Denervation findings on EMG in amyotrophic lateral sclerosis and correlation with prognostic milestones: Data from a retrospective study

Objective: To verify whether the finding of denervation activity on EMG at the time of diagnosis has a prognostic value in amyotrophic lateral sclerosis (ALS). Methods: We retrospectively studied all the patients discharged with a diagnosis of ALS between January 2009 and January 2017. 92 patients met the inclusion criteria. We mainly verified three prognostic targets: (1) Time to non-invasive ventilation (NIV) or tracheostomy. (2) Time to percutaneous endoscopic gastrostomy or parental nutrition. (3) Survival.All EMG examinations were reviewed and a denervation score (DS) was calculated. The association of DS with clinical milestones was analysed, adjusting for disease duration, age, sex, and clinical phenotype. Results: We found a significant association between bulbar DS and time to NIV/tracheostomy (HR: 3.34, 95% CI: 1.49 to 7.48, p = 0.002) and with survival (HR 3.633, 95% CI 1.681–7.848, p = 0.001), regardless of the clinical phenotype. Furthermore, we found a significant influence of a general DS on survival (HR: 2.62, 95% CI 1.335–5.160, p = 0.005). Conclusion: EMG assessment could be of value not just for ALS diagnosis but also for its intrinsic prognostic value. Significance: EMG could provide additional information about the rate of progression of ALS as early as the diagnosis is made.