Sciatica

Sciatica is not a disease — it is a description, and a precise one: pain running along the territory of the sciatic nerve, the largest nerve in the body, from the lower back or buttock down the back of the leg. People who have had it rarely need the definition. The pain has a character all its own — electric, shooting, sometimes breathtaking — and it obeys a line, tracing the leg like a wire. That line is the clue to everything else on this page.

Where sciatica actually starts

The sciatic nerve is built from nerve roots that exit the lowest levels of the spine and merge in the pelvis before traveling down the leg. And that is where sciatica almost always begins: in roughly nine cases out of ten, a herniated disc is pressing on one of those roots where it leaves the spinal canal. Less often the culprit is spinal stenosis — an age-related narrowing of the nerve’s exit passages — or a vertebra that has slipped forward on its neighbor. Rarely, the nerve is irritated further along its course. The practical point is counterintuitive and important: the leg is where sciatica is felt, not where it lives. Treating the leg misses the address.

Why it hurts: pinch plus fire

For decades sciatica was explained as pure mechanics — a disc physically squashing a nerve. The modern picture is richer. Herniated disc material does press, but it also leaks: the disc’s inner core is chemically inflammatory, and when it escapes it bathes the nerve root in irritant molecules that make the nerve fire at provocations it would normally ignore. This is why imaging finds disc herniations in plenty of people with no pain at all — compression without inflammation can be silent — and why a modest-looking herniation can hurt ferociously. It also explains sciatica’s character: this is neuropathic pain — pain from an irritated nerve itself — which is why it burns and shoots rather than aches, and why it answers to different treatments than ordinary back pain.

How clinicians recognize it

The diagnosis usually rests on the story and the exam, not the scanner. Leg-dominant pain radiating below the knee is the core feature; which line it follows tells the examiner which root is involved — pain into the big toe and the top of the foot points to one level, pain along the outer foot and calf to another. Numbness and tingling trace the same map, coughing or sneezing can fire the pain, and raising the straightened leg while lying down — the straight-leg-raise test — stretches the inflamed root and reproduces it. Imaging is not needed to recognize sciatica; per the same logic as low back pain, scans are reserved for red flags, significant weakness, or the point where their result would actually change the plan.

The disappearing disc

Here is the most underappreciated fact in all of sciatica: herniated discs are not permanent fixtures. The body treats escaped disc material as debris, and immune cells move in to clear it. On follow-up imaging, herniations shrink and often vanish over months — and the pattern is beautifully backwards. In a systematic review of the follow-up studies, free disc fragments — the most dramatic finding a scan can show — resolved in about 96% of cases, and extrusions in about 70%, while mild bulges barely changed. The angrier the herniation looks, the more of it there is for the immune system to eat. Clinically this matches the condition’s natural story: most episodes improve substantially within four to six weeks and resolve within about three months. If you are in the early weeks and a radiology report is frightening you, this figure is worth a second look.

The red flags

Sciatica’s warning signs are the same short list that governs all back pain, plus two of its own. Seek urgent, same-day care for new numbness in the groin or inner thighs, trouble controlling bladder or bowels, or sciatica in both legs at once — together these suggest cauda equina syndrome, a surgical emergency. And treat progressive weakness — a foot that has started to drag or slap, a leg that buckles — as a prompt-attention problem even without the others: a nerve losing strength is a nerve asking for a decision, not for more patience.

How sciatica is treated today

The first-line playbook is patience with structure: stay as active as the pain reasonably allows, keep walking, and let the biology above do its work — most sciatica is a condition you outlast, not one you defeat. The honest medication picture is humbler than most people expect. Ordinary anti-inflammatory painkillers help some people but have surprisingly thin trial evidence for sciatica specifically, and in a rigorous randomized trial, pregabalin — a mainstay for other nerve pain — worked no better than placebo for sciatica while causing more dizziness. Clinicians still use nerve-pain medications case by case, but nobody should feel like a failure when pills underwhelm; for this condition, they often do.

When pain is severe or persistent, an epidural steroid injection can deliver anti-inflammatory medication directly to the inflamed root — trials show modest, mostly short-term relief, which can still matter if it carries you through the worst weeks. And then there is surgery, where a landmark randomized trial produced one of the most useful results in spine medicine: early microdiscectomy relieved leg pain faster than continued conservative care, but by one year, both groups had recovered at essentially the same rate. Surgery is not a different destination — it is an express ticket to the same one. That makes it a genuine option for disabling pain that will not yield, and clearly indicated for progressive weakness or cauda equina syndrome; for everyone else it is a preference-sensitive decision about time, risk, and what the pain is costing you now — a decision to make with your surgeon and physician, not from a page.

When to bring in a specialist

If leg-dominant pain is still running your days after four to six weeks of first-line care — or sooner if weakness appears or the pain is unmanageable — pain medicine earns its keep: confirming which root is involved, timing imaging sensibly, delivering targeted injections, and coordinating the surgical conversation if it comes to that. Finding pain care near you explains how to start.