Mononeuropathies of the radial nerve: clinical and neurographic findings in 91 consecutive cases.

Retrospective features of 91 consecutive cases (68 men, 23 women; mean age 44.4 years) of radial mononeuropathy diagnosed over the last 8 years in two electromyography (EMG) services are reported to define the clinical and electrophysiological findings of radial neuropathies in relation to traumatic and non-traumatic causes and site of injury. The occurrence of radial neuropathy was 0.65 x 100 first electromyographic examinations. The most frequent site of damage was the main trunk at the spiral groove of the humerus (36%); the most frequent cause was nerve trauma (70%) due to fracture (36%). In neuropathies of the main trunk and posterior interosseous (PI) nerve, "complete nerve injury" was observed in 36% of cases, conduction motor block in 33% and motor conduction velocity slowing in 46%. At least one of these findings was present in 51%, whereas motor neurography was normal in 13% of cases. Sensory action potential (SAP) anomalies were observed in 51% of cases. In neuropathy of the superficial radial nerve, no SAP was detected in 30% of cases; in all others except one, SAP was reduced in amplitude. Non-traumatic neuropathies showed severer conduction block and less severe anomalies of SAP than traumatic neuropathies. No differences were found between men and women. EMG is essential for confirming the site of injury and neurographic study may be helpful for diagnosis, providing information about lesion type and severity.