Sciatica: why it hurts and when to operate

What sciatica really is

Sciatica is not a complete diagnosis: it describes where it hurts, not why. The sciatic nerve arises from several roots of the lumbar spine and runs down the leg, so when one of those roots is compressed as it leaves the spine, the pain is projected along its whole course. That is why the problem almost always starts in the back, even though the patient feels it in the buttock, thigh or calf.

Why it hurts: the most common causes

• Lumbar herniated disc: disc material moves out of place and presses on the root. It is the most frequent cause, especially between the ages of 30 and 55. See Herniated disc: symptoms and treatment.
• Lumbar canal stenosis: the canal the nerves pass through narrows, typically from the age of 60. See Lumbar stenosis: what it is.
• Other less frequent causes: spondylolisthesis, facet joint arthritis or, rarely, a tumour.

When conservative treatment is enough

In most people sciatica improves on its own or with non-surgical treatment within a few weeks. The aim is to control the pain and stay active: relative rest (not prolonged bed rest), scheduled pain relief, physiotherapy and, in selected cases, injections. If there is steady improvement within 6 to 8 weeks, surgery is not usually needed.

When surgery is considered

Surgery comes into play when:

• The pain is still disabling after several weeks of correct conservative treatment.
• There is loss of strength that is getting worse (foot drop, difficulty walking on tiptoe or on the heels).
• Neurological warning signs appear, such as loss of bladder or bowel control or saddle numbness. See Sciatica that won't go away: warning signs.

For sciatica caused by a herniated disc, the most common operation is a microdiscectomy: the fragment compressing the root is removed through a small incision. It is surgery aimed at the cause, with a quick recovery in most cases.

Surgical technique: microdiscectomy

Microdiscectomy is the reference technique for sciatica caused by a herniated disc. Through a small incision and with optical magnification, the neurosurgeon removes only the disc fragment compressing the nerve root and keeps the rest of the disc. The hospital stay is short and the return to activity is quick. When sciatica is caused by stenosis, the approach is decompression of the canal. In selected cases of both types, endoscopic surgery allows smaller incisions and a faster recovery.