SURGICAL EXCISION OF MENINGIOMAS INVOLVING THE CLIVUS - PREOPERATIVE AND INTRAOPERATIVE FEATURES AS PREDICTORS OF POSTOPERATIVE FUNCTIONAL DETERIORATION

Neurological deterioration is commonly seen after surgical excision of clival meningiomas; however, an understanding of the risk factors ass ociated with postoperative deterioration can lead to improvements in o utcome. In 75 patients with clival meningiomas operated on over a 7-ye ar period, the following data were studied: preoperative variables suc h as presenting Karnofsky scale score, age, sex, and prior operations or radiation therapy. Radiological findings on magnetic resonance imag ing or arteriography, such as the development of the arachnoidal cleav age plane between tumor and the brain stem, brainstem edema, tumor siz e, extent of compression on the brain stem, vascular encasement, and b lood supply from the basilar artery were among other data studied. In addition, intraoperative findings such as development of the arachnoid plane, vascular encasement, and the difficulty of dissection were not ed. Finally, each patient's neurological and functional statuses were recorded at 1 week postoperatively and at follow-up examinations. Earl y postoperative functional deterioration occurred in 45 patients (60%) and ranged from mild (30 patients) to severe (three patients). Signif icant improvement had occurred by the time of follow-up examination in all but four patients; however, permanent postoperative dysfunction w as present in 12 patients. Statistical analysis revealed significant c orrelations between early functional deterioration and preoperative Ka rnofsky scale scores, male gender, radiological findings of the absenc e of an arachnoid plane, edema of the brain stem, and arteriographic s upply from the basilar artery. Operative features included difficulty with dissection, an absent arachnoidal cleavage plane, and incomplete tumor resection. Permanent functional deterioration was statistically associated with the following: blood supply from the basilar artery, d ifficulty of dissection, incomplete tumor resection, and early postope rative dysfunction. Logistical regression analysis revealed that the m ost important risk factor for early postoperative deterioration was tu mor size. Patients with large or giant tumors had a 6.7 to 13 times gr eater risk of functional deterioration, respectively, than patients wi th small- or medium-sized tumors. Excluding tumor size, the most impor tant factor for permanent deterioration was blood supply from the basi lar artery. Patients in this category had a 4.4 times greater risk of permanent functional deterioration. Three stages of tumor relationship to the brainstem arachnoid and pial membranes are proposed. Based on the results of this clinical study of clival meningiomas, suggestions are made for changes in the management strategy of these difficult les ions.