Lumbar spinal canal stenosis
ANATOMY OF THE SPINE
The human spine is formed by individual vertebrae and connective tissue discs in between. The vertebrae form the spinal canal. There are seven cervical, twelve thoracic, and five lumbar vertebrae. The intervertebral discs are the link between the individual vertebral bodies.
Normal anatomy of the spine. Longitudinal section and cross sections through the cervical, thoracic and lumbar spine.
The little joints that link the vertebrae together are known as facet joints. They help to stabilize the spine and, together with the intervertebral discs, allow a certain degree of mobility of the spinal cord. The spinal canal should be wide enough to allow nerve roots to float freely in cerebrospinal fluid.
The front border of the spinal canal is built by the vertebral bodies and intervertebral discs, the side by the intervertebral joints (facets) and back by the ligamentum flavum (yellow band) and vertebral arches. Discs consist of an outer fibrous ring (annulus fibrosus), which surrounds an inner gel-like center (nucleus pulposus).
The spinal cord and nerve roots lie within the spinal canal. The spinal cord extends downwards approx. to the 1st lumbar vertebra. Below, only nerve roots are present in the spinal canal. At the level of the intervertebral disc the nerve roots pass through the neural root foramina to exit the spinal canal. The spinal cord and nerve roots conduct electric-like signals from the skin and joints to the brain, and process of movement is initiated from the brain to the muscles.
Lumbar stenosis is a narrowing of the spinal canal. This constriction compresses the nerve roots extending to the legs. The pressure on nerve roots usually increases slowly over months and years. Therefore, the symptoms slowly progress over time.
Spinal canal stenosis in the lumbar spine
A MRI image showing a transverse T2 section of a lumbar spinal canal stenosis
CAUSE OF SYMPTOMS
Gradually progressing compression of the nerve roots in the lumbar spine
SYMPTOMS AND SIGNS
Pain, numbness, weakness in the legs when standing upright or walking
Loss of bladder or bowel control
Numbness of the genitals and loss of sexual function
The symptoms are present when standing upright or walking and usually relieved by leaning forward or sitting down. Symptoms usually get worse over time. Symptoms begin gradually and tend to worsen over months and years.
THE DIAGNOSIS IS BASED ON Medical history Clinical exam
and at least one of the following tests: Magnetic resonance imaging (MRI) Computer tomography Myelography
additionally you may have to do: Radiographs Functional (dynamic) radiographs
Facet joints block
Sacroiliac joint block Electromyography
Non-surgical (conservative) treatment can temporarily improve some of the symptoms in less severe cases.
Non-surgical treatment may include Physiotherapy Physical exercise
Strengthening the back muscles Treatment with heat (Fango) Nonsteroidal anti-inflammatory drugs Corticosteroids
Epidural corticosteroid infiltrations
WHEN SHOULD AN OPERATION BE PERFORMED?
Because of the gradual worsening of the symptoms almost always surgery is required. Due to the chronic progressive nature of the disease an emergency operation is rarely necessary.
Elective surgery should be considered when a significant muscle weakness (>72 hours) is present or the symptoms (e.g. pain) impair the patient’s quality of life and conservative treatment fails to achieve significant improvement within 6-8 weeks.
WHAT IS THE GOAL OF SURGERY?
To release the compressed nerve roots
To improve symptoms (e.g. pain reduction)
To stop the worsening of the symptoms
To preserve the protective function of the spine
HOW IS SURGERY PERFORMED?
Posterior decompression of the spinal canal without fusion
Posterior decompression of the spinal canal with stabilisation
WHICH OTHER DISEASES SHOULD BE EXCLUDED (DIFFERENTIAL DIAGNOSIS)? Peripheral arterial occlusive disease (PAOD) A disease of peripheral nerves (e.g. polyneuropathy) Lower back pain / Lumbar facet joint pain Radiculitis Tumor of the spine Peripheral nerve compression syndromes Vertebral fractures
Diseases of the hip or knee Sacroiliac joint pain Disc herniation Lumbar epidural spinal canal lipomatosis