Overview

The foramen magnum is the opening in the skull that communicates the intracranial compartment to the cervical spine compartment. The brainstem passes through the foramen magnum to become the uppermost spinal cord in the spinal canal. Meningiomas arising at the foramen magnum compress the brainstem and upper cervical spinal cord. They often engulf the vertebral artery, which provides blood supply to the parts of the brain in the back of the

head. 

Presentation

Foramen magnum meningiomas tend to present initially with headache at the back of the head. As the tumor progresses, it compresses the brainstem and the spinal cord, and it can cause motor weakness. The weakness can be unilateral or bilateral, involving the upper and lower extremities, or affect only both upper extremities. The patient can also develop numbness in the upper and lower extremities. With further progression, the patient can become bedridden with quadriplegia and swallowing difficulties.

Management

Symptomatic foramen magnum meningiomas generally require surgical intervention. Smaller tumors may be treated primarily with CyberKnife radiation therapy or Proton beam Radiation Therapy. Incidental tumors in elderly patients may be managed with observation and surveillance MRIs.

Surgical Difficulties

• Deep location of the tumor
• Close relation to the brainstem and spinal cord
• Close relation to the major brain arteries (vertebral artery)

SURGICAL  MANAGEMENT AT THE CENTER FOR MENINGIOMA SURGERY

Foramen magnum meningioma is approached through a unilateral craniotomy around the foramen magnum and a unilateral laminectomy of the first vertebra to access the confined area of the foramen magnum. We use visual magnification with the surgical microscope throughout the approach and tumor dissection. At the Center for Meningioma Surgery, we refined a focused approach to the foramen magnum using a lazy S incision in the back of the head. This focused cranio-cervical approach allows extradural access to the origin of the tumor without retraction or manipulation of the brainstem, spinal cord, or cerebellum. It allows for the vertebral artery to be identified before any removal of the tumor, enhancing safe tumor dissection without injury to the brain’s main artery and its branches. The approach offers potential for complete resection of the tumor, including the meningeal root of the tumor. 

Prognosis

Treatment of foramen magnum meningiomas through a focused combined cervico-foramen magnum approach enhances the chances of total tumor removal, tumor cure, and the possibility of recovery from preoperative deficits. Patients have the potential to return to their pre-morbid lifestyle and job occupation.  Maximal removal of the tumor and its meningeal root maximizes the chances of patients progressing without tumor recurrence.