Editorial Comment on: B. Kowalska Assessment of the utility of ultrasonography with high-frequency transducers in the diagnosis of postoperative neuropathies

I have read the publication by Dr Berta Kowalska⁽¹⁾ on the utility of ultrasonography in the diagnosis of postoperative neuropathies, with great interest. When in 2001, a colleague of mine told me that he could diagnose neuropathies of the upper extremity in an ultrasound examination, I thought it was impossible. I even wondered how ultrasound imaging of the nerve can replace its functional assessment possible thanks to a nerve conduction study (NCS) or electromyography (EMG). In the subsequent years, US imaging was becoming more and more common in my daily surgical practice. What is more, it even started to supersede other imaging methods, which were, as it would seem, more accurate, such as magnetic resonance imaging.

Ultrasound assessment of nerves was attempted for many years. Initially, however, such examinations were focused on diagnosing entrapment neuropathies of the median and ulnar nerves. When high frequency transducers were introduced, parameters that had previously been difficult to define, became uniformed and standardized. At the same time, I (as a physician referring patients to a US examination) have greater expectations and requirements from my colleagues who conduct US examinations. At present, based on accurate clinical data of the patient, I ask specific questions when requesting an ultrasound examination to help verify my initial diagnoses. Imaging of neuropathies occupies a special place here. These conditions, in the form of disorders or lack of sensation, weakening or loss of motor function and pain, constitute one of the greatest problems for patients. In a patient after a hand trauma caused by a circular saw, with lost sensation diagnosed after initial or final wound dressing, ultrasound is the only examination that can help establish the prognosis concerning the return of nerve function and determine further management. In the initial period, a clinical examination or EMG test do not differentiate between neuropraxia and neurotmesis. The information whether the nerve is compressed, stretched or ruptured can only be obtained in a US examination conducted by an experienced diagnostician.

In the case of postoperative complications in the form of peripheral nerve palsy, there is no time to wait for its function to return. We want immediate information about whether the continuity of the nerve is retained and it was probably compressed with a retractor or trapped under the fixation material, or whether the continuity is not retained. The greatest concerns are caused by small nerves with important function, such as the posterior interosseous nerve or the musculocutaneous nerve. Even their slight compression during a procedure results in considerable dysfunction. Furthermore, the conversation with the patient about the prognosis can be different when the result of a US examination showing slight nerve edema with blurred bundle structure and retained continuity, is available. If a surgical procedure to release an entrapped nerve does not bring about a considerable improvement, some questions must be asked about its causes: Are the adhesions around the nerve to blame? Is a hematoma responsible, or was the surgeon ineffective and failed to remove the structure that is causing compression? When symptoms recur, even after many years, it is important to differentiate whether compression is present or a transformation in the nerve itself has taken place due to previous long-term compression. Such a differentiation cannot be made either in a clinical examination or in functional assessment (NCS or EMG), as both of them indicate a neuropathy. However, ultrasonography can help us make a decision concerning further management.

As I was reading Dr Berta Kowalska's article, two thoughts came to my mind. The first was that the paper presented a genuine image of my daily practice in which ultrasonography is used frequently, particularly to diagnose neuropathies (entrapment, posttraumatic and postoperative) – just as the author described them in her paper. Moreover, an accurate pain diagnosis, which we have been conducting recently, must be mentioned. Thanks to combining a clinical examination and ultrasound imaging of lesions, with the use of accurate ultrasound-guided anesthesia of particular structures, we are able to pinpoint the localization of pain, sometimes even after multiple ineffective attempts of surgical treatment (Fig. 1, Fig. 2). We are able to differentiate between localized pain and referred pain, and finally, we can institute adequate treatment to eliminate it.

Fig. 1.

Accurate US-guided pinpointing of the site of pathology in the dorsal branch of the ulnar nerve

Fig. 2.

Accurate distance between the site of pathology and constant points of the shaft of the ulna and pisiform bone

The second reflection was that we have greater and greater expectations and requirements for even more accurate results. As the author mentioned, the use of high-frequency transducers is very important in US imaging. The most important, however, are experience, which allows various pathologies to be accurately differentiated, and considerable involvement in or even fascination with what one is doing. There are few diagnosticians who can assess such complex pathologies and devote much more time and effort to present an unambiguous and undoubted result enabling further management. I belong to the lucky physicians who have the honor of working with enthusiasts and the masters of their profession who have not experienced discouragement or burnout.