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.

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

date: 05/18/2007
author: Behrman AL, Harkema SJ.
publication: Phys Med Rehabil Clin N Am. 2007 May;18(2):183-202, v.
pubmed_ID: 17543768

The initial level of injury and severity of volitional motor and clinically detectable sensory impairment has been considered the most reliable for predicting neurologic recovery of function after spinal cord injury (SCI). This consensus implies a limited expectation for physical rehabilitation interventions as important in the facilitation of recovery of function. The development of pharmacologic and surgical interventions has always been pursued with the intent of altering the expected trajectory of recovery after SCI, but only recently physical rehabilitation strategies have been considered to improve recovery beyond the initial prognosis. This article reviews the recent literature reporting emerging activity-based therapies that target recovery of standing and walking based on activity-dependent neuroplasticity. A classification scheme for physical rehabilitation interventions is also discussed to aid clinical decision making.

Shaping appropriate locomotive motor output through interlimb neural pathway within spinal cord in humans.

date: 06/01/2008
author: Kawashima N, Nozaki D, Abe MO, Nakazawa K.
publication: J Neurophysiol. 2008 Jun;99(6):2946-55. Epub 2008 Apr 30.
pubmed_ID: 18450579

Direct evidence supporting the contribution of upper limb motion on the generation of locomotive motor output in humans is still limited. Here, we aimed to examine the effect of upper limb motion on locomotor-like muscle activities in the lower limb in persons with spinal cord injury (SCI). By imposing passive locomotion-like leg movements, all cervical incomplete (n = 7) and thoracic complete SCI subjects (n = 5) exhibited locomotor-like muscle activity in their paralyzed soleus muscles. Upper limb movements in thoracic complete SCI subjects did not affect the electromyographic (EMG) pattern of the muscle activities. This is quite natural since neural connections in the spinal cord between regions controlling upper and lower limbs were completely lost in these subjects. On the other hand, in cervical incomplete SCI subjects, in whom such neural connections were at least partially preserved, the locomotor-like muscle activity was significantly affected by passively imposed upper limb movements. Specifically, the upper limb movements generally increased the soleus EMG activity during the backward swing phase, which corresponds to the stance phase in normal gait. Although some subjects showed a reduction of the EMG magnitude when arm motion was imposed, this was still consistent with locomotor-like motor output because the reduction of the EMG occurred during the forward swing phase corresponding to the swing phase. The present results indicate that the neural signal induced by the upper limb movements contributes not merely to enhance but also to shape the lower limb locomotive motor output, possibly through interlimb neural pathways. Such neural interaction between upper and lower limb motions could be an underlying neural mechanism of human bipedal locomotion.

Alternate leg movement amplifies locomotor-like muscle activity in spinal cord injured persons.

date: 02/01/2005
author: Kawashima N, Nozaki D, Abe MO, Akai M, Nakazawa K.
publication: J Neurophysiol. 2005 Feb;93(2):777-85. Epub 2004 Sep 22.
pubmed_ID: 15385590

It is now well recognized that muscle activity can be induced even in the paralyzed lower limb muscles of persons with spinal cord injury (SCI) by imposing locomotion-like movements on both of their legs. Although the significant role of the afferent input related to hip joint movement and body load has been emphasized considerably in previous studies, the contribution of the “alternate” leg movement pattern has not been fully investigated. This study was designed to investigate to what extent the alternate leg movement influenced this “locomotor-like” muscle activity. The knee-locked leg swing movement was imposed on 10 complete SCI subjects using a gait training apparatus. The following three different experimental conditions were adopted: 1) bilateral alternate leg movement, 2) unilateral leg movement, and 3) bilateral synchronous (in-phase) leg movement. In all experimental conditions, the passive leg movement induced EMG activity in the soleus and medial head of the gastrocnemius muscles in all SCI subjects and in the biceps femoris muscle in 8 of 10 SCI subjects. On the other hand, the EMG activity was not observed in the tibialis anterior and rectus femoris muscles. The EMG level of these activated muscles, as quantified by integrating the rectified EMG activity recorded from the right leg, was significantly larger for bilateral alternate leg movement than for unilateral and bilateral synchronous movements, although the right hip and ankle joint movements were identical in all experimental conditions. In addition, the difference in the pattern of the load applied to the leg among conditions was unable to explain the enhancement of EMG activity in the bilateral alternate leg movement condition. These results suggest that the sensory information generated by alternate leg movements plays a substantial role in amplifying the induced locomotor-like muscle activity in the lower limbs.