[Foramen magnum meningiomas: A report of 12 cases and literature review].

Objectives: The primary aim of this study was to assess the results attained for 12 patients with an anterior or lateral foramen magnum meningioma, treated microsurgically.

Methods: Between June 2005 and December 2016, 12 patients with foramen magnum meningiomas underwent microsurgical resection. Patients' age and gender, tumor localization (anterior or lateral), symptoms, approach, and postoperative results were analyzed.

Results: Eight of the 12 patients were women. The average age of the patients was 47 years. In 8 patients, the tumor was located anteriorly and in 4 patients laterally. The main symptom was occipitocervical pain (8 patients), followed by tetraparesia (3 patients). For all the anterior foramen magnum meningiomas, an extreme-lateral transcondylar approach was performed. In cases where the tumor was lateral, an extreme-lateral retrocondylar approach was adopted. Total and subtotal resection was achieved in 10 and 2 patients, respectively. In the latter instances, a very small piece of tumor remained around the vertebral artery or inside the jugular foramen. Three patients exhibited postoperative cranial nerve XII palsy and 2 cranial nerve XI palsy. One patient experienced cerebrospinal fluid leakage.

Conclusions: Microsurgery for both anterior and lateral foramen magnum meningiomas can be performed safely and effectively. What is necessary is: (a) good anatomical knowledge of the region; (b) two-step muscle dissection to expose the suboccipital triangle and vertebral artery; (c) to adopt an extreme-lateral retrocondylar approach for lateral meningiomas, and an extreme-lateral transcondylar approach for anterior tumors; and (d) good microsurgical techniques.