Sciatica refers to irritation of the sciatic nerve, which originates via the nerve roots in the lumbar spine. The most common cause of sciatic nerve irritation, or "true" sciatica is compression of one or more of the nerve roots due to disc herniation or spinal degeneration in the lower lumbar region (this is usually age dependent). Severe compression and inflammation of the sciatic nerve may extend the pain into the glutes, thigh, and down the leg to the foot.
Piriformis syndrome is actually referral pain (tingling, numbness, etc.) caused by tightness in the piriformis muscle. It mimics the pain of true sciatica which is why its often confused with sciatica even by those in the rehabilitation sector. The pain occurs due to compression of the areas surrounding the sciatic nerve. Contraction of the piniformis muscle results in pain in your buttocks and hips due to impingement of the nerve, that may radiate down your legs.
The piriformis muscle (pseudoscitican, wallet sciatica or hip neuropathy) can irritate or compress the proximal sciatic nerve due to spasm and/or contracture.
The piriformis muscle is a flat, pyramid-shaped, and oblique muscle which originates anterior of the S2-S4 vertebrae, the sacrotuberous ligament, and the upper margin of the greater sciatic foramen. It passes through the greater sciatic notch and inserts on the superior surface of the greater trochanter (femur). As can be seen above, the piriformis muscle is innervated by branches from L5, S1, and S2.
In approximately 20% of the population, the piriformis is split, with 1 or more parts of the sciatic nerve dividing the muscle belly itself. In 10% of the population, the tibial/peroneal divisions are not enclosed in a common sheath. Usually, the peroneal portion splits the piriformis muscle belly, although in rare cases, the tibial division does so.
So, how do you know if your self diagnosed sciatica really is sciatica? Well you visit someone who can assess it correctly for you. Both sciatica and piriformis syndrome needn't cause long term problems if they are addressed correctly.
Appropriate release techniques need to be taught along with correctly prescribed exercises to help rehabilitate the issues.