Needle electromyography of the frontalis muscle in patients with amyotrophic lateral sclerosis.

Abstract

We sought to determine which muscles to choose for better assessment of the craniobulbar region in establishing the diagnosis of amyotrophic lateral sclerosis (ALS). We studied the frontalis muscle in 83 controls and compared it with the tongue, sternocleidomastoid (SCM), and trapezius muscles in 105 definite or probable ALS patients (54 bulbar, 51 nonbulbar). More patients achieved complete relaxation of the frontalis muscle than the tongue or SCM. Motor unit potentials were of longer duration and higher amplitude in ALS patients than in controls (P < 0.05). The frontalis had the same frequency of spontaneous potentials as the tongue, SCM, and trapezius muscles in bulbar ALS patients, but fewer than in the trapezius in nonbulbar patients. Examining the frontalis provides useful information in establishing the diagnosis of ALS by identifying clinically evident or subclinical abnormalities in the craniobulbar region. Muscle Nerve 54: 1093-1096, 2016.