[Utility of muscle ultrasonography for the diagnosis of amyotrophic lateral sclerosis].

The diagnosis of amyotrophic lateral sclerosis (ALS) is frequently challenging, because motor neuron involvement is usually focal at disease onset and many syndromes mimic ALS. Neurological examination and needle EMG are important in the diagnosis of ALS, and patients with early-stage ALS usually undergo several EMG examinations before the diagnosis is confirmed. Ultrasonography has recently been used for the non-invasive assessment of neuromuscular disorders. This review discusses the recent advances in ultrasonography for ALS diagnosis. Ultrasonography could help detect lower motor neuron involvement by evaluating muscle volume, echo intensity, and fasciculations. Previous reports have documented the diagnostic values of all these parameters. In particular, fasciculations are characteristic features of ALS that can be easily and reliably visualized using ultrasonography. Moreover, the combined use of ultrasonography and EMG to detect fasciculations could substantially increase the diagnostic sensitivity of Awaji criteria for ALS. Attempts to utilize ultrasonography for ALS diagnosis have started only recently, and the technique used is yet to be standardized. However, ultrasonography has a major advantage over EMG in that it is non-invasive. Further studies are needed to understand the use of ultrasound as a novel non-invasive tool for ALS diagnosis.