Apnea in sleeping patients with syringobulbomyelia can be accounted for by damages in afferent and efferent impulsation from the respiratory centre due to cysts in medulla oblongata and spinal channel distension. Controlled lung ventilation has been applied to such patients in sleep for more than 8 years. In Arnold-Chiari syndrome apnea in sleep is associated with paroxysms of occlusive hydrocephalus. Periodic controlled lung ventilation during sleep is obligatory in these patients. Both nosological forms are characterized by lower sensitivity of the respiratory centre to hypoxia and hypercapnia. The nature of the pathological process is confirmed by magnetic resonance tomography.