Journal CME January 2025, Autonomic dysreflexia with relative tachycardia: Potential physiologic pathways for this head scratching clinical finding-PM R - 2024 - Solinsky - Autonomic dysreflexia with relative tachycardia Potential physiologic pathways for this head

PM R - 2024 - Solinsky - Autonomic dysreflexia with relative tachycardia Potential physiologic pathways for this head

Pdf Summary

The article by Ryan Solinsky and Wolfgang Singer from the Mayo Clinic addresses autonomic dysreflexia (AD) in individuals with spinal cord injury (SCI), focusing on the atypical presentation of relative tachycardia instead of the classical bradycardia. AD is a serious condition that affects over 70% of individuals with SCI, potentially causing dangerous hypertensive crises. Traditionally, AD is characterized by hypertension paired with bradycardia, triggered by stimuli below the injury level. This occurs due to sympathetic nervous system activation leading to vasoconstriction and baroreceptor-induced compensatory bradycardia via vagal pathways.<br /><br />Recent findings, however, reveal that tachycardia can also occur with AD, challenging the traditional understanding. Studies indicate tachycardia incidence ranges between 24% and 68% among AD patients. This discrepancy may arise from reduced baroreflex sensitivity and increased arterial stiffness in SCI patients, which diminish the neural drive for bradycardia.<br /><br />Additionally, the article explores physiological mechanisms that could cause tachycardia during AD, such as increased sympathetic activity. For instance, if the injury level is above T3, sympathetic activation may cause the adrenal glands to release catecholamines, leading to increased heart rate and blood pressure, thus overriding the typical bradycardia response.<br /><br />The authors emphasize that individuals with sensory incomplete SCI frequently exhibit tachycardia during AD episodes due to partially preserved autonomic pathways that trigger normal pressor responses. They argue for a nuanced understanding of heart rate changes during AD to avoid misdiagnosis and provide optimal care for SCI patients. The study encourages further research into the mechanisms driving these variations to enhance clinical management of AD.<br /><br />The article is presented as a continuing medical education (CME) activity, allowing medical professionals to earn CME credit. The CME is accessible online and is free for AAPM&R members for three years post-publication.

Keywords

autonomic dysreflexia

spinal cord injury

tachycardia

bradycardia

hypertensive crises

sympathetic nervous system

baroreflex sensitivity

catecholamines

CME activity

AAPM&R members