Same nerve, different pinch
The sciatic nerve runs from the low back, through the buttock, down the back of the leg. It can be irritated at the spine, where a disc or a narrowed opening presses on a nerve root, or in the buttock, where the piriformis muscle crosses over it. Both feel like leg pain. The first is true sciatica. The second is piriformis syndrome, and it fools a lot of people, including some clinicians.
Three differences you can feel
None of these is a diagnosis on its own. Together they point in a direction.
- Where it is worst. Disc sciatica: low back plus the leg, often to the calf or foot. Piriformis: deep in one buttock, sometimes to the back of the thigh, rarely past the knee.
- What makes it worse. Disc: sitting, bending forward, coughing or sneezing, first thing in the morning. Piriformis: sitting on a hard surface, crossing that leg, climbing stairs, running.
- Numbness. Disc sciatica often brings tingling or numbness in a specific patch of the foot or shin. Piriformis usually does not.
What the exam adds
Dr. Frank checks the things you cannot check at home: reflexes at the knee and ankle, strength in the big toe and the foot, sensation along the nerve, and a straight-leg raise that tightens a disc-related nerve root and does nothing for a piriformis. He also presses on the piriformis itself, which reproduces piriformis pain and leaves disc sciatica alone. Ten minutes, and the two are usually sorted.
Why the answer changes the treatment
A disc wants the pressure taken off: flexion-distraction or decompression, and a stop to the deep forward bending that loads it. A piriformis wants the opposite kind of attention: work on the muscle, an adjustment to the sacroiliac joint it usually guards, and hip movement, not spine traction.
Get it backwards and you can spend six weeks stretching a hip that was never the problem, or decompressing a spine that was fine. That is the most common story new patients bring in: "I did the stretches and it got worse."
When to stop reading and get seen
Go to the ER, not a chiropractor, for numbness in the groin or inner thighs, loss of bladder or bowel control, or a leg that is getting weaker by the day. For everything else, an exam this week beats a month of guessing.