Back pain is one of the commonest musculoskeletal symptoms. The cause in most cases is simple soft tissue strain, with muscles going into spasm to protect the back from being moved when there is minor wear and tear. This spasm can be intensely painful, and like simple cramp it requires stretching to resolve. Most people are concerned that the level of pain is indicative of a serious problem and do not do enough physical exercise to help relieve the situation. Only in a minority of cases is back pain due to a more serious cause – if there is increasing pain at night, loss of sensation around the anus or incontinence, then urgent medical advice should be sought.
In most cases, simple back pain needs no further imaging, but if there is pain going into the leg, and especially if it is down to the ankle, then a ‘trapped nerve’ may be the cause. In fact, most cases of true sciatica (compression of a nerve as it exits the spinal canal due to a slipped disc) do not have back pain, just leg pain, with or without pins and needles or weakness in the leg.
In rare cases, back pain is due to an inflammatory disease of the spine, such as Ankylosing Spondylitis. Under these circumstances, further imaging to confirm the diagnosis with an MRI scan is required.