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 vari ations, sympathetic skin responses, and plasma norepinephrine. Results: Two weeks after onset, all the patients had absent sympathetic skin response i n the palm and sole. Compared with controls, the heart rate variation of bo tulism patients was significantly decreased at rest (3.1 +/- 1.2% vs. 20.9 +/- 2.08, p = 0.0018) and during deep breathing (4.3 +/- 2.3% vs. 29.7 +/- 26%, p = 0.0018). The botulism patients had significantly lower plasma nore pinephrine 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 improv ed 6 months after onset. Conclusions: Heart rate variation, absence of symp athetic skin response, and low plasma norepinephrine are all manifestations of autonomic dysfunction in botulism patients.