Lumbar Disc Herniation

Overview

A lumbar disc herniation happens when part of an intervertebral disc in the lower back displaces beyond its normal margin and presses on or irritates a nearby nerve root. Each disc has a soft inner core held in by a tougher outer ring; when that ring weakens or tears, the inner material can bulge or extrude into the spinal canal. The L4–L5 and L5–S1 levels are most commonly affected because they carry the greatest load and motion. It is one of the most common causes of leg pain that originates in the spine, and it most often affects adults between 30 and 55.

What causes it

Symptoms are produced two ways at once: direct mechanical pressure on a nerve root, and a chemical and inflammatory response to the displaced disc material. Risk factors include age-related disc degeneration, heavy or repetitive lifting, prolonged sitting, obesity, smoking, and a genetic predisposition to early disc breakdown. Importantly, many disc herniations are found incidentally on imaging and cause no symptoms, so the clinical picture, not the scan alone, determines whether a finding is the source of the problem.

Symptoms and warning signs

Classically, a symptomatic herniation causes radicular pain: sharp, shooting, or burning pain that travels from the lower back or buttock down the leg along the affected nerve. This "sciatica" is often worsened by sitting, bending forward, coughing, or straining, and may come with numbness, tingling, and weakness in a specific pattern.

A small number of patients develop cauda equina syndrome, a surgical emergency signaled by saddle numbness, new bowel or bladder dysfunction, and weakness in both legs. This requires urgent evaluation.

How it's diagnosed

Diagnosis is primarily clinical, supported by imaging when symptoms are severe, progressive, or not improving. MRI is the preferred study because it shows the disc, the nerve roots, and the degree of compression in detail. CT or plain films may be used in specific situations, and electrodiagnostic studies can occasionally confirm the affected nerve or distinguish a radiculopathy from a peripheral nerve problem. Imaging is always interpreted alongside the history and exam, because the goal is to confirm the structural finding matches the symptoms.

Treatment options

The natural history is favorable, and most patients improve within six to twelve weeks without surgery. First-line treatment is conservative: relative activity modification, oral analgesics and anti-inflammatory medication, physical therapy, and sometimes a short course of other pain medicines. Epidural steroid injections can provide temporary relief and help patients participate in rehabilitation.

When surgery is considered

Surgery, most commonly a microdiscectomy, is considered when there is a significant or progressive neurologic deficit, cauda equina syndrome, or persistent disabling leg pain that has not responded to several weeks of appropriate conservative care. Surgery reliably relieves leg pain in well-selected patients, though back pain and recurrence remain possible over the long term.