Muscle ultrasound detects fasciculations and facilitates diagnosis in ALS

Ultrasound is a noninvasive, painless, and safe imaging technique that has become indispensable in diagnosis and management in many different areas of medical practice. Muscle ultrasound was pioneered by Heckmatt et al.1 in pediatric practice. More recently, real-time ultrasound imaging has been used to visualize peripheral nerve and muscle.2 This technique can image muscle contraction, fasciculations, and even fibrillations in skeletal muscle, suggesting that ultrasound imaging is the most sensitive technique available to detect fasciculations, especially in deeply located muscles.3,4 High-density surface EMG, which enables long periods of recording to be used, can also be used to detect fasciculations.5 A study of the relative sensitivity of these 2 methods suggested that ultrasound was more sensitive in detecting fasciculations and less susceptible to artifact.6 However, this study also found that fasciculations occurred in most neuromuscular diseases and even in most normal subjects if long recording periods (up to 20 minutes) were used, a finding that suggests that morphology and firing frequency of the electrically recorded fasciculation potential remain important characteristics. Mills7 has shown that with concentric needle EMG, a minimum period of 90 seconds of recording …