Citations

Background: Spasticity is common in spinal cord injury (SCI) and multiple sclerosis (MS), and it can manifest as repeated, rhythmic muscle contractions called clonus. The spontaneous nature of clonus can disrupt independent performance of activities of daily living and negatively impact overall health and quality of life. Objectives: To quantify biomarkers of clonus and explore management of clonus in individuals with SCI or progressive MS using epidural spinal cord stimulation (ES) or dorsal root stimulation (DRS). Methods: Four male participants were included in this case series study: 3 with SCI and 1 with MS. All participants underwent temporary percutaneous ES lead placement over the dorsolateral thoracolumbar region of the spinal cord. Participants with SCI were also implanted with DRS leads at the L4 dorsal root. Clonus was elicited mechanically at the ankle while recording electromyography of the soleus muscle synchronized to direct spinal cord field potential recordings from ES and DRS percutaneous leads. Results: Clonus was evident as a prominent band (5-8 Hz) in recordings from ES leads, DRS leads, soleus muscle, and accelerometry. In 4 participants, percutaneous spinal stimulation reduced median clonus duration and cycle count. Clonus was immediately suppressed upon activation of spinal cord stimulation, and the suppression persisted even when clonus was reinitiated after turning off the stimulation. Conclusion: The use of objective biomarkers, including spinal cord potentials, to quantify clonus in real time combined with the immediate and reversible effects of stimulation highlight the potential of neuromodulation as a therapeutic tool for managing clonus. These data demonstrate preliminary efficacy of ES and DRS for clonus monitoring and treatment in 4 participants.

Objectives: To describe changes in the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) exam in sublesional motor and sensory domains following short-term epidural electrical stimulation of lumbosacral spinal segments in individuals with spinal cord injury (SCI). Methods: Twenty individuals with SCI underwent implantation of percutaneous epidural spinal cord stimulation followed by stimulation parameter optimization and 10-12 sessions of stimulation-enabled motor training. Pre-/postintervention ISNCSCI exams were compared to determine changes in motor/sensory scores for regions within 3 levels of the neurological level of injury (NLI) and caudal to this, with subanalyses per motor/sensory complete versus incomplete baseline status. Results: Individuals with motor complete SCI gained 6% ± 3% of available motor points within 3 levels of NLI and 1% ± 0% of motor points caudal to this ( P = .08). Motor incomplete individuals gained 9% ± 22% of available motor points within 3 levels of NLI and lost 4% ± 7% of motor points caudal to this ( P = .63). Following stimulation, changes in motor scores with potential high functional impact occurred in 3 individuals (5 total muscle groups with conversion from baseline <3/5 strength to ≥3/5 at completion). Individuals with sensory complete SCI had fewer sensory gains within 3 levels of NLI (6%) compared to those with sensory incomplete SCI (30%, P = .02). Discussion: Spinal cord stimulation after SCI rapidly induces changes in both motor and sensory domains that are retained after stimulation is removed. These changes primarily occur within 3 levels of the NLI and occur to a greater degree in those with incomplete SCI.

Background: Autonomic dysfunction is common after spinal cord injury (SCI). There are currently limited tools to comprehensively characterize its deficits. While individual established autonomic tests have a long history and sound scientific background, translating these autonomic testing results to inform clinical understanding is a major barrier. Objectives: To assess a strategic battery of autonomic tests to characterize and act as a biomarker of autonomic regulation for individuals with SCI and to develop a novel graphical representation of these data to facilitate understanding of autonomic dysfunction after SCI. Methods: We outline a battery of six laboratory autonomic tests that were curated to collectively describe the ability of individuals with SCI to inhibit and recruit sympathetic activity through the injured spinal cord. Heart rate/blood pressure variability, bolus phenylephrine, hand and foot cold pressor, Valsalva maneuver, and bladder pressor are herein described. Incorporating normative control data for 30 uninjured individuals completing this testing battery, we further demonstrate the utility of a composite biomarker, comparing these control results to 11 individuals with SCI. Results: Results demonstrate strong normality of data with testing psychometrics, suggesting stable reproducibility with repeat testing. Even in this preliminary sample of individuals with SCI, clear differences begin to emerge compared to uninjured norms. This illustrates the ability of this collective testing battery to characterize autonomic regulation after SCI. To aid in clinical translation, we further present a graphical representation, an autonomic phenotype , which serves as a snapshot of how normal or abnormal sympathetic inhibition and recruitment of activation may be after SCI. Conclusion: Utilizing these autonomic phenotypes, three example cases of individuals with SCI highlight evidence of varied degrees of autonomically complete SCI. Together, this represents a key advancement in our understanding of autonomic function after SCI.

AbstractBackgroundIndividuals 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.ObjectiveTo evaluate the relationship between baroreflex and blood vessel sensitivity with AD symptoms.DesignCase control.SettingTertiary academic center.Patients14 individuals with SCI, 17 matched uninjured controls.InterventionsAll 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 MeasuresBaroreflex sensitivity after increased SBP; Vascular responsiveness through quantified mean arterial pressure (MAP) 2‐minute area under the curve and change in vascular resistance.ResultsSCI and control cohorts were well matched with mean age 31.9 and 29.6 years (p = .41); 21.4% and 17.6% female, respectively. Baseline MAP (p = .83) and R‐R interval (p = .39) were similar. ADFSCI‐AD scores were higher following SCI (27.9 ± 22.9 vs. 4.2 ± 2.9 in controls, p = .002). To quantify SBP response, MAP area under the curve was normalized to dose/body weight. Individuals with SCI had significantly larger responses (0.26 ± 0.19 mmHg*s/kg*μg) than controls (0.06 ± 0.06 mmHg*s/kg*μg, p = .002). Similarly, leg vascular resistance increased after SCI (24% vs. 6% to a normalized dose, p = .007). Baroreflex sensitivity was significantly lower after SCI (15.0 ± 8.3 vs. 23.7 ± 9.3 ms/mmHg, p = .01). ADFSCI‐AD subscore had no meaningful correlation with vascular responsiveness (R2 = 0.008) or baroreflex sensitivity (R2 = 0.092) after SCI.ConclusionsAlthough this confirms smaller previous studies suggesting increased α1 adrenoreceptor sensitivity and lower baroreflex sensitivity in individuals with SCI, contrary to our hypothesis these differences lacked correlation to increased symptoms of AD. Further research into physiologic mechanisms is needed to explain why some individuals with SCI develop symptoms.

Spinal cord stimulation for motor recovery after spinal cord injury is a popular research intervention, though off-target effects are a concern. Using continual blood pressure and heart rate recordings during passive spinal cord stimulation parameter testing, we identified frequent episodes of autonomic dysreflexia that were rarely associated with symptoms. This presents a previously unrecognized risk of spinal cord stimulation and appropriate vigilance in targeted monitoring is urged to maintain participant safety.

Abstract Study Design: Secondary outcome measures analysis of a randomized, controlled study. Objectives: To assess the effects of hybrid-functional electrical stimulation (FES) rowing, arms only (AO) rowing and waitlist (WL) controls on pain, pain interference, and depression in individuals with spinal cord injury (SCI). Setting: Outpatient rehabilitation networks Methods: 44 participants were randomly assigned to FES (n = 19), AO (n= 12) or WL (n=13). The FES group completed 6 months of rowing scheduled 3 times per week. Individuals in the AO and WL groups were allowed to cross over to FES rowing after 6 months and were included in subsequent analyses of the effects of FES rowing. Rowing distance and intensity was logged, and maximal oxygen consumption (VO2max) measures were obtained before and after the intervention. Changes in the Patient-Reported Outcomes Measurement Information System (PROMIS-56) derived pain interference, pain, and depression scores were analyzed. Results: FES-rowing led to modest improvements in depression, AO led to modest improvements in pain intensity, and WL did not improve pain nor depression. After incorporating individuals who crossed over to FES rowing, we observed modest but significant improvement in depression scores but not in pain. Among the participants who benefited from the FES intervention, the reduction in depression was correlated to the average weekly rowing distance (r2=0.79 p=0.0001). Conclusions: 6 months of FES rowing spent in a supportive environment can help persons with spinal cord injuries alleviate moderate depression in a dose-dependent manner.

Abstract Study design: Cross-sectional study Objectives: Determine how well common clinical assessments of level and completeness of injury are correlated with symptoms of autonomic blood pressure instability and secondary medical complications after spinal cord injury (SCI). Setting: Academic medical center, United States Methods: Eighty-two individuals with (n=48) and without (n=34) SCI had symptoms of autonomic blood pressure instability quantified with the Autonomic Dysfunction Following SCI (ADFSCI) survey. Health histories quantified the secondary medical complications through number of urinary tract infections and hospitalizations in the past year, time to complete bowel program, and lifetime pressure injuries. Regression models were completed to identify strengths of associated correlations. Results: ADFSCI scores were significantly higher in individuals with SCI than controls. Neurological level of injury and ASIA impairment scale were both minimally correlated to symptoms of autonomic blood pressure instability, accounting for only 11.5% of variability in regression models. Secondary medical complications had similar, minimal correlations to level and motor/sensory completeness of SCI (R2=0.07 and R2=0.03 respectively). Contrasting this, symptoms of blood pressure instability on ADFSCI far outperformed the common clinical motor/sensory bedside exam, with moderately strong correlations to the ranked number of secondary medical complications after SCI (R2=0.31). Conclusion: Neurological level of injury and motor/sensory completeness provided limited insights into which individuals with SCI would have blood pressure instability or secondary medical complications. Interestingly, symptoms of blood pressure instability outperform the clinical motor/sensory bedside exam, with higher correlations to autonomically-mediated secondary medical complications after SCI.

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.