Autonomic Dysreflexia, Autonomic Imbalance, Orthostatic; Hypotension, Neurogenic, Spinal Cord Injuries
Conditions
Brief summary
This study looks to characterize autonomic nervous system dysfunction after spinal cord injury and identify the potential role that transcutaneous spinal cord stimulation may play at altering neuroregulation. The autonomic nervous system plays key parts in regulation of blood pressure, skin blood flow, and bladder health- all issues that individuals with spinal cord injury typically encounter complications. For both individuals with spinal cord injury and uninjured controls, experiments will utilize multiple parallel recordings to identify how the autonomic nervous system is able to inhibit and activate sympathetic signals. The investigators anticipate that those with autonomic dysfunction after spinal cord injury will exhibit abnormalities in these precise metrics. In both study populations, transcutaneous spinal cord stimulation will be added, testing previously advocated parameters to alter autonomic neuroregulation. In accomplishing this, the investigators hope to give important insights to how the autonomic nervous system works after spinal cord injury and if it's function can be improved utilizing neuromodulation.
Interventions
DIAGNOSTIC_TESTTests of sympathetic inhibition
Bolus phenylephrine infusion using the Oxford technique will generate the need to inhibit sympathetic activity. Similarly, resting state Mayer waves will be assessed with regard to heart rate and blood pressure responses.
DIAGNOSTIC_TESTTests of sympathetic activation
Cold pressor test of the hand will be used to cause sympathetic activation. Valsalva's maneuver will assess the ability to buffer against blood pressure fall (phase II).
DIAGNOSTIC_TESTTesting of autonomic dysreflexia
Cold pressor test of the foot and bladder pressor response (in individuals with SCI) will be tested.
DEVICETranscutaneous spinal cord stimulation
Transcutaneous spinal cord stimulation will be applied at T7-L1 spinal segments to assess alterations in autonomic neuroregulation.
Sponsors
Medical University of South Carolina
Spaulding Rehabilitation Hospital
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
All participants \- age 18-30 years old. Participants with spinal cord injury * Adult onset, traumatic spinal cord injury. * Time since injury 1 year, in an effort to limit baroreflex desensitization. * American Spinal Injury Association Impairment Scale, A, to limit potential confounders. * Neurological level of injury, T1-T6, as defined by the International Standards for Neurological Classification of Spinal Cord Injury.
Exclusion criteria
* History of cardiovascular disease, hypertension, neurologic disorders (with exception of spinal cord injury), or diabetes. * Women who are pregnant or lactating. * Currently taking blood thinners. * Taking anti-hypertensive or other medication that could influence any of the dependent autonomic variables.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Valsalva Maneuver Phase II | Through study completion, average 3 months | Presence or absence of phase II on Valsalva maneuver testing, which takes approximately 15 seconds to complete. This will be repeated x3. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Beat-to-beat heart rate | Through study completion, average 3 months | Electrocardiogram will record continuous measures with changes in R-R interval (ms) quantified and compared to baseline. |
| Beat-to-beat blood pressure | Through study completion, average 3 months | Non-invasive continuous blood pressure monitors will be used, with changes in systolic and diastolic pressure (in mmHg) from resting baseline measured. |
| Muscle sympathetic nerve activity | Through study completion, average 3 months | Microneurography will be performed to characterize cardiovascular autonomic phenotypes between uninjured controls and individuals with spinal cord injury. This will be quantified by spike frequency. |
| Quantify autonomic dysreflexia and orthostatic hypotension | Baseline, prior to initial laboratory diagnostic testing session | Participants will be given the Autonomic Dysfunction Following Spinal Cord Injury questionnaire (score range 0-436, with higher scores indicating more autonomic dysfunction). |
| Quantify secondary autonomic complications | Baseline, prior to initial laboratory diagnostic testing session | Participants will be given the Composite Autonomic Symptom Score (range 0-100, with higher scores indicating more autonomic dysfunction). |
| Continuous galvanic skin response | Through study completion, average 3 months | Changes from resting state conductance with be quantified with a smartwatch. |
Countries
United States
Outcome results
None listed