gms | German Medical Science

Clinoidal meningiomas continue to be surgically challenging lesions. They are frequently associated with a high mortality and morbidity rate, failure of total removal, and recurrence. Recent advances in cranial base surgery have enabled and facilitated radical resection. In this retrospective study, the surgical results and visual outcomes were investigated in 18 patients who underwent surgical treatment at our institution.

A retrospective analysis was performed on 18 consecutive patients with clinoidal meningiomas who and underwent surgical resection at our institution from January 1996 to December 2004. There were 8 males and 10 females, and their mean age was 56 years (ranged 28 to 78 years). Mean diameter of the tumors was 41mm (ranged 25 to 60 mm). 17 patients showed the visual impairment in preoperative ophthalmological examination. A pterional approach with cranial base modifications including extradural anterior clinoidectomy, unroofing of the optic canal and opening the optic sheath, which was mentioned by Lee et al., was adopted in all patients. Meticulous microsurgical techniques were used to keep the arachnoid membrane and the vessels related to vital structures. We never attempted an aggressive removal of the tumor within the cavernous sinus. Involvement of the internal carotid artery was classified into four categories according to Hirsch grading system [Ref. 1]. Site of origins were classified into three categories according to Al-Mefty’s classifications [Ref. 2]. The follow-up period ranged from 2 to 96 months (mean, 48.6 months).

The site of origin was Al-Mefty grade 1 in five patients, grade 2 in eleven patients and grade 3 in two patients. Hirsch grade was grade 0 in 10 patients, grade 1 in 3 patients, grade 2 in 3 patients and grade 3 in 2 patients. Total resection was achieved in 13 patients (73%), who included eleven Al-Mefty grade 2 patients and two Al-Mefty grade 3 patients. Hirsch grade was 0 in 10 patients and 1 in 3 patients, respectively. In all 5 patients who had tumors encasing the internal carotid artery in the C4 segment and/or invading into the cavernous sinus (Al-Mefty Grade 1 and Hirsch Grade 2 or 3), total resection could not be accomplished. There was no case of mortality. The rate of visual improvement was 76% in 17 patients with preoperative visual impairment. Visual outcomes were significantly associated with the respectability of the tumors and preoperative visual acuity.

Postoperative complications occurred in four patients. One patient showed a postoperative hemiparesis caused by damage to the perforating arteries to the anterior perforated substance during operation. Postoperative disturbance of ocular movement was observed in three patients, in whom the tumor involved the cavernous sinus. Postoperative epilepsy was not found in any patients. No patient suffered diabetes insipidus and insufficiency of the hypophyseal function postoperatively, however one patient suffered transient electrolyte imbalance of hyponatremia. The overall rate of nonvisual morbidity was 22.2%. Karnofsky Performance Scale scores were over 80 in most patients (94%) at the last follow-up period. Among five patients in whom total resection was not achieved, stereotactic radiosurgery was performed in two patients because of the tumor growth during the follow-up period. One patient developed a regrowth of tumor three years after Simpson’s grade 2 resection, and underwent reoperation.

Meningiomas arising from the anterior clinoidal process, are considered to be different entity from suprasellar meningiomas and sphenoid ridge meningiomas, because surgical treatment for these lesions are more frequently associated with a high morbidity and mortality rate. Recent advancement in cranial base techniques, microsurgical techniques, neuroimaging, and neuroanesthesia have resulted in an improvement of surgical results. Surgical results reported in the recent series indicated total resection rates ranging from 59 to 91%. However, the mortality rate and visual outcomes still remains to be less than desirable in the management of patients with clinoidal meningiomas [Ref. 2], [Ref. 3], [Ref. 4], [Ref. 5], [Ref. 6]. We investigated the impact of cranial base technique on the outcomes of patients with clinoidal meningiomas.

With the use of the cranial base techniques, clinoidal meningiomas without involving the cavernous sinus and the internal carotid artery (Al-Mefty grade 2 or 3, and Hirsch grade 0 or 1) could be resected with minimal morbidity. However, the tumors involving them (Al-Mefty grade 1 and Hirsch grade 2, 3 or 4) could not be resected completely, and adjuvant therapy such as radiotherapy and stereotactic radiosurgery might be worth consideration in patients with residual tumor. Our surgical results were comparable to those of recent surgical series in both respectability and visual outcomes [Ref. 2], [Ref. 3], [Ref. 4], [Ref. 5], [Ref. 6] (Table 1 [Tab. 1]). Visual outcomes were well correlated to the preoperative visual acuity and the amount of resection. Recent advancement of cranial base techniques provides us a wide and shallow operative view, and might contribute the improvement of both respectability and visual outcomes. The tumor grade should be accurately evaluated by modern diagnostic technology, such as MR images and 3-dimensional CT angiography, to predict the respectability of the tumor and the visual outcomes.