Cubital tunnel syndrome, what is it?

By Cristiano Antonino Last updated Jun 18, 2023

Cubital tunnel syndrome is a condition that affects the ulnar nerve, and consists of its compression or traction. The sufferer experiences a pain in the elbow that can have a more or less severe intensity

Caused by the continuous repetition of certain movements or the assumption of incorrect postures, the syndrome is generally treated with conservative therapy but may require surgical decompression in more severe cases.

Recognising cubital tunnel syndrome early is crucial for prompt intervention, which can prevent symptoms from worsening and the disorder from becoming chronic.

Cubital tunnel syndrome: what is it?

Cubital tunnel syndrome is an entrapment neuropathy (or peripheral canalicular syndrome), i.e. an inflammation of a peripheral nerve at the point where it passes through an anatomical canal, between bones and ligaments or within a joint.

Entrapment neuropathies are diverse, and can affect different body segments, particularly the elbow, wrist, calf and foot.

Cubital tunnel syndrome affects the ulnar nerve in its course through the humeral-ulnar aponeurosis, or cubital tunnel, below the elbow.

The cubital tunnel is formed by the tendon arches of the two heads of the ulnar flexor muscle of the carpus.

The ulnar nerve is a sensory-motor nerve of the upper limb that extends between the brachial plexus and the hand, passing through the arm and forearm.

It contains nerve fibres from the C8 and T1 spinal roots, and controls some forearm muscles and part of the intrinsic hand musculature.

In addition, it is responsible for the sensory innervation of the fifth finger and the ulnar half of the fourth finger.

With both its motor and sensory functions, it is the largest unprotected nerve in the human body (a term, this, indicating non-envelopment by muscles or bony portions).

Problems with the ulnar nerve are not uncommon: it can be injured, compressed, and have both its sensory and motor function seriously altered.

Depending on where the injury occurs, particular symptoms occur.

The causes of cubital tunnel syndrome are

pressure: not being ‘protected’, direct pressure (such as resting the arm on an armrest) can compress the nerve causing the arm and hand, particularly the ring and little finger, to ‘fall asleep’;
traction: if one keeps the elbow bent for a long time, the nerve may be pulled behind the elbow (a condition that occurs mainly during sleep or during surgery involving prolonged adoption of abnormal postures);
the anatomy: it can happen that the ulnar nerve does not remain in the correct position and ‘snaps’ back and forth on a bony protuberance when the elbow moves (as if to make a ‘snap’). Other times, the soft tissue above it thickens, preventing it from functioning properly;
trauma;
arthrosis of the elbow;
an incorrect posture maintained for too long: this often happens to people who spend a lot of time on the phone or who sleep with their elbow under the pillow;
abnormal growth of the elbow;
intense physical activity, as in the case of baseball (the rotational movement required for throwing can damage the delicate ligaments of the elbow).

Middle-aged males are most affected by the syndrome, especially those who have suffered an elbow dislocation or fracture or if they suffer from tendonitis.

Cubital tunnel syndrome: what are the symptoms?

The typical symptoms of cubital tunnel syndrome consist of pain and numbness in the elbow and tingling in the ring and little finger.

Compared to other compression neuropathies, such as carpal tunnel, the motor symptomatology is more frequent and prominent.

Since many muscles in the hand are innervated by the ulnar nerve, there will be loss of dexterity and decreased grip and force.

In addition, there may be atrophy of the hypothenar eminence.

In more severe cases, there may be a deformity of the hand with flexion of the 4th and 5th fingers, due to weakness of the extensor muscles (“blessing hand” or “ulnar claw”).

Other motor symptoms may be

reduced ability to touch the thumb with the little finger
weakness in the ring and little finger
decreased hand grip

Sensory symptoms usually remain localised to the hand.

Cubital tunnel syndrome: diagnosis

Often the specialist is able to diagnose cubital tunnel syndrome by means of the objective test alone, by applying pressure to the ulnar nerve: the patient suffering from it feels a kind of jolt from the forearm to the little finger when the pressure is applied.

When the pathology reaches a more severe level, a ‘claw-like’ hand with the little finger and ring finger bent towards the palm can be seen (however, this symptomatology is also typical of Guyon’s canal syndrome).

Once the syndrome has been diagnosed, in order to be completely certain that the patient has the syndrome, the doctor may order electromyography, a test to assess how much the nerve roots and nerves are in pain and to detect whether nerve trunk lesions are present.

During the test, the speed of conduction of an electrical stimulus along the nerve is measured by means of a surface stimulator placed on the nerve and electrodes placed on the muscles.

By inserting a needle electrode into the muscle, first at rest and then during contraction, the spontaneous electrical activity, amplitude and duration of muscle electrical potentials are measured.

Cubital tunnel syndrome: treatment and cure

If cubital tunnel syndrome is in its initial manifestation, and electromyography reveals minimal pressure on the ulnar nerve, no specific treatment is usually prescribed.

To relieve the symptoms, it is sufficient to avoid putting pressure on the elbow during daily activities and to immobilise it with a brace at night.

More serious cases, which resist conservative therapy, require surgery: during the operation, the nerve is freed from external compression, but – if the patient suffers from a serious form of muscular atrophy – complete recovery of its function is ruled out.

Undergoing the operation, however, prevents the worsening of the compression, which could also lead to paralysis of the muscles connected to the ulnar nerve.

There are two ways in which the surgeon can intervene:

in situ decompression: the nerve is decompressed but left in place
decompression with anterior transposition, which can take place with subcutaneous, intramuscular and submuscular anteposition and is recommended in specific cases (e.g. ulnar nerve dislocation, skeletal traumas, etc.).

After the operation, a bandage and, if necessary, a brace is applied.

Immobilisation can last from 48 hours to up to three weeks, after which the patient – with appropriate exercises – works to gradually regain movement.