Ulnar Nerve Injury - Cause, Clinical Manifestations, and Treatment

What Is Ulnar Nerve?

The ulnar nerve runs from the shoulder to the little finger of the hands. It is also known as the musician's nerve, as it supplies the intrinsic muscles (small muscles located within the hand) of the hand, which are responsible for fine movements. It is named ulnar as it runs along the medial side of the upper limb. It is the largest branch of the medial cord of the brachial plexus (the nerve network in the shoulder which relays sensory and motor signals from the spinal cord to the hands and arms).

What Is Ulnar Nerve Injury?

Nerves are protected by muscle or bones throughout their course; however, the ulnar nerve is not protected the same way and runs near and below the skin surface, making it susceptible to injuries and compression. Damage or compression to the ulnar nerve causes ulnar nerve injury resulting in pain near the elbow. It also causes tingling, numbness, and weakness in the forearm and the hand. In addition, damage to the ulnar nerve hampers fine hand movements and makes it difficult to perform many daily activities. The ulnar nerve is responsible for the movement of the fourth and fifth fingers of the hand; thus, the symptoms appear on the fourth and fifth fingers.

What Are the Common Sites of Ulnar Nerve Injury?

There are two major sites where the ulnar nerve is damaged.

• At the Elbow - The ulnar nerve lies behind the medial epicondyle. Injuries at the elbow cause medial epicondyle fractures, resulting in ulnar nerve damage.

• At the Wrist - The ulnar nerve lies in front of the flexor retinaculum (fibrous connective tissue band that covers the carpal bones at the palmar side of the hand at the wrist region). The position of the ulnar nerve at the wrist makes it vulnerable to damage caused by cuts and stabs at the wrist region.

What Are the Causes of Ulnar Nerve Injury?

Ulnar nerve injury can occur due to our daily activities; thus, anybody can suffer from ulnar nerve injury.

• Nerve injury due to daily activities:

  • Playing sports that involve continuous swinging and bending at the elbow and wrist joints, like golf and tennis.

  • Long-distance driving or sitting with the elbow rested on the car window.

  • Working in the office with elbows resting on the table for long hours.

  • Trauma to the elbow caused by an object or surface.

• Injuries due to underlying disease conditions include diabetes, ganglion cysts (non-cancerous lumps often present on the tendons and joints of the hands and wrist), arthritis, and bony spurs (bony projections that are present at the joints and the spinal cord).

What Are the Signs and Symptoms of Ulnar Nerve Injury?

• Ulnar Nerve Injuries at the Elbow - It results in cubital tunnel syndrome. Symptoms appear late unless trauma is the cause of nerve injury. Pain is the main symptom only in acute cases of nerve injury. The patient experiences numbness and paresthesia that involves the ulnar aspect of the fourth and fifth fingers. Ulnar nerve injury at the elbow is associated with elbow flexion (the forearm moves towards the body by bending at the elbow). Gradually the symptoms progress to permanent numbness and paraesthesia (abnormal sensations like prickling or tingling due to peripheral nerve damage). Muscle weakness results in decreased hand movements and handgrip and pinch strength. In severe cases, clawing of the fourth and fifth fingers of the hand is present, known as claw hands.

• Ulnar Nerve Injury at the Wrist - It results in ulnar tunnel syndrome. Small muscles of the hand are paralyzed and show shrinkage. Claw hands are a prominent feature in ulnar nerve injury at the wrist due to the bending of the terminal phalanges (the last finger of the hand).

What Is the Diagnosis of Ulnar Nerve Injury?

The doctor examines the patient's arm, wrist, and hand to test for motor and sensory functions. Sometimes the doctors also advise additional tests like electromyography (measures the electrical response of the muscles to nerve stimulation) and nerve conduction tests (measures how fast electrical signals travel down the nerve).

What Is the Treatment of Ulnar Nerve Injury?

It is essential to treat ulnar nerve injury so that the lesion heals appropriately and does not hinder daily activities upon recovery.

• Conservative Treatment - It is done to treat patients with mild to moderate symptoms. It aims at reducing the frequency of compression on the ulnar nerve and reducing the bending of the elbow joint.

  • Medication - Pain medication helps reduce the pain and inflammation caused due to ulnar nerve compression.

  • Elbow Splints, Pads, and Sleeves - Wearing a protective covering or splinting the arm prevents further injury to the nerve while the arm is healing. In addition, an elbow pad is placed beneath the elbow in cases where the patient cannot avoid leaning on the elbow.

  • Physiotherapy - Exercise strengthen the hands, forearm, and elbow. These exercises are performed under the guidance of physiotherapists before the patient can start doing them on their own.

• Injection Procedure - Corticosteroid injections are injected for ulnar neuropathy at the elbow; however, data from studies are needed to support this treatment.

• Surgery - Surgical approach is recommended for patients with lasting symptoms and sensory changes accompanied by muscle atrophy. The type of surgery that needs to be performed depends on the location of the injury.

  • Anterior Transposition Technique - This surgery is indicated when the ulnar nerve is compressed or has moved on its own. The surgeon moves the ulnar nerve in front of the medial epicondyle. The pain and numbness decrease after the surgery; however, the patient must wear the braces for many days to stabilize and allow proper healing.

  • Medial Epicondylectomy - Medial epicondyle (bony bump positioned inside the elbow) is removed, enabling the ulnar nerve to move smoothly whenever the elbow is straightened and flexed.

  • Decompression - In this surgical procedure area around the elbow through which the ulnar nerve passes is appropriately explored to remove any substance that causes compression and dysfunction of the ulnar nerve.

Conclusion:

Ulnar nerve injury is a common occurrence, and most of the cases are treated without surgery. It is not permanent, but repeated injury and avoidance can lead to permanent damage. The neurologist and the hand surgeon must confirm the diagnosis and obtain a treatment plan. Ulnar nerve injury impacts the functioning of the hands and fingers. Thus, early intervention is needed to prevent further damage and improve the patient's lifestyle.