Contribution of ultrasound in a neurophysiological lab in diagnosing nerve impairment: a one-year systematic assessment.

Electrodiagnostic studies, including electromyograpy (EMG) and nerve conduction studies (NCS), are objective methods for the diagnosis (and classification) of nerve involvement. In an EMG laboratory, diagnosis is usually based on clinical findings and neurophysiological evaluation. Clinical evaluation allows to assess which nerve is involved, the presence of motor and sensitive deficits, the onset and other useful information. All these findings are useful to perform a finalized neurophysiogical pathway. EMG assessment provides evidence of myelin impairment, neuroapraxic block, axonal involvement and other useful information. Moreover, EMG evaluation usually shows the level of the lesion but does not provide spatial information about anatomy of the nerve and its surroundings which might be important for the aetiology. Recently, detail resolution has been increasingly used to aid diagnosing compression and entrapment neuropathies. Advances in ultrasound (US) technology have made it possible to gain higher spatial resolution and even depict nerves with excellent visual quality. The importance of US technique in focal nerve involvement is that we can see, from an anatomic point of view, the nerve along its course. Some of the advantages of US is that it is a non-invasive, low-cost and easily available technique which allows a dynamic examination. We conducted many neurophysiological studies on nerve entrapments and more generally in nerve lesions. Because of the complementary perspectives provided by US and EMG, we acquired an US instrument and we started to add the US assessment simultaneously to EMG evaluation in the same session. In literature, Several case reports were reported in which it is underlined the complementarity of US and EMG in diagnosing nerve involvement. To our knowledge, no systematic evaluation of the usefulness of the combination of these tools was performed. We performed a prospective study to evaluate the usefulness of combination of EMG and US assessments in diagnosing nerve diseases. We hypothesized that in some cases US could provide etiopathologic information not reached through EMG, and sometimes it would have been able to modify therapeutical decision.