[Microsurgical resection of anterior clinoid meningiomas-- 46 cases report]

To investigate the microsurgical tchniques and effects for the resection of anterior clinoid meningioma (ACM).

Between January 2003 and March 2013, a total of 46 ACM patients were operated on via the pterion approach or lateral subfrontal approach. There were 16 male patients and 30 female patients, their mean age was 48.5 (16-69) years. Symptoms lasted from 1 month to 9 years(average 24.7 months). Preoperative CT and MRI examination showed that the tumors were located in the anterior clinoid process (25 cases on the right side, 21 cases on the left side). The average maximal tumor diameter was 4.4 cm (1.9-7.4 cm). The patients were peroidly followed-up on outpatient on 3 months to 6 months, then every year postoperativelly. The clinical data, radiological findings, surgical records and outcome of patients were retrospectively analyzed, and the prognostic factors were ananlyzed by using of the unpaired data χ(2) test with continuity correction.

Of fourty-six patients operated on, apparently complete removal was achieved in 36 patients (78.3%), 10 patients (21.7%) had minimal residual tumors, 5 of which had gamma knife radiosurgery. Preexisting visual deficit improved in 21 of 41 patients (51.2%), unchanged in 16(35.6%), and worsened in 9(20.0%). At 3-6 months after discharge, 37(80.4%) patients had a good recovery, 7(15.6%) patients were moderately disabled, 1(2.2%) presented with severe disability, and 1 (2.2%) patient died of surgery-related causes. The tumor wrapping blood vessels (χ(2) = 4.676, P = 0.031) and violating cavernous sinus(χ(2) = 4.973, P = 0.026) were causes of unfavorable prognosis. During the mean follow-up of 35.1 months (range, 4-107 months) for 40 patients, the average Karnofsky score was 83.2. Tumor recurred in 4 cases: 2 of which required reoperation, and 2 had gamma knife radiosurgery.

Tumor wrapped vessels and invasion of the cavernous sinus are important unfavorable prognostic factors for ACM resection. By using appropriate surgical strategies and techniques, ACM can be removed safely via the pterion approach or lateral subfrontal approach with relatively low morbidity and mortality.