Back pain is an extremely common complaint. 90% of the adult population would have experienced back pain at some point in their lives and approximately half of these people would have experienced recurrent back pain.
Many conditions give rise to back pain. The most common source of pain is related to the encountered causes include disorders of abdominal oragans (pancreatitis, kidney stones or infection), blood vessels injuries (aortic dissection) and infections affecting nerves (shingles). Despite investigations, some cases of back pain have not attributable cause. The good news is that, no matter what the cause of the pain is, the majority of back pain resolves spontaneously within six to eight weeks.
The following are common causes of back pain related to the spine and surrounding structures.
Degenerated lumbar disc
A lumbar disc is the soft tissue found between each vertebra. It is responsible for spinal stability, mobility and absorption of shock transmitted through the spine. 80% of the composition of a normal disc is water. This gives it a springy consistency and allows for normal function. When a disc undergoes degeneration, it loses some of its water content. As a consequence of this, the disc loses its thickness and bulges at its periphery. This bulging irritates nerves found at the edge of the disc, giving rise to back pain. This pain can radiate down to the buttocks and is aggravated by prolonged sitting, one would tend to slouch and this flexes the spine, increasing the pressure on the disc. This further irritates the nerve, thus worsening the pain in the back and buttocks (discogenic back pain).
Herniated lumbar disc (slipped disc)
A herniated lumbar disc occurs when the central jelly-like part of the disc (nucleus pulposus) bulges through a fissure in the outer capsule (annulus fibrosis) of the disc. This herniation often causes pressure on the nerves supplying the lower limbs resulting in leg pain, in addition to back pain. There can also be lower limb weakness and numbness due to impairment of nerve function secondary to compression. Occasionally, the herniated disc can cause compression of the nerves supplying the bowel and bladder resulting in incontinence (cauda equina syndrome). This is an emergency condition which requires urgent surgery. If there is a delay in the treatmetn of cauda equina syndrome, incontinence can be permanent.
Spinal stenosis is characterised by back pain associated with leg pain after walking for a certain distance. This phenomenon is known as neurogenic claudication. The walking distance achievable is predictable and the leg pain can also be predictably relieved by sitting down but not by standing still. This condition is caused by narrowing of opening of the spine through which the nerves supplying the lower limbs exit. The narrowing is often due to arthritis of the small joints of the spine (facet joints) which results in enlargement of the joints from growth of bone spurs (osteophytes). The narrowing is also contributed by bulging, degenerate discs.
This is pain originating from the muscles and supporting soft tissues surrounding the skeletal portion of the spine. It is characterised by tenderness over localised areas on the back (trigger points). Pain is typically relieved by stretching the involved muscle group or by trigger point release (massage) or injection.
Spinal Fractures, Infections and Tumours
While uncommon, these are particularly sinister causes of back pain associated with poor outcomes if not detected and treated early.
When to Seek Treatment
These are factors that may point towards a condition that requires urgent treatment such as a fracture, infection or tumour (“red flags”).
- Recent trauma such as a fall from a height or motorcycle accident.
- Recent mild trauma in an individual above the age 50 such as a fall onto the buttocks.
- History of prolonged steroid use.
- Someone with a history of osteoporosis.
- Any person above the age of 70 due to increased risk of cancer, infection and non-spinal cause of back pain.
- Previous history of cancer.
- History of recent infection.
- Temperature over 38.5 degrees Celsius associated with back pain.
- Intravenous drug use.
- Back pain worse at rest which is associated with infections and tumours.
- Recent unexplained weight loss.
Other characteristics of pain which warrant urgent medical attention include –
- Prolonged back pain.
- Back pain associated with acute onset weakness or numbness of the lower limbs or lower limb pain.
- Back pain associated with incontinence.
Assessment and Treatment
A doctor’s assessment of back pain includes obtaining a history regarding the pain, associated symptoms and conditions. This is followed by an examination of the back and nerve function of the lower limbs.
The majority of back pain is treated with rest, medications and physical therapy. In very selected conditions, surgery is necessary.