Cubital tunnel syndrome

Introduction

• Neuropathy of the ulnar nerve can cause symptoms such as tingling, numbness, and shooting pain along the medial aspect of the forearm.
• Symptoms often extend to the medial half of the fourth digit and the fifth digit.
• Commonly caused by compression or irritation of the nerve at the elbow.

Ulnar Nerve Anatomy

• C8 and T1 nerve roots join to form the medial cord of the brachial plexus.
• Ulnar nerve originates from the medial cord.
• Travels down the arm with the brachial artery towards the elbow joint.
• Enters the posterior compartment via the arcade of Struthers.
• Traverses the medial aspect of the triceps to enter the cubital tunnel.
• Passes between the olecranon and the medial epicondyle beneath the Osborne ligament.
• Exits the cubital tunnel and passes under the aponeurotic head of flexor carpi ulnaris to enter the forearm.
• Common compression points include the cubital tunnel, arcade of Struthers, and the aponeurotic head of flexor carpi ulnaris.
• Innervates the medial side of the forearm, ulnar side of the palm, little finger, and medial half of the ring finger.
• Supplies motor branches to flexor carpi ulnaris, flexor profundus of the little and ring fingers, hypothenar muscles, adductor pollicis, interossei, and third and fourth lumbricals.
• No motor or sensory branches above the elbow.

Etiology

• Compression at the cubital tunnel causing tingling along the medial forearm, little finger, and medial ring finger.
• Common causes include:
  • Pressure on the superficial ulnar nerve at the medial epicondyle.
  • Stretching of the nerve due to repetitive elbow flexion.
  • Anatomical changes or injuries to the elbow joint.
  • Direct pressure from sitting or occupational activities.

Epidemiology

• Second most common compression neuropathy of the arm after carpal tunnel syndrome.
• 60% of patients have anatomical changes in the cubital tunnel.
• Common causes include subluxation, osteophytes, luxation, and post-traumatic lesions.

Pathophysiology

• Exact mechanism unknown; some association with smoking.
• More common in males and more frequently affects the left side.

History and Physical

Presenting Complaint:

• Common Symptoms: Patients typically present with “pins and needles” or tingling in the forearm and hand.
• Affected Areas: The tingling sensation is often localized to the little finger and the medial half of the ring finger.
• Aggravating Factors: Symptoms are generally aggravated by elbow flexion, as this position increases tension on the ulnar nerve.
• Symptom Progression: Initially, symptoms may be transient but tend to worsen over time if the compression persists.

Physical Examination Findings:

• Sensory Loss:
  • In advanced cases, there may be a reduced or complete loss of sensation on both the palmar and dorsal sides of the little finger and the medial part of the ring finger.
• Tinel’s Sign:
  • Positive Tinel’s sign may be elicited along the cubital tunnel. This involves tapping over the ulnar nerve at the elbow, which can reproduce the tingling sensation.

• Provocative Tests:
  • Sustained elbow flexion for one minute can provoke symptoms, causing paresthesia along the ulnar nerve distribution.
  • Compression of the ulnar nerve at the cubital tunnel region can also elicit similar symptoms.
  • While these tests may be positive, their diagnostic value is limited due to poor specificity and sensitivity.
• Nerve Subluxation:
  • In some cases, the ulnar nerve may subluxate over the medial epicondyle with elbow flexion, which can be palpated during the examination.

Motor Symptoms:

• Common Complaints:
  • Motor symptoms are less common but may appear in severe cases.
  • Patients may report hand weakness and frequent dropping of objects.
• Examination Findings:
  • Mild weakness of the interosseous muscles may be noted.
  • Severe cases can show atrophy of the intrinsic hand muscles and significant weakness of the handgrip.
  • Froment’s Sign: This test can be positive, indicating weakness of the adductor pollicis muscle (supplied by the ulnar nerve). Froment’s sign is elicited by having the patient grasp a piece of paper between the thumb and index finger; compensatory flexion at the thumb’s interphalangeal joint indicates weakness of the adductor pollicis.
  • Ulnar Claw Hand: This deformity is unlikely in cubital tunnel syndrome because the flexor digitorum profundus to the ring and little fingers is also denervated, preventing the typical claw-like posture of the hand.

Evaluation

• Diagnosis primarily clinical, supported by nerve conduction studies.
• X-rays to exclude bony pathologies.
• MRI and ultrasound have high sensitivity and specificity, useful for identifying soft tissue causes of compression.

Treatment / Management

• Non-surgical Treatment:
  • Correcting provoking postures.
  • Night splinting to keep elbows straight.
  • NSAIDs for pain relief.
  • Evidence supports improvement in mild cases with conservative management.
• Surgical Treatment:
  • Indicated for severe cases or failure of conservative treatment after 6 months.
  • Procedures include in-situ decompression, endoscopic decompression, various transpositions, and medial epicondylectomy.

Differential Diagnosis

• Lesions in the Guyon canal, cervical spondylosis, brachial plexus injuries, thoracic outlet syndrome, syringomyelia, Pancoast tumors, motor neuron disease, carpal tunnel syndrome, and polyneuropathy.

Prognosis

• About 50% improve with conservative management.

Complications

• Symptoms may recur after surgery.
• Slow and incomplete recovery.
• Possible injury to the medial antebrachial cutaneous nerve.

Postoperative and Rehabilitation Care

• Full range of motion generally allowed post-surgery.
• Physical therapy usually not required unless significant muscle weakness.

Deterrence and Patient Education

• Educate patients on the etiology and slow symptom improvement of conservative management.
• Educate on the use of NSAIDs and the importance of gastric protection.

Pearls and Other Issues

• Consider differential diagnosis in patients with ulnar neuropathy.
• Thorough knowledge of motor and sensory distribution of the ulnar nerve is crucial for evaluation and identifying the pathology site.