[Microsurgical treatment of foramen magnum tumors]

To review the radiological features, and results of microsurgical treatment of foramen magnum tumors.

We retrospectively analyzed the results of microsurgical treatment of 31 patients with foramen magnum tumor. Fifteen patients had pathological schwannomas (neurinomas), 13 patients meningiomas, and 3 patients chordomas. According to tumor extension, MRI findings and microsurgical approaches, the tumors were classified in two types. Type I tumors located at the ventral foramen magnum, including those originated from the posterior fossa with minimal enlargement of the ventral or anterior-lateral (15 patients). Type II tumors located at the posterior or lateral foramen magnum, including those arising from the spinal canal with minimal enlargement of the foramen magnum (16 patients). Surgical approaches to tumors in this series included suboccipital posterior approach (18 patients), extreme lateral or transcondylar approach (10), and suboccipital retrosigmoid approach (3).

Total removal was achieved in 25 patients, subtotal removal in 5, and partial removal in 1. No operative death occurred. Type I foramen magnum tumors were totally removed in 9 patients, subtotally removed in 5 and partially removed in 1. All of type II foramen magnum tumors were totally removed.

To totally resect type I foramen magnum tumors, extreme lateral transcondylar approach is an optimal choice. Type II foramen magnum tumors can be totally removed with good prognosis.