Pinched Nerve vs Herniated Disc: What Is the Difference?

A pinched nerve and a herniated disc are not the same thing, although they often go together. A herniated disc happens when the soft centre of a spinal disc pushes out through a tear in its tougher outer ring: it is a structural problem. A pinched nerve means a nerve is being squeezed or irritated by surrounding tissue, such as bone, ligament, muscle or disc material: it describes a situation rather than a cause.

A herniated disc is one of the common causes of a pinched nerve. But not every herniated disc pinches a nerve, and not every pinched nerve is caused by a disc. Treatment depends on where the nerve is compressed and why.

What is a herniated disc?

Each disc between the vertebrae has a strong outer ring (the annulus) and a gel-like core (the nucleus). With age-related wear or a sudden strain, the ring can weaken and the core can push out. This is called a disc herniation, also known as a slipped or bulging disc.

If the herniated material touches and irritates a nearby nerve root, it can cause pain that spreads into the leg (from the lower back) or the arm (from the neck). If it does not, the herniation may cause no symptoms at all. Many people whose MRI shows a disc herniation have no pain.

What is a pinched nerve?

"Pinched nerve" is an everyday description rather than a precise medical diagnosis. Doctors go on to identify where the nerve is compressed and what is compressing it. Broadly, this happens in one of two places.

In the spine: nerve root compression

Nerve roots leave the spine through narrow openings. Common causes of compression here include:

• A herniated disc in the lower back or neck
• Bone spurs (osteophytes) from wear and tear
• Narrowing of the opening the nerve exits through (foraminal stenosis)
• Narrowing of the spinal canal (spinal stenosis)
• A slipped vertebra (spondylolisthesis)

Compression of a nerve root is called radiculopathy: pain and other symptoms that radiate along the path of the nerve. In the lower back, this is commonly known as sciatica.

Outside the spine: peripheral nerve entrapment

As nerves travel down the arms and legs, they pass through tight tunnels around joints, where they can also become compressed:

• The median nerve at the wrist: carpal tunnel syndrome
• The ulnar nerve at the elbow: numbness in the ring and little fingers
• A sensory nerve of the thigh near the groin: burning and numbness on the outer thigh (meralgia paraesthetica)
• The tibial nerve at the ankle: burning in the sole of the foot (tarsal tunnel syndrome)

How can you tell them apart?

Both can cause pain, numbness, tingling and weakness. Some clues help:

• Distribution: with nerve root compression, symptoms tend to travel in a band from the neck into the arm or from the lower back into the leg. With peripheral entrapment, they stay within the area that nerve supplies; in carpal tunnel syndrome, for instance, the thumb, index and middle fingers.
• Triggers: with root compression, moving the neck or back, coughing or sneezing may make the pain worse. Carpal tunnel symptoms are often worse at night or when the wrist stays bent for a long time.
• Onset: root compression from a disc can start suddenly, while compression from bone spurs or narrowing usually develops gradually.

These clues are not definitive. Some people have a neck disc problem and carpal tunnel syndrome at the same time. A compressed nerve can also produce burning or electric-shock-like neuropathic pain.

Two common mix-ups

Numbness in the hand: with a pinched nerve root in the neck, numbness often starts together with neck pain and changes with neck movement. In carpal tunnel syndrome, numbness usually concentrates in the thumb, index and middle fingers, can wake you at night and may ease when you shake your hand.

Leg pain: pain from a lumbar disc herniation is usually in one leg and gets worse with sitting and bending forward. Pain from spinal stenosis is often felt in both legs while walking and eases when you sit down or lean forward.

The role of MRI and EMG

Diagnosis starts with a careful history and a neurological examination. An MRI shows the discs, the spinal canal and the nerve roots, so it is used to assess compression in the spine. Electromyography and nerve conduction studies (EMG) measure how nerves and muscles conduct electrical signals. They show where along its course a nerve is affected and how severely, which is particularly useful for telling a root problem from compression at the wrist or elbow.

Imaging must always be interpreted alongside the examination. A disc herniation seen on an MRI may not be the real cause of the numbness in your hand.

Why the treatment differs

For a nerve root pinched by a herniated disc, treatment usually begins with time, staying active, a medication review and exercise. If the pain is severe or persistent, procedures such as an epidural steroid injection may be considered, and in specific situations surgery. The non-surgical lumbar disc treatment page gives an overview of the options, and our guide on when herniated disc surgery is needed explains when an operation comes into question.

For peripheral entrapment such as carpal tunnel syndrome, the options include a wrist splint, a targeted injection and, if needed, surgery to release the band of tissue pressing on the nerve. Because treatment aimed at the wrong site will not help, pinpointing where the nerve is compressed matters.

When to see a doctor

It is worth being assessed if numbness or pain has lasted several weeks, disturbs your sleep or makes everyday tasks difficult. Seek help without delay if you notice worsening weakness in an arm or leg, clumsy hands, unsteadiness when walking, or any problem controlling your bladder or bowels.

To find out what is behind your symptoms, you can contact us to arrange a consultation. For more on disc problems, see lumbar disc herniation.