Benign tumors of the foramen magnum

Abstract

The authors reviewed 102 documented cases of benign extramedullary tumors of the foramen magnum treated at their institution between 1924 and 1982. There was 78 meningiomas, 23 neurofibromas, and one teratoma. Approximately 40% of the patients had a normal neurological examination upon first evaluation. The most frequent presenting complaints were suboccipital neck pain, dysesthesias, gait disturbances, weakness, and hand clumsiness. The average time from initial symptoms to diagnosis was 2 1/4 years. The most common findings included hyperreflexia, arm or hand weakness, Babinski sign, spastic gait, sensory loss, and 11th cranial nerve involvement. Based on these cases, an attempt is made to distinguish foramen magnum tumors from other disease entities by a grouping of signs and symptoms. There is no clinical finding that is pathognomonic. Metrizamide computerized tomography scanning and Pantopaque myelography have been the radiographic tests most commonly used to evaluate the foramen magnum. Recent experience suggests that nuclear magnetic resonance scanning will be a very useful noninvasive means of evaluating the foramen magnum region.

Surgical Experience With Skull Base Approaches for Foramen Magnum Meningioma.

“…2,4,5,10,11,15,16,24,26,27) Meningiomas in the foramen magnum area frequently elude early diagnosis because their ill-defined symptoms mimic cervical spondylosis, multiple sclerosis, syringomyelia, normal pressure hydrocephalus, amyotrophic lateral sclerosis, Chiari type I malformation, cervical disc disease, carpal tunnel syndrome, other intramedullary or extramedullary tumors, and even carotid artery stenosis. 17,20,23,32) Foramen magnum meningioma has been identified in our department since 1983, due to the introduction of CT in 1976 and MR imaging in 1983. Before then, the combination of neurological and neurosurgical expertise and available studies could not provide accurate evaluation of meningioma in the foramen magnum region.…”

“…6) Foramen magnum meningioma is often identified only at an advanced stage due to the unusual and unrecognized pathognomonic symptomatology. 14,20,29,32) The complex anatomy of this area, together with the deep, central, and vital location, creates various problems for operative treatment, especially if the tumors are attached ventral to the neuraxis. 3,9) Total removal of foramen magnum meningioma is difficult and is associated with high rates of complications and recurrence even if performed by experienced surgeons, 18) and may result in high morbidity and mortality or incomplete removal.…”

Foramen magnum schwannoma with an unusual clinical presentation: case report

“…5 Most are meningiomas or schwannomas, and most of the latter are spinocranial in location. 3,4 The tumor in this patient was a spinocranial schwannoma.…”

The far-lateral approach for foramen magnum meningiomas

“…Variations of the standard technique were described and included lateral occipital bone resection and/or C-1 and C-2 laminectomies. 6,22,26,28,31,37,48,49 This surgical approach proved adequate for lesions located posterior to the dentate ligament. However, anterior or anterolateral lesions were associated with increased surgical morbidity, due to medullary tissue retraction needed for adequate exposure.…”

“…14,37,41 Early reports of FMMs describe a multitude of progressive neurological deficits at the time of clinical presentation. 12,13,28,37,48,49 With few exceptions, early reports of resection describe a standard suboccipital craniectomy. Variations of the standard technique were described and included lateral occipital bone resection and/or C-1 and C-2 laminectomies.…”