Understanding Sciatica

 In Lower Limb

What is it?

Sciatica is a commonly experienced condition that affects many people. The word in itself is an ‘umbrella term’ that collectively denotes any pain, pins and needles, or numbness felt in the ‘dermatomes’ of the leg that has a spinal origin. Dermatomes are the ‘areas of the leg’ that are innervated by the nerve roots as they exit out of the lower back and pass into the leg.

How Does it Occur?

When these exiting nerve roots become irritated or compressed sciatica symptoms will ensue. The cause of irritation is normally:

  1. Disc protrusion/bulge: the lumbar discs of your lower back can incur a bulging of the disc wall or internal material. Typically these bulges occur to the back and outside of lumbar discs which brings the disc into either close proximity or direct compression with the exiting nerve roots coming out of the spinal cord. The lumbar discs that are most commonly affected are L4/5 and L5/S1. These discs form the last two discs of the spinal column. Because they ‘sit’ at the bottom of the spine they are subjected to the most load and therefore they are the most susceptible to bulging/injury.

  2. Bony compression of the exiting nerve roots where the nerves exit the lumbar verterbrae. The nerves must pass through structures in the vertebrae known as ‘foramina’. Foramina is Latin for ‘hole’.  That is the nerve roots ordinarily must pass through the holes of the vertebrae unencumbered. If advanced osteoarthritis of the spine is present the space that these nerve roots have to exit from is lessened and the nerve root will become irritated. This irritation will produce sciatic type symptoms. Plain film x-rays will detect such bony foraminal narrowing.

A caution:

If your sciatic pain or symptoms are very intense than this may be a medical emergency. See your health professional immediately. If your pain is >8/10 see a GP or visit your local Emergency Ward to get some immediate pain relief medication.  You may also be sent for imaging (typically a CT or MRI scan to assess for any disc protrusions/bulges that may be intending on your spinal nerve roots).

Brad Beer (APAM)

POGO Physio Guru

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