# Autonomic Dysfunction and Blood Pressure Variability in Botulinum Intoxication: A Prospective Observational Study from a Single-Center Italian Outbreak

## TL;DR

This study shows that botulinum poisoning causes autonomic dysfunction and low blood pressure, with partial recovery over six months but lasting issues requiring monitoring.

## Contribution

The study provides new insights into autonomic and blood pressure changes during botulinum intoxication and their long-term recovery patterns.

## Key findings

- Patients with botulinum intoxication had significantly lower blood pressure and variability compared to healthy controls.
- Orthostatic hypotension improved from 55% at baseline to 5% after six months.
- Respiratory failure occurred in 40% of cases, with partial autonomic recovery but residual abnormalities at follow-up.

## Abstract

Botulinum neurotoxin (BoNT) intoxication is a rare but severe condition that is characterized by autonomic and neuromuscular dysfunction. This study aimed to evaluate autonomic impairment and blood pressure variability in patients with botulinum intoxication during an outbreak, compared to healthy controls, and to assess their progression over a six-month follow-up period. Methods: Twenty (n = 20) male patients diagnosed with BoNT intoxication and 34 age- and sex-matched healthy controls were enrolled. At baseline, all subjects underwent 24 h ambulatory blood pressure monitoring (ABPM), and clinostatic and orthostatic blood pressure measurements. Autonomic function parameters, including mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP), SBP and DBP variability, SBP and DBP load, pulse pressure (PP), blood pressure variability ratio (BPVR), and morning surge, were analyzed. Follow-up assessments were conducted after six months. Results: Patients with botulinum intoxication exhibited significantly lower SBP, DBP, and blood pressure variability parameters compared to healthy controls. Orthostatic hypotension was present in 55% of patients at baseline, improving to 5% at follow-up. Respiratory failure occurred in 40% of cases, necessitating non-invasive ventilation in 35% and intubation in 20%. At six-month follow-up, mean SBP, DBP, heart rate, and blood pressure variability parameters increased significantly, indicating partial recovery of autonomic control. However, residual abnormalities in autonomic regulation persisted. Conclusions: BoNT intoxication leads to notable autonomic dysfunction, marked by impaired blood pressure regulation and a high prevalence of orthostatic hypotension. Although partial recovery occurs, long-term autonomic impairment persists, highlighting the necessity for ongoing cardiovascular monitoring and further research to accelerate autonomic recovery through targeted therapeutic interventions.