Lower back pain: facts you should know

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Back pain or lower back pain

Lower back pain is commonly known as back pain. Back pain is very common nowadays. Lower back pain is a symptom not a disease. Many people complain low back pain. But most of them do not have spine related problem like nerve compression. Up to 80% of the population experience low back pain at some time. The lifetime prevalence of low back pain has been reported at between 60 and 80 per cent. Although the prevalence has not increased, reported disability from back pain has risen significantly in the last 30 years. In Western countries, back pain is the most common cause of sickness related work absence. In the UK, 7% of adults consult their GP each year with back pain.

Causes of lower back pain

  • mechanical back pain
  • Inter vertebral disc hernia
  • vertebral fracture
  • internal disc disruption
  • degenerative disc disease
  • segmental instability of lumber disc
  • break in the integrity of the neural arch of lumber vertebra
  • slippage of a vertebra on the one below
  • inflammation of arachnoid matter
  • spinal canal narrowing
  • bone metastases
  • Paget’s disease
  • osteoarthritis

Symptoms of low back pain: a misnomer

Lower back pain is itself a symptom. So it does not have symptoms. Rather there are features of the diseases lower back pain represents.

Mechanical lower back pain

  • Pain varies with physical activity (improved with rest)
  • Sudden onset, precipitated by lifting or bending
  • Recurrent episodes
  • Pain limited to back or upper leg
  • No clear-cut nerve root distribution
  • No systemic features
  • Prognosis good (90% recovery at 6 weeks)
  • It can cause chronic lower back pain if the physical activity is related to job or daily activity.

Most of other causes cause lower back pain by compressing the nerve roots either in the spinal canal or at the beginning of spinal roots.

Severe lower back pain a sign of nerve root compression

  • Unilateral leg pain worse than low back pain
  • Pain radiates beyond knee along the nerve distribution
  • Decreased sensation in same distribution
  • Nerve irritation signs (reduced straight leg raising test that reproduces leg pain)
  • Motor, sensory or reflex signs (limited to one nerve root)
  • Prognosis reasonable (50% recovery at 6 wks)
  • Both legs might be involved if both nerve roots are compressed

When we think of spinal pathology like spinal malignancy, degenerative disc disease and vertebral fracture etc:

  • Age: presentation <20 yrs or >55 yrs
  • Character: constant, progressive pain unrelieved by rest
  • Location: thoracic pain
  • Past medical history: carcinoma, tuberculosis, HIV, systemic corticosteroid use, osteoporosis
  • Constitutional: systemic upset, sweats, weight loss
  • Major trauma
  • Painful spinal deformity
  • Severe/symmetrical spinal deformity
  • Saddle anesthesia
  • Progressive neurological signs/muscle-wasting
  • Multiple levels of root signs
  • unexplained weight loss
  • Constitutional symptoms (fever, chills)
  • Immune suppression (intravenous drug abuse, prolonged steroid use)
  • Severe or progressive sensory alteration or motor weakness
  • Acute difficulty with urination (painless retention)

Symptomatic lumbar disc hernia occurs during the lifetime of approximately 2–4 per cent of the population. Risk factors include family history, male gender, age (30–50 years), heavy lifting or twisting, stressful occupation, lower income and cigarette smoking. Over 90 per cent of lumbar disc hernia occurs at the L4–5 or L5–S1 levels. A posterior lateral disc protrusion will affect the traversing root, e.g. an L4–L5 disc protrusion affects the L5 nerve root. A far lateral disc protrusion (extra foramen) will affect the exiting nerve root, e.g. a far-lateral L5–S1 disc protrusion affects the L5 nerve root. Symptoms typically commence with a period of back pain followed by sciatica. There may be decreased sensation, motor weakness, loss of reflexes and a reduction in straight leg raise. For simple sciatica, a period of 6–12 weeks of conservative treatment is advised. Up to 70 per cent of patients will settle within this period.lower back pain

Narrowing of spinal canal

  • Extremely common condition in the 50–70 year age group
  • Classic symptoms: back, buttock, thigh and calf pain
  • Provoked by walking and extended posture
  • Relieved by flexed posture

Narrowing of the spinal canal can cause narrowing of nerve root canal or inter vertebral foramen. The resultant nerve root compression leads to nerve root reduction of blood supply presenting with back, buttock or leg pain provoked by exercise. It may be congenital or acquired as is the case for degenerative types (commonly presenting between 50 and 70 years of age). The narrowing is caused by facet joint hypertrophy, disc bulge and ligamentum flavum thickening. Patient feels pain while walking. Then patient take rest and walk again. The patient can go a certain distance. This distance reduces gradually. And at a point patient can’t walk. A time comes when patient feels pain at rest. This also occurs in vascular disease like peripheral vascular disease. Symptoms of spinal disease can be distinguished from vascular one because they are frequently associated with neurological symptoms, are often worse in extension, and pedal pulses are present on clinical examination.

Bone metastasis

These usually affect bone from primary carcinoma of breast, lungs, prostate, thyroid, kidney and intestine. These can show symptoms of primary tumors. Otherwise their identification can be done only by investigation.

Investigations for lower back pain

Investigations are not required in patients with acute mechanical back pain. Those with persistent pain (>6 weeks) should undergo further investigation. MRI is the investigation of choice since it can demonstrate spinal narrowing, cord compression or nerve root compression, as well as inflammatory changes in spine, and infectious causes such as spinal abscess. Plain radiographs can be of value in patients suspected of having vertebral compression fractures, osteoarthritis and degenerative disc disease. If metastatic disease is suspected, radionuclide bone scan should be considered. Additional investigations that may be required include routine biochemistry and hematology with measurement of ESR and CRP (to screen for sepsis and inflammatory disease), protein and urinary electrophoresis (for myeloma) and prostate specific antigen (for prostate carcinoma)

Back pain relief

Education is important in patients with mechanical back pain. It should emphasize the self limiting nature of the condition and the fact that exercise is helpful rather than damaging. Exercises for lower back pain reduce pain as well as reduce disabilities. Regular analgesia and/or NSAIDs may be required to improve mobility and facilitate exercise. Return to work and normal activity should take place as soon as possible. Bed rest is not helpful and may increase the risk of chronic disability. Referral for physiotherapy or manipulation should be considered if a return to normal activities has not been achieved by 6 weeks. Low dose antidepressant drugs may help pain, sleep and mood. Other treatment modalities that are occasionally used include epidural and facet joint injection, traction and lumbar supports, though there is little evidence to support their use. Malignant disease, osteoporosis, Paget’s disease and other diseases require specific treatment of the underlying condition. Surgery is required in less than 1% of patients with low back pain but may be needed in spinal narrowing, in spinal cord compression and in some patients with nerve root compression.

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