What is Radial Tunnel Syndrome

What is Radial Tunnel Syndrome?

Radial Tunnel syndrome is a compression of the radial nerve in the proximal forearm. The radial tunnel is not commonplace for radial nerve compression and so many times it can go undiagnosed. Cubital Tunnel, carpal tunnel, brachial plexus are some common places for the nerve compression.

Anatomy of the Radial Nerve:

The radial nerve is one of the three major nerves for the forearm. It originates from the brachial plexus and runs downwards into the arm, forearm, wrist and extends into the hand. During the travel, the nerve branches several times into the smaller nerves. The branches of the radial nerve innervate the muscles of the dorsal arm. Thus, the branches provide the movement of the muscles they innervated and the sensation to the skin of the area.

At the lateral aspect of the elbow, radial nerve branches into the posterior interosseous nerve (PIN) and enters the radial tunnel. The radial tunnel is formed by bone and the supinator muscle (the muscles used for the supination of the forearm). The nerve is compressed into this tunnel causing symptoms like tingling, numbness, and pain in the area of the distributions.

It is important to note that the radial nerve can get compressed at several places including a cubital and carpal tunnel. Radial tunnel syndrome is the least common from carpal tunnel syndrome and cubital tunnel syndrome.

Etiology of Radial Tunnel Syndrome:

• Bone fractures on a lateral elbow or proximal forearm
• Trauma to the muscles, tendons or other soft tissues surrounding the nerve
• The repetitive motion of the lateral elbow
• Inflammation of the supinator muscle.

Symptoms of Radial Tunnel Syndrome:

• Pain during wrist extension and forearm pronation (inward rotation of the forearm)
• Weakness or inability to perform a range of motion of the forearm, wrist, and hand mainly due to the pain
• Tenderness at the elbow (mainly at the site of the compression)
• Painful or decrease the ability to grip an object, a cup of coffee.

Diagnosis of Radial Tunnel Syndrome:

Detailed history, as well as a thorough physical examination, are crucial in the diagnosis of radial tunnel syndrome. Additionally, palpating the local area of tenderness and comparing it to the other side is important. A person usually complains of tenderness on the forearm at the area where a radial nerve enters into the radial tunnel.

A physician may recommend an X-ray of the elbow, MRI of the cervical spine, electromyography, or nerve conduction studies when appropriate.

There is some controversy in the research regarding this diagnosis as well as the site of the compression.

The fact that a person complains of pain more than numbness or tingling with the nerve compression does not really fit into “the box of nerve compression” but more of neuropathy of some sort. Additionally, EMG studies usually come back negative with compressive neuropathy of PIN. There are no clear cut answers to these questions in literature yet.

Medical Management of Radial Tunnel Syndrome:

The medical management of radial tunnel syndrome concentrates on the reduction of pain and inflammation. NSAIDs are usually the first treatment choice with rest in the area of involvement.

Physical therapy is the treatment of choice once the pain and inflammation are controlled.

If a person developed radial tunnel syndrome secondary to an occupation that involves repetitive movement of the elbow, environmental modification as well as proper ergonomics are advised.

When all conservative measures fail, and a person remains symptomatic, patients can consider surgery to decompress the nerve in the tunnel.

When the radial tunnel syndrome is not treated appropriately or proper changes in body mechanics are not made, the nerve remains compressed inside the tunnel. This can lead to severe atrophy of the forearm muscles, weakness in the wrist as well as hand movement. It may even result in permanent disability if the compression is not relieved.

How can Physical Therapy help?

As mentioned above, physical therapy is a first choice of treatment to manage pain, improve range of motion as well as strength. Additionally, a clinician will also concentrate on stretching the nerve by some nerve gliding exercises to improve the mobility of the nerve in the tunnel.

Radial Nerve Stretch:

Here is how to stretch the radial nerve.

In a standing position, reach back, with your palm up.

Bend your head to the opposite side of the arm. (so if you are stretching right side radial nerve, bend your head to the left).

Hold it for 10 to 15 seconds and release.

Repeat it 3 times twice a day.

Range of motion exercise for Wrist :

Wrist Flexion exercise:

• In sitting or standing position, keep your arm straight with the palm facing downward.
• Bend your wrist downwards, hold for 2 to 3 seconds and release
• Repeat 10 times twice a day.

• You can choose to perform the same exercise to stretch wrist flexors.
• Here, you are applying additional pressure gently with the other hand and holding it for 15 seconds Repeat it 3 times.

Wrist Extension Exercise:

• You can perform these exercises in sitting or in a standing position.
• Keep your arm straight with the palm facing up.
• Bend your wrist downwards, hold for 2 to 3 seconds and release
• Repeat 10 times twice a day.

• You can choose to perform the same exercise to stretch wrist extensors.
• Here, you are applying the gentle pressure with the other hand and holding it for 15 seconds
• Repeat it 3 times.

Wrist Supination Exercise:

• In a sitting or a standing position, keep your elbow bent at the side of your body with palm facing the ceiling as shown on the bottom of the figure below.
• With your opposite hand, bring the forearm into the palm-up position as shown in the first part of the picture below.
• You can perform the exercises actively without the use of the opposite hand if you have no pain.

• Hold for 2 to 3 seconds and repeat 10 times twice a day.

Wrist strengthening exercises:

Muscle weakness is usually not a primary symptom form the compression. It is usually pain that limits the range of motion. The pain also leads to weakness in chronic cases. So if a person gets relief from symptoms with conservative management in acute cases, strengthening exercises may not be necessary. As a person will be able to return to his daily routine with no problem. However, in chronic cases, it is good to initiate the strengthening exercise with the patient.

The strengthening exercises are similar to the range of motion exercises. The only difference is we add some external resistance while a person is performing the exercise.

Here are a few examples of strengthening devices that you could use.

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Here is a PDF version of the exercises to print out.