Ambiguous mechanisms of dysphagia in multiple system atrophy

Sir, we read with great interest the article by Schwarzacher et al. (2011) describing the neuroanatomical characteristics of the human pre-Botzinger complex and its involvement in multiple system atrophy and spinocerebellar ataxia 3 (SCA3). In this study, the authors provide a thorough analysis of the pre-Botzinger complex and demonstrate that somatostatin and neurokinin 1 receptor expressing neurons are severely reduced in a neurodegenerative disorder presenting with severe central respiratory dysfunction (multiple system atrophy), but spared in patients with no history of such respiratory deficits (SCA3). This study provides strong neuropathological evidence that degeneration of the pre-Botzinger complex occurs in multiple system atrophy and extends previous findings showing a drastic reduction of putative brainstem chemosensory neurons in this disease (Benarroch, 2007). Altogether, these findings strongly support the hypothesis that degeneration of these brainstem respiratory neurons underlies respiratory dysfunction in multiple system atrophy.In addition to the characterization of the pre-Botzinger complex, Schwarzacher et al. (2011) also provide a detailed analysis of the nucleus ambiguus in multiple system atrophy and SCA3. In both diseases, the ventral part of the nucleus ambiguus (containing pre-ganglionic cardiovagal neurons) display severe neuronal …