Sciatica and lumbar radicular pain

Sciatica is pain that travels from the lower back or buttock down the leg, usually below the knee. In medical terms it is called lumbar radicular pain, because it comes from irritation of a spinal nerve root (the “radix”) in the lower back.

What is it?

The nerves to the leg leave the spine through small openings between the vertebrae. If a nerve root becomes inflamed or compressed, most often by a bulging or herniated disc and less often by narrowing of the spinal canal or the openings around the nerve, it can produce pain that is felt along the leg.

Not all leg pain that comes from the back is sciatica. Pain from the joints, discs or ligaments of the spine can also spread into the buttock and thigh. This is called somatic referred pain, and it behaves differently and is managed differently.

Common symptoms

• Shooting, burning or electric pain travelling down the leg, often below the knee, sometimes into the foot.
• Leg pain that is often worse than the back pain.
• Pins and needles or numbness in part of the leg or foot.
• Sometimes weakness in particular muscles, for example difficulty lifting the foot or standing on the toes.

Why does it happen?

Disc material that bulges or escapes from the disc can press on a nerve root and also release chemicals that cause inflammation. An inflamed nerve root becomes sensitive and can fire abnormally, producing pain felt in the leg. When the nerve’s function is also affected, numbness, weakness or reduced reflexes can develop. This is called radiculopathy.

How is it assessed?

Diagnosis is based mainly on your history and a physical and neurological examination. Scans such as MRI are not needed for everyone. They are usually reserved for people with features suggesting a serious cause, worsening neurological symptoms, or when a procedure or surgery is being considered. Many disc bulges seen on scans occur in people without symptoms, so scan findings are always interpreted together with your symptoms and examination.

Treatment options

For many people, sciatica improves over weeks to months. Treatment aims to relieve symptoms, keep you active and support recovery.

• Understanding and staying active. Information about the condition and remaining as active as comfortably possible are central to management.
• Physical therapy. A guided exercise or rehabilitation program may help.
• Medicines. Medicines have a limited role. Some medicines commonly tried for nerve pain have not shown benefit for sciatica in good-quality studies. For example, a large Australian trial found pregabalin was no better than placebo and caused more side effects. Opioid medicines are used cautiously, if at all, and only for short periods.
• Epidural or nerve root injections. For people with acute and severe sciatica, an injection of local anaesthetic and steroid near the affected nerve may be considered. Any benefit is usually modest and short to medium term, and it does not repair the disc.
• Surgery. Surgery may be considered for people with persistent, severe symptoms that match the scan findings, or with significant or progressive weakness. A spinal surgeon assesses this.

The role and limits of procedures

Procedures such as epidural injections can be one part of a broader plan. They aim to reduce pain enough to allow movement and rehabilitation. They do not change the underlying disc, they do not help everyone, and they carry some risks. See Epidural & Nerve Root Injections for details.