Ulnar nerve entrapment is a common problem that may cause functional impairment of the upper limb.
Anatomy of the ulnar nerve;
- Derives from C8 and T1, with variable contribution from C7
- It runs through the medial bicipital sulcus, the medial epicondylar groove at the elbow, and enters the hand through the Guyon’s canal.
- Sensory innervation to the dorsal and palmar aspects of the medial one and half digits
- Motor innervation to intrinsic muscles of the hand
The most common site of entrapment is the elbow( cubital tunnel syndrome), followed by the wrist( Guyon canal syndrome)
Etiology
1. Cubital tunnel syndrome-
- Blunt trauma
- Leaning on the elbow or prolonged elbow flexion
- Tumors, hematomas
- Metabolic abnormalities, e.g., diabetes mellitus
- Arthritis of the elbow
- Synovitis
2. Guyon canal syndrome
- Bone fractures
- Lacerations
- Direct often repetitive trauma
- Ganglia arising from the wrist
- Intraneural ganglia
*most cases are idiopathic
Clinical presentation
Elbow;
- Numbness and tingling in the fourth and fifth digits
- Positive tinnel test
- Medial elbow pain, with referred pain in the forearm
- Nocturnal numbness and paraesthesia
- Worsening of symptoms with repeated elbow and/ or wrist flexion
Wrist;
- Hand weakness and atrophy
- Claw hand deformity
- Variable sensory involvement
- Loss of dexterity
- Wartenberg sign
- Froment sign
- Jeanne sign
Diagnosis
- Nerve conduction studies and electromyography- identify the level of compression
- Ultrasound and MRI- to detect possible masses such as tumors
- Xray- to rule out other possible causes of entrapment
Management
- Conservative management;
-Suggested for initial management
- Analgesia
- Modification of activities;
- Avoid leaning on the elbow
- Use of a soft elbow pad
- Padded gloves
- Bracing at night
- Surgery;
Indications
- Moderate to severe ulnar neuropathy at the elbow caused by trauma, nerve compression, or structural abnormality
- Ulnar neuropathy of fewer than six months duration with moderate to severe continued or progressive symptoms despite conservative measures
Surgical approaches;
- Decompression
- Transposition
Differential diagnosis
- Motor neurons disease
- Syringomyelia
- Small subcortical infarctions
