Letter to the Editor concerning “The Haleem–Botchu classification: a novel CT-based classification for lumbar foraminal stenosis” by Haleem S et al. [Eur Spine J (2020): DOI 10.1007/s00586-020-06656-5]

Abstract

We read with great interest an article titled “The Haleem–Botchu classification: a novel CT-based classification for lumbar foraminal stenosis.” authored by Haleem S et al. [1]. We congratulate the authors for addressing this important topic—lumbar foraminal stenosis (LFS) is indeed a degenerative disease that we tend to overlook. They proposed a novel partially quantitative classification system for grading LFS on the basis of CT imaging findings. The grading was developed as four grades: normal foramen— Grade 0, anteroposterior (AP)/superoinferior (SI) (single plane) fat compression—Grade 1, both AP/SI compression (two planes) without distortion of nerve root—Grade 2 and Grade 2 with distortion of nerve root—Grade 3. A total of 800 lumbar foramen of a cohort of 100 random patients were reviewed by two radiologists independently to assess agreement of the novel CT classification against the MRI-based grading system. They get a conclusion that the novel CT-based classification correlates well with the MRI grading system and can safely and accurately replace it where required. However, we wish to bring a few points which we think are extremely relevant to the notice of this journal’s readership which would send out the message expounded in this study with more clarity. Firstly, the novel CT-based classification is still made to classify LFS radiologically using the quantitative system looking at the amount of fat obliteration and nerve root compression. There is no doubt that CT is significantly inferior to MRI of fat and nerve root on sagittal imaging. But, we also noticed that Figs. 3a and 4a did not obviously show the fat compression and distortion of nerve root. Is there a better reading technique for identifying fat nerve roots on bone and soft tissue windows of CT? We hold that it is an important and such conditions may grossly influence the reliability of novel CT classification. Secondly, the CT-based classification showed near-perfect agreement when compared to the MRI grading system (Lee system) [2, 3]. However, whether subgroup analysis was performed for patients of different ages? We believe that this is crucial to evaluate whether the scale can be applied to a wide range of people. Thirdly, the study did not analyze the clinical correlation of the CT-based method for assessing LFS. Neurologic clinical manifestations (paresthesia, extremity weakness, numbness and funicular or radicular pain), positive neurologic signs (Lhermitte sign, Spurling sign), decreased response of DTR or positive denervation sign on EMG should be collected. We think that it is important to evaluate whether the novel imaging grading system correlated with symptoms and neurologic signs and could replace the previous grading system. Once again, we compliment the authors for their work and hope that the readers may benefit from it. Mengchen Yin, Chongqing Xu and Wen Mo took part in concept and design; drafting the manuscript; revising manuscript critically for important intellectual content; approval of final manuscript; and agree to be accountable for all aspects of the work. Mengchen Yin and Chongqing Xu are co-first authors.