Narrowing of the dimensions of the spinal canal is called spinal stenosis. Spinal canal is present inside the vertebral bones and it contains the spinal cord, nerve roots and blood vessels supplying the spinal cord and nerves. The vertebral bones form the vertebral column (back bone). The reduction in the size of spinal canal can compress the spinal cord, nerve roots or blood vessels that supply the spinal cord. Spinal stenosis may be congenital (present from birth) or acquired. Spinal canal stenosis can occur in the lumbar, cervical or thoracic level. Spinal stenosis is common in the lumbar level and rare in the thoracic region. In 5% of the cases, cervical and lumbar spinal stenosis occurs together.
What are the causes for lumbar spinal stenosis?
What are the symptoms of lumbar spinal stenosis?
- Thickening of the ligaments normally present in the spinal canal due to aging.
- Hypertrophy of the facet joints (Facet joints are the joints that connect the adjacent vertebral bodies).
- Lumbar disc prolapse (slipping of the shock absorbing cushion which is present in between the vertebral body)
- Spondylolisthesis( slipping of the adjacent vertebral bodies in relation to each other)
- Congenital as in achondroplastic dwarf.
- Following trauma
- Ankylosing spondylitis
- Paget's disease
What are the other conditions that mimic lumbar spinal stenosis?
- Symptomatic lumbar canal stenosis is common between lumbar vertebra 4-5 and 3-4. The patient often presents with neurogenic claudication or pseudoclaudication. In Latin, Claudicate means "to limp". The patient with lumbar spinal stenosis presents with discomfort and pain in the buttock, hip, thigh or leg, which is mostly unilateral and the pain comes usually when standing or walking and it is reduced when squatting, sitting or lying down.
- There may be numbness or tingling sensation in the leg while walking.
- Some patients may get weakness of the leg while walking which becomes normal on taking rest.
- The cause for the pain, numbness and weakness is due to the reduced blood supply to the spinal nerve roots due to the compression of the blood vessels because of narrow spinal canal.
How do you diagnose lumbar canal stenosis?
- Vascular insufficiency: Here the pain is usually present in group of muscles with common blood supply and the pain is brought on by walking. But it is relieved by taking rest and he need not sit or squat. The pain relief is immediate. There will be pallor of the foot and the peripheral pulses in the leg are absent. The skin temperature of the feet is decreased due to poor blood circulation.
- Trochanteric bursitis: It is a degenerative condition of the hip.
- Disc herniation(lumbar or thoracic)
- Spinal cord tumor
- Diabetic neuritis
What is the treatment for lumbar spinal stenosis?
- X-rays are taken to rule out spondylolisthesis.
- CT scan of the lumbosacral spine is taken and it will show the shape of the lumbar spinal canal and exact measurements of the spinal canal. Normal Antero-posterior diameter on CT scan of the lumbar spinal canal is greater than 11.5mm.
- MRI scan of the lumbosacral spine is taken to see the degree of compression of the spinal cord and nerve roots and to plan for surgery.
- Doppler study of the lower limb is done to rule out vascular insufficiency.
Treatment for lumbar canal stenosis is either by drugs and physiotherapy or surgery. In one study of 27 patients who were treated by drugs and physiotherapy, 19 remained unchanged, 4 improved and 4 worsened. Analgesics and physiotherapy are the main stays of medical management.
Surgical decompression for lumbar spinal stenosis is undertaken when pain and numbness becomes severe in spite of medical management. The goals of surgery are pain relief, halting the progression of symptoms and if possible to reverse some of the existing neurological deficits. Decompressive laminectomy with nerve root decompression is the surgical procedure performed for lumbar canal stenosis. Success rate for surgery is 78-88 percent at the end of 6 months after surgery but on following the patients for five years, the success rate is reduced to around 70%.