Pathophysiology
Clinical meaning
Spinal stenosis is the narrowing of the spinal canal, nerve root canals (lateral recesses), or intervertebral foramina, resulting in compression of the spinal cord or spinal nerve roots. The condition most commonly occurs in the lumbar spine (L3-L5) and the cervical spine (C4-C7). The spinal canal is bounded anteriorly by the vertebral bodies and intervertebral discs, laterally by the pedicles and facet joints, and posteriorly by the laminae and ligamentum flavum. Degenerative changes are the most common cause in adults over age 50. As the spine ages, intervertebral discs lose water content and height (desiccation), leading to disc bulging into the spinal canal. Osteophytes (bone spurs) form at the vertebral body margins and facet joints as a compensatory response to increased mechanical stress. The ligamentum flavum, which connects adjacent laminae, undergoes hypertrophy and thickening with age, further encroaching on the spinal canal from the posterior aspect. In lumbar stenosis, the hallmark symptom is neurogenic claudication (pseudoclaudication): bilateral leg pain, heaviness, and weakness that worsens with walking or standing upright (spinal extension) and improves with sitting or leaning forward (spinal flexion)....