Cognitive Impairment and Central Sleep Apnea Secondary to Tortuous Vertebral Artery Compression of the Medulla, Mimicking Alzheimer's Disease.

We report the case of a man in his 60s, who was previously diagnosed with Alzheimer's disease and presented with acute respiratory failure. Investigations revealed severe hypercapnia and central sleep apnea. Imaging revealed a tortuous right vertebral artery compressing the ventral medulla. Cerebrospinal fluid analysis showed a normal amyloid-β 1-42/1-40 ratio, and he exhibited pyramidal and autonomic signs of brainstem involvement. Despite microvascular decompression, the patient remained ventilator dependent. This case illustrates that medullary compression can cause central hypoventilation that mimics a neurodegenerative disorder, with cognitive decline driven by chronic hypoxia rather than by Alzheimer's pathology.