Solinsky, Ryan

Individuals with spinal cord injury (SCI) have significant dysfunction in cardiovascular autonomic regulation. While recent findings postulate that spinal cord stimulation improves autonomic regulation, limited scope of past methods have tested only above level sympathetic activation, leaving significant uncertainty. To identify whether transcutaneous spinal cord stimulation improves cardiovascular autonomic regulation, two pairs of well-matched individuals with and without high-thoracic, complete SCI were recruited. Baseline autonomic regulation was characterized with multiple tests of sympathoinhibition and above/below injury level sympathoexcitation. At three subsequent visits, testing was repeated with the addition sub-motor threshold transcutaneous spinal cord stimulation at three previously advocated frequencies. Uninjured controls demonstrated no autonomic deficits at baseline and had no changes with any frequency of stimulation. As expected, individuals with SCI had baseline autonomic dysfunction. In a frequency-dependent manner, spinal cord stimulation enhanced sympathoexcitatory responses, normalizing previously impaired Valsalva's maneuvers. However, stimulation exacerbated already impaired sympathoinhibitory responses, resulting in significantly greater mean arterial pressure increases with the same phenylephrine doses compared to baseline. Impaired sympathoexcitatory response below the level of injury were also further exacerbated with spinal cord stimulation. At baseline, neither individual with SCI demonstrated autonomic dysreflexia with the noxious foot cold pressor test; the addition of stimulation led to a dysreflexic response in every trial, with greater relative hypertension and bradycardia indicating no improvement in cardiovascular autonomic regulation. Collectively, transcutaneous spinal cord stimulation demonstrates no improvements in autonomic regulation after SCI, and instead likely generates tonic sympathoexcitation which may lower the threshold for dangerous autonomic dysreflexia.

AbstractBackgroundAutonomic dysreflexia (AD) is a frequent complication of spinal cord injury (SCI), though current clinical practice patterns for medication management of this condition are unknown. Correspondingly, it is unclear if national differences in practice patterns exist.ObjectiveTo determine trends in current pharmacologic management of AD throughout the Americas.DesignInternational survey of current physician practice patterns.SettingAcademic medical center.ParticipantsSixty physicians managing patients with SCI and prescribing medications to manage AD.InterventionsNot applicable.Main Outcome MeasuresPresence of a formal pharmacologic AD management protocol, first‐ and second‐line medications, patient characteristics influencing pharmacologic management.ResultsThe majority of physicians (69%) had a formal AD management protocol for inpatient care, with nitroglycerin ointment (82%) being the most common first‐line medication. Strong national differences existed regarding the use of nitroglycerin ointment, with 98% of U.S.‐based physicians using this as first‐line medication and 0% of physicians in Canada or Latin America using this due to recent lack of medication availability. Only 67% of physicians had a preferred second‐line medication, with preferences split between hydralazine (48%) and nifedipine (28%). A systolic blood pressure threshold for pharmacologic management was used by 56% of physicians, wheres 26% considered neurological level of injury in decisions to use medications for AD. Heart rate was used by only 5% of physicians in their decision to manage AD with medications.ConclusionsAs of 2023, U.S.‐based physicians caring for individuals with SCI largely have formal inpatient protocols in place for medication management of AD, with nearly all relying on nitroglycerin ointment as their first‐line medication. In areas outside of the United States where nitroglycerin ointment is unavailable, pharmacologic practice patterns significantly differ.