What Is Radial Tunnel Syndrome

The radial nerve, one of the three nerves in your forearm, originates from the side of your neck and extends down the back of your arm, traversing through your forearm and into your hand. This crucial nerve plays a vital role in various arm movements, including forearm rotation, elbow extension, and controlling wrist and finger movements. As the nerve approaches the elbow, it passes through a structure known as the radial tunnel, which comprises of muscles.

Radial tunnel syndrome is a condition which should be kept in mind when assessing elbow and forearm discomfort or pain. The condition is identified by experiencing lateral elbow and dorsal forearm pain that may extend to the wrist and the back of the fingers.

Radial tunnel syndrome involves compression of the posterior interosseous nerve (PIN) within the radial tunnel, resulting in pain unaccompanied by motor or sensory dysfunction. Typically, conservative measures are employed for treatment, reserving surgical radial tunnel release for cases resistant to non-invasive interventions. This article delves into the pathophysiology, epidemiology, assessment, management, and outlook of radial tunnel syndrome, emphasizing the collaborative efforts of healthcare professionals in diagnosing this condition.

This condition tends to affect women within the age range of 30 to 50 years more frequently.¹ It arises from intermittent compression of the radial nerve, extending from the radial head to the lower edge of the supinator muscle, and typically does not present with evident weakness in the extensor muscles. Diagnosing radial tunnel syndrome places greater emphasis on clinical examination than on paraclinical tests such as electrodiagnostic assessments and imaging studies.²

Symptoms and presentation

You may experience pain and tenderness on the outer side of your elbow, extending to your forearm. This persistent ache can lead to fatigue and worsen with certain activities, including:

• General activities require extensive use of your forearm and/or wrist
• Heavy lifting
• Excessive extension of your elbow
• Forearm rotation
• Wrist flexion

Over time, radial tunnel syndrome has the potential to weaken forearm muscles and overall wrist strength, making gripping or lifting objects more challenging. Pain may intensify during sleep, and in some cases, radial tunnel syndrome can result in wrist drop, limiting your ability to lift your hand beyond a certain point.

It's crucial to differentiate radial tunnel syndrome from conditions like tennis elbow, which shares similar symptoms. When discussing your symptoms with your doctor, providing specific details can aid in accurate diagnosis and appropriate treatment.²

Demographics

Radial tunnel syndrome is relatively rare, with an estimated annual incidence of 0.003%.¹ It appears to be involved in approximately 2.97 cases per 100,000 instances of radial neuropathy in males and 1.42 cases per 100,000 instances in females.²

Causes and mechanism

Radial tunnel syndrome arises when the radial nerve traverses the radial tunnel beneath the elbow, navigating between various muscles and beneath facial bands—tissue fibers that encase, separate, or connect muscles and other soft structures in the body. Inflammation of the radial tunnel and its internal structures exerts pressure on the nerve, giving rise to this condition. Several activities can contribute to the development of radial tunnel syndrome, including:

Repetitive motions

Engaging in repetitive motions, often encountered in occupational settings. Examples include typing or using a screwdriver.

Push-and-pull activities

Regularly subjecting the arm to push-and-pull activities, such as those involved in throwing a football or baseball. These actions typically entail pulling the arm back and pushing it forward during the release.

Direct trauma

Sustaining a direct, forceful impact to the outer part of the elbow or forearm.

Excessive wrist movements

Excessively gripping, pinching, or bending the wrist, which can contribute to the development of radial tunnel syndrome.³

Diagnosis

Diagnosing radial tunnel syndrome presents challenges due to the absence of dedicated imaging tests. Nevertheless, your doctor might order an X-ray, MRI, or electromyography to eliminate the possibility of other injuries or conditions.

The diagnostic process involves:

Patient history

Your doctor will inquire about your specific pain, medical history, and symptoms.

Physical examination

Examination of the elbow and forearm involves palpating the outside of the elbow and applying gentle pressure to pinpoint the nerve compression site within the radial tunnel.

Specialized tests

Two specific tests are commonly employed for diagnosis:

a. Palm rotation test

You'll be asked to turn your palm from a palm-down to a palm-up position against resistance. Forearm pain during this motion may indicate radial tunnel syndrome.

b. Middle finger test

Keeping your middle finger straight against resistance may cause pain if radial tunnel syndrome is present.

Rule of nine test

With your arm facing up and your elbow slightly flexed, your doctor divides the elbow into nine areas across three rows. Gentle pressure is applied to each spot, and you report any sensations—pain, discomfort, or nothing. Pain in the outermost spots of the top two rows may indicate radial tunnel syndrome.³

Treatment

The primary approach to treating radial tunnel syndrome involves ceasing or significantly reducing activities that trigger symptoms. Resting the affected arm and avoiding painful movements are key steps, with most patients experiencing symptom relief within three to six weeks through rest and medical treatment.

Additional measures to consider if pain persists include:

Over-the-counter medications

• Taking anti-inflammatory medications to alleviate pain and inflammation

Steroid injections

• Undergoing steroid injections to reduce inflammation and alleviate pressure on the radial nerve if necessary

Splinting

• Wearing a wrist and/or elbow splint, especially during sleep, to minimize movement and irritation on the radial nerve

Physical therapy exercises can also be beneficial, including

• Wrist extension stretch

Straighten the affected arm with the hand facing up, using the other hand to pull back on the fingers until a stretch is felt in the forearm.

• Wrist flexion stretch

Extend the affected arm with the hand facing down, using the other hand to pull back on the back of the palm until a stretch is felt in the forearm.

• Wrist supination

Keep the affected arm at a 90-degree angle with the forearm and hand facing up. Rotate the forearm inward towards the body without moving other parts of the arm.

• Radial nerve glides

Stand straight, drop your shoulders slightly, and rotate your arms into your body. Flex your wrist on one side, raise your arm to waist level, and tilt your head in the opposite direction. Hold the stretch for three to five seconds.

Consistency in performing these exercises on both sides of the body is recommended, even if radial tunnel syndrome is only present in one arm.

The overall treatment goal is to eliminate symptoms and prevent their recurrence. If work-related activities contribute to symptoms, adjustments to the work environment or increased breaks may be necessary. Athletes should incorporate strength and flexibility exercises, along with proper warm-ups before engaging in sports activities.^2,3

Surgery is also a potential treatment for radial tunnel syndrome, but it is typically considered when rest and non-operative therapies prove ineffective.

The surgical objective is decompression, aiming to alleviate pressure on the radial nerve within the radial tunnel. The procedure involves making an incision just below the outer part of the elbow and extending into the forearm. By navigating through the muscle tissues within the radial tunnel, the surgeon identifies the precise location where the nerve is pinched or compressed.

Subsequently, the surgeon removes the compressing elements within the radial tunnel, expanding the tunnel in the process. Following the completion of the procedure, the incision is stitched closed.

This surgery is relatively uncommon, and it is often performed on an outpatient basis, meaning patients do not need to stay overnight in the hospital. Anesthesia options include general anesthesia (patient is asleep) or local anesthesia, where only the operated arm is numbed, allowing the patient to remain awake during the procedure.

It's important to note that surgery is typically considered a last resort, and non-operative approaches are generally explored first. The decision to undergo surgery is made in consultation with a healthcare professional based on the individual's specific circumstances and the response to conservative treatments.

After undergoing surgery for radial tunnel syndrome, the post-operative care and recovery process typically involve several stages:

Initial post-surgery period

You will be provided with an elbow splint to wear home, immobilizing your arm immediately after surgery.

Follow-up appointment (about a week-and-a-half after surgery)

• Return to your doctor's office for a follow-up appointment
• Removal of stitches
• Issuance of a removable splint

Initiation of range of motion activities (around two weeks post-surgery)

Introduction of activities to improve range of motion, including:

• Gentle exercise program
• Soft-tissue massages
• Stretching

Six weeks post-surgery

Commencement of strength-building exercises for the forearm and hand under the supervision of a therapist.

Activities may include squeezing silly putty.

Recovery phase guidelines

• During the initial recovery phase, avoid lifting and activities requiring elbow bending
• Therapist-guided exercises focus on stabilizing and strengthening the wrist, elbow, and shoulder
• Fine motor control improvement exercises for the hand

Recovery timeline factors

The overall recovery timeline varies based on individual factors, including:

• Specific medical history and condition
• Severity of radial nerve damage before surgery

Expected full recovery

Patients are generally expected to achieve full recovery within four to six months.

Some cases may require a longer recovery period.

It's crucial to follow the prescribed rehabilitation plan and adhere to the guidance provided by your healthcare team. The success of the surgery and the speed of recovery depend on various factors, and individual experiences may vary. Regular communication with your medical professionals and engagement in recommended activities contribute to a smoother recovery process.³

Summary

Radial tunnel syndrome is characterized by the pinching or compression of the radial nerve as it enters the radial tunnel. This compression results in undesired pressure on the radial nerve, leading to persistent and nagging pain.

Medical treatment is generally successful for radial tunnel syndrome, especially when patients meticulously adhere to instructions and take precautions to prevent future injuries to the radial nerve. Conservative approaches, such as rest, activity modification, and physical therapy, can effectively alleviate symptoms for many individuals.

For those who do not achieve the desired relief through medical treatment, surgery is a viable option that has demonstrated success in improving symptoms. However, it's important to note that, even after surgery, some patients may continue to experience mild pain.