The impact of obstructive sleep apnea and the prognostic role of level III polysomnography at the onset of amyotrophic lateral sclerosis.

Purpose: Sleep disturbances are considered an early manifestation of Amyotrophic lateral sclerosis (ALS). However, sleep-disordered breathing (SDB) in ALS remains underexplored. The primary outcome of this study is to describe the clinical, functional and polygraphic characteristics of ALS patients with baseline SDB and to compare those with and without obstructive sleep apnea (OSA) in level III polysomnography (PSG) at diagnosis. Secondary outcomes included identification of baseline factors predictive of non-invasive ventilation (NIV) initiation/death during follow-up and assessing the role of level III PSG performed at the initial clinical evaluation in ALS prognosis regarding timing to NIV initiation and death.

Methods: A cross-sectional study was conducted on 74 patients between September 2023 and September 2024. For the primary outcome, only patients that exhibited baseline SDB were included (45 patients). The population (45) was divided into 2 groups: Group 1 (n = 26; obstructive apnea/hypopnea index ≥ 5) and Group 2 (n = 19; obstructive apnea/hypopnea index < 5). For the secondary outcomes, all 74 patients were included regardless of sleep events.

Results: Patients with OSA had a higher baseline body mass index (p = 0.03) and lower nocturnal average oxygen saturation (p = 0.03). A lower forced vital capacity (p < 0.001) and higher transcutaneous carbon dioxide (p = 0.005) at baseline were predictive of timing to NIV initiation.

Conclusions: Our study highlights the importance of performing respiratory functional testing and transcutaneous carbon dioxide assessment in ALS prognosis, regarding timing to NIV initiation. Although level III PSG is vital in the diagnosis and treatment of SDB, further studies are needed to clarify its role at disease onset and identify additional potentially predictors of timing to NIV initiation/death in ALS patients.