous system. A far lateral approach provided direct access for complete tumor removal while preserving critical neurological structures.
A tumor in a small space surrounded by critical anatomy
Foramen magnum meningiomas arise at the opening at the base of the skull where the brainstem transitions into the spinal cord. Even benign tumors in this location can become dangerous as they grow because there is very little room for the surrounding neurological structures to accommodate them.
In this case, a 65-year-old woman presented with progressive imbalance, upper extremity numbness and persistent neck pain. MRI demonstrated a ventral foramen magnum meningioma extending into the craniocervical junction and upper cervical spinal canal, with significant compression and displacement of the brainstem. The tumor was closely associated with the vertebral artery and lower cranial nerves — structures involved in swallowing, speech and airway protection.
The case was reviewed by a multidisciplinary Brain Tumor Board, including neurosurgical, neuro-oncology, neuroradiology and vascular expertise. The surgical objective was not simply to reach the tumor. It was to create a safe working corridor that allowed maximal removal while minimizing manipulation of the brainstem, spinal cord, lower cranial nerves and vertebral artery.
Why a far lateral approach?
The far lateral approach is a specialized skull base technique designed to reach lesions located along the front and side of the foramen magnum and lower brainstem. Rather than approaching directly through neurological structures, the operation creates a surgical corridor around the side of the skull base.
For this ventral tumor, the far lateral trajectory provided a low-angle corridor to the ventral brainstem and skull base, avoiding the greater brainstem manipulation that a traditional posterior approach could require. The exposure improved visualization of the tumor's relationship to the brainstem, lower cranial nerves and vertebral artery.
Key operative elements included gravity-assisted cerebellar relaxation; targeted bone removal at the skull–spine junction with limited drilling of approximately 10–15% of the occipital condyle; early identification and mobilization of the vertebral artery; a T-shaped dural opening; internal tumor debulking followed by microsurgical dissection along natural arachnoid planes; and continuous intraoperative monitoring of the lower cranial nerves.
The technical goal
Achieve sufficient skull base exposure for microsurgical tumor dissection while preserving neurological and vascular structures and maintaining stability at the craniocervical junction. Direct treatment of the tumor's dural attachment supported complete resection, while limited condyle drilling preserved stability and avoided the need for spinal fusion.
From brainstem compression to complete decompression
The imaging demonstrates the anatomical challenge before surgery and the result following resection.
Gross total resection was achieved, and postoperative MRI confirmed complete removal of the ventral foramen magnum meningioma with full decompression of the brainstem and upper cervical spinal cord. The patient recovered without new neurological deficits, and her preoperative symptoms resolved.
At 3 months, MRI showed no residual tumor. Annual surveillance imaging has remained stable with no evidence of recurrence. The operation preserved stability at the craniocervical junction, so spinal fusion was not required.
Skull base surgery is about more than removing a tumor
Foramen magnum meningiomas illustrate why the surgical approach matters as much as the diagnosis. Tumors that may be considered benign based on pathology can still present a significant surgical challenge when they develop beside the brainstem, cranial nerves and major blood vessels.
Experienced skull base surgeons evaluate not only whether a tumor should be removed, but which operative corridor provides the safest access based on the patient's individual anatomy.
Yaron A. Moshel, MD, PhD
Dr. Yaron Moshel is President of Atlantic Brain and Spine, Chair of Neurosurgery at Morristown Medical Center and Director of the Brain Tumor Center. His practice focuses on complex brain and skull base tumors, with surgical strategies tailored to tumor anatomy and the neurological structures involved.
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