Introduction: Individuals with spinal cord injury (SCI) commonly have autonomic dysreflexia (AD) with increased sympathetic activity. After SCI, individuals have decreased baroreflex sensitivity and increased vascular responsiveness.
Objective: To evalate relationship between baroreflex and blood vessel sensitivity with autonomic dysreflexia symptoms.
Design: Case control.
Setting: Tertiary academic center.
Patients: 14 individuals with SCI, 17 matched uninjured controls.
Interventions: All participants quantified AD symptoms using the Autonomic Dysfunction Following SCI (ADFSCI)-AD survey. Participants received three intravenous phenylephrine boluses, reproducibly increasing systolic blood pressure (SBP) 15-40 mmHg. Continuous heart rate (R-R interval, ECG), beat-to-beat blood pressures (finapres), and popliteal artery flow velocity were recorded. Vascular responsiveness (α1 adrenoreceptor sensitivity) and heart rate responsiveness to increased SBP (baroreflex sensitivity) were calculated.
Main Outcome Measures: Baroreflex sensitivity after increased SBP; Vascular responsiveness through quantified mean arterial pressure (MAP) 2-minute area under the curve and change in vascular resistance.
Results: SCI and control cohorts were well-matched with mean age 31.9 and 29.6 years (p=0.41), 21.4% and 17.6% female respectively. Baseline MAP (p=0.83) and R-R interval (p=0.39) were similar. ADFSCI-AD scores were higher following SCI (27.9+/-22.9 vs 4.2+/-2.9 in controls, p=0.002).To quantify SBP response, MAP area under the curve was normalized to dose/bodyweight. Individuals with SCI had significantly larger responses (0.26+/-0.19 mmHg*s/kg*ug) than controls (0.06+/-0.06 mmHg*s/kg*ug, p=0.002). Similarly, leg vascular resistance increased after SCI (24% vs 6% to a normalized dose, p=0.007). Baroreflex sensitivity was significantly lower after SCI (15.0+/-8.3 vs 23.7+/-9.3 ms/mmHg, p=0.01). ADFSCI-AD subscore had no meaningful correlation with vascular responsiveness (R=0.008) or baroreflex sensitivity (R=0.092) after SCI.
Conclusions: While this confirms smaller previous studies suggesting increased α1 adrenoreceptor sensitivity and lower baroreflex sensitivity in individuals with SCI, these differences lacked correlation to increased symptoms of AD. Further research into physiologic mechanisms to explain why some individuals with SCI develop symptoms is needed.
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http://dx.doi.org/10.1101/2024.05.02.24306772 | DOI Listing |
Acta Neurochir (Wien)
December 2024
Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke Hospital, University of Cambridge, Cambridge, UK.
Background: Traumatic brain injury (TBI) can significantly disrupt autonomic nervous system (ANS) regulation, increasing the risk for secondary complications, hemodynamic instability, and adverse outcome. This retrospective study evaluated windowed time-lagged cross-correlation (WTLCC) matrices for describing cerebral hemodynamics-ANS interactions to predict outcome, enabling identifying high-risk patients who may benefit from enhanced monitoring to prevent complications.
Methods: The first experiment aimed to predict short-term outcome using WTLCC-based convolution neural network models on the Wroclaw University Hospital (WUH) database (P = 31 with 1,079 matrices, P = 16 with 573 matrices).
J Electrocardiol
November 2024
Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, United States of America.
Hypertension
December 2024
Department of Epidemiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands. (M.K., A.H., F.J.W., M.A.I.).
Background: Increased blood pressure (BP) variability is linked to dementia risk, but the relationship between baroreflex sensitivity (BRS), a fundamental mechanism for maintaining stable BP, and dementia risk is undetermined.
Methods: We tested the hypothesis that impaired BRS is associated with increased dementia risk in 1819 older adults (63% women; age, 71.0±6.
Sci Rep
December 2024
Operative Unit of Vascular Surgery, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
Niger Med J
November 2024
Department of Gastroenterology, RUHS College of Medical Sciences, Jaipur, India.
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