Phenotyping of the thoracic-onset variant of amyotrophic lateral sclerosis

Thoracic-onset amyotrophic lateral sclerosis (T-ALS) is a rare subform, affecting only 3% of all patients with amyotrophic lateral sclerosis (ALS).1 In order to facilitate a better understanding of this variant, we aimed at characterising typical features of T-ALS including clinical presentation, propagation patterns and prognosis. We performed a retrospective chart analysis of 59 patients with T-ALS derived from a clinical database comprising 3549 patients with ALS from the Department of Neurology at Ulm University Hospital (Ulm, Germany) between 2002 and 2018 including a query for death records in 2020. Inclusion criteria were diagnosis of probable or definite ALS according to revised El Escorial criteria and weakness of thoracic muscles as first symptom of ALS. The control group comprising 517 patients with non-thoracic-onset amyotrophic lateral sclerosis (NT-ALS) was derived from the epidemiological database of the ALS Registry Swabia2 between 2010 and 2018, excluding specific variants such as primary lateral sclerosis, progressive muscle atrophy and flail-arm/flail-leg syndrome, as well as familial/genetic forms. We compared both cohorts with regard to clinical parameters including sex, age at disease onset, diagnostic delay, survival (time from onset of symptoms to death), body weight, use of non-invasive ventilation (NIV) and invasive ventilation (IV), and spreading patterns. Disease onset was defined as occurrence of first paresis. For description of clinical parameters, absolute and relative frequencies or median and IQR were used as appropriate. Comparison of categorical variables was done Pearson’s χ2 test. For continuous parameters, the Mann-Whitney U test was used. Survival was analysed using the Kaplan-Meier method and log-rank test. All statistical tests were performed at a two-sided significance level of alpha=0.05. Statistical analysis was done with SPSS V.25.0. Out of 3549 patients with ALS treated at the Department of Neurology at Ulm University Hospital (Ulm, Germany) between 2002 and 2018, 59 (1.7%) had …