Severe sleep-related hypoventilation in antibody-positive and antibody-negative autoimmune encephalitis: an emergency

Background and objectives Although sleep disorders of neurological origin have been extensively documented in cases of autoimmune encephalitis, the impact and clinical significance of sleep-disordered breathing remain underexplored. We aimed at determining the prevalence of sleep-disordered breathing in autoimmune encephalitis. Methods A cohort study of consecutive patients with autoimmune encephalitis referred to a tertiary center for sleep pathology was conducted over a period of four and a half years. Patients underwent an overnight video-polysomnography with capnography. We investigated the presence of sleep-related breathing disorders, including sleep-related hypoventilation, sleep apnoea-hypopnoea syndrome, central hyperventilation, irregular breathing and excessive sighing. Results Forty-six participants with autoimmune encephalitis were included, with a median age of 60 Quartiles 1,3: 40, 69 years, of whom three were previously treated with non-invasive ventilation after acute respiratory failure and three were previously treated with positive airway pressure. A total of 26/46 (56.5%) participants had sleep-disordered breathing, including 19/46 (41.3%) participants with moderate to severe apnoea-hypopnoea syndrome. Capnography revealed sleep-related hypoventilation in 12/33 (36%) cases, including 4/5 (80%) anti-IgLON5, 1/4 (25%) anti-GAD65, 1/4 (25%) anti-CASPR2, and 6/14 (42.8%) antibody-negative cases. Nocturnal stridor was observed in 2/5 (40%) anti-IgLON5 cases. Overall, 20/46 (43%) subjects required respiratory support, including positive airway pressure (n=13) and non-invasive ventilation (n=7). Conclusion More than one third of participants with autoimmune encephalitis required nocturnal mechanical ventilation. Particular attention should be paid to sleep-related hypoventilation (assessed by nocturnal capnography) in patients with autoimmune encephalitis to guide timely respiratory support and reduce morbidity and mortality.