Blunted heart rate response to vagal withdrawal in persons with tetraplegia

Exploring the vagus nerve and the inflammatory reflex for therapeutic benefit in chronic spinal cord injury

PURPOSE OF REVIEW

To describe features and implications of chronic systemic inflammation in individuals with spinal cord injury (SCI) and to summarize the growing therapeutic possibilities to explore the vagus nerve-mediated inflammatory reflex in this context.

RECENT FINDINGS

The discovery of the inflammatory reflex provides a rationale to explore neuromodulation modalities, that is, electrical vagus nerve stimulation and pharmacological cholinergic modalities to regulate inflammation after SCI.

SUMMARY

Inflammation in individuals with SCI may negatively impact functional recovery and medical consequences after SCI. Exploring the potential of the vagus nerve-based inflammatory reflex to restore autonomic regulation and control inflammation may provide a novel approach for functional improvement in SCI.

The effect of arm-crank exercise training on power output, spirometric and cardiac function and level of autonomy in persons with tetraplegia

Studies on the effects of exercise training in persons with cervical spinal cord injury (CSCI) are scarce. The aim of this study was to determine the effect of an 8-week stationary arm-crank exercise (ACE) training programme on the level of autonomy, exercise performance, pulmonary functional parameters and resting heart rate variability (HRV) in persons with CSCI. Quadriplegia Index of Function (QIF), arm-crank peak power output (Ppeak), spirometric variables, and HRV indices were measured before and after the training programme in a group of 11 persons with CSCI. ACE training increased Ppeak in both groups (p < 0.05), whereas maximum voluntary ventilation (MVV) and low frequency HRV (LF) improved only in the lower CSCI group (p < 0.05). Moreover, QIF and Ppeak were significantly correlated before (r = 0.88; p < 0.01) and after (r = 0.86; p < 0.01) the training period. However, no significant changes were found in the level of autonomy (QIF) as a result of the intervention. Therefore, stationary ACE training appears to be a feasible and effective method for aerobic exercise in persons with tetraplegia and a short-term intervention is able to significantly improve exercise capacity, cardiac autonomic regulation and respiratory muscle endurance, regardless of the absence of significant immediate changes in the level of autonomy.

A call to reevaluate cardiac autonomic assessment after spinal cord injury

This "Perspectives" article puts forward the notion that measuring heart rate variability, or other forms of cardiac autonomic regulation, after spinal cord injury must be performed during a test of autonomic stress. Resting values of heart rate variability are often similar to those obtained from able-bodied individuals, which may therefore be falsely interpreted as normal or healthy autonomic regulation. However, evidence shows that despite normal resting values, cardiac autonomic control is impaired when individual with spinal cord injury are subjected to a cold face test, head-up tilt, or recovery from exercise. Accordingly, examination of cardiac autonomic function must be performed during an autonomic challenge, as resting measures do not accurately reflect the state of cardiovascular regulation after spinal cord injury and can provide false information.

Epidural Spinal Cord Stimulation of Lumbosacral Networks Modulates Arterial Blood Pressure in Individuals With Spinal Cord Injury-Induced Cardiovascular Deficits

Disruption of motor and autonomic pathways induced by spinal cord injury (SCI) often leads to persistent low arterial blood pressure and orthostatic intolerance. Spinal cord epidural stimulation (scES) has been shown to enable independent standing and voluntary movement in individuals with clinically motor complete SCI. In this study, we addressed whether scES configured to activate motor lumbosacral networks can also modulate arterial blood pressure by assessing continuous, beat-by-beat blood pressure and lower extremity electromyography during supine and standing in seven individuals with C5-T4 SCI. In three research participants with arterial hypotension, orthostatic intolerance, and low levels of circulating catecholamines (group 1), scES applied while supine and standing resulted in increased arterial blood pressure. In four research participants without evidence of arterial hypotension or orthostatic intolerance and normative circulating catecholamines (group 2), scES did not induce significant increases in arterial blood pressure. During scES, there were no significant differences in electromyographic (EMG) activity between group 1 and group 2. In group 1, during standing assisted by scES, blood pressure was maintained at 119/72 ± 7/14 mmHg (mean ± SD) compared with 70/45 ± 5/7 mmHg without scES. In group 2 there were no arterial blood pressure changes during standing with or without scES. These findings demonstrate that scES configured to facilitate motor function can acutely increase arterial blood pressure in individuals with SCI-induced cardiovascular deficits.

Alterations in autonomic cerebrovascular control after spinal cord injury

Among chronic cardiovascular and metabolic sequelae of spinal cord injury (SCI) is an up-to four-fold increase in the risk of ischemic and hemorrhagic stroke, suggesting that individuals with SCI cannot maintain stable cerebral perfusion. In able-bodied individuals, the cerebral vasculature is able to regulate cerebral perfusion in response to swings in arterial pressure (cerebral autoregulation), blood gases (cerebral vasoreactivity), and neural metabolic demand (neurovascular coupling). This ability depends, at least partly, on intact autonomic function, but high thoracic and cervical spinal cord injuries result in disruption of sympathetic and parasympathetic cerebrovascular control. In addition, alterations in autonomic and/or vascular function secondary to paralysis and physical inactivity can impact cerebrovascular function independent of the disruption of autonomic control due to injury. Thus, it is conceivable that SCI results in cerebrovascular dysfunction that may underlie an elevated risk of stroke in this population, and that rehabilitation strategies targeting this dysfunction may alleviate the long-term risk of adverse cerebrovascular events. However, despite this potential direct link between SCI and the risk of stroke, studies exploring this relationship are surprisingly scarce, and the few available studies provide equivocal results. The focus of this review is to provide an integrated overview of the available data on alterations in cerebral vascular function after SCI in humans, and to provide suggestions for future research.

Autonomic dysreflexia: a cardiovascular disorder following spinal cord injury

Autonomic dysreflexia (AD) is a serious cardiovascular disorder in patients with spinal cord injury (SCI). The primary underlying cause of AD is loss of supraspinal control over sympathetic preganglionic neurons (SPNs) caudal to the injury, which renders the SPNs hyper-responsive to stimulation. Central maladaptive plasticity, including C-fiber sprouting and propriospinal fiber proliferation exaggerates noxious afferent transmission to the SPNs, causing them to release massive sympathetic discharges that result in severe hypertensive episodes. In parallel, upregulated peripheral vascular sensitivity following SCI exacerbates the hypertensive response by augmenting gastric and pelvic vasoconstriction. Currently, the majority of clinically employed treatments for AD involve anti-hypertensive medications and Botox injections to the bladder. Although these approaches mitigate the severity of AD, they only yield transient effects and target the effector organs, rather than addressing the primary issue of central sympathetic dysregulation. As such, strategies that aim to restore supraspinal reinnervation of SPNs to improve cardiovascular sympathetic regulation are likely more effective for AD. Recent pre-clinical investigations show that cell transplantation therapy is efficacious in reestablishing spinal sympathetic connections and improving hemodynamic performance, which holds promise as a potential therapeutic approach.

Baroreceptor reflex during forced expiratory maneuvers in individuals with chronic spinal cord injury

Pulmonary and cardiovascular dysfunctions are leading causes of morbidity and mortality in patients with chronic Spinal Cord Injury (SCI). Impaired respiratory motor function and decreased Baroreflex Sensitivity (BS) are predictors for the development of cardiopulmonary disease. This observational case-controlled clinical study was undertaken to investigate if respiratory motor control deficits in individuals with SCI affect their ability to perform the Valsalva maneuver, and to determine if a sustained Maximum Expiratory Pressure (MEP) effort can serve as an acceptable maneuver for determination of the BS in the event that the Valsalva maneuver cannot be performed. The BS outcomes (ms/mmHg) were obtained using continuous beat-to-beat arterial blood pressure (BP) and heart rate (HR) recordings during Valsalva or MEP maneuvers in thirty nine individuals with chronic C3-T12 SCI. Twenty one participants (54%) reported signs of intolerance during the Valsalva maneuver and only 15 individuals (39%) were able to complete this task. Cervical level of injury was a significant risk factor (p=0.001) for failing to complete the Valsalva maneuver, and motor-complete injury was a significant risk factor for symptoms of intolerance (p=0.04). Twenty eight participants (72%) were able to perform the MEP maneuver; the other 11 participants failed to exceed the standard airway pressure threshold of 27cm H2O. Neither level nor completeness of injury were significant risk factors for failure of MEP maneuver. When the required airway pressure was sustained, there were no significant differences between BS outcomes obtained during Valsalva and MEP maneuvers. The results of this study indicate that individuals with high-level and motor-complete SCI are at increased risk of not completing the Valsalva maneuver and that baroreflex-mediated responses can be evaluated by using sustained MEP maneuver when the Valsalva maneuver cannot be performed.

Assessing complexity of heart rate variability in people with spinal cord injury using local scale exponents

Detrended fluctuation analysis (DFA) has been widely used to study dynamics of heart rate variability (HRV), which provides a quantitative parameter, the scaling exponent a, to represent the correlation properties of RR interval series. However, it has been demonstrated that HRV exhibits complex behavior that cannot be fully described by a single exponent. This study aimed to investigate whether local scale exponent α(t) with t being the time scale can reveal new features of HRV that cannot be reflected by DFA coefficients. To accurately estimate α(t), we developed an approach for correcting a(t) at small scales and verified the approach using simulated signals. We studied HRV in 12 subjects with spinal cord injury and 14 able-bodied controls during sitting and prone postures. The results showed that α(t) provides complementary views of HRV, suggesting that it may be used to evaluate the effects of SCI-induced autonomic damage on HRV.

Using local scale exponent to characterize heart rate variability in response to postural changes in people with spinal cord injury

Heart rate variability (HRV) is a promising marker for evaluating the remaining autonomic function in people with spinal cord injury (SCI). HRV is commonly assessed by spectral analysis and detrended fluctuation analysis (DFA). This study aimed to investigate whether local scale exponent α(t) can reveal new features of HRV that cannot be reflected by spectral measures and DFA coefficients. We studied 12 participants with SCI and 15 healthy able-bodied controls. ECG signals were continually recorded during 10 min sitting and 10 min prone postures. α(t) was calculated for scales between 4 and 60 s. Because α(t) could be overestimated at small scales, we developed an approach for correcting α(t) based on previous studies. The simulation results on simulated monofractal time series with α between 0.5 and 1.3 showed that the proposed method can yield improved estimation of α(t). We applied the proposed method to raw RR interval series. The results showed that α(t) in healthy controls monotonically decreased with scale at scales between 4 and 12 s (0.083–0.25 Hz) in both the sitting and prone postures, whereas in participants with SCI, α(t) slowly decreased at almost all scales. The sharp decreasing trend in α(t) in controls suggests a more complex dynamics of HRV in controls. α(t) at scales between 4 (0.25 Hz) and around 7 s (0.143 Hz) was lower in subjects with SCI than in controls in the sitting posture; α(t) at a narrow range of scales around 12 s (0.083 Hz) was higher in participants with SCI than in controls in the prone posture. However, none of normalized low frequency (0.04–0.15 Hz) power, the ratio of low frequency power to high frequency (0.15–0.4 Hz) power and long-term (>11 beats) DFA coefficient showed significant difference between healthy controls and subjects with SCI in the prone posture. Our results suggest that α(t) can reveal more detailed information in comparison to spectral measures and the standard DFA parameters.

Kalpakjian C, W. Choi S, Jette AM, Forchheimer M, Cella D. Overview of the Spinal Cord Injury--Quality of Life (SCI-QOL) measurement system

CONTEXT/OBJECTIVE

The Spinal Cord Injury--Quality of Life (SCI-QOL) measurement system was developed to address the shortage of relevant and psychometrically sound patient reported outcome (PRO) measures available for clinical care and research in spinal cord injury (SCI) rehabilitation. Using a computer adaptive testing (CAT) approach, the SCI-QOL builds on the Patient Reported Outcomes Measurement Information System (PROMIS) and the Quality of Life in Neurological Disorders (Neuro-QOL) initiative. This initial manuscript introduces the background and development of the SCI-QOL measurement system. Greater detail is presented in the additional manuscripts of this special issue.

DESIGN

Classical and contemporary test development methodologies were employed. Qualitative input was obtained from individuals with SCI and clinicians through interviews, focus groups, and cognitive debriefing. Item pools were field tested in a multi-site sample (n=877) and calibrated using item response theory methods. Initial reliability and validity testing was performed in a new sample of individuals with traumatic SCI (n=245).

SETTING

Five Model SCI System centers and one Department of Veterans Affairs Medical Center across the United States.

PARTICIPANTS

Adults with traumatic SCI.

INTERVENTIONS

n/a

OUTCOME MEASURES

n/a

RESULTS

The SCI-QOL consists of 19 item banks, including the SCI-Functional Index banks, and 3 fixed-length scales measuring physical, emotional, and social aspects of health-related QOL (HRQOL).

CONCLUSION

The SCI-QOL measurement system consists of psychometrically sound measures for individuals with SCI. The manuscripts in this special issue provide evidence of the reliability and initial validity of this measurement system. The SCI-QOL also links to other measures designed for a general medical population.

Preserved cardiac autonomic dynamics during sleep in subjects with spinal cord injuries

BACKGROUND

Spinal cord injuries (SCI) are associated with altered cardiovascular autonomic control (CAC). Sleep is characterized by modifications of autonomic control across sleep stages; however, no data are available in SCI subjects on CAC during sleep. We aim to assess cardiac autonomic modulation during sleep in subjects with SCI.

PATIENTS AND METHODS

27 participants with a neurological and radiological diagnosis of cervical (Cerv, n = 12, ie, tetraplegic) and thoracic SCI (Thor, n = 15, ie, paraplegic) and healthy subjects (Controls) were enrolled. Overnight polysomnographic (PSG) recordings were obtained in all participants. Electrocardiography and respiration were extracted from PSG, divided into sleep stages [wakefulness (W), non-REM sleep (NREM) and REM] for assessment of CAC, using symbolic analysis (SA) and corrected conditional entropy (CCE). SA identified indices of sympathetic and parasympathetic modulation and CCE evaluated the degree of complexity of the heart period time series.

RESULTS

SA revealed a reduction of sympathetic and predominant parasympathetic control during NREM compared to W and REM in SCI patients, independent of the level of the lesion, similar to the Controls. In all three groups, complexity of autonomic regulation was higher in NREM compared to W and REM.

CONCLUSIONS

In subjects with SCI, cardiac autonomic control changed across sleep stages, with a reduction of sympathetic and an increase of parasympathetic modulation during NREM compared to W and REM, and a parallel increase of complexity during NREM, which was similar to the Controls. Cardiac autonomic dynamics during sleep are maintained in SCI, independent of the level of the lesion.

Cardiac acceleration at the onset of exercise: a potential parameter for monitoring progress during physical training in sports and rehabilitation

There is a need for easy-to-use methods to assess training progress in sports and rehabilitation research. The present review investigated whether cardiac acceleration at the onset of physical exercise (HRonset) can be used as a monitoring variable. The digital databases of Scopus and PubMed were searched to retrieve studies investigating HRonset. In total 652 studies were retrieved. These articles were then classified as having emphasis on HRonset in a sports or rehabilitation setting, which resulted in 8 of 112 studies with a sports application and 6 of 68 studies with a rehabilitation application that met inclusion criteria. Two co-existing mechanisms underlie HRonset: feedforward (central command) and feedback (mechanoreflex, metaboreflex, baroreflex) control. A number of studies investigated HRonset during the first few seconds of exercise (HRonsetshort), in which central command and the mechanoreflex determine vagal withdrawal, the major mechanism by which heart rate (HR) increases. In subsequent sports and rehabilitation studies, interest focused on HRonset during dynamic exercise over a longer period of time (HRonsetlong). Central command, mechanoreflexes, baroreflexes, and possibly metaboreflexes contribute to HRonset during the first seconds and minutes of exercise, which in turn leads to further vagal withdrawal and an increase in sympathetic activity. HRonset has been described as the increase in HR compared with resting state (delta HR) or by exponential modeling, with measurement intervals ranging from 0-4 s up to 2 min. Delta HR was used to evaluate HRonsetshort over the first 4 s of exercise, as well as for analyzing HRonsetlong. In exponential modeling, the HR response to dynamic exercise is biphasic, consisting of fast (parasympathetic, 0-10 s) and slow (sympathetic, 1-4 min) components. Although available studies differed largely in measurement protocols, cross-sectional and longitudinal training studies showed that studies analyzing HRonset in relation to physical training primarily incorporated HRonsetlong. HRonsetlong slowed in athletes as well as in patients with a coronary disease, who have a relatively fast HRonsetlong. It is advised to include both HRonsetlong and HRonsetshort in further studies. The findings of this review suggest that HRonset is a potential tool for monitoring and titrating training in sports as well as in rehabilitation settings, particularly in patients with ventricular fibrillation. Monitoring HRonset in the early phase of training can help optimize the effectiveness of training and therapy. More research is needed to gain a better understanding of the mechanisms underlying HRonset in relation to their application in sports and rehabilitation settings.

Comparison of changes in heart rate variability and sacral skin perfusion in response to postural changes in people with spinal cord injury

The current clinical practice has established guidelines to assess influences of severity of autonomic injury on the control of heart and blood pressure following spinal cord injury (SCI). However, the influences of SCI-induced autonomic impairment on microvascular dysfunction have not yet been established. Heart rate variability (HRV) has been shown to be a potential tool for quantifying residual sympathovagal regulation of the cardiovascular system following SCI and may be used to assess the effect of autonomic injury on skin microvascular dysfunction. A total of 26 people were recruited into the study, including 12 people with SCI and 14 nondisabled controls. HRV and sacral skin intervals and sacral skin perfusion were continually recorded during 10 min upright and 10 min prone postures. The sympathovagal balance was defined as the ratio of the power of the low frequency to the high frequency of HRV. The results showed that postural changes of nondisabled people produced significant changes in the sympathovagal balance; lower sympathovagal balance was associated with higher skin perfusion (p < 0.05). People with SCI did not show a significant change of HRV and skin perfusion in response to postural changes. In this study, we have demonstrated that the sympathovagal balance assessed by HRV was associated with the skin vasoconstrictive response to postural changes.

Decentralized cardiovascular autonomic control and cognitive deficits in persons with spinal cord injury

Spinal cord injury (SCI) results in motor and sensory impairments that can be identified with the American Spinal Injury Association (ASIA) Impairment Scale (AIS). Although, SCI may disrupt autonomic neural transmission, less is understood regarding the clinical impact of decentralized autonomic control. Cardiovascular regulation may be altered following SCI and the degree of impairment may or may not relate to the level of AIS injury classification. In general, persons with lesions above T1 present with bradycardia, hypotension, and orthostatic hypotension; functional changes which may interfere with rehabilitation efforts. Although many individuals with SCI above T1 remain overtly asymptomatic to hypotension, we have documented deficits in memory and attention processing speed in hypotensive individuals with SCI compared to a normotensive SCI cohort. Reduced resting cerebral blood flow (CBF) and diminished CBF responses to cognitive testing relate to test performance in hypotensive non-SCI, and preliminary evidence suggests a similar association in individuals with SCI. Persons with paraplegia below T7 generally present with a normal cardiovascular profile; however, our group and others have documented persistently elevated heart rate and increased arterial stiffness. In the non-SCI literature there is evidence supporting a link between increased arterial stiffness and cognitive deficits. Preliminary evidence suggests increased incidence of cognitive impairment in individuals with paraplegia, which we believe may relate to adverse cardiovascular changes. This report reviews relevant literature and discusses findings related to the possible association between decentralized cardiovascular autonomic control and cognitive dysfunction in persons with SCI.

31st g. Heiner sell lectureship: secondary medical consequences of spinal cord injury

Persons with spinal cord injury (SCI) have secondary medical consequences of paralysis and/or the consequences of extreme inactivity. The metabolic changes that result from reduced activity include insulin resistance with carbohydrate disorders and dyslipidemia. A higher prevalence of coronary artery calcification was found in persons with SCI than that in matched able-bodied controls. A depression in anabolic hormones, circulating testosterone and growth hormone, has been described. Adverse soft tissue body composition changes of increased adiposity and reduced skeletal muscle are appreciated. Immobilization is the cause for sublesional disuse osteoporosis with an associated increased risk of fragility fracture. Bowel dysmotility affects all segments of the gastrointestinal tract, with an interest in better defining and addressing gastroesophageal reflux disease and difficulty with evacuation. Developing and testing more effective approaches to cleanse the bowel for elective colonoscopy are being evaluated. The extent of respiratory dysfunction depends on the level and completeness of SCI. Individuals with higher spinal lesions have both restrictive and obstructive airway disease. Pharmacological approaches and expiratory muscle training are being studied as interventions to improve pulmonary function and cough strength with the objective of reducing pulmonary complications. Persons with spinal lesions above the 6th thoracic level lack both cardiac and peripheral vascular mechanisms to maintain blood pressure, and they are frequently hypotensive, with even worse hypotension with upright posture. Persistent and/or orthostatic hypotension may predispose those with SCI to cognitive impairments. The safety and efficacy of anti-hypotensive agents to normalize blood pressure in persons with higher level cord lesions is being investigated.

Systemic and cerebral hemodynamics during cognitive testing

OBJECTIVE

Cognitive deficits are reported in 10-60% of individuals with SCI, the primary etiology of these deficits is believed to be concomitant traumatic brain injury (TBI). We recently documented diminished memory and marginally deficient attention and processing speed in individuals with SCI discordant for hypotension but matched for TBI.

METHODS

Twenty-nine individuals participated: 16 non-SCI controls, 6 paraplegic (T2-T10) and 7 tetraplegic (C4-C8). The Stroop test was used to measure cognitive function and transcranial Doppler ultrasound was used to measure cerebral blood flow (CBF) while resting (5 min) and continuously during cognitive testing. Mean arterial pressure (MAP) was calculated from three brachial blood pressures and cerebral vascular resistance index was calculated as: CVRi = MAP/CBF.

RESULTS

The paraplegia group (54 ± 6) was marginally older than the non-SCI (42 ± 15; p = 0.06) and tetraplegic (42 ± 11; p = 0.09) groups. Compared to non-SCI group, normalized t-score on the Stroop Color (SC) task was significantly lower in the paraplegic group (p < 0.05). In the tetraplegic group, MAP was significantly lower (p < 0.05) than the non-SCI and paraplegic groups, and related to SC t-score (r (2) = 0.873; p < 0.01). In the paraplegic group, CBF was reduced (p < 0.05) and CVRi increased (p < 0.05) compared to the non-SCI group, and CVRi was increased compared to the tetraplegic group (p < 0.05). A significant inverse relationship was noted between change in CVRi and SC t-score in the non-SCI group.

CONCLUSION

Asymptomatic hypotension relates to cognitive performance in persons with tetraplegia; therefore, BP normalization should be considered. The inappropriate cerebral vascular response to cognitive testing and poor test performance should be investigated in persons with paraplegia.

The isolated sympathetic spinal cord: Cardiovascular and sudomotor assessment in spinal cord injury patients: A literature survey

OBJECTIVES

To present a comprehensive approach to the assessment of the severity of the autonomic lesion in spinal cord injury (SCI) patients, with regard to the level of lesion. To discuss how to assess an isolated sympathetic spinal cord that has lost supraspinal control (sympathetically complete lesion).

METHOD

PubMed was searched for articles related to cardiovascular (mainly cold pressor test, respiratory and postural challenges) and sudomotor (sympathetic skin responses) tests that have been used. The results of these evaluations are analysed with regard to the site of stimulation (above or below the lesion) according to three types of SCI that offer typical autonomic reactions (tetraplegics, paraplegics at T6 and at T10).

RESULTS

Non-invasive cardiovascular and sudomotor testing allows the assessment of the isolated sympathetic spinal cord in SCI patients. Typical responses are found in relation with the level of the sympathetic lesion. Its definition would allow comparison with the somatic motor and sensory level of lesion of SCI patients and provide additional aid to the classification of those patients.

CONCLUSION

For research purposes on the integrity of the spinal sympathetic pathways, a battery of test approach is probably needed, using a combination of stimuli above and below the lesion, evaluating both cardiovascular and sudomotor pathways.

Cognitive performance in hypotensive persons with spinal cord injury

BACKGROUND

Due to sympathetic de-centralization, individuals with spinal cord injury (SCI), especially those with tetraplegia, often present with hypotension, worsened with upright posture. Several investigations in the non-SCI population have noted a relationship between chronic hypotension and deficits in memory, attention and processing speed and delayed reaction times.

OBJECTIVE

To determine cognitive function in persons with SCI who were normotensive or hypotensive over a 24-h observation period while maintaining their routine activities.

METHODS

Subjects included 20 individuals with chronic SCI (2-39 years), 13 with tetraplegia (C4-8) and 7 with paraplegia (T2-11). Individuals with hypotension were defined as having a mean 24-h systolic blood pressure (SBP) below 110 mmHg for males and 100 mmHg for females, and having spent >or=50% of the total time below these gender-specific thresholds. The cognitive battery used included assessment of memory (CVLT), attention and processing speed (Digit Span, Stroop word and color and Oral Trails A), language (COWAT) and executive function (Oral Trails B and Stroop color-word).

RESULTS

Demographic parameters did not differ among the hypotensive and normotensive groups; the proportion of individuals with tetraplegia (82%) was higher in the hypotensive group. Memory was significantly impaired (P < 0.05) and there was a trend toward slowed attention and processing speed (P < 0.06) in the hypotensive compared to the normotensive group.

INTERPRETATION

These preliminary data suggest that chronic hypotension in persons with SCI is associated with deficits in memory and possibly attention and processing speed, as previously reported in the non-SCI population.