Fasciculations in nerve and muscle disorders - A prospective study of muscle ultrasound compared to electromyography

•Muscle ultrasound (MUS) may add valuable information regarding fasciculations in patients with nerve and muscle disorders.•MUS can assist in making the diagnosis of ALS more certain.•Fasciculations in nine muscles per patient predict the ALS diagnosis with high specificity.

ObjectivesWe examined the clinical utility of muscle ultrasound (MUS) in detecting fasciculations in patients with nerve and muscle disorders (NMD) and investigated the impact on diagnostic sensitivity when combining electromyography (EMG) and MUS.MethodsWe included 58 consecutive patients suspected to have NMD and 38 healthy subjects (HS). Patients and HS underwent MUS in 14 skeletal and two bulbar muscles and the video recordings of the MUS were anonymised. Only patients underwent EMG.ResultsThe follow-up diagnoses were: 15 Amyotrophic lateral sclerosis (ALS), 15 polyneuropathy, 14 patients had other diagnoses (disease-control group) and 14 patients had no pathological findings.MUS detected more muscles with fasciculations among ALS patients compared to all other groups. In ALS patients, the dominating pattern of fasciculations was continuous (45%). More proximal muscles showed fasciculations among ALS patients compared to all other patient groups. MUS was more sensitive than EMG in detecting fasciculations (58% vs. 48%). When combining the two methods, the sensitivity in detecting fasciculations increased to 65%. Fasciculations in nine muscles could predict the ALS diagnosis with high sensitivity and specificity.ConclusionsMUS is a sensitive tool in detecting fasciculations in patients with NMD and performs well compared to EMG in diagnosing ALS.SignificanceMUS may add valuable information in the clinic, especially in diagnosing ALS.