Spinal Cord Injuries
Conditions
Brief summary
The purpose of this research is to learn about how the participant's body is able to balance changes in blood pressure, and how spinal cord stimulation affects these changes as well as immune & cardiovascular function in participants with spinal cord injury.
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 above level 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 below level sympathetic activation
Cold pressor test of the foot and bladder pressor response (in individuals with SCI) will be tested.
DEVICEEpidural stimulation
Currently implanted epidural stimulation will be used during diagnostic testing.
Transcutaneous stimulation will be used for participants with spinal cord injury without an implanted stimulator during diagnostic testing.
Sponsors
Mayo Clinic
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Age 18-50. * American Spinal Injury Association Impairment Scale A-D,64 to encompass a representational spectrum of autonomic dysfunction after spinal cord injury. * Neurological level of injury, C6-T8, as defined by the International Standards for Neurological Classification of Spinal Cord Injury.64 Incorporating level of injury over this broad range to capture the spectrum of autonomic dysfunction. Individuals with injuries below T8 will not be included to ensure transcutaneous spinal cord stimulation does not occur over the injury/glial scar, where it may have altered properties. The C6 level was chosen to ensure hand cold pressor stimuli triggers above level sympathetic activation. * Time since injury of greater than six months, given early changes in spinal cord connectivity and recovery prior to this. * Both individuals with and without currently implanted epidural spinal cord stimulators will be enrolled. * Twenty uninjured controls will also be enrolled.
Exclusion criteria
* History of clinically diagnosed cardiovascular disease, diabetes, autonomic neuropathies, neurological disorders (with exception of spinal cord injury for individuals in those cohorts), or are active smokers. * Individuals who are taking betablockers, antihypertensives, or other sympathetically active medications which they are unable to hold. * Women who are pregnant or lactating, given known hormonal influences on autonomic regulation.65,66 * Cognitive issues preventing informed consent for participation. * Body mass index \>30 kg/m2 for the uninjured controls only given increased risk of prediabetes and potential confounding normative values. * taking or being administered a medication known to potentially have adverse interactions with phenylephrine * in the judgement of the principal investigator, any illness or condition that will interfere with the patient's ability to comply with the protocol, compromise patient safety, or interfere with the interpretation of the study results
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Valsalva Maneuver Phase II | During laboratory diagnostic testing session | 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 | During laboratory diagnostic testing session | Electrocardiogram will record continuous measures with changes in R-R interval (ms) quantified and compared to baseline. |
| Beat-to-beat blood pressure | During laboratory diagnostic testing session | Non-invasive continuous blood pressure monitors will be used, with changes in systolic and diastolic pressure (in mmHg) from resting baseline measured. |
| Continuous galvanic skin response | During laboratory diagnostic testing session | Changes from resting state conductance with be quantified with a smartwatch. |
| Quantify autonomic dysreflexia and orthostatic hypotension | Baseline, prior to 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). |
| Respiration | During laboratory diagnostic testing session | Elastic respiratory transducer bands around mid-chest and upper abdomen will monitor breathing depth and frequency. |
| Beat-by-Beat Popliteal and Brachial Blood Flow | During laboratory diagnostic testing session | The investigators will use Doppler derived flow velocities to estimate whole limb blood flow through the popliteal and brachial arteries |
| Immunology Blood Draw | During laboratory diagnostic testing session | Baseline samples will be collected and compared against changes to blood pressure. |
| Serum Catecholamines and Cortisol | During laboratory diagnostic testing session | Baseline resting catecholamines (norepinephrine, epinephrine, dopamine) and cortisol will be drawn from the IV after 10 minutes of quiet rest at baseline and prior to bladder filling or foot cold pressor. Just prior to the conclusion of this testing, an additional blood draw will take place through the IV to assess changes in these levels. |
Countries
United States
Contacts
CONTACTErin Lund
PRINCIPAL_INVESTIGATORRyan J. Solinsky, MD
Mayo Clinic
Outcome results
None listed