Home / Conditions / Radial tunnel syndrome
An aching pain in the top of the forearm, a few centimetres below the outside of the elbow, from pressure on the radial nerve where it passes through a tunnel of muscle. Radial tunnel syndrome, or RTS, is often mistaken for tennis elbow, and the two can occur together. It causes pain rather than numbness, and most people improve without an operation.
Pain on the outside of the elbow and forearm has three common sources. They sit within a few centimetres of each other, which is why they are confused — but where exactly it hurts, and whether there is weakness, tells them apart.
| Tennis elbow | Radial tunnel syndrome | Weakness from the same nerve | |
|---|---|---|---|
| Where it hurts | On the bony point on the outside of the elbow | In the forearm muscle, a few centimetres below | Often little pain |
| Weakness | None, though gripping hurts | None — it is pain | Cannot lift the fingers or thumb straight at the knuckles |
| What brings it on | Gripping and lifting with the palm down | Twisting the forearm, gripping, repeated pulling | Often a swelling or injury near the elbow |
| A telling test | Pressing the bony point hurts | Straightening the middle finger against resistance hurts | Weakness on testing; nerve tests abnormal |
| What it needs | Rest from what aggravates it, then exercises | Easing the load, a splint, sometimes an injection | Prompt assessment, often a scan |
New weakness lifting the fingers or thumb should be seen within a few days. It means the nerve's movement branch is under more pressure than it usually is here, sometimes from a swelling near the elbow. Pain that runs down from the neck, or numbness in the hand, points to a different cause again. Call the clinic and come in.
The radial nerve runs down the back of the arm, around the outside of the elbow, and into the forearm through a narrow tunnel formed by layers of muscle. Twisting the forearm and gripping tighten those muscles around it, and that is where it can be squeezed.
What a picture cannot show is why it aches rather than tingles. The part of the nerve in the tunnel mainly controls muscles rather than feeling, so pressure there causes a deep, tiring ache in the forearm instead of numbness in the hand.
It also explains the confusion with tennis elbow. The tunnel lies just below the bony point where the tennis elbow tendon attaches, so the two pains sit close together — and because the pressure is usually mild, nerve tests are often normal, which is why the examination matters most.
Most people improve with simple measures over a few weeks to a few months. Surgery is kept for pain that persists despite them.
Cutting down on the movements that bring it on — repeated twisting, gripping and pulling — and taking more frequent breaks from them. Often a change in technique at work or in a hobby makes the most difference.
A wrist splint rests the forearm muscles that squeeze the nerve. Once the pain settles, gentle stretching and strengthening help stop it returning.
A steroid injection near the nerve can ease the pain for some people. With a local anaesthetic, it also helps confirm the diagnosis if the pain goes away.
For pain that lasts several months despite treatment, the tight bands of tissue over the nerve can be released. Results are less predictable than for carpal tunnel release, and recovery takes weeks to months, so it is considered carefully.
Radial tunnel syndrome here is seen by Dr Mathew Tung Yu Yee, a neurosurgeon whose profile names radial tunnel syndrome among the spine and nerve conditions he treats. He trained in neurosurgery in Singapore and the United Kingdom, holds the FRCS (Surgical Neurology) and is a Fellow of the Academy of Medicine, Singapore. He consults in English, Mandarin, Malay and Hokkien.
No, though they are often confused and can occur together. Tennis elbow hurts on the bony point on the outside of the elbow; this hurts a few centimetres lower, in the forearm muscle over the nerve.
The part of the radial nerve involved mainly controls muscles rather than feeling, so it causes a deep ache in the forearm rather than numbness or tingling in the hand.
Yes. Nerve tests are often normal in this condition, because the pressure on the nerve is usually mild. The diagnosis rests mainly on where it hurts and how the examination tests respond.
Most people do not. Easing the load, a splint and sometimes an injection help most. Surgery is considered only for pain that persists for several months.
Many people improve within a few weeks to a few months of changing what brings it on. After surgery, recovery can take several months.
No. Bring any nerve test or scan reports, and be ready to point to exactly where it hurts.
Carpal tunnel syndrome · Cubital tunnel syndrome · Pinched nerve in the neck · Neuropathic pain
Be ready to point to exactly where it hurts. A few centimetres makes the difference between tennis elbow and a nerve.
