Involvement of vagal autonomic nuclei in multiple system atrophy and Lewy body disease

Background: Multiple system atrophy (MSA) and Lewy body disorders (LBDs) are associated with impaired control of gastrointestinal and cardiac functions. The dorsal vagal nucleus (DMV) innervates enteric neurons, whereas the ventrolateral nucleus ambiguus (NAmb) innervates the heart. The relationship between DMV and NAmb involvement and the gastrointestinal or cardiovagal manifestations in MSA and LBD is unclear. Methods: The authors counted the cholinergic neurons in the DMV and NAmb in 15 cases of neuropathologically confirmed MSA, 14 of LBD (4 brainstem, 3 limbic, and 7 neocortical), and 12 control cases. All MSA and 8 of the 14 LBD cases had gastrointestinal symptoms; 8 of 12 MSA and 1 of 4 LBD cases had laboratory evidence of cardiovagal failure; 5 of the MSA and no LBD cases had laryngeal stridor. Results: There was loss of cholinergic DMV neurons in all MSA and LBD cases. The degree of DMV cell loss was similar in LBD patient with or without gastrointestinal symptoms. In MSA but not in LBD cases, there was neuronal loss in the ventrolateral NAmb, with lower counts in patients with cardiovagal failure. Conclusions: There is comparable involvement of the dorsal vagal nucleus (DMV) in multiple system atrophy (MSA) and different stages of Lewy body disorders (LBDs). The relationship of DMV involvement and gastrointestinal symptoms is uncertain. Loss of neurons in the ventrolateral nucleus ambiguus may explain the more consistent cardiovagal failure in MSA than in LBD.