Clinical Validation of a Proposed Intraoperative Consistency Grading System for Meningiomas

Background The present study aims to clinically assess the utility of a previously proposed intraoperative meningioma grading system to objectively assess tumor consistency and relate consistency scores to the extent of tumor resection.

Methods The proposed grading system was prospectively assessed in 128 consecutive patients undergoing craniotomy for meningioma resection by multiple neurosurgeons at LAC + USC Medical Center and Keck Hospital. Grading scores (using a previously validated scoring system ranging from 1 to 5) were subjected to chi-square analysis for independence with extent of tumor resection, categorized by gross total resection (GTR) or subtotal resection (STR), which was determined by postoperative MRI findings.

Results A total of 128 patients were included in the analysis. The distribution of overall tumor consistency scores was as follows: Grade I, 3.1%; Grade II, 14.1%; Grade III, 44.5%, Grade IV, 32.0%, Grade V, 6.3%. For statistical analysis, individual grades were grouped into soft (Grades I–II), average (Grade III), and firm (Grades IV–V), the distribution of which was as follows: 17.2, 44.5, and 38.3%, respectively. The proportion of STR for each category was as follows: Grades I to II, 23%; Grade III, 32%; Grades IV to V, 57%. A chi-square test of independence between consistency scores and extent of resection was significant, chi-square (5, N = 128) = 10.4, p < 0.05.

Conclusion These data demonstrate evidence for the clinical validity of the proposed intraoperative grading scale with respect to extent of tumor resectability, a measure of surgical outcome in the resection of meningiomas. Future studies will relate intraoperative consistency scores to preoperative MRI studies to predict tumor consistency and, thus, extent of resectability during the preoperative planning stage.