Our lower back (Lumbar spine) consists of five big bones (aka vertebrae) in the lower part of the spine between the ribs and the pelvis with intervening soft cushion like pads referred to as discs.
By Dr SK Rajan
Our lower back (Lumbar spine) consists of five big bones (aka vertebrae) in the lower part of the spine between the ribs and the pelvis with intervening soft cushion like pads referred to as discs. Each of the bones have a hole in them and these holes align to form a pipe for passage of spinal nerves. Narrowing of this passage is referred to as Lumbar Canal Stenosis (LCS). This stenosis results in compression of the nerves traveling through the lower back into the legs.
While it may affect younger population due to developmental (birth related) causes, it is more often a degenerative (wear and tear) condition that affects people age 50 and older. The discs may become less spongy as you age, resulting in reduced disc height and bulging of the hardened disc into the spinal canal. Currently, it is estimated that over 4 Lakh Indians above the age of 60 years are suffering from its symptoms and over 12-15 Lakh across age brackets having some sort of spinal stenosis.
Depending on the severity of the condition, Lumbar spinal stenosis may or may not produce symptoms. While the narrowing of the spinal canal itself does not produces the symptoms but due to the inflammation of the nerves caused by the increased pressure attributes to the cause. Varying from person to person the various symptoms include –
• Pain, weakness, or numbness in the legs, calves, or buttocks
• Pain may radiate to one or both the legs (resembling a painful condition referred to as Sciatica)
• In rare cases, there is loss of motor functioning in the legs, and loss of bowel control.
• Excruciating pain while walking that may subside while bending forward, sitting or lying down.
Degenerative spondylolisthesis and degenerative scoliosis (curvature of the spine) are two conditions associated with lumbar spinal stenosis. Degenerative spondylolisthesis (slippage of one vertebra over another) is caused by arthritis of the facet joints. Most commonly, it involves the L4 slipping over the L5 vertebra. It usually is treated with the same conservative or surgical methods as lumbar spinal stenosis.
Degenerative scoliosis occurs most frequently in the lower back and more commonly affects people age 65 and older. Back pain associated with degenerative scoliosis usually begins gradually and is linked with activity. The curvature of the spine in this form of scoliosis often is relatively minor, so surgery is required when conservative methods fail to alleviate pain associated with the condition.
Based on the medical history, symptoms, hereditary risk factors, physical examination and diagnostic tests are required to confirm the condition. Radiology tests including X-rays, CT Scan and MRI are helpful in identifying the structure of the vertebrae and outline of the joints. These imaging techniques help the surgeons a detailed view of the spinal canal, its content and the structures around it. 3 D imaging produced through MRI are also helpful in analyzing the nerve roots, adjacent areas, any enlargements, degeneration or tumors.
In specific cases a myelogram may be required, which is a special X-ray of the spinal cord that is taken after injecting a contrast material in the surrounding cerebrospinal fluids (CSF). This is helpful in monitoring the pressure on the spinal cord or on the related nerves due to the compression, herniated disc, bone spurs or tumors.
How can this be treated?
While medication and physical therapy remain the first line of treatment module, surgical intervention is only preferred when these fails to provide relief.
Medications & injections – Anti inflammatory medications and analgesics may be helpful in the initial stages to subside pain. But in case is the pain is persistent of worsens with time, the doctor may prescribe other medications or injections. Epidural injections also help in reducing pain and swelling, but is only a temporary relief method followed.
Physical therapy – this along with prescribed exercises may help stabilize your spine, build your endurance and increase your flexibility. Therapy may help you resume your normal lifestyle and activities.
In those cases where these conservative options fail, surgery may be the only resort. Depending upon age, overall health, associated co-morbidities and pre-existing conditions doctors may consider the type of surgery.
There are several different surgical procedures that can be utilized, the choice of which is influenced by the severity of your case. In a small percentage of patients, spinal instability may require that spinal fusion be performed — this decision generally is determined prior to surgery. Spinal fusion is an operation that creates a solid union between two or more vertebrae. This procedure may assist in strengthening and stabilizing the spine, and may thereby help to alleviate severe and chronic back pain.
Decompressive laminectomy – The most common surgery in the lumbar spine is called decompressive laminectomy, in which the laminae (roof) of the vertebrae are removed to create more space for the nerves. A neurosurgeon may perform a laminectomy with or without fusing vertebrae or removing part of a disc. A spinal fusion with or without spinal instrumentation may be recommended when spondylolisthesis or scoliosis occurs with spinal stenosis. Various devices (such as screws or rods) may be used to enhance fusion and support unstable areas of the spine.
Other types of surgery, including several methods of spinal fusion to treat lumbar spinal stenosis and associated conditions, are:
• Anterior Lumbar Interbody Fusion (ALIF): Removal of the degenerative disc by going through the lower abdomen. Bone graft material or a metal device filled with bone then is placed into the disc space.
• Foraminotomy: Surgical opening or enlargement of the bony opening traversed by a nerve root as it leaves the spinal canal to help increase space over a nerve canal. This surgery can be done alone or together with a laminotomy.
• Laminotomy: An opening made in a lamina, to relieve pressure on the nerve roots.
• Laparoscopic Spinal Fusion: A minimally invasive procedure involving small incisions in the abdomen, through which a graft is placed into the disc space.
• Medial Facetectomy: Surgical procedure to remove part of the facet (a bony structure in the spinal canal) to increase the space.
• Posterior Lumbar Interbody Fusion (PLIF): Removal of the posterior bone of the spinal canal, retraction of the nerves and removal of the disc material from within the disc space, followed by insertion of bone graft and sometimes hardware in order to fuse the bones. This procedure is called an ‘interbody fusion’ because it is performed between the ‘bodies’ of the vertebral bones and across the diseased disc space. This procedure typically is performed on both sides of the spine.
• Posterolateral fusion: Placing bone on the back and side of the spine to achieve a fusion.
• Transforaminal Lumbar Interbody Fusion (TLIF): Removal of the posterior bone of the spinal canal, retraction of the nerves, and removal of the disc material from within the disc space, followed by insertion of bone graft and sometimes hardware in order to fuse the bones. Similar to a PLIF, but frequently performed from only one side.
The benefits of surgery should always be weighed carefully against its risks. Although a large percentage of lumbar spinal stenosis patients report significant pain relief after surgery, there is no guarantee that surgery will help every individual.
(The author is Head, Spine Surgery, Agrim institute of Neurosciences, Artemis Hospital, Gurugram. Views expressed are personal. Consult medical professional before statrting any treatment/medication.)