Entrapment of ulnar nerve at the elbow

Entrapment of the ulnar nerve within the cubital tunnel and subsequent inflammation may present with medial elbow pain, hand weakness (positive Froment's and Wartenberg's signs and dysaesthesiae or pins and needles radiating down the medial forearm)

Examination may reveal a positive Tinel's test (medial elbow pain and 4th and 5th digit pins and needles upon tapping the cubital tunnel over the medial aspect of the elbow ('funny bone'))

In isolated cubital tunnel syndrome, the elbow joint should have a normal ROM; however this condition can also be seen in rheumatoid arthritis or osteoarthritis of the elbow joint where the joint itself may also be affected.

Investigation

• diagnosis of cubital tunnel syndrome can be made clinically but should be confirmed with a nerve conduction study
• a plain x-ray will show if there is bony impingement of the cubital tunnel
• ultrasound may show swelling of the ulnar nerve and is useful in confirming the position of the ulnar nerve before surgery

Management

• patients with mild sensory symptoms may benefit from ergonomic advice and physiotherapy
• ultrasound-guided injections of hydrocortisone may offer temporary relief
• patients presenting with weakness (positive Froment's and Wartenberg's) should be referred for surgical decompression

Froment's sign - click here for video of testing Froment's sign

Wartenberg's sign - click here for video of testing of Wartenberg's sign

Reference:

1. Arthritis Research UK (2011). Hands On (11) - upper limb in primary care