Meningiomas of the ventral foramen magnum
Meningiomas of the ventral foramen magnum are rare lesions that account for less than 3% of all meningiomas. Their treatment remains one of the most challenging among all meningiomas. The authors comprehensively analyzed multiple features in the series of patients who harbored these lesions. The authors conducted a retrospective study of 18 patients who harbored lesions in the ventral foramen magnum (mean follow up 40 months) in whom surgery was performed via a transcondylar approach. Sixteen patients underwent surgery for the first time: in 12 patients (75%) gross total, in two (12.5%) near total, and in two (12.5%) subtotal tumor removal was achieved. The remaining two patients were treated for a recurrent tumor. Karnofsky Performance Scale (KPS) scores obtained at follow-up review demonstrated statistically significant improvement compared with those obtained preoperatively. The extent of surgical resection and preoperative KPS score were variables that demonstrated statistically significant favorable influence on outcomes. Ninth and 10th cranial nerve palsies were the most common complication that contributed to the prolonged hospital stay; six patients who experienced nerve palsy preoperatively worsened postoperatively, and four other patients developed nerve palsy after surgery. There were no perioperative deaths. Four patients died during the follow-up period. One patient died of multiple myeloma; another, who underwent surgery for a recurrent tumor, died 3 years after this second surgery from new tumor recurrence at 80 years of age; and the remaining two patients died 1.5 and 5 months postsurgery of pulmonary embolus and endocarditis, respectively. Meningioma of the ventral foramen magnum can be radically removed in a majority of patients in whom complications will be frequent but transient, resulting from lower cranial nerve palsies. The radical removal of a recurrent tumor provides for the patient a relatively long, stable follow-up period. Patients presenting with a low KPS score have a poor prognosis. Early diagnosis and treatment are recommended.