Peripheral nerve injuries are pretty ordinary events after accidental or iatrogenic trauma, and depending
on their severity can lead to a variable grade of motor and sensory defi cit and neuropathic pain. Until now, the
electrophysiological study and electromyography were the method of evaluation. Currently, neuromuscular
ultrasound is used as a complementary technique to help us in the diagnostic and staging process and favor
the treatment of the affected nerves. We present a practical algorithm on ultrasound-guided interventions for
managing this pathology.

dextrose water, growth factors, hyaluronic acid, nerve injury, regenerative interventions

To the Editor,

Accidental or iatrogenic trauma may cause peripheral nerve injuries, most of which occur in the upper limb. Men are twice as affected as women, with an overall incidence of 11.2 per 100,000 population per year. Depending on their severity, nerve injuries can lead to variable degrees of motor and sensory defi cits and neuropathic pain up to complete paralysis, anesthesia, and severe intractable neuropathic pain. Current interventions are purely surgical, including neurosynthesis and graft procedures. However, outcomes remain poor [1-3].

Nerve conduction studies and electromyography can reveal the type of nerve injury and severity and delineate the prognosis, but they can't distinguish complete axonotmesis from neurotmesis, while neuromuscular ultrasound (NMUS) can differentiate them. Accordingly, NMUS should be used as a complimentary for the electrophysiologic evaluation. Also, ultrasound can assess the degree of muscle denervation compared to the non-injured side after surgical repair, Table1 provides summary of pathology, electrophysiology, and ultrasound findings of different types of peripheral nerve injuries [4-7].

Additionally, ultrasonography can help regenerative interventions avoiding the collateral damage of neurovascular structures and help with accurate placement of the injectate [8,9].

Reinnervation does not mean functional recovery, and muscles distal to injury atrophies within three weeks from the injury with gradual fibrosis. Irreversible complete muscle fibrosis (end organ failure) occurs two years from the onset of the damage, leading to permanent loss of function [10-12].

Based on expert opinion, the authors have developed an algorithm designed to expedite sensory recovery, achieve full motor power recovery, and enhance muscle echogenicity to normal levels with improved thickness as measured by ultrasound. However, the echogenicity of the nerve remains unchanged [13-15].

The optimal timing for starting regenerative interventions is not well-studied in the available literature, but current data suggest starting 14 days after the injury [16].

When it comes to the intervals of injections, there is no consensus in the literature about the timing for regenerative injections. Some sources suggest weekly injections, while others recommend bi-weekly intervals. Additionally, some literature states that injections should be administered monthly, or at intervals of one and a half to two months [17-19].

The authors suggest that injections of 5%, 10%, or 15% glucose/dextrose water should be administered every two weeks. Other injectables should be given at intervals of either four or six weeks, based on the evaluation of patients at follow-up visits (see algorithm in Figure 1).

Finally, ultrasound-guided perineural injection can be employed to reduce mechanical compression by fibrosis of the surrounding scar after surgical repair and fasten nerve and muscle regeneration [13-15,20].

Table 1. Peripheral Nerve Pathology and Findings

Figure 1. A Practical Algorithm for Peripheral Nerve Injuries
DW, dextrose; HA, hyaluronic acid; LA: local anesthetic; LPDGF, lipolyzed platelets derived growth factor; PE, placental extract; PRP, platelets
rich plasma; US, ultrasound.