The Essence of Clinical Practice Guidelines for Lumbar Spinal Stenosis, 2021: 1. Definition, Epidemiology, and Natural History.

Based on a historical background, LSS is not a single disease but a combination of various symptoms. At present, there is no uniform view on the definition of LSS. Disorders of the nervous and/or vascular elements are caused by the lumbar spinal canal or intervertebral foramen (anatomically not included in the spinal canal), and they induce symptoms in patients with LSS. In this edition, the diagnostic criteria (draft) of the 1 edition were revised, and the diagnostic criteria for LSS are proposed as follows: 1) presence of pain and numbness from the buttocks to the lower limbs, 2) symptoms from the buttocks to the lower limbs that appear or are exacerbated by continuous standing or walking and are alleviated with the maintenance of a forward flexion or sitting position, 3) either with or without low back pain, and 4) presence of findings of degenerative stenosis in imaging results, such as MRI, that can explain clinical findings. There is no consensus on the LSS definition as the etiology and pathological changes have not been completely elucidated.