Where Does That Pain Come From?
Sciatica Pain Distribution
Sciatica is pain running down your leg in a pattern determined by the sciatic nerve. The pain often starts in the low back – (due to a herniated disc) – or in the buttock – (due to piriformis syndrome) – and extends as far as your toes. It can be accompanied by numbness, ‘pins and needles’ (“paresthesias”) or, in more severe cases, actual weakness affecting the ankle or toes may accompany the sciatica.
Sciatica is a form of pain that is called a “radiculopathy” in medical terminology. This means that it often follows the path of a single spinal nerve root such as the Lumbar 5 (L5) or Sacral 1 (S1). This is often the case when sciatica is due to a herniated disc or bulging disc. If the cause is in the lumbar spine, the sciatica – or leg pain – is often accompanied by back pain.
Some patients also experience sciatica affecting all the dermatomes in the nerve, L4, L5 and S1. This sort of “pan-sciatic syndrome” may be due to piriformis muscle syndrome. This condition is due to a muscle in the buttock that goes into spasm and pinches the sciatic nerve.
When sciatica is due to a herniated disc, it often affects a single strip of skin or dermatome. A far lateral herniated disc affects the exiting nerve root – in this picture, the L4 root is compressed by an L4/L5 lateral disk herniation. More commonly, however, the disk bulge is close to the body’s midline. The illustration shows an L5/S1 disk herniation affecting the transiting S1 root but leaving the L5 root undisturbed. The patient’s detailed distribution of symptoms must match exactly with the MRI findings in the spine before a surgery can be recommended.