A proposed grading system for standardizing tumor consistency of intracranial meningiomas

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Tumor consistency plays an important and underrecognized role in the surgeon's ability to resect meningiomas, especially with evolving trends toward minimally invasive and keyhole surgical approaches. Aside from descriptors such as “hard” or “soft,” no objective criteria exist for grading, studying, and conveying the consistency of meningiomas.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors designed a practical 5-point scale for intraoperative grading of meningiomas based on the surgeon's ability to internally debulk the tumor and on the subsequent resistance to folding of the tumor capsule. Tumor consistency grades and features are as follows: 1) extremely soft tumor, internal debulking with suction only; 2) soft tumor, internal debulking mostly with suction, and remaining fibrous strands resected with easily folded capsule; 3) average consistency, tumor cannot be freely suctioned and requires mechanical debulking, and the capsule then folds with relative ease; 4) firm tumor, high degree of mechanical debulking required, and capsule remains difficult to fold; and 5) extremely firm, calcified tumor, approaches density of bone, and capsule does not fold. Additional grading categories included tumor heterogeneity (with minimum and maximum consistency scores) and a 3-point vascularity score. This grading system was prospectively assessed in 50 consecutive patients undergoing craniotomy for meningioma resection by 2 surgeons in an independent fashion. Grading scores were subjected to a linear weighted kappa analysis for interuser reliability.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Fifty patients (100 scores) were included in the analysis. The mean maximal tumor diameter was 4.3 cm. The distribution of overall tumor consistency scores was as follows: Grade 1, 4%; Grade 2, 9%; Grade 3, 43%; Grade 4, 44%; and Grade 5, 0%. Regions of Grade 5 consistency were reported only focally in 14% of heterogeneous tumors. Tumors were designated as homogeneous in 68% and heterogeneous in 32% of grades. The kappa analysis score for overall tumor consistency grade was 0.87 (SE 0.06, 95% CI 0.76–0.99), with 90% user agreement. Kappa analysis scores for minimum and maximum grades of tumor regions were 0.69 (agreement 72%) and 0.75 (agreement 78%), respectively. The kappa analysis score for tumor vascularity grading was 0.56 (agreement 76%). Overall consistency did not correlate with patient age, tumor location, or tumor size. A higher tumor vascularity grade was associated with a larger tumor diameter (p = 0.045) and with skull base location (p = 0.02).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The proposed grading system provides a reliable, practical, and objective assessment of meningioma consistency and facilitates communication among providers. This system also accounts for heterogeneity in tumor consistency. With the proposed scale, meningioma consistency can be standardized as groundwork for future studies relating to surgical outcomes, predictability of consistency and vascularity using neuroimaging techniques, and effectiveness of various surgical instruments.</jats:p></jats:sec>

Predicting Meningioma Consistency on Preoperative Neuroimaging Studies

“…In 2013, Zada and colleagues 2 proposed a meningioma consistency grading system that would be based on an ordinal scale rather than simply labeling meningiomas as either “soft” or “hard”. The impetus for their approach was due to the common practice in neuroimaging studies of retrospectively using this binary approach based on neurosurgical operative reports - a method that also failed to recognize areas of mixed consistency within the tumor.…”

“…The authors of a very recent neuroimaging study of meningioma consistency felt that the Zada classification resulted in less variability and subjectivity compared to a neurosurgeon's qualitative assessment of “hard” vs “soft” 5 . Utilization of grading schemes such as those proposed by Zada et al 2 may allow for more objective comparison of studies examining meningioma consistency.…”

“…extremely soft vs extremely firm). While it appears that water and collagen content are important determinants of meningioma consistency, no definite association with histopathological subtype has been established 2,5-7,15-17 . This review will summarize the current neuroimaging literature as it relates to the pre-operative evaluation of meningioma consistency.…”

“…With surgery being a primary mode of therapy, minimally invasive alternatives to conventional open approaches to the resection of intracranial meningiomas, such as key-hole or endoscopic transnasal approaches, have recently become more commonplace in tumors of the skull base 2-5 . However, proper patient selection is critical to determine which neurosurgical operation is most appropriate for a given patient.…”

Higher-Resolution Magnetic Resonance Elastography in Meningiomas to Determine Intratumoral Consistency

“…As the role of endoscopic and other minimally invasive approaches for intracranial tumor resection becomes more prevalent, there is greater need for an imaging modality that can give detailed information regarding tumor consistency 12 . Ostensibly, tumors that are harder would be more amenable to conventional open approaches, while softer tumors might favor minimally invasive procedures; in addition, knowing the consistency of a tumor would aid in preoperative planning regardless of the approach.…”