From the Guidelines
Ulnar nerve palsy presents with a characteristic set of clinical features primarily affecting the hand and forearm, including weakness, sensory deficits, and characteristic deformities such as "claw hand". The clinical features of ulnar nerve palsy can be understood through the evaluation methods used to assess ulnar nerve neuropathy, as discussed in the study on acr appropriateness criteria for chronic elbow pain 1. Patients typically experience weakness in the intrinsic hand muscles, particularly the hypothenar muscles, interossei, and medial two lumbricals.
Key Clinical Features
- Sensory deficits include numbness and paresthesia along the medial aspect of the hand, affecting the little finger and medial half of the ring finger
- Difficulty with fine motor tasks, weakness in grip strength, and clumsiness when manipulating small objects
- Positive Froment's sign, where the patient compensates for weakness in the adductor pollicis by flexing the thumb interphalangeal joint when pinching
- Wartenberg's sign (abduction of the little finger due to unopposed action of the extensor digiti minimi) and Duchenne's sign (inability to adduct the thumb) may also be present
- Muscle atrophy of the hypothenar eminence and interosseous muscles can develop in chronic cases, creating visible hollowing between the metacarpals The severity of symptoms depends on the location of nerve compression, with high ulnar nerve lesions (above the elbow) additionally affecting flexor carpi ulnaris and flexor digitorum profundus to the ring and little fingers. Evaluation methods such as US elbow, as mentioned in the study 1, can help assess ulnar nerve neuropathy and guide diagnosis.
From the Research
Clinical Features of Ulnar Nerve Palsy
The clinical features of ulnar nerve palsy include:
- Loss of sensation and profound weakness, leading to a dysfunctional hand 2
- 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
- Deficits in hand/wrist function, including loss of ring- and small-finger distal interphalangeal flexion, decreased wrist flexion, and loss of dorsal sensory innervation in high-level ulnar nerve palsy 2
- Impaired grip and pinch strength, as well as recognized deformities due to dysfunction of the intrinsics 3
- Sensory loss, digital clawing, thumb deformity, abduction of the small finger, and asynchronous finger motion in low ulnar nerve palsy 3
- Paralysis of the ulnar profundi and the flexor carpi ulnaris in high ulnar nerve palsy 3
- Neuropathic pain, numbness, tingling, and possible motor deficits in the ulnar distribution of the arm 4
Motor and Sensory Deficits
Ulnar nerve palsy can result in significant motor and sensory deficits, including:
- Loss of muscle function and balance in the hand 5
- Impaired hand function, including grip and pinch strength 3
- Sensory loss and numbness in the ulnar distribution of the arm 4
- Motor deficits, including paralysis of the ulnar profundi and the flexor carpi ulnaris 3
Treatment and Management
Treatment and management of ulnar nerve palsy may involve: