From the Guidelines
Ulnar nerve palsy is a condition where the ulnar nerve becomes damaged or compressed, resulting in weakness, numbness, and tingling in the hand and fingers, and the most accurate diagnosis can be made using T2-weighted MR neurography or US elbow assessment. The ulnar nerve runs from the neck down the arm to the hand, and its compression typically affects the pinky finger, ring finger, and the side of the hand where these fingers are located. The most common sites of compression are at the elbow (cubital tunnel) and at the wrist (Guyon's canal) 1. Symptoms of ulnar nerve palsy include:
- Weakness in grip strength
- Difficulty with fine motor tasks
- Clumsiness when handling objects
- A characteristic "claw hand" deformity in severe cases where the pinky and ring fingers curl inward. Treatment depends on severity and may include rest, splinting, anti-inflammatory medications, physical therapy, and nerve gliding exercises, and in more severe cases, surgical decompression may be necessary to relieve pressure on the nerve 1. Early diagnosis and treatment are important as prolonged compression can lead to permanent nerve damage, and the use of diffusion-tensor imaging can increase diagnostic confidence 1. The condition occurs because the ulnar nerve has limited protective tissue covering in certain areas, making it vulnerable to compression, especially during activities that involve prolonged elbow flexion or direct pressure on the nerve. Some of the key findings in ulnar nerve palsy include high signal intensity and nerve enlargement on MRI, and hourglass constriction of the nerve on US elbow assessment 1.
From the Research
Definition and Characteristics of Ulnar Nerve Palsy
- Ulnar nerve palsy is a condition that results in significant loss of sensation and profound weakness, leading to a dysfunctional hand 2.
- Typical clinical findings include loss of key pinch, clawing, loss of normal flexion sequence of the digits, loss of the metacarpal arch, and abduction of the small finger 2.
- High-level ulnar nerve palsy can lead to further deficits in hand/wrist function, including loss of ring- and small-finger distal interphalangeal flexion, decreased wrist flexion, and loss of dorsal sensory innervation 2.
Causes and Types of Ulnar Nerve Palsy
- Ulnar nerve palsy can be caused by various factors, including trauma, nonunion of the lateral epicondyle, and chronic conditions such as tardy ulnar nerve palsy 3.
- Low ulnar nerve palsy preserves ulnar innervated extrinsics, resulting in sensory loss, digital clawing, thumb deformity, abduction of the small finger, and asynchronous finger motion 4.
- High ulnar nerve palsy is characterized by the above symptoms plus paralysis of the ulnar profundi and the flexor carpi ulnaris 4.
Symptoms and Diagnosis
- Symptoms of ulnar nerve palsy include weakness of grasp and pinch, poorly coordinated flexion, and clawing of digits 5.
- Diagnosis of ulnar nerve palsy can be made through clinical examination and radiological findings, such as nonunion of the lateral condyle 3.
- Ulnar neuropathy at the elbow (UNE) is a common entrapment neuropathy that can occur due to mechanical forces that produce traction or ischemia to the nerve 6.
Treatment Options
- Treatment options for ulnar nerve palsy include surgical intervention, such as ulnar nerve transposition, and conservative management 3, 6.
- Tendon transfer procedures can be used to restore grasp and improve flexion at the metacarpophalangeal joint 5.
- Preoperative patient education is paramount to success if realistic expectations are to be met 5.