The lower back consists of the lumbar and sacral vertebra with the intervening intervertebral discs, nerves, ligaments and muscles. Low back pain can occur due to pathology in any of these sites, and in this article we shall take a brief look at the various causes of low back pain.
Non-specific Low Back Pain
In most patients with low back pain, no clear cause can be identified. Over 80% of back pain is non-specific. The pain is usually musculoskeletal in origin that originates from an abnormal movement of the low back.
Cauda Equina Syndrome
This is a medical emergency that is characterised by low back pain and compression of the nerve roots that emerge from the lower end of the spinal cord. This can cause weakness of the legs along with bowel and bladder dysfunction.
Nerve Root Compression
Compression of the nerve roots by a slipped or degenerated intervertebral disc can cause low back pain. Sciatica is a well recognized cause that occurs due to compression of the nerve fibers that not only causes low back pain but also radiating pain down the leg.
Age related thinning of the bone, also called osteoporosis can cause fractures of the bone from minimal trauma. Collapse of the vertebra as a consequence can compress the nerves and cause low back pain. Inflammation of the vertebra and the intervening cartilage i.e. osteoarthritis is also a recognized cause of low back pain. This condition is rare however. Other arthritic conditions such as ankylosing spondylitis and rheumatoid arthritis are rare but recognized caused of low back pain. Infection of the bone, also called osteomyelitis is a rare condition and cause of low back pain.
Lumbar disc herniation due to degeneration or trauma can compress the nerve fibers and cause back pain. Stenosis of the spinal canal is a condition where the canal through which the spinal nerves pass is narrowed. This narrowing is often due to prolapsed intervertebral discs along with degeneration of the spinal bones.
Rarely, muscle diseases such as fibromyalgia and muscular dystrophy can cause low back pain. The source of the pain is muscular and is unrelated to the vertebral bones and nerve fibers. Patients typically have tender, stiff muscles.
Tumours and Cancer
These are rare causes of low back pain. These form less than 1% of the causes.
There are a large number of causes of low back pain. A detailed assessment is necessary to ascertain the exact cause so that the right treatment can be prescribed.