Cardiorespiratory Responses to Acute Intermittent Hypoxia in Humans With Chronic Spinal Cord Injury.

Brief exposure to repeated episodes of low inspired oxygen, or acute intermittent hypoxia (AIH), is a promising therapeutic modality to improve motor function after chronic, incomplete spinal cord injury (SCI). Although therapeutic AIH is under extensive investigation in persons with SCI, limited data are available concerning cardiorespiratory responses during and after AIH exposure despite implications for AIH safety and tolerability. Thus, we recorded immediate (during treatment) and enduring (up to 30 min post-treatment) cardiorespiratory responses to AIH in 19 participants with chronic SCI (>1 year post-injury; injury levels C1 to T6; American Spinal Injury Association Impairment Scale A to D; mean age = 33.8 ± 14.1 years; 18 males). Participants completed a single AIH (15, 60-sec episodes, inspired O2 ≈ 10%; 90-sec intervals breathing room air) and Sham (inspired O2 ≈ 21%) treatment, in random order. During hypoxic episodes: (1) arterial oxyhemoglobin saturation decreased to 82.1 ± 2.9% (p < 0.001); (2) minute ventilation increased 3.83 ± 2.29 L/min (p = 0.008); and (3) heart rate increased 4.77 ± 6.82 bpm (p = 0.010). Considerable variability in cardiorespiratory responses was found among subjects; some individuals exhibited large hypoxic ventilatory responses (≥0.20 L/min/%, n = 11), whereas others responded minimally (<0.20 L/min/%, n = 8). Apneas occurred frequently during AIH and/or Sham protocols in multiple participants. All participants completed AIH treatment without difficulty. No significant changes in ventilation, heart rate, or arterial blood pressure were found 30 min post-AIH p > 0.05). In conclusion, therapeutic AIH is well tolerated, elicits variable chemoreflex activation, and does not cause persistent changes in cardiorespiratory control/function 30 min post-treatment in persons with chronic SCI.

The 3-Meter Backward Walk Test (3MBWT): Reliability and validity in individuals with subacute and chronic stroke.

INTRODUCTION: Backward walking (BW) is an important gait adaptation and BW speed may be an important indicator of walking function and fall risk. However, the measurement characteristics of a standardized assessment of BW post-stroke have not been fully established. OBJECTIVES: To determine intra- and interrater reliability, concurrent validity and minimal detectable change (MDC) scores for the 3-Meter Backward Walk Test (3MBWT) post-stroke. METHODS: Thirty-four individuals with subacute and 29 individuals with chronic stroke participated. Two trials of comfortable BW was measured over a total distance of 5-meters, while speed was calculated during the middle 3-meters of the walking distance. Intra and interrater reliability were determined by comparing the two trials from one rater and simultaneous assessment of two raters, respectively. Two additional trials were performed and BW speed was calculated using 3MBWT and an instrumented walkway to determine concurrent validity. Intraclass correlation coefficients (ICC) estimated reliability and validity. The MDC was calculated from the standard error of measurement. RESULTS: Excellent ICC values were obtained for the 3MBWT in the subacute (interrater: ICC2,1 = 0.99; intrarater: ICC2,1 = 0.96; validity: ICC2,1 = 0.96) and chronic (interrater: ICC2,1 = 0.99; intrarater: ICC2,1 = 0.94; validity: ICC2,1 = 0.97) groups. The MDC was 0.07 m/s (subacute) and 0.11 m/s (chronic). CONCLUSIONS: Establishment of the 3MBWT as a reliable and valid measure in assessing BW speed is an important addition to the assessment toolbox for rehabilitation post-stroke.

The use of assisted technologies in early aggressive mobilization with an individual in a minimally conscious state: a case report.

INTRODUCTION: Early neurorehabilitation and passive, upright mobilization strategies have been shown to be beneficial for individuals with disorders of consciousness (DOC). However, literature is limited in illustrating the use of an early, aggressive program with an added focus on dynamic and active upright mobilization. The purpose of this case report is to describe a two-week aggressive, upright standing and walking program with an individual with traumatic brain injury in an acute inpatient rehabilitation setting. The case investigates the association between aggressive mobilization with changes in level of consciousness and daily cognitive, motor and communicative behaviours. CASE DESCRIPTION: A 30-year-old male classified in DOC as minimally conscious state (MCS) participated in an early upright mobilization program. The two-week intervention consisted of aggressive static/passive and dynamic/active upright mobilization activities, involving a multidisciplinary rehabilitation team. Expressive communication, motor responses and current level of consciousness were monitored and assessed twice a day. Additionally, the patient's activation and arousal were subjectively monitored during daily therapy sessions. RESULTS: Following the dynamic/active mobilization activities, the patient demonstrated improved expressive communication, motor scores and increased activation and arousal during the mobilizations. After the two-week intervention, he emerged from DOC. CONCLUSION: This case report illustrates intense, more active/dynamic upright mobilization with the use of assisted technologies provides promise as an effective intervention for improving communication, motor responses, arousal and level of consciousness in a patient in MCS. Initiating upright, active activity sooner in the recovery process, may lead to improved outcomes and quicker emergence.IMPLICATIONS FOR REHABILITATIONAggressive upright mobilization may be delivered safely to patients in DOC early in their rehabilitative care.Aggressive upright mobilization may be beneficial for patients in DOC.Higher intensity, more active/dynamic upright mobilization such as the use of Erigo®Pro + stepping and locomotor training on a treadmill with body weight support demonstrated positive outcomes with expressive communication, motor responses and arousal.Earlier initiation of aggressive mobilization may promote recovery.

Feasibility of transcutaneous spinal direct current stimulation combined with locomotor training after spinal cord injury.

STUDY DESIGN: Feasibility study, consisting of random-order, cross-over study of a single intervention session, followed by a parallel-arm study of 16 sessions. OBJECTIVES: To investigate the feasibility of a novel combinatorial approach with simultaneous delivery of transcutaneous spinal direct current stimulation (tsDCS) and locomotor training (tsDCS + LT) after spinal cord injury, compared to sham stimulation and locomotor training (sham + LT), and examine preliminary effects on walking function. SETTING: Clinical research center in the southeastern United States. METHODS: Eight individuals with chronic incomplete spinal cord injury (ISCI) completed the two-part protocol. Feasibility was assessed based on safety (adverse responses), tolerability (pain, spasticity, skin integrity), and protocol achievement (session duration, intensity). Walking function was assessed with the 10 m and 6 min walk tests. RESULTS: There were no major adverse responses. Minimal reports of skin irritation and musculoskeletal pain were consistent between groups. Average training peak heart rate as percent of maximum (mean(SD); tsDCS + LT: 66 (4)%, sham + LT: 69 (10)%) and Borg ratings of perceived exertion (tsDCS + LT: 17.5 (1.2), sham + LT: 14.4 (1.8)) indicate both groups trained at high intensities. Walking speed gains exceeded the minimal clinically important difference (MCID) in three of four who received tsDCS + LT (0.18 (0.29) m/s) and one of four in sham + LT (-0.05 (0.23) m/s). Gains in walking endurance exceeded the MCID in one of four in each group (tsDCS + LT: 36.4 (69.0) m, sham + LT: 4.9 (56.9) m). CONCLUSIONS: Combinatorial tsDCS and locomotor training is safe and feasible for individuals with chronic ISCI, even those with considerable walking impairment. Study outcomes support the need to investigate the efficacy of this approach.