Radial Tunnel Syndrome

Radial tunnel syndrome also known as supinator syndrome occurs when the radial nerve is compressed as it enters the radial tunnel. The radial nerve is one of three nerves of the forearm, traveling from the side of the neck, down the back of the arm, through the forearm, and into the hand. The radial nerve causes movements, like forearm rotation, elbow extension, and wrist and finger movement. 

When the radial nerve, or the structures around it, becomes inflamed, it leads to this condition. The causes for radial tunnel syndrome can be:

• Swelling or fluid in the arm, or surrounding tissues
• Repetitive activities of forearm and wrist
• Extending the elbow too much
• Typing or using a screwdriver
• Repeated push-and-pull activities
• Lifting heavyweights
• Sports activities like throwing a football or baseball
• Direct blow to the outside of the elbow or forearm
• Gripping, pinching or bending the wrist
• Poor strength and flexibility
•  Swelling in the forearm
• Injury
• Tumors
• Diabetes.

The symptoms vary from person to person, some of the symptoms are given below:

• Deep, aching pain below the elbow in the forearm muscles
• Pain aggravates by twisting, pushing, or gripping
• The altered or absent sensation between the thumb and index finger on the back of the hand
•  Weakness of the forearm muscles 
• Decreased wrist strength
• Difficult to grip or lift certain objects
• Pain may get worse while sleeping
• Wrist drop causing loss of ability to lift the hand.

Pathology

Radial Tunnel Syndrome occurs due to the compression of the posterior interosseous nerve which lies in the proximal part of the forearm. 

Physical exam

Physical examination is done to look for the painful spot. Pinpointing the source of the pain will be most helpful to check for nerve damage or problems with the bones, muscles, or tendons.

The patient is asked to turn the palm from a palm down position to a palm-up position and apply resistance. If the patient experiences pain in the forearm, then it is a sign of radial tunnel syndrome.

Another test requires, to keep the middle finger straight against resistance. If it is painful then it is a sign of radial tunnel syndrome.

Rule of nine tests:

During this test, when the arm is facing up and the elbow slightly flexed, the physiotherapist separates the elbow into nine equally sized areas, in three rows. Then slight pressure is applied to each spot, if the patient feels pain on the outermost spots of the top two rows, it is a sign of radial tunnel syndrome.

X-Ray:

X-Ray is done to exclude any degenerative elbow changes.

Magnetic Resonance Imaging (MRI):

Though Magnetic Resonance Imaging is not often able to determine the level to which the nerve is irritated or compressed, but can be beneficial in excluding other problems.

Electromyogram (EMG) Tests:

Electromyogram (EMG) tests are recommended to see if the muscles of the forearm are working properly. If the test shows a problem in the muscles, it indicates that it may be caused by a problem in the radial nerve.

Nerve Conduction Velocity (NCV) Test:

Nerve conduction velocity (NCV) test measures the speed of an electrical impulse as it travels along the radial nerve. If the speed is very slow, indicates that the nerve is pinched.

Medication: Non-steroidal anti-inflammatory medications like aspirin, naproxen, ibuprofen, etc.

Note: Medication should not be taken without the doctor's permission.

Surgical treatment is recommended in case rest and non-operative therapy fails. Surgical decompression is done to remove the unwanted pressure from the radial nerve. 

Rest:

Rest is recommended to avoid movement that causes pain. A wrist brace or splint is used to reduce movement in the forearm. Wear a wrist or an elbow splint to reduce movement and irritation in the radial nerve.

Ice therapy:

Apply ice for 10-15 minutes every 2 to 3 hours, it helps to decrease the swelling. It causes vasoconstriction of the blood flow, relaxation and makes the muscles more flexible.

Ultrasound massage:

Ultrasound therapy is given to decrease pain and increase circulation.

Manual Therapy:

Manipulation and massage, are given to the soft tissues to prevent the development of adhesions, thus restricting the nerve. Mobility of the nerve reduces nerve entrapment.

Strengthening Exercises:

Strengthening exercises of the muscles help to maintain the balance between agonist and antagonist muscles, closed-kinetic chain activities, proprioceptive neuromuscular facilitation (PNF) diagonal strengthening patterns, and a full range of motions with protective strength, drills, and plyometrics are recommended.

Stretching Exercises:

Wrist Extension Stretch:

Place the affected arm straight in front, with the hand up and fingers facing towards the sky. Use another hand to pull back on the fingers, until a stretch is felt in the forearm.

Wrist Flexion Stretch:

Place the affected arm straight in front, with the hand down and the fingers facing towards the ground. Use the other hand to pull back on the back of the palm until a stretch is felt in the forearm.

Wrist supination:

Place the affected arm by the side at 90-degree, with the forearm and hand facing up. Put the other hand on the wrist and rotate the forearm inward, toward the body, without moving the other parts of the arm.

Self-directed nerve gliding Exercises:

Radial nerve glides:

Stand straight, drop the shoulders slightly and rotate the arms into the body. Flex the wrist on one side and raise the arm up to waist level as the head is tilted to the opposite way. Once the stretch is felt, hold the position for 5 seconds.

These exercises should be done on both sides, even though dealing with radial tunnel syndrome in one arm.

The patient needs to wear a wrist strap during the day and an elbow pad or splint at night to control symptoms. After the recovery, exercises should be continued to maintain the mobility and strength gained.  Avoid repetitive motion that causes symptoms, take frequent breaks or modify the work duties. Pain should not be ignored during exercises. If the elbow pain worsens, due to exercising or if the pain does not improve after performing the exercises for 6 to 12 weeks, then the patient is advised to inform his physiotherapist.