SCIATICA, AND THE THINGS THAT IMPERSONATE IT
Not everything that runs down a leg is sciatica.
“Sciatica” has become the word people use for any pain that travels below the buttock. Several different problems produce that pattern, they respond to completely different treatments, and telling them apart is a physical examination rather than a guess.
What the word actually means
Sciatica describes pain in the distribution of the sciatic nerve, generated by irritation or compression of a lumbar nerve root — most often L5 or S1. It is a symptom of radiculopathy, not a diagnosis in itself. The correct clinical question is never “is this sciatica?” but “which structure is producing leg pain, and at what level?”
That distinction is not pedantry. True radicular pain gets better with treatment aimed at a nerve root. Facet or sacroiliac referral into the same leg gets worse under that treatment, or simply does not respond, and the patient is then told their sciatica is stubborn when in fact they never had it.
The four things that look like sciatica
TRUE RADICULAR PAIN
A nerve root. The pain follows a defined line you could draw with a finger, it usually goes below the knee, and it commonly comes with numbness, tingling or weakness in a matching pattern. Coughing or sneezing may shoot it. A straight leg raise reproduces it.
This is the one that responds to an epidural steroid injection at the right level, and the one where progressive weakness changes the urgency entirely. Radiculopathy in full.
FACET REFERRAL
The facet joints refer into the buttock and the back of the thigh, and characteristically stop above the knee. There is no true numbness and no weakness, because no nerve root is involved. It is worse in extension and better in flexion, which is the reverse of the classic disc pattern.
Frequently mislabeled as sciatica for years. Facet syndrome.
SACROILIAC JOINT REFERRAL
The sacroiliac joint refers into the buttock, the groin and sometimes down the back of the leg, and it can go below the knee, which is what makes it convincing. The giveaways are pain that centers below the belt line, a worst moment rolling over in bed, and reproduction on provocation testing rather than on straight leg raise.
This is the single most commonly missed cause of “failed sciatica treatment” we see. The SI joint.
NEUROGENIC CLAUDICATION
Narrowing of the canal produces leg pain and heaviness that comes on with walking and eases when you sit or lean forward. The tell is that it is limited by distance rather than by position, and that leaning on a cart buys you more distance than willpower does.
The examination that separates them
- Where does it stop? Above the knee moves the odds toward facet or sacroiliac referral. Below the knee, in a line, moves them toward a nerve root.
- What makes it worse? Flexion and sitting suggests disc and root. Extension and standing suggests facet or canal. Rolling over and single-leg loading suggests the sacroiliac joint.
- Is there a neurological deficit? Real numbness in a dermatome, a weak toe extensor, a lost reflex. Deficit means a root and changes the plan.
- Provocation testing. A cluster of sacroiliac provocation maneuvers, straight leg raise and its crossed version, and a proper hip examination — because a worn hip refers into the groin and thigh and is regularly treated as a spine problem for a year.
- Then, where it still matters, a diagnostic block to confirm rather than infer.
Why the leg is the part that frightens people
Back pain is familiar. Leg symptoms are not, and numbness in particular carries an implication of permanence that a sore back does not. That fear is reasonable and it is also the reason this presentation gets over-treated in one direction and under-examined in the other — people are moved quickly toward imaging and surgical opinion, and slowly or never toward the tests that would say which structure is responsible.
There is a second reason the leg matters. Sustained nerve root irritation drives central sensitization faster than axial pain does, so the window in which this is a straightforward mechanical problem is shorter. After a few months the leg can keep reporting after the compression has resolved, which is how a person ends up with a clean post-operative scan and an unchanged symptom.
What the terrain contributes
Nerve tissue is metabolically expensive and it is unusually sensitive to the state of its blood supply. Chronic hyperinsulinemia and the low-grade inflammation that accompanies it impair microvascular perfusion of the nerve root and its sheath, which lowers the threshold at which mechanical contact becomes symptomatic and slows recovery once it is. In practice a root that is mildly compressed in a metabolically healthy person is often asymptomatic, and the same degree of contact in an inflamed system produces months of leg pain.
This is also why the same MRI can be read as trivial by one clinician and damning by another. The image is identical. The tissue it describes is not.
Questions people ask
What can be mistaken for sciatica?
Facet joint referral, sacroiliac joint referral, hip osteoarthritis, greater trochanteric pain syndrome, piriformis-related sciatic irritation, neurogenic claudication from stenosis, and occasionally vascular claudication, which is a different specialty entirely. That list is why the examination matters more than the label.
This is set out in A worn hip refers into the buttock. A bad back refers into the groin. They get treated as each other for years..
Should you walk if you have sciatica?
Usually yes, within tolerance, and prolonged rest makes it worse rather than better. The exception is progressive weakness or any of the red-flag findings, where the instruction is to be seen rather than to keep walking.
Is sciatica curable?
Most acute radicular episodes settle substantially over weeks to a few months without surgery. The ones that do not are the ones worth investigating properly, and “curable” is the wrong frame for them — the useful question is which structure is responsible and what is the most durable thing that can be done about it.
There is more on this in The worst moment of your day is rolling over in bed. That sentence points at a joint nobody examined..
What vitamin stops sciatica?
None, and we are not going to pretend otherwise. B vitamins have a role in genuine deficiency states and correcting a documented deficiency is worth doing on its own merits. There is no supplement that decompresses a nerve root.
The mechanism is covered in You can sit through a meal. You cannot get through a grocery line..
Do I need an MRI first?
Not necessarily. If there is no deficit and no red flag, the examination determines whether imaging would change anything. Ordering a scan before knowing what you would do with the result is how people end up being treated for an incidental finding.
You can draw the line where it goes. That line is most of the diagnosis. goes through it in detail.
Related reading
- Lumbar radiculopathy
- Sacroiliac joint pain
- Spinal stenosis
- Epidural steroid injection
- When back pain is an emergency
The piriformis label is applied far more often than the condition occurs.
Bring the leg symptoms, not just the back
Where it starts, where it stops, what makes it worse and whether anything is numb or weak. Those four answers do more to narrow this than any scan you have had.
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Sources
- Guedes F et al. Nondiscogenic Sciatica: What Clinical Examination and Imaging Can Tell Us?. World neurosurgery, 2020. PubMed 31760186
- Troutner AM et al. The ambiguity of sciatica as a clinical diagnosis: A case series. Journal of the American Association of Nurse Practitioners, 2020. PubMed 31567779
- Valat JP et al. Sciatica. Best practice & research. Clinical rheumatology, 2010. PubMed 20227645
- Park JW et al. Deep gluteal syndrome as a cause of posterior hip pain and sciatica-like pain. The bone & joint journal, 2020. PubMed 32349600