Objective:

The aim of this study was to describe unique morphological changes on neuromuscular ultrasound in nerves distal to gunshot injuries and to identify the frequency with which these changes occur.

Background:

A spectrum of peripheral nerve injuries is seen secondary to gunshot wounds. The assessment of these injuries has traditionally been limited to clinical evaluation and supplemented by electrodiagnostic testing. Neuromuscular ultrasound is a versatile imaging technique that has been used to assess peripheral nerve structural integrity, neuroma formation or other structural abnormalities following trauma. The extent of sonographic changes at nerve segments distal to gunshot injuries has not been well described.

Design/Methods:

A retrospective chart review was performed on all patients referred to the electromyography laboratory with peripheral nerve injuries from gunshot wounds who also had neuromuscular ultrasound performed as part of their evaluation. 

Results:

17 patients were evaluated. All had either a nerve transection or neuroma in continuity of a major upper or lower extremity nerve at the site of the gunshot wound. 13 (76%), however, also had significant morphological changes in distal segments of the injured nerve and 12 (71%) had changes in other nearby distal nerves. Common findings included enlarged nerve cross sectional area, enlarged fascicles and hypoechogenicity. One patient had a repeat study nine months following the initial study which demonstrated improvement in sciatic nerve cross sectional area, decreasing from 130 mm² to 79 mm².

Conclusions:

Following gunshot injuries, major morphological changes commonly occur in nerve segments distal to the injury; both in the injured nerve and nearby nerves. Marked enlargement of hypoechoic fascicles is seen along with enlarged cross-sectional area of nerve. We hypothesize that ballistic trauma, such as gunshot injuries, can lead to concussive damage that disrupts the normal architecture of distal nerves. Follow up ultrasound studies suggest that these changes may be partially reversible.