Radial tunnel syndrome is uncommon. However, it could also be mistaken for other conditions such as posterior interosseous nerve syndrome or even tennis elbow. Read on to learn more about radial tunnel syndrome. Let’s start with anatomy!
The elbow
The elbow joint is where the humerus, ulna, and radius come together. The humerus is the upper arm bone and forms individual joints with the ulna and radius, which are the forearm bones. Movements of the elbow include flexion and extension. Flexion is when the forearm and upper arm come closer together (bending the elbow) and extension is when move farther apart (straightening the elbow). The radioulnar joint allows for the movements of pronation and supination. Pronation is rotating the forearm, so the palm faces downward, and supination is forearm rotation where the palm faces upward.
The supinator
The supinator is a muscle just below the elbow. It attaches to the humerus and ulna. From there, it spirals around the radius and connects to several different areas of the radius. This positioning allows the supinator to perform the action of supination. It is a wide muscle with a superficial and deep layer. An arch is formed between the superficial and deep layers of the supinator muscles. This is called the arcade of Frohse.
The radial tunnel
The radial tunnel is a 5cm long area that begins at the humeroradial joint and ends at the bottom of the supinator muscle. It is bordered by several other muscles in the forearm. There is also an artery and vein that courses through the tunnel.
The radial nerve
The radial nerve is one of the major nerves of the upper extremity. It begins near the armpit and travels all the way down to the hand. As it travels down the arm, the radial nerve will divide into superficial and deep branches at the level of the elbow. The superficial branch of the radial nerve only provides sensation and no motor function. It provides sensation to the back of the hand and wrist. The deep branch provides only motor innervation and no sensory.
The posterior interosseous nerve
The deep branch of the radial nerve turns into posterior interosseous nerve as it goes into the supinator muscle. The posterior interosseous nerve enters at the arcade of Frohse. It travels between the superficial and deep layers of the supinator. The posterior interosseous nerve continues down the forearm to innervate the the muscles of wrist extension, finger extension, thumb extension, and thumb abduction.
Wrist extension is when the back of the wrist moves toward the back of the forearm. Finger extension is straightening the fingers. Thumb extension is moving the thumb away from the index finger while thumb abduction is moving the thumb forward of the index finger.
What is radial tunnel syndrome?
Radial tunnel syndrome is a compressive neuropathy of the posterior interosseous nerve while it is in the radial tunnel. Neuropathy indicates some type of damage to the nerve. There are many different ways that the nerve could become compressed or pinched. These include:
- Repetitive pronation and supination
- Using a screwdriver
- Throwing and overhead activities
- Throwing a baseball or football
- Activities that involve repetitive forceful gripping
- Trauma or a hard blow to your elbow or forearm
The site of the compression is most commonly at the arcade of Frohse. Radial tunnel syndrome is extremely rare but is most likely to affect people between the ages of 30-50. Women are more likely to develop it than men.
What are the symptoms of radial tunnel syndrome?
There are several symptoms associated with radial tunnel syndrome. These include:
- Deep, dull, or burning pain in the forearm
- Pain may radiate up to elbow or down to the wrist
- Pain with supination and wrist extension
- Pain is worse at night or at the end of the day
- Sensation changes in the thumb, index, and long finger
Could this be tennis elbow (aka lateral epicondylitis)?
The symptoms of radial tunnel syndrome do mirror tennis elbow. Tenderness and pain at the elbow are in very similar locations for both conditions. Having an injection of a local anesthetic into the radial tunnel can be helpful in making the correct diagnosis.
Who should I see?
- Physical therapy – Physical therapy can help decrease pain and inflammation with techniques including manual therapy and dry needling. PT can evaluate and address abnormal joint mobility, muscle weakness, muscle tone, and flexibility. With radial tunnel it is important to decrease the amount of work the supinator and forearm muscles are performing. Your PT can help you activate other muscles to decrease the load on the supinator and other forearm muscles. They can assess your posture during work or sports to prevent the problem from happening again.
- Orthopedic physician – An orthopedist might be necessary if the condition is not responding to physical therapy. Your physician can prescribe medication, give an injection, or order testing/imaging if needed. Surgery is an option if all conservative measures fail.
What can I do?
- Relative rest – Resting the area to decrease further pain and damage from occurring is one of the best ways to treat radial tunnel syndrome. Basically, stay away from the activities that are causing pain. This gives the nerve time to heal. If you keep doing what is causing the injury, it is not going to get better. This might include not participating in your sport or changing how you perform a task or job. If you are not able to participate in your activity or sport, then you can supplement with non-irritating activities such as biking, walking, or jogging while your condition is being treated.
- Ice – Ice can help decrease pain and symptoms at the forearm. Ice the painful area for 15 to 20 minutes at a time. I would recommend using an ice pack several times per day if the pain is constant or is preventing you from participating in an activity. Ice immediately after activity.
- Posture – Having forward, rounded shoulders cause muscular imbalances in the shoulder and elbow. It decreases the ability of the scapular stabilizers to stabilize the shoulder joint. This causes the muscles at the elbow and forearm to work more. It also shortens the pectoralis major, pectoralis minor, and biceps and causes them to get tight. Stretching this area will make better posture more attainable. Below is a video showing how to stretch the pecs and biceps, and also how to use a wall to check your posture.
- Soft tissue mobilization – Soft tissue mobilization helps release the muscles around the forearm and decreases the pressure on the nerve. Use a massage ball, lacrosse ball, tennis ball, or your own fingers to massagepainful areas all around the elbow. Spend a good 3 to 5 minutes rolling. Do not roll so hard that you bruise the area, but it should be a pretty painful sensation. Roll out the area no more than a few times a week. See the video below.
- Supinator stretch – Stretching out the supinator after releasing it is a great way to lengthen the muscle. It is a good idea to perform soft tissue mobilization first because you will get a better stretch afterwards. Below is a video on how to stretch the supinator.
- Radial nerve flossing – You can mobilize the radial nerve to ensure that it is not entrapped in an area. Flossing will free-up the nerve if it is stuck and allow it to move along its pathway. Below is a video of radial nerve flossing.
- Thumb and finger strengthening – Strengthening the muscles in the thumb and fingers is important since radial tunnel syndrome can affect these areas. Performing extension exercises is important for recovering hand strength. See the video below.
- Wrist strengthening – It is important to strengthen the wrist as well. Radial tunnel syndrome can affect wrist extension and ulnar deviation strength. Below is a video showing how to strengthen the wrist using resistance bands.
- Strengthen the rotator cuff and scapular stabilizers– Elbow injuries tend to occur because of weakness of the rotator cuff muscles and scapular stabilizers. These are the stabilizing muscles of the shoulder that allow the arm to reach, lift, and hold without injury or irritation. Using loop resistance bands and resistance bands can increase strength and difficulty.
In review
- The elbow joint is where the humerus, ulna, and radius come together.
- Movements of the elbow include flexion, extension, pronation, and supination.
- The supinator is a muscle just below the elbow.
- The radial nerve is one of the major nerves of the upper extremity. It begins near the armpit and travels all the way down to the hand.
- As it travels down the arm, the radial nerve will divide into superficial and deep branches at the level of the elbow.
- The deep branch turns into posterior interosseous nerve as it goes into the supinator muscle.
- The posterior interosseous nerve continues down the forearm to innervate the the muscles of wrist extension, finger extension, thumb extension, and thumb abduction.
- Radial tunnel syndrome is a compressive neuropathy of the posterior interosseous nerve.
- Symptoms include forearm pain that is worse at night and at the end of the day.
- Physical therapy is often successful in treating this condition.
- An orthopedist would be needed if the condition is not responding to physical therapy.
- There are things you and do.
- Rest
- Ice
- Posture
- Soft tissue mobilization
- Supinator stretch
- Radial nerve flossing
- Thumb and finger strengthening
- Wrist strengthening
- Strengthen rotator cuff and scapular stabilizers
As always, If you have questions about the content of this post or any other musculoskeletal questions, please e-mail me.
Additional resources
https://www.ncbi.nlm.nih.gov/books/NBK555937/