GGC - MSK Index
Cubital Tunnel Syndrome
Cubital Tunnel Syndrome is the second most common entrapment neuropathy after carpal tunnel syndrome. Symptoms are most commonly caused by compression of the nerve as it passes through the cubital tunnel near the skin surface. There are numerous aspects that need to be considered with regards to the compression of the ulnar nerve. The nerve experiences increasing levels of friction, traction and compression with increased ranges of elbow flexion (Chimenti and Hammert, 2013). Early signs of compression are pain at the elbow and tingling of the little and ring fingers. As the condition progress patients may present with weakness of the little and ring fingers, reduced ability to pinch thumb and little finger, reduced hand grip, muscle wasting of the hand and development of a claw-like deformity (Mallette et al, 2007).
The cause of symptoms can vary from compression by bone/loose body, soft tissue or overuse. Patients can often develop symptoms by persistently leaning on an elbow or by sustained flexion postures i.e. holding the telephone to the ear. According to Richardson et. al. (2001), and Contreras et. al. (1998) entrapment of the ulnar nerve at the elbow is a more common occurrence in men than in women due to anatomical variance in the coronoid tubercle (Yildirim et al, 2015)
The use of McGowan classification as a subjective measure of objective changes has been used in the past for studies into ulnar neuropathy (McGowan, 1950). The modified version of this scaling is included in the below table.
Grade 1 – Mild parasthesia or sensory loss , no weakness
Grade 2A – Moderate sensory loss, no intrinsic atrophy, mild weakness
2B - Moderate sensory loss, 3/5 intrinsic strength, moderate weakness
Grade 3 – Severe sensory loss or parasthesia, severe intrinsic atrophy and weakness
(Goldberg et al 1989)
Differential Diagnosis:
- Other sites of ulnar nerve lesion - e.g., Guyon's canal at the wrist. Causes of ulnar nerve lesions at the wrist include compression by tumour or ganglion, blunt trauma, fractures.
- Acute pressure-related nerve palsy after lying or leaning on the elbow.
- Other causes of neurological dysfunction along the C8-T1 distribution - e.g., cervical spondylosis with cervical radiculopathy, brachial plexus damage, thoracic outlet syndrome, syringomyelia, Pancoast's tumour (apical lung cancer) and motor neurone disease.
- Carpal tunnel syndrome.
- Polyneuropathy - e.g., diabetes, renal disease, multiple myeloma, amyloidosis, chronic alcoholism, malnutrition, leprosy
Radial Nerve Syndrome
Also known as deep radial nerve syndrome or supinator syndrome. The main cause of radial nerve neuropathies is due to traumatic injury rather than entrapment. The radial nerve is most commonly affected by midshaft and distal third humeral shaft fractures due to its close proximity to the bone. Lesions at the elbow mainly affect the muscle groups supplied by the Posterior Interosseous Nerve (PIN) (Wang, 2013). It is the most commonly injured nerve associated with long-bone fractures, with a reported incidence up to 34% (Tyser, 2012). PIN supplies motor function to Supinator, extensor carpi radialis brevis, extensor carpi ulnaris and the finger extensors. Radial nerve syndrome however does not often manifest as loss of motor control but as chronic pain. Pain is often worsened by supination or finger and wrist extension, and the patient complains of pain on palpation of the area distal to the lateral epicondyle (Wang, 2013).
Differential Diagnosis:
- Lateral Epicondylitis
- Other sites of Radial nerve lesions: Axilla, humeral shaft/arm and superficial branch.
- Other lesions along the motor pathway of the extensors compartment of the forearm. (posterior cord, brachial plexus, cervical roots, and the cerebral cortex).
- Polyneuropathy - e.g., diabetes, renal disease, multiple myeloma, amyloidosis, chronic alcoholism, malnutrition, leprosy.
Anterior Interosseous Nerve Syndrome
Also known as ‘Kiloh-Nevin Syndrome’, Anterior Interosseous Nerve Syndrome is caused by compression of the nerve in the proximal part of the forearm. Patients often present with a dull pain in the palmar aspect of the forearm combined with an acute onset of muscle weakness affecting the thumb, index and occasionally middle finger (radial 2 (FDP), flexor pollicis longus (FPL), pronator quadratus) (Salama and Stanley, 2008).
Numbness is not a symptom as the anterior interosseous nerve does not innervate the skin.
Differential Diagnosis:
- Other nerve lesion – e.g. high median nerve lesion will also have a positive test outcome (see below) however there will be sensory loss.
- Other causes of neurological dysfunction along the C8-T1 distribution - e.g., cervical spondylosis with cervical radiculopathy, brachial plexus damage, thoracic outlet syndrome, syringomyelia, Pancoast's tumour (apical lung cancer) and motor neurone disease.
- Polyneuropathy – e.g. diabetes, renal disease, multiple myeloma, amyloidosis, chronic alcoholism, malnutrition, leprosy
- Parsonage Turner Syndrome is bilateral AIN palsy which is caused by viral brachial neuritis and motor loss is preceded by severe intense pain around the shoulder area (Salama and Stanley, 2008).