Spinal cord is a tubular structure and the nerves branches out and passes through the tunnel (spinal canal) and stenosis means narrowing of passage of nerves which can compress and pinch the nerve. Diminishing size of the spinal canal usually occurs due to changes associated with aging process as a result nerves become increasingly irritated and squeezed as the diameter of the canal becomes narrower referring to lumbar canal stenosis(LCS)
- LCS – Most common cause of back pain and disability
- Prevalence of LCS is 9 % in general population
- 47 % prevalence in people older than 60 years
- 21% of non-symptomatic population over 60 years of age demonstrate stenosis on MRI
- Have leg and back pain both (but majority of population have predominant leg)
- Uphill is easier to walk than downhill
- LCS, starts slowly and worsens over time followed gradual loss of leg strength, worsening severe pain that greatly affects a person’s ability to work or enjoy life
- LCS – most common indication for spine surgery above 65 years
Risk factors:
- Age – more than 50 years – age related changes such as osteoarthritis of facet joint, bony spurs, thickening of flavum (soft tissue tissue covering the canal and nerves)
- Congenital narrowed canal is developmental defect (2.6% – 4.7) which causes narrowing of abnormalities or disorders in postnatal development
Causes:
- Connective tissues – ligaments (ligamentum flavum ) get thicker
- Facet hypertrophy (over growth of joints in the spine)
- Spondylolisthesis – Slippage of one vertebrae over another with displacement of disc (pseudo disc bulge) compressing the nerves
- Degenerative scoliosis – deformed curvature of spine as a consequence of degeneration of spine
- Previous lumbar surgery (post-surgical scaring)
- Infection – Uncommon cause
Symptom:
- Pain in the buttocks, hips and legs or sciatica – Less pain with leaning forward or sitting or lying, pain aggravates on bending backwards (unilateral or bilateral)
- Difficultly in walking – Neurogenic claudication – Cramping in the calf with walking, requiring frequent multiple short rests to walk a distance
- Pain in the legs at rest
- Numbness or tingling in legs
- Loss of sensation in the feet
- Weakness in Legs
- Weakness in the foot that causes the foot to slap down when walking
- Sexual dysfunction
Diagnosis is made based on symptoms, examination and finally imaging
MRI is noninvasive imaging method of choice to justify the presence of anatomic narrowing of the spinal canal or the presence of nerve root impingement
Treatment options:
- Medication – Analgesic, NSAIDS, Anti convulsants (Pregabalin , Gabapentin ) can give relief when there is mild canal narrowing. In moderate to severe canal narrowing it might not be beneficial or may provide only temporary relief.
- Physiotherapy – It is important to do regular physiotherapy to keep the back and joints flexible, though physiotherapy itself doesn’t help in reducing the nerve compression. Physiotherapy should be done in consultation with a qualified physiotherapist and should not be done in presence of severe pain.
- Epidural steroid injection – Good short-term relief in terms of leg pain (2-6 months)
- Lumbar braces or belt/corset – Minimal relief in terms of walking distance – But no sustained results
A patient may be considered a candidate for surgery if:
- Back and leg pain limits normal activity or impairs quality of life
- Progressive neurological deficits develop (leg weakness, foot drop, numbness in the limb)
- Loss of normal bowel and/or bladder functions
- Difficulty standing or walking
- Failed medical therapy
The primary goal of surgery is to create space for the nerve to pass through and relieve compression on the nerve and can in form of decompression and fusion which is performed in a minimal invasive fashion.
- Decompression – Laminectomy and Foraminotomy – removal part of bone, soft tissue and ligaments – for patients with predominant leg pain without instability. This can be done minimally invasive, using either a tube or an endoscope.
- Spinal fusion – In case of dominant back pain coupled with leg pain and spine instability. Here an artificial graft/ cage is placed in between the two vertebral bones and stabilised with screws and rod to achieve fusion between the two adjacent bones.
For details – read section on “Surgery for Lumbar canal stenosis”
What can I expect after surgery?
- In both cases you are made to walk on next day morning
- Immediate relief of leg pain is felt
- Minimal operative site pain and back pain as a result of surgery is expected with numbness in leg at times
- Benefits of surgery appear to last for many years (long term relief)
For details – read section on “Surgery for Lumbar canal stenosis”
In small percentage of cases there is risk of adjacent segment disease (upper or lower level), but with timely physiotherapy and life style modification risk can be reduced
