Standardizing Tumor Consistency of Intracranial Meningiomas
Standardizing Tumor Consistency of Intracranial Meningiomas
Object 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.
Methods 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.
Results 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).
Conclusions 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.
Over the past decade, a great deal of interest has been generated in the resection of extraaxial skull base tumors via minimally invasive, endoscopic, and keyhole surgical approaches. Open surgical approaches for skull base meningiomas of the anterior and middle skull base, which still define the gold-standard intervention for many of these lesions, have been challenged by more recent series of endoscopic transnasal and keyhole approaches. Minimally invasive approaches have in turn been galvanized by advancements in endoscopic technology, instrumentation, and the development of novel techniques for skull base reconstruction and CSF leak repair. As neurosurgical approaches to meningiomas and other cerebral tumors continue to evolve in terms of minimal invasiveness, the selection of patients for minimally invasive versus traditional open surgical approaches is likely to become even more critical in optimizing patient outcomes. A priori knowledge of key tumor characteristics (including pathology, vascularity, invasiveness, and so on) acquired using advanced neuroimaging modalities is likely to contribute greatly to this patient selection process.
One key characteristic of skull base tumors that remains rather elusive with regard to preoperative assessment, yet greatly affects the ease of the operation, is tumor consistency (also referred to as texture or firmness). In previous attempts to predict meningioma consistency based on neuroimaging studies, investigators have generally referred to the meningiomas as either "hard" or "soft" and have often reported this information in a retrospective fashion derived from operative notes. As neurosurgeons are increasingly having to decide between minimally invasive and open craniotomy approaches, tumor consistency is likely to become a more important factor in determining the operative procedure as well as any intraoperative or preoperative adjunctive measures. Furthermore, as newer and more advanced neuroimaging modalities provide improved means of assessing tumor consistency, a more detailed and objective tumor consistency scoring system would greatly improve our ability to analyze and convey surgical parameters relating to tumor consistency in a standardized fashion. Finally, the ability to objectively assess surgical tools for tumor resection may be improved by the application of a standardized grading system for tumor consistency.
For these reasons, the authors aimed to establish and test the validity of an objective and practical grading system for meningioma consistency, which could more accurately account for the continuous, rather than binary, spectrum of meningioma texture, as well as accounting for regions of intratumoral heterogeneity with respect to consistency. We created a practical 5-point grading system to quantify the consistency of intracranial meningiomas based on the ease of internal debulking and ability to fold in the tumor capsule following debulking. We subsequently assessed the validity of this 5-point grading system through the independent grading of each tumor by 2 neurosurgeons who were involved with the resection and who did not discuss the tumor grading during the operation.
Abstract and Introduction
Abstract
Object 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.
Methods 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.
Results 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).
Conclusions 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.
Introduction
Over the past decade, a great deal of interest has been generated in the resection of extraaxial skull base tumors via minimally invasive, endoscopic, and keyhole surgical approaches. Open surgical approaches for skull base meningiomas of the anterior and middle skull base, which still define the gold-standard intervention for many of these lesions, have been challenged by more recent series of endoscopic transnasal and keyhole approaches. Minimally invasive approaches have in turn been galvanized by advancements in endoscopic technology, instrumentation, and the development of novel techniques for skull base reconstruction and CSF leak repair. As neurosurgical approaches to meningiomas and other cerebral tumors continue to evolve in terms of minimal invasiveness, the selection of patients for minimally invasive versus traditional open surgical approaches is likely to become even more critical in optimizing patient outcomes. A priori knowledge of key tumor characteristics (including pathology, vascularity, invasiveness, and so on) acquired using advanced neuroimaging modalities is likely to contribute greatly to this patient selection process.
One key characteristic of skull base tumors that remains rather elusive with regard to preoperative assessment, yet greatly affects the ease of the operation, is tumor consistency (also referred to as texture or firmness). In previous attempts to predict meningioma consistency based on neuroimaging studies, investigators have generally referred to the meningiomas as either "hard" or "soft" and have often reported this information in a retrospective fashion derived from operative notes. As neurosurgeons are increasingly having to decide between minimally invasive and open craniotomy approaches, tumor consistency is likely to become a more important factor in determining the operative procedure as well as any intraoperative or preoperative adjunctive measures. Furthermore, as newer and more advanced neuroimaging modalities provide improved means of assessing tumor consistency, a more detailed and objective tumor consistency scoring system would greatly improve our ability to analyze and convey surgical parameters relating to tumor consistency in a standardized fashion. Finally, the ability to objectively assess surgical tools for tumor resection may be improved by the application of a standardized grading system for tumor consistency.
For these reasons, the authors aimed to establish and test the validity of an objective and practical grading system for meningioma consistency, which could more accurately account for the continuous, rather than binary, spectrum of meningioma texture, as well as accounting for regions of intratumoral heterogeneity with respect to consistency. We created a practical 5-point grading system to quantify the consistency of intracranial meningiomas based on the ease of internal debulking and ability to fold in the tumor capsule following debulking. We subsequently assessed the validity of this 5-point grading system through the independent grading of each tumor by 2 neurosurgeons who were involved with the resection and who did not discuss the tumor grading during the operation.
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