Selective stroke of the solitary tract nuclei in two cases of central sleep apnoea

Central sleep apnoea (CSA) is a breathing disorder characterized by repetitive central apnoeas with hypoxia interrupted by hyperventilation phases. In the literature, there are reports of CSA caused by brainstem infarcts. We report two patients (38 and 53 years old) with longstanding history of central sleep apnoea who died during sleep. In both cases the autopsy revealed acute bilateral hypoxic lesions at the level of the solitary tract nuclei. In one case, symmetrical selective neuronal necrosis was found in the dorsal part of the solitary tract nuclei. A chronic obstructive vasculopathy was also found, with thickening and fibrosis of the smallest vessels of the medullary tegmentum. In the other case, bilateral infarctions were found with the base at the ependymal lining of the 4th ventricle floor and the apex towards the solitary tract. An acute intramural hemorrhagic lesion in the premedullary segment of the left vertebral artery was also found. Episodes of hypoxemic hypoxia during sleep may worsen the effects of focal oligohemic hypoxia in the medullary tegmentum. Selective stroke of the solitary tract nuclei may be the acute fatal lesion in patients with both central sleep apnoea and lesions of the vertebro-basilar system. To the best of our knowledge, this is the first neuropathologic report of acute medullary ischemic-hypoxic lesions which may not be considered the cause of the CSA because of their recent onset. Our findings suggest that CSA, besides being caused by ischemic events at the level of the medulla, may also contribute to pathogenesis of strokes, through hypoxia or hemodynamic oscillations.