F95. Laryngeal electromyography in patients with Amiotrophic Lateral Sclerosis (ALS): Preliminary results

Introduction Amyotrophic Lateral Sclerosis (ALS) is the most relevant motor neuron disease in adults and characterized by widespread weakness. Despite frequent bulbar involvement, little is known about clinical and electrophysiological changes in the larynx in patients with ALS. The objective of this study was to evaluate the frequency and pattern of involvement of laryngeal muscles in ALS and its functional relevance. In addition, we assessed whether laryngeal EMG (LEMG) would increase the diagnostic sensitivity for ALS. Methods Fourteen ALS patients, 13 with spinal onset and 1 with bulbar onset, underwent nasofibroscopy (NF) followed by LEMG, in which a concentric needle was used to evaluate the thyroid-arytenoid (TA), lateral crico-arytenoid (CAL), posterior crico-arytenoid (CAP) and crico-thyroid (CT) muscles, at rest and during activation. After LEMG, resting and activation of the genioglossus and masseter muscles were also studied using the same concentric needle. Results The mean age of the patients was 48.5 years and there were 6 women. The procedures were fast (30 min on average) and uneventful. Thirteen patients presented neurogenic changes in at least one laryngeal muscle. A single patient had entirely normal LEMG. We found a pattern compatible with chronic denervation (MUAPs remodeling and incomplete recruitment) with the following frequency: TA muscle in 11/14 patients (78.5%); CT in 10/14 patients (71.4%); CAP in 10/14 patients (71.4%) and CAL in 7/14 patients (50%). In 8 patients, there were fibrillations and/ or fasciculations associated with chronic neurogenic changes in the same muscle; of these, 4 had no alteration in the genioglossus muscle and 2 had only chronic alterations in the same muscle. NF revealed motor abnormalities in the larynx in 9 patients; in the remaining 5, NF was normal but LEMG identified signs of denervation in 4 of them. Conclusion LEMG is able to identify laryngeal denervation in patients with ALS. This procedure may increase diagnostic sensitivity for ALS by identifying bulbar involvement in patients without tongue denervation. Changes in LEMG may precede clinical involvement of the larynx in these patients.