Intermuscular Coherence as a Biomarker for ALS

The specific aims of this study are to: 1. Determine if a painless and quick measurement of muscle activity using surface electrodes can help with the diagnosis of ALS. Specifically, we ask if a measure of intermuscular coherence (IMC-βγ), when added to current diagnostic criteria (Awaji criteria), can differentiate ALS from mimic diseases more accurately and earlier than currently possible. 2. Characterize IMC-βγ in neurotypical subjects by age, sex, race, and ethnicity. 3. Follow a cohort of ALS patients longitudinally to determine if IMC-βγ changes with ALS disease progression and whether such changes correlate with functional and clinical scores, or survival.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease caused by neuronal death in the motor system, both in the brain and spinal cord. It results in progressive weakness throughout the body, and typically leads to respiratory failure 3-5 years after symptom onset. Therapy initiation and drug development are hindered, in part, by the lack of objective disease markers. This is a multi-center trial to validate a potential biomarker for ALS, known as intermuscular coherence (IMC-βγ). IMC measures the correlation in the activity of two muscles during a simple motor task. In a preliminary study we found that patients with ALS have lower IMC than do control subjects. Because measuring IMC is quick, non-invasive, painless, and only requires equipment readily available in standard clinical neurophysiology labs, if validated it would be an important biomarker for ALS.