LUMBAR CANAL STENOSIS

Lumbar canal stenosis is the narrowing of the spinal canal or the tunnel through which nerves pass. Narrowing of the spinal canal can be congenital but usually occurs due to changes associated with aging that decrease the size of the canal. The levels involved are most commonly L4/5, followed by L5/S1 and L3/4.

 

Treatment requires spinal decompression at the level of the compression usually from thickened ligaments (ligamentum flavum) and thickened joints of the spine (facet joints). In some cases it is associated with spondylolisthesis (slippage of one vertebra over the other) leading to further stenosis. These patients will require decompression of the nerves being compressed together with stabilization (either with pedicle screws or dynamic inter-laminar or inter-spinous devices).

 

SYMPTOMS
  • Numbness in the legs on walking or neurogenic claudication. The distance at which symptoms appear gets shorter and shorter with time. In severe cases patients are unable to leave home because they develop numbness and weakness of the lower limbs at very short distances.

  • Sciatica or pain in the legs, radiating from the back or buttocks down the lower limb, to a varying degree even  up to the ankle and toes.

  • These patients may have significant back pain if the facet joints are also significantly degenerated and hypertrophied. Weakness of back muscles, reduced calcium in the bone (osteoporosis), slippage of one vertebrae on the other (listhesis) and obesity all contribute to back pain. In most patients there is a combination of the above factors contributing to back pain.  

  • Weakness of muscles of the foot:  may be found in chronic cases. This may be detected only on examination by your doctor, and involve the big toe, dorsi-flexion and/ or plantar flexion of the foot.  Weakness, if present, may be detected on walking on the heels or toes. More proximal weakness of hip and knee muscles are present only if lumbar canal stenosis involves higher levels i.e . L1/2, L2/3 or L3/4.

 

INVESTIGATIONS
  1. MRI of the Lumber spine shows the spinal cord, the nerve roots arising from it, the vertebra and the discs. MRI shows the degree of degeneration of the disc, the extent of disc herniation and the degree of nerve root compression. Though several discs may show abnormality on MRI the surgeon decides which of the discs is causing the problem and treats accordingly.

  2. X-Ray of the lumbar spine shows the vertebra and there alignment. Most commonly this is done in flexion and extension to check for any instability (listhesis).

  3. CT scan of the spine is done in certain cases where, after MRI and X-ray, some more information is required by the surgeon. This is particularly relevant in traumatic disc prolapse to look at associated injuries and the size of the pedicles. 

  4. Electromyography (EMG) / Nerve conduction test (NCV) is an electro-physiological test of the limbs that is done in certain cases where the diagnosis is in doubt, to rule out conditions like neuropathy that may be from diabetes, hypothyroidism or certain vitamin deficiencies. EMG can also give an indication of which nerve root may be involved by compression from a disc or bony spur called osteophyte, resulting in acute or chronic changes on EMG.

 

TREATMENT OPTIONS
  1. Medications:

    • Medication like Non–steroidal anti-inflammatory drugs (NSAID) may help back pain and drugs like Gabapentin or Pregabalin may relieve the leg symptoms. These may give some symptomatic relief initially.

  2. Physical Therapy:

    • Physiotherapy is used tfor back and leg pain and to strengthen the back muscles.  

  3. Surgical Management – using techniques of Minimal Invasive spine surgery (MISS)

    • Microscopic lumbar laminotomy involves excising the tissues and bone compressing the nerves and it is covering, the dura. In most degenerative lumbar canal stenosis, narrowing of the spinal canal, resulting in nerve compression, is caused by thickened soft tissue (ligamentum flavum), enlarged lumbar spine facet joints and protruding hard discs. Decompression can be achieved by excising the soft tissue and a small part of the inner (medial) facet joint (without performing a laminectomy) using minimal invasive techniques with the help of the microscope or endoscope. This procedure is called lumbar laminotomy. If the nerve roots are compressed as they leave the spinal canal in the foramen, foraminotomies are performed, in addition, to decompress the nerve roots. This is adequate in most cases of lumbar canal stenosis.  

    • Laminectomy : In some cases, particularly in congenital stenosis,  a part or all of the lamina have to be removed to complete the decompression (laminectomy). Many surgeons perform laminectomies in all cases.

    • Spinal fusion using implants are used in cases where there is spinal instability (Sondylolisthesis) or in patients who have significant back pain. These can be done using pedicle screws and TLIF procedure in addition to the decompression. 

    • Dynamic spine stabilization using pedicle screws, interlaminar or inter-spinous devices like Coflex (Medtronic) are used in cases with significant back pain  where is no instability or mild ( grade 1) listhesis. This is performed in addition to the decompression ( laminotomy).

 
 
 

Disclaimer : The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content, including text, graphics, images and information, contained on or available through this web site is for general information purposes only.

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