Title : When respiratory acidosis is neurologic: A case of Anti-IgLON5 disease
Abstract:
Background: Anti-IgLON5 disease is a rare neurologic disorder characterized by overlap between autoimmune encephalitis and neurodegeneration. Clinical manifestations commonly include sleep disturbances, bulbar dysfunction, gait instability, autonomic symptoms, and progressive respiratory compromise. Early recognition is critical, as immunotherapy may improve or stabilize symptoms.
Case Presentation: A 68-year-old female with previously diagnosed Anti-IgLON5 autoimmune encephalitis presented with two weeks of progressive dyspnea, fatigue, intermittent choking episodes, daytime somnolence, and worsening orthopnea. Examination revealed mild respiratory distress, dysarthria, weak gag reflex, reduced palatal elevation, and truncal instability. Arterial blood gas analysis demonstrated respiratory acidosis with hypercapnia (pH 7.29, PaCO? 58 mmHg), consistent with hypoventilation. Chest radiography showed low lung volumes without infiltrates, and brain MRI demonstrated only chronic nonspecific changes. The patient was admitted for acute-on-chronic hypoventilation secondary to neurologic dysfunction. She was treated with non-invasive ventilation, respiratory therapy, and continuation of intravenous immunoglobulin (IVIG). Multidisciplinary management involving neurology, pulmonology, speech therapy, and rehabilitation services led to gradual clinical improvement and resolution of oxygen requirements.
Discussion: Anti-IgLON5 disease is increasingly recognized as a unique overlap syndrome involving both autoimmune and neurodegenerative mechanisms. Respiratory dysfunction may result from bulbar weakness, impaired central respiratory control, sleep-related breathing disorders, and neuromuscular fatigue. This case highlights the importance of considering neurologic etiologies in patients with respiratory acidosis despite minimal pulmonary pathology. Prompt recognition and supportive respiratory management, combined with immunotherapy, may improve outcomes.
Conclusion: Anti-IgLON5 disease should be considered in older adults presenting with unexplained hypoventilation, bulbar symptoms, and sleep-related complaints. Early multidisciplinary intervention is essential to reduce morbidity and improve functional recovery.
