Introduction
Anatomy
Causes
Symptoms
Diagnosis
Non-surgical treatment
Surgical treatment
Lumbar spinal stenosis is defined as narrowing of the spinal canal (central stenosis), lateral recess (lateral recess stenosis) or the intervertebral foramen (foraminal stenosis) with neural impingement. It is most common in men over the age of 50.
The spinal column is a three-dimension structure made up of the spinal vertebral body complex including the bony vertebra, the intervertebral disc, the facet joints as well as the surrounding ligamentous complex. Understanding the relationship between the neural elements and the anatomical structures, in their static or dynamic state, is important in the analysis of the problem and in the formulation of a treatment plan.
The spinal canal consists of the bony part and the soft tissue part. The bone element includes the posterior wall of vertebral body, the lamina and the facet joints. The soft tissue includes the intervertebral disc, the facet joints capsule and the yellow ligaments. Depending on the anatomical location of the stenosis, it can be classified as central, lateral recess or foraminal stenosis.
1. Congenital stenosis
Idiopathic
Dwarfism
2. Acquired
Degenerative stenosis
Aging and degenerative processes make the spinal canal become narrower. These include formation of the osteophytes around the facet joints, thickening of the capsule and ligaments, and thinning and degenerative changes of the intervertebral disc.
Spondylolisthesis
Slippage of the vertebra – one over the other – can cause narrowing of the central canal as well as impingement of the nerve roots at the foramens.
Iatrogenic
The spinal canal becomes narrow after decompression or fusion surgery due to scar formation or excessive growth of fusion mass.
Post-traumatic
Fracture of the vertebral body particularly burst fracture with retropulsion of the body fragments into the spinal canal.
Miscellaneous
Some metabolic bone disease processes e.g. Osteomalacia, Osteoporos and Paget's disease can cause gradual narrow of the spinal canal.
Pain is typically over the lower back, buttocks, and lower extremities. It is worse when standing and walking and is relieved by rest, flexion posture, and sitting. 50% of patients have claudication-like symptoms with pain getting worse with increasing walking distances. In severe case, patients may experience weakness in both lower extremities and loss of urinary and bowel control.
Clinical examination includes a neurological examination that tests for any pain and loss of extension range of the trunk. Typical tension signs for nerve root impingement may not be present. Patients may be asked to perform a walking test on the treadmill and to test for any reproducible claudication symptoms.
Plain x-ray of the lumbar spine may reveal loss of normal lumbar curve and narrowing of the disc spaces, hypertrophy of the facet joints, presence of osteophytes on the facets or ,spondylolisthesis in the lower lumbar segments.
A CT scan is helpful to assess the canal dimensions. A MRI scan is the best modality for evaluating lumbar spinal stenosis, impingement of the dural sac or the nerve roots and other soft tissue pathology.
Conservative treatment includes nonsteroidal antiinflammatory drugs, trunk flexion and extension exercises. Epidural or foraminal injection will be tried in indicated patients.
Surgery is indicated when conservative treatment has failed, and where patients have progressive motor weakness, limb pain and claudication symptoms affecting quality of life and in severe case such as cauda equina syndrome.
Surgical techniques include decompression surgery and in some situations, spinal fusion is recommended, if there is an element of spinal instability.
Recent advance in motion preservation technique e.g. interspinous process spacer or distraction device may be helpful in selected patients.
Dr. SUN, Lun-kit