Lumbar Spinal Stenosis: How Is It Classified?

Gregory D. Schroeder, MD; Mark F. Kurd, MD; Alexander R. Vaccaro, MD, PhD, MBA


J Am Acad Orthop Surg. 2016;24(12):843-852. 

In This Article

Clinical Severity of Lumbar Stenosis

Importantly, although the aforementioned radiographic classifications are designed to determine the severity of lumbar stenosis, multiple studies have reported a poor correlation between stenosis on imaging and patients' symptoms.[3] Thus, radiographic findings should be interpreted with these symptoms in mind. Currently, no classification combines the clinical and radiographic severity of spinal stenosis; instead nonspecific health-related quality of life metrics, such as the Oswestry Disability Index (ODI) or Medical Outcomes 36-Item Short Form Health Survey, are often used. Alternatively, spinal stenosis[FIGURE DASH]specific instruments, such as the Swiss Spinal Stenosis (SSS) Questionnaire—also known as the Zurich Claudication Scale—and the Fukushima LSS Scale 25 (FLS-25), have been published, but they have not been widely adopted in the literature.[27,28]

The ODI is the most commonly used metric in the literature. Although it is designed for lumbar spine pathology, it was initially used in chiropractic trials for low back pain.[29] However, since its publication, the ODI has had excellent reliability in patients with lumbar stenosis. Furthermore, changes in ODI scores after treatment have correlated strongly (r = 0.80)[30] with patient satisfaction.

The SSS Questionnaire was one of the first instruments designed specifically to evaluate patients with LSS. It has three scales for determining symptom severity, physical function, and patient satisfaction with treatment. The first six questions in the severity score are graded from 1 to 5, and the seventh question is graded as 1, 3, or 5. A high score is associated with increasing severity. Similarly, the questions in the physical function and satisfaction scales are scored from 1 to 4, and the higher the score, the more disabled or less satisfied the patient.[28] Multiple studies have found the SSS Questionnaire to be internally consistent, reliable, and responsive to changes in the clinical presentation of the patient.[28,31] In a Rasch Analysis of the questionnaire, Comer et al[31] found the severity and physical function scales to be reliable and appropriately targeted to patients with lumbar stenosis. However, the symptom severity scale is multidimensional, focusing on both pain and neuroischemic symptoms, whereas the functional scale is unidimensional, focusing only on a patient's ability to walk.

The FLS-25 is a newer assessment tool designed to determine the severity of symptoms in patients with LSS. It comprises 25 questions, and the responses are graded on a Likert scale, such that zero indicates strongly disagree, 1 indicates somewhat disagree, 2 indicates neither agree nor disagree, 3 indicates somewhat agree, and 4 indicates strongly agree. In a multicenter study of nearly 200 patients with lumbar stenosis, Sekiguchi et al[27] demonstrated good correlation between patient-reported severity of leg pain (r = 0.59) and FLS-25 score, as well as patient-reported leg numbness (r = 0.0437) and FLS-25 score. In a separate study by Sekiguchi et al,[32] FLS-25 scores were correlated with symptoms during a lumbar extension test and a walking stress test in 167 patients. They found that FLS-25 scores increased as the time the patients were able to stand with the lumbar spine in extension decreased (P = 0.003). Similarly, the FLS-25 score increased as the time a patient could walk (P = 0.054) and the distance a patient could walk (P = 0.002) decreased.