Upper Limb Peripheral Mononeuropathy
February 15th, 2021
Overview
Peripheral mononeuropathy is a type of peripheral neuropathy affecting a single peripheral nerve.
Causes of Peripheral Mononeuropathy
- Compression (particularly carpal tunnel and ulnar tunnel) - prolonged pressure, hereditary neuropathy with liability to pressure palsies (HNPP)
- Trauma - blunt trauma, penetrating injury (e.g. knife, gunshot, glass)
- Nerve ischaemia - trauma, thromboembolism, diabetes, atherosclerosis, excessive tourniquet use
- Radiation injury
Peripheral Nerves of the Upper Limb
-
Nerve Sensory Motor Radial Snuff box
Anterior forearm + AC fossa (proximal lesion)Wrist drop
Wrist extension
Finger extension
Elbow extension (proximal lesion)Median Palmar aspect of thumb, 2nd & 3rd fingers
Thenar eminence (proximal lesion)Hand of benediction
Thumb abduction
Wrist flexion & pronation (proximal lesion)Ulnar 5th finger + medial 4th finger
Ulnar aspect of forearm (proximal lesion)Claw hand
Finger abduction
Ulnar deviation (proximal lesion)Musculocutaneous Lateral forearm Elbow flexion Axillary Lateral upper arm Shoulder abduction, flexion & extension Long Thoracic Nil Scapular winging
Shoulder elevationSuprascapular Nil Shoulder abduction & external rotation Spinal Accessory Superior shoulder Shoulder elevation & abduction
Radial Nerve Palsy
Signs of Radial Nerve Palsy
Sensory
- Sensory loss over the snuff box
- Anterior forearm & AC fossa (proximal lesion)
Motor
- Wrist drop - inability to extend the wrist
- Weakness of wrist extension and finger extension
- Weakness of elbow extension (proximal lesion)
Radial Nerve Syndromes
- Radial neuropathy at the spiral groove
- Posterior interosseous syndrome - palsy affecting the posterior interosseous nerve, a branch of the radial nerve
- Crutch palsy - prolonged crutch use resulting in compression of the radial nerve in the axilla
- Saturday night palsy - compression of the radial nerve during sleep, usually while intoxicated
- Handcuff neuropathy - radial neuropathy at the wrist
Median Nerve Palsy
Signs of Median Nerve Palsy
Sensory
- Sensory loss over the palmar aspect of the thumb, 2nd and 3rd fingers
- Sensory loss over the thenar eminence (proximal lesion)
- Tinel's sign - percuss over the flexor retinaculum and ask about symptoms
- Phalen's sign - reverse prayer position and ask about symptoms
Motor
- Weakness of thumb abduction
- Hand of benediction (proximal lesion) - inability to flex the index and middle fingers
- Thenar eminence wasting (proximal lesion)
- Weakness of wrist pronation and flexion (proximal lesion)
- Inability to maintain an O between the thumb and index finger (proximal lesion)
Median Nerve Syndromes
- Carpal tunnel syndrome - compression of the median nerve beneath the flexor retinaculum at the wrist
- Pronator teres syndrome - entrapment of the median nerve by the pronator teres
- Anterior interosseous syndrome - palsy affecting the anterior interosseous nerve, a branch of the median nerve
Causes of Carpal Tunnel Syndrome
- Idiopathic
- Trauma - Colle's fracture
- Endocrine - hypothyroidism, acromegaly, diabetes
- Rheumatoid arthritis
- Amyloidosis
- Gout
- Pregnancy
Ulnar Nerve Palsy
Signs of Ulnar Nerve Palsy
Sensory
- Sensory loss over the palmar and dorsal aspect of the 5th finger and medial half of the ring finger
- Sensory loss of the ulnar aspect of the forearm (proximal lesion)
Motor
- Claw hand - extension of the MCP joints and flexion of the IP joints of the ring and little fingers
- Wasting of the small muscles of the hand (sparing the thenar eminance)
- Weakness of finger abduction
- Weakness of ulnar deviation of the wrist (proximal lesion)
Ulnar Nerve Syndromes
- Cubital tunnel syndrome - trauma or compression of the ulnar nerve within the cubital tunnel at the elbow
- Guyon's canal palsy (cyclist's palsy) - compression of the ulner nerve at the wrist
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