Contribution of ultrasonography in evaluating traumatic lesions of the peripheral nerves

To assess the indications for and utility of diagnostic ultrasonography (US) in a series of consecutive patients with suspected traumatic peripheral nerve lesions (TPNL).

We retrospectively reviewed the electronic medical records of consecutive patients referred from February 2013 to May 2018 to our US laboratory. All included patients were examined using standard US equipment, with a 4-13MHz linear array transducer.

In the analyzed period, we performed US examinations in 143 patients with 149 suspected TPNL. Electrodiagnostically (EDx) complete TPNL were found in 63 (45%), partial in 59 (42%), and only demyelination (i.e., neurapraxia) in four (3%) patients. TPNL could not be confirmed in 14 (10%) patients. Nerve discontinuity was not demonstrated by US in any of the patients with EDx incomplete nerve lesions. Contact of the nerve with osteosynthetic material (OSM) was found in eight of 33 patients (24%). In five patients, the nerve could not be adequately evaluated throughout its course due to extensive changes in the surrounding tissues.

In acute situations, US is most useful in EDx complete TPNL to differentiate between nerve axonotmesis and neurotmesis. High-velocity trauma, lacerations, and bone fractures are all risk factors for neurotmesis. In chronic situations, US is useful in cases of functionally inefficient reinnervation, neuropathic pain, or progressive nerve dysfunction. In such patients, the surrounding tissues and the relation of the nerve to any OSM need to be carefully examined. US examination is probably not needed in patients with TPNL following acute blunt trauma, only minor clinical deficits and/or slightly/moderately abnormal EDx findings.