Ultrasonography of muscles
Ultrasonography (US) of the muscle has been recently introduced in clinical neurophysiology. The typical US image of a normal muscle is hypoechoic, interrupted by small hyperechoic foci corresponding to fibrous tissue stroma .Moreover US as a dynamic imaging technique can demonstrate the muscle in-live mode, which makes US a useful method for visualizing abnormal involuntary movements, such as fasciculations or percussion myotonia. Indeed studies have shown that US is even better than the needle EMG to visualize fasciculations . This is due to the fact that US inspects a larger area or the entire muscle and can show kinetic and temporal aspects of fasciculations.
In our lab, we examined the role of US in visualizing fasciculations.and found that US is a fast and a reliable method. We also found that US and electrodiagnosis supplement each other in increasing the diagnostic yield in patients with nerve and muscle diseases.
In this group of patients, US has the potential to demonstrate chronic muscle changes, including heterogeneous increases in echogenicity, atrophy, and increased subcutaneous tissue thickness.Echogenicity in the muscle can be analysed with semi-quantitative methods, such as Heckmatt scale, and quantitative techniques, such as muscle elastography.
We are looking at the moment at the utility of elastography of muscles in diagnosing chronic changes in patients with nerve and muscle disorders. The data are being compared with a reference material from healthy volunteers.