Herniated Disc

What a herniated disc actually is

Each disc has a tough outer ring and a softer centre. A herniation is what happens when some of that centre pushes through a weak point in the ring. The escaped material can sit against a nerve root, and it also releases inflammatory chemicals that irritate the nerve directly, which is why a small herniation can hurt a great deal and a large one can sometimes cause nothing at all.

That second mechanism explains something patients find confusing. Pain can improve substantially before the MRI looks any different, because the inflammation settles before the fragment shrinks.

Herniations happen in the neck and in the lower back. The anatomy is the same idea; what changes is which nerve is affected and therefore where the symptoms turn up.

Where the pain goes tells you more than where it started

Most people arrive describing back or neck pain, but the diagnostic information is usually in the limb.

A lumbar herniation that reaches a nerve root typically produces pain running into the buttock, thigh, calf or foot, often described as sharp, electric or burning. That pattern is called sciatica when it follows the sciatic distribution. A cervical herniation produces the equivalent in the arm, covered in more detail on cervical radiculopathy.

Each nerve root supplies a reasonably predictable strip of skin and a particular set of muscles. A patient with numbness along the outside of the calf and into the big toe, plus weakness lifting the foot, is describing a different level than one with numbness in the little toe and a weak calf. Working out which nerve is involved from the history and the examination, before looking at the film, is what makes the film useful when you do look at it.

How the diagnosis is confirmed

The examination comes first: reflexes, strength in specific muscle groups, sensation in specific territories, and nerve tension signs.

An MRI is the imaging study that shows disc material and nerve roots well. It is ordered when the answer will change what happens next, not automatically. The reason for that caution is worth knowing: degenerative findings, including disc bulges and herniations, turn up commonly in people with no symptoms at all, and their prevalence climbs steadily with age.

So an MRI report listing a herniation is not by itself a diagnosis. The question is whether the herniation on the film is at the level that explains the symptoms in the room. When those agree, the plan is usually straightforward. When they do not, more imaging rarely settles it, and the answer is a more careful examination.

Nerve conduction studies are occasionally useful, mostly to distinguish a compressed nerve root from a problem further down the arm or leg such as carpal tunnel syndrome.

What usually helps first

Most herniated discs are managed without an operation.

Time is the main treatment, and it does more work than it gets credit for. Alongside it: activity modification rather than bed rest, anti-inflammatory medication where it is appropriate for the patient, and physical therapy aimed at the specific problem rather than generic core strengthening.

An epidural steroid injection can be useful when pain is limiting sleep or function enough to stall recovery. It does not remove the herniation, and it is best thought of as reducing the inflammation around the nerve while the body deals with the fragment.

None of this is a delay tactic. A patient whose leg pain is improving week on week, with a stable neurological examination, is on the path most people take out of this.

When an operation starts to make sense

Three situations move the conversation.

The first is a neurological deficit that is getting worse. Progressive weakness in a specific muscle group is the clearest reason to act rather than wait.

The second is limb pain that has not settled after a fair trial of non-operative care, in a patient whose imaging shows a herniation at exactly the level the examination points to. The target is specific and the operation is focused.

The third is the emergency: the red flags listed above, and in particular loss of bladder or bowel control with numbness around the groin. That combination needs assessment the same day, not an appointment next week.

Back or neck pain on its own, without a clear nerve target, is a much weaker reason to operate. An operation aimed at a structure that is not producing the symptoms tends to disappoint everyone involved.

What the operation would be

For a lumbar herniation producing leg pain, the usual operation is a microdiscectomy: removing the fragment pressing on the nerve through a small opening, leaving the rest of the disc in place. In selected cases the same job can be done through an endoscope, which is a smaller corridor again.

For a cervical herniation, the options include cervical disc replacement, which decompresses the nerve and keeps that segment moving, and anterior fusion. Which one suits depends on the facet joints, the alignment and the specific pathology, not on a preference stated in advance.

None of these is a repair. The disc is not restored to its original state. What changes is the pressure and the inflammation on the nerve, and for the right patient that is the whole problem.