Botulism: Heart rate variation, sympathetic skin responses, and plasma norepinephrine

Background: Botulism may involve the autonomic nervous system. Methods: We assessed the autonomic function of 6 botulism patients with heart rate variations, sympathetic skin responses, and plasma norepinephrine. Results: Two weeks after onset, all the patients had absent sympathetic skin response in the palm and sole. Compared with controls, the heart rate variation of botulism patients was significantly decreased at rest (3.1 ± 1.2% vs. 20.9 ± 2.0%, p = 0.0018) and during deep breathing (4.3 ± 2.3% vs. 29.7 ± 2.6%, p = 0.0018). The botulism patients had significantly lower plasma norepinephrine levels (supine 29.2 ± 10.1 pg/ml vs. 257.5 ± 65.8 pg/ml, p = 0.0018; standing 40.3 ± 13.1 pg/ml vs. 498.5 ± 85.6 pg/ml, p = 0.0018). The heart rate variation and sympathetic skin response was greatly improved 6 months after onset. Conclusions: Heart rate variation, absence of sympathetic skin response, and low plasma norepinephrine are all manifestations of autonomic dysfunction in botulism patients.