Respiratory onset in amyotrophic lateral sclerosis: clinical features and spreading pattern

Objective To describe the clinical features and progression of patients with respiratory onset amyotrophic lateral sclerosis (ALS). Methods: We analyzed the clinical features, including respiratory tests, functional score, noninvasive ventilation (NIV) time and survival of ALS patients with respiratory-onset in our database consisting of 1688 patients. In a subset of 625 ALS patients we analyzed the spreading pattern to other bodily regions. Results: We included 1579 patients with ALS. Sixty-three patients (4%) presented respiratory-onset (79.4% men, mean onset-age 67.7 ± 8.9yrs). All had predominant LMN involvement, and significant weight loss (>10%) was identified in 38.9%. The respiratory tests were abnormal in these respiratory-onset patients (p < 0.001). ALSFRS-R respiratory subscore was lower in this population (p < 0.001). NIV was adapted in 84.1%, sooner than in the larger group of ALS patients (p < 0.001), and survival from disease onset was shorter (p < 0.001). Respiratory-onset was a predictor of time to NIV (X²=42.0, p < 0.001) and of survival (X²=7.1, p = 0.008). The spreading pattern was studied in 18 patients with isolated respiratory-onset. The progression interval to the 2nd region was 4.7 ± 5.7mo and to a 3rd region 6.1 ± 8.7mo. Different patterns of spread had no impact on survival. Conclusions: This phenotype is typically seen in emaciated older men with predominant lower motor neuron involvement, and is associated with diaphragm paresis and central respiratory involvement. NIV adaptation is rapid but total survival is shorter than in the other patients. Spreading pattern did not affect time to NIV adaptation or total survival, as NIV support is a modifying treatment in the course of ALS.