Reduced Reflex Autonomic Responses Following Intradetrusor OnabotulinumtoxinA Injections: A Pre-/Post-study in Individuals With Cervical and Upper Thoracic Spinal Cord Injury

Effects of exercise on autonomic cardiovascular control in individuals with chronic, motor-complete spinal cord injury: an exploratory randomised clinical trial

STUDY DESIGN

Secondary analysis of a clinical trial.

OBJECTIVE

To assess the impact of 6 months of arm cycle ergometry training (ACET), or body weight-supported treadmill training (BWSTT), on autonomic cardiovascular responses to a laboratory sit-up test (SUT) in individuals with chronic (≥1-year post-injury) spinal cord injury (SCI).

SETTING

Tertiary Rehabilitation Centre, Vancouver, Canada.

METHODS

Sixteen individuals with motor-complete (American Spinal Injury Association Impairment Scale A-B) SCI between the fourth cervical and sixth thoracic spinal cord segments, aged 39 ± 11 years, were assessed. Participants were randomized to receive 72 sessions of moderate-to-vigorous intensity ACET (n = 8) or passive BWSTT (n = 8). Changes in mean arterial pressure (finger plethysmography), hemodynamics (Modelflow® method), and heart rate/heart rate variability (HR/HRV; electrocardiography) were measured in response to a  SUT before and after 6 months of exercise training. Spontaneous cardiovagal baroreflex sensitivity (cvBRS) was assessed using the sequence method.

RESULTS

Neither ACET nor BWSTT impacted hemodynamic responses to SUT or the incidence of orthostatic hypotension (all P > 0.36). ACET increased HR (P < 0.01, ηp2 = 0.34) and high frequency (HF) power HRV responses (P < 0.01, ηp2 = 0.42) to SUT following 6 months of training while BWSTT did not. Consistent with this, cvBRS improved (P < 0.05, ηp2 = 0.16) only following ACET. Improvements in cvBRS were correlated with both the HR (r = 0.726, P < 0.0001) and HF power (r = -0.484, P < 0.01) responses to SUT.

CONCLUSION

Six months of ACET, but not BWSTT, improved cardiovagal baroreflex control of HR but had no effect on BP responses to SUT in individuals with chronic, motor-complete SCI.

SPONSORSHIP

Canadian Institutes of Health Research (CIHR) CLINICAL TRIAL REGISTRATION: NCT01718977.

From Toxin to Treatment: A Narrative Review on the Use of Botulinum Toxin for Autonomic Dysfunction

Since its regulatory approval over a half-century ago, botulinum toxin has evolved from one of the most potent neurotoxins known to becoming routinely adopted in clinical practice. Botulinum toxin, a highly potent neurotoxin produced by Clostridium botulinum, can cause botulism illness, characterized by widespread muscle weakness due to inhibition of acetylcholine transmission at neuromuscular junctions. The observation of botulinum toxin's anticholinergic properties led to the investigation of its potential benefits for conditions with an underlying etiology of cholinergic transmission, including autonomic nervous system dysfunction. These conditions range from disorders of the integument to gastrointestinal and urinary systems. Several formulations of botulinum toxin have been developed and tested over time, significantly increasing the availability of this treatment for appropriate clinical use. Despite the accelerated and expanded use of botulinum toxin, there lacks an updated comprehensive review on its therapeutic use, particularly to treat autonomic dysfunction. This narrative review provides an overview of the effect of botulinum toxin in the treatment of autonomic dysfunction and summarizes the different formulations and dosages most widely studied, while highlighting reported outcomes and the occurrence of any adverse events.