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What is... a trapped nerve?

· 6 min read

Part of the "What is...?" series

Most of us would be familiar with the term "trapped nerve" but can just any nerve get trapped? How do you tell if you've got a trapped nerve? And what should you do about it?

What do nerves do?#

Nerves are responsible for carrying information all over the body and simplistically speaking this information falls into 2 categories:

  • Information about movement - signals being taken from the brain to the muscles of the body. And not just your skeletal muscles which control your voluntary movement. This would also include the muscles that push food through your digestive system, the muscles that squirt saliva from the salivary glands into your mouth and the muscles which make the pupils of your eyes smaller or larger, depending on the light.
  • Information about sensation - signals being taken from the body to the brain, carrying information about sensations in the skin, stretching in the muscles, heat or inflammation in the tissues and more.

The term "trapped nerve" is one that is commonly used, but it doesn't really represent what is actually happening in the body. Nerves don't really get trapped, but they can sometimes be compressed by nearby structures, irritated by chemicals, usually inflammatory chemicals from a nearby injury or damaged from a direct injury. When this happens, you would expect to see problems with the carrying of all this information to and from the affected nerve:

  • The muscles would not be getting information about movement, and so they may seem weaker than usual. Sometime this can even make the affected area feel heavy or more effort to move.
  • The sensation signals travelling from the area will be affected, so the area may start to feel tingly with pins and needles, or even numb
  • The compression on the nerve would send signals back up to the brain, causing sharp pains along the course of the nerve. This means you could get pain very far away from the original nerve compression, such as in sciatica, where there is pain in the leg but the original compression occurs in the back.

Whilst the nerve is compressed in the spine, the pain of sciatica is felt in the leg

Where do nerves get trapped?#

Nerves are usually very mobile structures, and most of the time they have lots of space and "wiggle room" to accommodate movement or change in the tissues around them.

Nerves are most at risk of getting trapped at points where they run through narrow tunnels in the body, because they have less "wiggle room". The space around them is restricted. The nerves are usually able to glide through these tunnels. But now imagine if that tunnel became squashed or inflamed. The nerve would start to feel the pressure of that and would not be able to glide smoothly.

The most common place for a nerve to get trapped in a tunnel is in the IVF (intervertebral foramina - a posh word for spinal tunnels), where the nerve first exits the spinal cord. When this happens, you will hear people say they've trapped a nerve in their neck or back. But there are other tunnels all over the body, particularly in the arms and legs:

  • The Carpal Tunnel, in the wrist, where the nerve runs underneath a stiff ligament
  • The Tunnel of Guyon, on the outside edge of the lower palm, where the nerve runs under the pisiform bone
  • The Olecranon Fossa, where the nerve runs close to the bones of the elbow
  • The Deep Gluteal Space, where the nerve runs underneath or through the piriformis muscle
  • The Thoracic Outlet, where the nerve bundle runs on top of the ribs and under the muscles of the neck and chest
  • ...and many more

The median nerve runs through the carpal tunnel under a stiff ligament, which may compress it

Why do nerves get trapped?#

When a nerve sits in a tunnel as described above, it is confined. If something then pushes into that tunnel the nerve becomes compressed. There are a few common things that may push into the tunnel to squash the nerve:

  • Disc - in the spine, discs may sometimes bulge and push onto the nerve
  • Arthritis - in arthritis, the extra bone that grows may sometimes push onto a nerve
  • Muscle - sometimes when muscles become tight or shortened, they put pressure onto the tunnel in which the nerve sits, causing the nerve to be compressed
  • Swelling - if inflammation occurs within the tunnel, the pressure of this swelling would compress the nerve

It is possible to have any or all of these without it affecting the nerve.

There are several other very rare causes of nerve compression such as bleeding (like in Compartment Syndrome) or space-occupying lesions (like a tumour).

A disc bulge is a common cause of trapped nerve in the spine

What can I do about a trapped nerve?#

1. Find out what is pressing on which nerve#

In this blog, I am usually very hesitant to say "go and see a chiropractor", because I believe that most patients, with the right information, can take care of themselves. However, in this case it's important to get a diagnosis. The treatment for disc bulges, arthritis and muscle tension are very different and if you target the wrong one you may not feel any relief, or may possibly even make it worse.

2. Take pressure off the nerve#

This will mostly be in the form of hands-on treatment from your chiropractor, who will use gentle, specific techniques to decompress the nerve and resolve the underlying cause of the compression

3. Get the nerve gliding again#

Once you know from your chiropractor which nerve is affected, you can start doing gliding exercises specifically for that nerve. There's a different nerve-glide exercise for every single nerve in your body so it's important to chose the right ones, and your chiropractor can help with this.

4. Support the healing of the nerve#

Nerves can heal quite slowly so if you want a full and speedy recovery there are several things you can do (or stop doing) to encourage healing. Nerve healing is hugely slowed down by smoking, and quitting or cutting down significantly will improve your chances. Your nerves will also use lots of B vitamins, magnesium and omega-3 in the healing process, so taking a good supplement with high levels of these three ingredients will help. Taking regular gentle exercise during recovery will improve blood flow to the nerves, which will provide all the oxygen and energy needed for repair.

See other posts in the "What is...?" series