Ultrasonographic detection of fasciculations markedly increases diagnostic sensitivity of ALS.

Abstract

To study the utility of muscle ultrasound (US) for detection of fasciculations and its contribution to diagnosis in amyotrophic lateral sclerosis (ALS). Fasciculations are characteristic features of ALS, and US can detect them easily and reliably. New diagnostic criteria for ALS, the Awaji algorithm, reintroduced fasciculations as evidence of acute denervation equivalent to that of fibrillations and positive sharp waves. In 81 consecutive patients with sporadic ALS, we prospectively performed needle EMG and US in 6 muscles (tongue, biceps brachii, first dorsalis interosseous, paraspinalis, vastus lateralis, and tibialis anterior), and diagnostic category were determined by revised El Escorial criteria and Awaji criteria. Fasciculations were much more frequently detected by US than by EMG in the tongue (60% vs 0%), biceps brachii (88% vs 60%), and tibialis anterior muscles (83% vs 45%). The proportion of the patients with definite or probable ALS was 48% by revised El Escorial criteria and 79% by Awaji criteria using US. Muscle US is a practical and efficient tool to detect fasciculations, particularly in the tongue. A combination of US and EMG substantially increases the diagnostic sensitivity of ALS.