Sciatica is a big deal for many clients I see in my clinic. Pretty much everyone has heard of the term ‘sciatica’, even if they have not experienced it. However, the symptom can occur in several ways, each of which demonstrate different pathologies - in a sense, the good, the bad and the ugly!

The Sciatic Nerve
Let's start with the sciatic nerve. It is a nerve that is the confluence of several other nerves exiting the spinal cord in the lumbo-sacral area (L4-S3 specifically). Think of it like several streams merging to become a river.

The sciatica nerve carries information back and forth to the brain via the spinal cord that relates to either the left or right lower limb. More specifically it is the posterior and medial aspect of the thigh, posterior calf and bottom of foot. The region you get pain depends on what nerve root(s) are affected and are mapped using dermatome maps. These can vary from person to person.

Sciatica is pain caused by irritation of the sciatic nerve directly, or to one or more of its associated nerve roots. This usually presents as pain (or pins and needles) in the back / side of the leg combined with weakness typically in the hamstring muscle and aspects of foot function. Reflexes are likely to be affected too which represents an impediment to how effectively the brain is communicating with the body's limbs.

So what are the possible factors that can irritate the sciatic nerve or its nerve roots?

1) A disc protrusion or herniation
Each vertebra in the spine (excluding the sacrum) is separated by a disc which can be imagined as a tough jelly-filled sack bonded to the vertebra above and below. The discs function is to cushion impacts on the spine, allow movement and create space for nerve roots to exit the spinal cord.
If too much abnormal pressure is exerted on the disc, the walls of the disc may weaken and the gel-like nucleus will start to bulge out and may push on a nerve.

2) Stenosis
This is where the space between two (or more) vertebrae is narrowed to the extent that the bone compresses a nerve. As mentioned in discussing herniated discs, discs may become more compressed and thinner which will increase the chances of the nerve being compressed. It can also occur with age-related degeneration as the discs (like all material in the body) dehydrate. This is a more complex problem to resolve as the disc can’t be plumped up. Treatment options are usually therapy to align the spine optimally, surgery to remove encroaching body material or steroid injections to mitigate pain and inflammation.
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3) Facet syndrome
The facet joints at the back of each vertebra can become inflamed if poorly aligned. The inflammatory chemicals can irritate the spinal nerve, creating pain down the sciatic nerve

4) Piriformis Syndrome.
The sciatic nerve passes beneath a muscle in the pelvis called the piriformis muscle. If this muscle becomes too tight due to misalignments and mechanical tension through the pelvis, the sciatic nerve may become compressed and radiate pain down the leg. More commonly, referral is in the buttock and hamstring.

So these are the things I evaluate and check for with patients that present in my clinic. As I said at the start, diagnosis is not straight forward and resolution is not a magic bullet.
On top of the four causes of sciatica outlined here, there are other factors that need to be considered, however these are 4 common ones.
I hope this gives you some useful insights. If you have any questions, please don’t hesitate to email me