Experience of diagnostics and treatment of 34 cases of foramen magnum meningiomas

Abstract

Objective: optimization microsurgical methods of meningioma resection in foramen occipitalis magnum.Materials and methods. Our study includes 34 observations, patients aged 18 to 75 years (median age 52.8 years) in the period from 1991 to 2016. There were 7 men, 27 women (ratio M : F — 1 : 3.9). This amounted to about 1.6% of the total number of patients with symptomatic meningiomas. To assess the extent of surgical treatment, we used the gradation system of D. Simpson.Results. Total tumor resection was performed in 24 (70.6%) cases, subtotal — in 6 (17.6%) cases, partial — in 4 (11.8%) patients. There was no postoperative mortality. Tumor recurrence was not observed during the whole observation period. Tumor resection was performed in two stages, in one case, because of decrease in blood pressure to 60 mm Hg and bradycardia during the first intervention, probably due to brainstem dislocation. The remaining tumor portion was completely removed after 5 months.In the early postoperative period, lower cranial nerves and C1-C2 rootlets dysfunctions were registered in 19 (55.9%) patients, and 13 (38.2%) patients had mild or moderate pyramidal disorders. Cerebellar ataxia was revealed in 22 (64.7%) observations. Clinically significant pneumocephalus was diagnosed in 3 (8.8%) cases, which required air extraction (patients were operated in the sitting position). There were no hemorrhagic complications in any case.Postoperative radiosurgery (gamma-knife) was carried out in 1 (2.9%) case (after subtotal tumor removal), radiotherapy — in 4 (11.8%) cases after partial and subtotal fossa magnum meningioma resection.Functional outcomes were initially estimated according to the Karnofsky performance status scale in the period from 6 to 14 months after the surgery. Twenty-three patients (67.7%) experienced 90–100% (no disability or vital activity), 8 (23.5%) patients had 70–80% (mild disability and vital dysfunction), 3 (8.8%) patients experienced 50–60% (moderate disability and life-support needed), whose tumor was partially removed. There were no gross neurological disorders, which significantly restricted the ability to work and live.All patients were or continue to be monitored according to clinical protocols, all of them were recommended to undergo a control MRI at least once a year. Catamnesis was up to 19 years. There were no repeated complaints about recurrence or continued fossa magnum meningioma growth in either case, even after subtotal or partial tumor removal.Conclusions. The suboccipital lateral approach with laminectomy to the level of the lower tumor pole was sufficient enough to provide adequate microsurgical craniovertebral meningioma resection without resection of the atlantooccipital articulation. The approach to neoplasm matrix was performed after tumor partial resection without brain stem traction. The use of intraoperative neuromonitoring provided the control of brain stem functions at all stages of tumor resection and vertebral artery isolation.