Analysis of vestibular schwannoma size: A literature review on consistency with measurement techniques.
BACKGROUND
Vestibular schwannoma (VS) tumor size, a significant prognostic indicator, is closely analyzed in patients undergoing observation or treatment. It has historically been reported in terms of linear size; however, volumetric assessments can now be performed routinely. We examine the use of described measurement techniques in large published clinical series to assess their consistency.


METHODS
Computerized searches of the MEDLINE database (Pubmed) from 1975 to August 2014 were conducted with the purpose of identifying large series describing the management of VSs. Articles that reported tumor size measurements were included if they described greater than 600 patients.


RESULTS
19 studies were found fitting the inclusion criteria, consisting of large retrospective studies with sample sizes ranging from 614 to 2991. A total of 17 studies reported linear measurements, while 2 studies reported volumetric assessments of tumor size. Significant variations were found regarding methods for linear measurement. Furthermore, several papers did not provide any details regarding the measurement technique. Inclusion of intracanalicular portions of the tumor was highly variable. Volume assessments were performed by segmented volume analysis.


CONCLUSIONS
Among the large published series on VSs, significant variation exists regarding the utilized measurement technique to assess size. Volumetric assessments have the greatest clinical utility, sensitivity and accuracy in measuring tumor size and growth. Standardization of volume assessments will provide the best method for producing consistent literature findings.
Department of Neurological Surgery, Loyola University School of Medicine, Maywood, IL, United States.
Daphne
D
Li
Department of Neurological Surgery, Loyola University School of Medicine, Maywood, IL, United States.
Asterios
A
Tsimpas
Department of Neurological Surgery, Loyola University School of Medicine, Maywood, IL, United States; Edward Hines, Jr. VA Medical Center, Hines, IL, United States. Electronic address: agermanwala@gmail.com.
Anand V
AV
Germanwala
D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods; D009464:Neuroma, Acoustic / Q000473:pathology* / Q000601:surgery; D016634:Radiosurgery / Q000379:methods*
Acoustic neuroma; Linear measurement; Tumor size; Vestibular schwannoma; Volumetric measurement