S17-4. Nerve and muscle ultrasound assessment in ALS

Abstract

In the diagnosis and assessment of amyotrophic lateral sclerosis (ALS), the roles of nerve and muscle ultrasound vary widely. Nerve ultrasound has revealed that cross-sectional area (CSA) was decreased in the median and ulnar nerves and the nerve roots in ALS. In addition, a longitudinal study demonstrated the possibility that ulnar nerve CSA could be a useful biomarker to monitor disease progression in ALS. Muscle ultrasound is useful for detecting widespread fasciculations in the diagnosis of ALS. Ultrasound technique is suitable for assessing the distribution and frequency of fasciculations non-invasively. Furthermore, muscle ultrasound is also used to measure the thickness of the diaphragm and bulbar muscles. Decreased thickness of the diaphragm indicates pulmonary dysfunction, and decreased the thickness of the tongue suggests swallowing dysfunction. Interestingly, the thickness change of the bulbar muscle during swallowing relates to the severity of upper motor neuron dysfunction. Although modern MRI technique also has progressed and is increasingly being used as a nerve and muscle imaging tool, nerve and muscle ultrasound can be disseminated widely due to its convenience and non-invasiveness and will enable neurologist/neurophysiologists to diagnose and to assess ALS more accurately coupled with an electromyography machine.