Cardiovascular response of individuals with spinal cord injury to dynamic functional electrical stimulation under orthostatic stress

date: 2013 Jan;21(1):37-46.
author: Yoshida T.
publication: IEEE Trans Neural Syst Rehabil Eng.
PubMed ID: 22899587

Abstract

In this pilot study, we examined how effectively functional electrical stimulation (FES) and passive stepping mitigated orthostatic hypotension in participants with chronic spinal cord injury (SCI). While being tilted head-up to 70 (°) from the supine position, the participants underwent four 10-min conditions in a random sequence: 1) no intervention, 2) passive stepping, 3) isometric FES of leg muscles, and 4) FES of leg muscles combined with passive stepping. We found that FES and passive stepping independently mitigated a decrease in stroke volume and helped to maintain the mean blood pressure. The effects of FES on stroke volume and mean blood pressure were greater than those of passive stepping. When combined, FES and passive stepping did not interfere with each other, but they also did not synergistically increase stroke volume or mean blood pressure. Thus, the present study suggests that FES delivered to lower limbs can be used in individuals with SCI to help them withstand orthostatic stress. Additional studies are needed to confirm whether this use of FES is applicable to a larger population of individuals with SCI.

Comparison of orthostatic reactions of patients still unconscious within the first three months of brain injury on a tilt table with and without integrated stepping. A prospective, randomized crossover pilot trial.

date: 2008 Dec;22(12):1034-41
author: Luther MS
publication: Clin Rehabil
PubMed ID: 19052242

Abstract

OBJECTIVE:

To determine whether passive leg movement during tilt table mobilization reduces the incidence of orthostatic dysfunction in mobilization of patients being comatose or semi-comatose early after brain injury.

DESIGN:

Randomized crossover pilot trial using sequential testing.

SETTING:

Neurorehabilitation hospital.

SUBJECTS:

Nine patients still unconscious within the first three months of brain injury (5 men, 4 women; age 51 +/- 20 years).

INTERVENTION:

Patients were subjected once to a conventional tilt table and once to a tilt table with an integrated stepping device.

MAIN OUTCOME MEASURE:

The number of syncopes/presyncopes (orthostatic hypotension, tachypnoea, increased sweating) during interventions.

RESULTS:

One patient had presyncopes on both devices, six patients had presyncopes on the conventional tilt table but not on the tilt table with integrated stepping, and two patients did not exhibit presyncopal symptoms on either device. There were significantly more incidents on the tilt table without than on the one with an integrated stepping device (P < 0.05) at tilts of 50 or 70 degrees respectively.

CONCLUSION:

Patients tolerate greater degrees of head-up tilt better with simultaneous leg movement.

Effect of dynamic weight bearing on neuromuscular activation after spinal cord injury.

date: 2007 Jun;86(6):499-506
author: Edwards LC, Layne CS.
publication: Am J Phys Med Rehabil
PubMed ID:17515690

Abstract

OBJECTIVE:

To determine whether individuals who have a spinal cord injury have neuromuscular and physiologic responses to a personalized exercise program during dynamic weight bearing (DWB).

DESIGN:

Four subjects with spinal cord injuries (T6, T5-6, C2-5, and C5) completed a 12-wk exercise program that included DWB. Surface electromyography (EMG) was recorded from the right gastrocnemius, biceps femoris, rectus femoris, rectus abdominus, and external oblique. Heart rate (HR) and blood pressure (BP) were recorded throughout training. Descriptive statistics were used to analyze the data.

RESULTS:

The results of this study indicate that the subjects actively responded to exercise during DWB, as measured by EMG, HR, and BP.

CONCLUSIONS:

The results suggest that exercise during DWB can induce physiologic and neuromuscular responses in individuals who have a spinal cord injury, and that exercise during DWB may serve as a preparatory program for more advanced rehabilitation.

Comparison of the effects of body-weight-supported treadmill training and tilt-table standing on spasticity in individuals with chronic spinal cord injury.

date: 2011;34(5):488-94.
author: Adams MM, Hicks AL.
publication: J Spinal Cord Med.
PubMed ID: 22118256

Abstract

OBJECTIVE:

Determine the effects of body-weightsupported treadmill training (BWSTT) and tilt-table standing (TTS) on clinically assessed and self-reported spasticity, motor neuron excitability, and related constructs in individuals with chronic spinal cord injury (SCI).

DESIGN:

Random cross-over.

METHODS:

Seven individuals with chronic SCI and spasticity performed thrice-weekly BWSTT for 4 weeks and thrice-weekly TTS for 4 weeks, separated by a 4-week wash-out. Clinical (Modified Ashworth Scale, Spinal Cord Assessment Tool for Spinal reflexes) and self-report (Spinal Cord Injury Spasticity Evaluation Tool, Penn Spasm Frequency Scale) assessments of spasticity, quality of life (Quality of Life Index Spinal Cord Injury Version – III), functional mobility (FIM Motor Subscale), plus soleus H-reflex were measured at baseline, after the first training session and within 2 days of completing each training condition.

RESULTS:

In comparison with TTS, a single session of BWSTT had greater beneficial effects for muscle tone (effect size (ES) = 0.69), flexor spasms (ES = 0.57), and the H/M ratio (ES = 0.50). Similarly, flexor spasms (ES = 0.79), clonus (ES = 0.66), and self-reported mobility (ES = 1.27) tended to benefit more from 4 weeks of BWSTT than of TTS. Participation in BWSTT also appeared to be favorable for quality of life (ES = 0.50). In contrast, extensor spasms were reduced to a greater degree with TTS (ES = 0.68 for single session; ES = 1.32 after 4 weeks).

CONCLUSION:

While both BWSTT and TTS may provide specific benefits with respect to spasticity characteristics, data from this pilot study suggest that BWSTT may result in a broader range of positive outcomes.

Comparison of orthostatic reactions of patients still unconscious within the first three months of brain injury on a tilt table with and without integrated stepping. A prospective, randomized crossover pilot trial

date: 2008 Dec;22(12):1034-41.
author: Luther MS1, Krewer C, Müller F, Koenig E.
publication:Clin Rehabil.
pubmed_ID:19052242

 

Abstract

OBJECTIVE:

To determine whether passive leg movement during tilt table mobilization reduces the incidence of orthostatic dysfunction in mobilization of patients being comatose or semi-comatose early after brain injury.

DESIGN:

Randomized crossover pilot trial using sequential testing.

SETTING:

Neurorehabilitation hospital.

SUBJECTS:

Nine patients still unconscious within the first three months of brain injury (5 men, 4 women; age 51 +/- 20 years).

INTERVENTION:

Patients were subjected once to a conventional tilt table and once to a tilt table with an integrated stepping device.

MAIN OUTCOME MEASURE:

The number of syncopes/presyncopes (orthostatic hypotension, tachypnoea, increased sweating) during interventions.

RESULTS:

One patient had presyncopes on both devices, six patients had presyncopes on the conventional tilt table but not on the tilt table with integrated stepping, and two patients did not exhibit presyncopal symptoms on either device. There were significantly more incidents on the tilt table without than on the one with an integrated stepping device (P < 0.05) at tilts of 50 or 70 degrees respectively.

CONCLUSION:

Patients tolerate greater degrees of head-up tilt better with simultaneous leg movement.

Physical rehabilitation as an agent for recovery after spinal cord injury.

date: 2007 May;18(2):183-202
author: Behrman AL1, Harkema SJ
publication: Phys Med Rehabil Clin N Am

 

Cardiac output and blood pressure during active and passive standing.

date: 03/16/1996
author: Tanaka H, Sjöberg BJ, Thulesius O.
publication: Clin Physiol. 1996 Mar;16(2):157-70.
pubmed_ID: 8964133
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/8964133
The present study compared the haemodynamic pattern of active and passive standing. We used non-invasive techniques with beat-to-beat evaluation of blood pressure, heart rate and stroke volume. Seven healthy subjects, aged 24-41 (mean 30) years were examined. Finger blood pressure was continuously recorded by volume clamp technique (Finapres), and simultaneous beat-to-beat beat stroke volume was obtained, using an ultrasound Doppler technique, from the product of the valvular area and the aortic flow velocity time integral in the ascending aorta from the suprasternal notch. Measurements were performed at rest, during active standing and following passive tilt (60 degrees). Active standing caused a transient but greater reduction of blood pressure and a higher increase of heart rate than passive tilt during the first 30s (delta mean blood pressure: -39 +/- 10 vs. -16 +/- 7 mmHg, delta heart rate: 35 +/- 8 vs. 12 +/- 7 beats m-1 (active standing vs. passive tilt; P < 0.01). There was a significantly larger increase in cardiac output during active standing (37 +/- 24 vs. 0 +/- 15%, P < 0.01) and a more marked decrease in total peripheral resistance (-58 +/- 11 vs. -16 +/- 17%, P < 0.01). A precipitous rise in intra-abdominal pressure (43 +/- 22 mmHg) could be observed upon rising only in active standing. This was interpreted as an indication of translocation of blood to the thorax. There was no significant difference in haemodynamic changes during the later stage of standing (1-7 min) between both manoeuvres. These results suggest that active standing causes a marked blood pressure reduction in the initial phase which seems to reflect systemic vasodilatation caused by activation of cardiopulmonary baroreflexes, probably due to a rapid shift of blood from the splanchnic vessels in addition to the shift from muscular vessels associated with abdominal and calf muscle contraction. Moreover, the ultrasound Doppler technique was found to be a more adequate method for rapid beat-to-beat evaluation of cardiac output during orthostatic manoeuvres.

Moving the arms to activate the legs.

date: 07/01/2006
author: Ferris DP, Huang HJ, Kao PC.
publication: Exerc Sport Sci Rev. 2006 Jul;34(3):113-20.
pubmed_ID: 16829738

Recent studies on neurologically intact individuals and individuals with spinal cord injury indicate that rhythmic upper limb muscle activation has an excitatory effect on lower limb muscle activation during locomotor-like tasks. This finding suggests that gait rehabilitation therapy after neurological injury should incorporate simultaneous upper limb and lower limb rhythmic exercise to take advantage of neural coupling.

Neural coupling between upper and lower limbs during recumbent stepping.

date: 10/01/2004
author: Huang HJ, Ferris DP.
publication: J Appl Physiol. 2004 Oct;97(4):1299-308. Epub 2004 Jun 4.
pubmed_ID: 15180979
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/15180979
During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient’s lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes (P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.

Locomotor training after human spinal cord injury: a series of case studies.

date: 07/01/2000
author: Behrman AL, Harkema SJ.
publication: Phys Ther. 2000 Jul;80(7):688-700.
pubmed_ID: 10869131

Many individuals with spinal cord injury (SCI) do not regain their ability to walk, even though it is a primary goal of rehabilitation. Mammals with thoracic spinal cord transection can relearn to step with their hind limbs on a treadmill when trained with sensory input associated with stepping. If humans have similar neural mechanisms for locomotion, then providing comparable training may promote locomotor recovery after SCI. We used locomotor training designed to provide sensory information associated with locomotion to improve stepping and walking in adults after SCI. Four adults with SCIs, with a mean postinjury time of 6 months, received locomotor training. Based on the American Spinal Injury Association (ASIA) Impairment Scale and neurological classification standards, subject 1 had a T5 injury classified as ASIA A, subject 2 had a T5 injury classified as ASIA C, subject 3 had a C6 injury classified as ASIA D, and subject 4 had a T9 injury classified as ASIA D. All subjects improved their stepping on a treadmill. One subject achieved overground walking, and 2 subjects improved their overground walking. Locomotor training using the response of the human spinal cord to sensory information related to locomotion may improve the potential recovery of walking after SCI.