Introduction In patients with radiating pain in extremities foraminal stenosis is commonly evaluated with radiology, however there is a lack of consensus regarding the methodology to assess the compression of the nerve roots. The purpose of this systematic review was to evaluate validated classification systems for foraminal stenosis in the lumbar and cervical spine based on Magnetic Resonance Imaging (MRI).

Methods A systematic review was performed according to PRISMA guidelines. The systematic search was conducted by a professional librarian in Cochrane, Embase, Medline and PubMed databases for the time period 1980 to september 2021 in English literature using numerous search words within three categories: foraminal stenosis, MRI and scoring. From the yielded search, two of the authors selected articles according to the predefined criteria, including reliability testing of the classification systems.

Results A total of 823 articles were identified based on the used search words. The selection process included initial abstract reviews and thereafter full-text review of 64 articles. Finally 14 articles were included, fulfilling the predefined inclusion criteria. One validated classification system for foraminal lumbar stenosis by Lee et al [1] and two validated classification systems for the cervical spine were identified [2, 3]. The remaining included articles presented validations and modifications of these three classification systems (fig 1 and 2). The reliability was found to be moderate to good for all three classifications, both in the original articles and in the articles validating them.

Discussion The three identified validated classification systems for lumbar and cervical foraminal stenosis demonstrated all moderate to good reliability and have all been shown to be feasible to use in the clinical setting. There is however a need for studies evaluating how valid these classifications are in relation to both clinical symptoms/findings and to surgical outcome data, when used in the surgery selection process.