Benign extramedullary tumors of the foramen magnum.

This paper analyzes the clinical, diagnostic and surgical data of 18 benign extramedullary tumors at the foramen magnum extending into the posterior fossa and the spinal canal. These cases represent 30% of 60 foramen magnum tumors operated on between 1952 and 1978, among 4187 brain tumors and 587 tumors of the spinal cord. Foramen magnum meningiomas constitute 11 of this series (1.2% of 873 meningiomas, 113 of which were spinal). The considerable difficulty in early diagnosis is emphasized. However, in the present series, myelography showed positive findings in all cases, and angiography in most of them. CT scan, performed in one case, demonstrated the lesion. Surgical mortality was 11% (two deaths). On both patients who died after the operation, multiple surgical procedures had been performed because of erroneous diagnoses made in another unit. At the time of operation neurological symptoms were very advanced, and large tumors were located anteriorly. The review of the remaining patients showed a regression of preoperative symptoms with good to excellent results in all. No recurrences were recorded.