What are the clinical manifestations of radial nerve palsy?

Radiculopathy or peripheral nerve injury affecting the radial nerve—often referred to clinically as radial nerve palsy—typically presents with a characteristic constellation of motor and sensory deficits. The radial nerve originates from the posterior cord of the brachial plexus (C5–T1) and innervates the triceps brachii, anconeus, brachioradialis, extensor carpi radialis longus and brevis, supinator, and all extensor muscles of the fingers and thumb. Consequently, patients commonly exhibit wrist drop (inability to extend the wrist against gravity), finger drop (inability to actively extend the metacarpophalangeal joints), and impaired thumb extension and abduction—particularly at the interphalangeal joint. Sensory loss typically involves the dorsal aspect of the lateral three-and-a-half fingers (thumb, index, middle, and radial half of the ring finger), extending proximally to the dorsum of the hand, though sparing the dorsal web space between the thumb and index finger in some cases due to overlapping innervation from the median nerve.

Clinically, radial nerve palsy may result from acute trauma (e.g., humeral shaft fracture, improper crutch use, or prolonged arm compression—“Saturday night palsy”), iatrogenic injury during surgery, or compressive neuropathies such as those associated with radial tunnel syndrome. Diagnosis relies on detailed history, physical examination—including assessment of muscle strength (graded using the Medical Research Council scale), tendon reflexes (triceps reflex may be diminished), and sensory mapping—and is often confirmed with electrodiagnostic studies (nerve conduction studies and electromyography). Early recognition is critical, as timely intervention—including splinting to maintain functional wrist and finger positioning, physical therapy to prevent contractures, and, when indicated, surgical exploration for traumatic or compressive etiologies—can significantly influence functional recovery.