Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury

The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 ± 0.22 1·min⁻¹ and 171.6 ± 19.2 beats·min⁻¹, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE.     

Effects of transcutaneous electrical spinal cord stimulation on stepping patterns during walking

Effects of transcutaneous electrical spinal cord stimulation (tESCS) on the parameters of stepping movements in healthy subjects were investigated during two kinds of activity: walking on a moving treadmill belt (active treadmill) as well as pushing the treadmill belt by effort of the legs (passive treadmill). It was found that the total interference electromyogram (EMG) activity during stepping performance on a passive treadmill was 1.5–2 times higher than during stepping on an active treadmill. In addition, the amplitude of angular displacement of the hip joint and ankle was 2.5 times and 1.7 times higher, respectively, during passive vs. active treadmill, while the duration of stepping cycle decreased by 19%. Although the muscles were exposed to different load and the parameters of motion on the active and passive treadmill were different, tESCS caused an increase in the total EMG activity in 96% of cases both on the active and on the passive treadmill. In both cases, the stepping cycle period decreased by 4–43% in all subjects. These results suggest that tESCS can affect voluntary stepping patterns under conditions of different afferent control.     

Electrical stimulation in multiple sclerosis. Comparison of transcutaneous electrical stimulation and epidural spinal cord stimulation

Forty-nine multiple sclerosis patients with bladder symptoms and/or walking disability were subjected to a therapeutic trial with electrical spinal cord stimulation and transcutaneous electrical stimulation, a second aim being to compare these two treatments. A clear subjective improvement in bladder symptoms was achieved in the majority of the cases, and this was substantiated by objective parameters. In a proportion of cases a more moderate improvement seems to have been achieved in a variety of symptoms. Transcutaneous electrical stimulation seems to be a useful selection procedure for later electrical spinal cord stimulation.     

Influence of spinal cord stimulation on peripheral blood flow

In 27 vasculopathic and 9 nonvasculopathic patients who underwent spinal cord stimulation to treat pain in lower extremities, Doppler recordings and thermography were used to study peripheral blood flow changes during stimulation. Generally, poststimulation pain relief coincided with a improvement of Doppler recording, a normalization of morphology and increase of pulse wave amplitude, and a rise of skin temperature in the painful area.     

Effect of arm cranking exercise on skin blood flow of lower limb in people with injuries to the spinal cord

The purpose of this study was to examine whether arm cranking exercise induces changes in skin blood flow in the paralyzed lower limbs of people with injuries to the spinal cord (PISC). Ten PISC with lesions located between Th5 and L5 and six control subjects performed arm cranking exercise for 6 min at three intensities, 10, 30 and 50 W, at a room temperature of 25°C. Oxygen uptake (Vo₂) and heart rate (HR) were measured for the last 2 min of each exercise period. The skin blood flow at the anterior thigh (BF_sk,t) was continuously monitored using laser Doppler flowmetry for the whole 6-min period and for the first 10 min of recovery following exercise. During exercise, the PISC showed lower Vo₂ and greater HR than the control subjects. No increase in BF_sk,t was found in six of the PISC with lesions at or above Th12, irrespective of the exercise intensity. On the other hand, in PISC with lesions at L1 or below, BF_sk,t increased significantly (P < 0.05) with an increase in Vo₂ and HR, although the BF_sk,t at a given Vo₂ and HR was lower than that in the control subjects. These results would suggest that arm exercise can promote the blood circulation in the skin of the lower limbs if the injury level is below L1.     

Electrical stimulation of the cervical spinal cord increases cerebral blood flow in humans

Ten patients were studied to determine the effect of spinal cord stimulation on CBF. In 5 patients using a cervical spinal cord stimulator, the stimulation produced a significant increase in CBF in the hemisphere ipsilateral to the induced paresthesia. Thoracic cord stimulation, used by the other 5 patients, had no effect on CBF. Atropine had no effect on the alteration in CBF produced by cervical cord stimulation. Indomethacin, however, partially blocked the effect. These heuristic observations may have implications for the future treatment of cerebrovascular insufficiency in humans.     

Mechanisms of spinal cord electrical stimulation action on autonomic functions

The method of transcutaneous electrical stimulation of the spinal cord (ESSC) has recently begun to be actively used for both experimental studies of human motor functions and the rehabilitation of motor function in patients with spinal cord pathology. The spinal cord is the most important center of the regulation of vital functions, and ESSC affects as spinal locomotor networks as the visceral system too, which should be taken into account for the development of an improved method of rehabilitation and its use in experiments on healthy volunteers. We present a review of studies on the possible mechanisms of ESSC effects on the peripheral and cerebral circulation, cardiovascular, respiratory, excretory, and digestive systems of mammals.     

Response of external inspiration to the movements induced by transcutaneous spinal cord stimulation

The dynamic of the parameters of lung ventilation and gas exchange have been studied in 10 young male subjects during involuntary stepping movements induced by transcutaneous spinal cord electrical stimulation applied in the projection of T ₁₁–T ₁₂ vertebrae and during voluntary stepping movements. It has been found that the transcutaneous spinal cord stimulation inducing stepping movements leads to an increase in breathing frequency and a reduction in tidal volume. These effects may be mediated by some neurogenic factors associated with muscular activity during stepping movements, the activation of abdominal expiratory muscles, and the interaction between the stepping pattern and breathing generators.     

Symptomatic relief precedes improvement of myocardial blood flow in patients under spinal cord stimulation

Background

Spinal cord electrical stimulation (SCS) has shown to be a treatment option for patients suffering from angina pectoris CCS III-IV although being on optimal medication and not suitable for conventional treatment strategies, e.g. CABG or PTCA. Although many studies demonstrated a clear symptomatic relief under SCS therapy, there are only a few short-term studies that investigated alterations in cardiac ischemia. Therefore doubts remain whether SCS has a direct effect on myocardial perfusion.

Methods

A prospective study to investigate the short- and long-term effect of spinal cord stimulation (SCS) on myocardial ischemia in patients with refractory angina pectoris and coronary multivessel disease was designed. Myocardial ischemia was measured by MIBI-SPECT scintigraphy 3 months and 12 months after the beginning of neurostimulation. To further examine the relation between cardiac perfusion and functional status of the patients we measured exercise capacity (bicycle ergometry and 6-minute walk test), symptoms and quality of life (Seattle Angina Questionnaire [SAQ]), as well.

Results

31 patients (65 ± 11 SEM years; 25 male, 6 female) were included into the study. The average consumption of short acting nitrates (SAN) decreased rapidly from 12 ± 1.6 times to 3 ± 1 times per week. The walking distance and the maximum workload increased from 143 ± 22 to 225 ± 24 meters and 68 ± 7 to 96 ± 12 watt after 3 months. Quality of life increased (SAQ) significantly after 3 month compared to baseline, as well. No further improvement was observed after one year of treament. Despite the symptomatic relief and the improvement in maximal workload computer based analysis (Emory Cardiac Toolbox) of the MIBI-SPECT studies after 3 months of treatment did not show significant alterations of myocardial ischemia compared to baseline (16 patients idem, 7 with increase and 6 with decrease of ischemia, 2 patients dropped out during initial test phase). Interestingly, in the long-term follow up after one year 16 patients (of 27 who completed the one year follow up) showed a clear decrease of myocardial ischemia and only one patient still had an increase of ischemia compared to baseline.

Conclusion

Thus, spinal cord stimulation not only relieves symptoms, but reduces myocardial ischemia as well. However, since improvement in symptoms and exercise capacity starts much earlier, decreased myocardial ischemia might not be a direct effect of neurostimulation but rather be due to a better coronary collateralisation because of an enhanced physical activity of the patients.     

High-frequency, but not low-frequency, transcutaneous electrical nerve stimulation reduces aspartate and glutamate release in the spinal cord dorsal horn

Transcutaneous electrical nerve stimulation (TENS) is a commonly utilized non-pharmacological treatment for pain. Studies show that low- and high-frequency TENS utilize opioid, serotonin and/or muscarinic receptors in the spinal cord to reduce hyperalgesia induced by joint inflammation in rats. As there is an increase in glutamate and aspartate levels in the spinal cord after joint inflammation, and opioids reduce glutamate and aspartate release, we hypothesized that TENS reduces release of glutamate and aspartate in animals with joint inflammation by activation of opioid receptors. Using microdialysis and HPLC with fluorescence detection, we examined the release pattern of glutamate and aspartate in the dorsal horn in response to either low-frequency (4 Hz) or high-frequency (100 Hz) TENS. We examined the effects of TENS on glutamate and aspartate release in animals with and without joint inflammation. High-frequency, but not low-frequency, TENS significantly reduced spinal glutamate and aspartate in animals with joint inflammation compared with levels in those without joint inflammation. The reduced release of glutamate and aspartate by high-frequency TENS was prevented by spinal blockade of delta-opioid receptors with naltrindole. Thus, we conclude that high-frequency TENS activates delta-opioid receptors consequently reducing the increased release of glutamate and aspartate in the spinal cord.     

Excessive reflexes in spinal cord injury triggered by electrical stimulation

Interaction of electrocutaneous stimulation with an impaired human motor control system may result in unstable reflex loops causing excessive spastic reactions. These contractions are usually excluded from analysis since the presence of spasm is one of the criteria commonly applied for discarding a contraction. They may, however, provide interesting information on the nature of spasticity. The dorsiflexor muscles of four SCI subjects were activated by means of surface electrical stimulation and the isometric ankle moment was measured. Short bursts of constant stimulation frequency at seven different frequencies (8, 12, 16, 20, 25, 33, 50 Hz) triggered spastic reactions in all subjects. The onset times of spastic activity during an electrically elicited contraction shortened with increased stimulation frequency. A stimulation burst may also have a spasticity reduction effect on a subsequent burst, indicating potential short term therapeutic effects of stimulation on spasticity in isometric conditions.     

Modulation of spinal inhibitory reflexes depends on the frequency of transcutaneous electrical nerve stimulation in spastic stroke survivors

Neurophysiological studies in healthy subjects suggest that increased spinal inhibitory reflexes from the tibialis anterior (TA) muscle to the soleus (SOL) muscle might contribute to decreased spasticity. While 50?Hz is an effective frequency for transcutaneous electrical nerve stimulation (TENS) in healthy subjects, in stroke survivors, the effects of TENS on spinal reflex circuits and its appropriate frequency are not well known. We examined the effects of different frequencies of TENS on spinal inhibitory reflexes from the TA to SOL muscle in stroke survivors. Twenty chronic stroke survivors with ankle plantar flexor spasticity received 50-, 100-, or 200-Hz TENS over the deep peroneal nerve (DPN) of the affected lower limb for 30?min. Before and immediately after TENS, reciprocal Ia inhibition (RI) and presynaptic inhibition of the SOL alpha motor neuron (D1 inhibition) were assessed by adjusting the unconditioned H-reflex amplitude. Furthermore, during TENS, the time courses of spinal excitability and spinal inhibitory reflexes were assessed via the H-reflex, RI, and D1 inhibition. None of the TENS protocols affected mean RI, whereas D1 inhibition improved significantly following 200-Hz TENS. In a time-series comparison during TENS, repeated stimulation did not produce significant changes in the H-reflex, RI, or D1 inhibition regardless of frequency. These results suggest that the frequency-dependent effect of TENS on spinal reflexes only becomes apparent when RI and D1 inhibition are measured by adjusting the amplitude of the unconditioned H-reflex. However, 200-Hz TENS led to plasticity of synaptic transmission from the antagonist to spastic muscles in stroke survivors.     

Pulsed subcutaneous electrical stimulation in spinal cord injury: preliminary results

The treatment of long-term, stable para- and quadriplegics with pulsed electrical stimulation for pain control resulted in, anecdotally, a significant number of these individuals showing increased motor function as well as sensory awareness. This small pilot study was conducted in order to assess the hypothesis that pulsed electrical fields can effect diseased neurological function. Thirteen para- and quadriplegic subjects with 18 months of stable neurological signs and symptoms were exposed daily to pulsed electrical stimulation for a 6-month period and assessed for any improvement in motor function or sensory perception. The hypothesis is that pulsed electromagnetic fields can normalize viable but dysfunctional neuronal structures. Results were encouraging.     

Regional blood flow changes in response to thermal stimulation of the brain and spinal cord in the Pekin duck

Summary In conscious Pekin ducks, carotid and sciatic blood flows, respiratory rate, core and skin temperatures were measured during selective thermal stimulations of the spinal cord and rostral brain stem in thermoneutral (20 °C) and warm (32 °C) ambient conditions.At thermoneutral ambient temperature selective heating of the spinal cord by 2–3 °C (to 43–44 °C) increased the carotid blood flow by 138% and the sciatic blood flow by 46%. Increase in blood flows was correlated with increased breathing rate and beak and web skin temperatures.Selective cooling of the spinal cord at warm ambient temperatures and panting reduced the blood flow in both arteries and decreased the breathing rate.Heating or cooling of the brain stem showed generally very weak but otherwise similar responses as thermal stimulation of the spinal cord. In one duck out of six there was a marked effect on regional blood flow during brain stimulation.The results show that thermal stimulation of the spinal cord exerts a marked influence on regional blood flow important in thermoregulation, whereas the lower brain stem shows only a weak thermosensitivity, and stimulation caused only small cardiovascular changes of no major consequence in thermoregulation.     

The role of skin afferent in regulation of locomotion evoked by electrical epidural stimulation of spinal cord in decerebrated cats

The role of hindpaw skin afferent input in the locomotor pattern formation induced by epidural spinal cord stimulation was investigated in decerebrated cats. Locomotor activity was evoked by continuous 3-5Hz stimulation of dorsal surface of L4-L5 spinal segments. Kinematic and electromyographic activity (EMG) of m. Quadriceps, m. Semitendinosus, m. Tibialis anterior an m. Gastrocnemius lateralis before and after blocking of skin receptors in one hind limb were recorded. In addition, reflex responses in the hind limb muscles to epidural stimulation with frequency 0.5 Hz were analysed. Blocking of skin receptors of the foot with chlorothane paw irrigation or 2 % lidocaine administrated into the hind paw was performed. After blocking of skin receptors of the foot the stepping pattern changed. Stepping with dorsal foot placement and dragging during swing phase was observed. Duration of stance phase significantly decreased. Inhibition of polysynaptic activity of proximal and distal extensor muscles and distal flexor muscles of hind paw during locomotion was found. Monosynaptic responses after blocking of skin receptors of the foot changed insignificantly.     

Effect of experimentally induced changes in blood flow on the heat and electrical conductivity of the skin]

This paper reports on the influence of experimentally induced changes in blood flow in upper extremities on both electrical resistance (1100 Hz; 30 kHz) and heat conductivity of the skin in 19 healthy adults. Exsanguination (ESMARCH bandage) caused a small decrease in resistance with recovery of the blood flow. Both changed of skin resistance and resting values of skin resistance have shown sex-related differences. The changes of heat conductivity are higher as compared to values of skin resistance. The results are discussed and compared with data from the literature.     

Modulation of cardiovascular excitatory responses in rats by transcutaneous magnetic stimulation: role of the spinal cord.

This study investigated the efficacy of magnetic stimulation on the reflex cardiovascular responses induced by gastric distension in anesthetized rats and compared these responses to those influenced by electroacupuncture (EA). Unilateral magnetic stimulation (30% intensity, 2 Hz) at the Jianshi-Neiguan acupoints (pericardial meridian, P 5-6) overlying the median nerve on the forelimb for 24 min significantly decreased the reflex pressor response by 32%. This effect was noticeable by 20 min of magnetic stimulation and continued for 24 min. Median nerve denervation abolished the inhibitory effect of magnetic stimulation, indicating the importance of somatic afferent input. Unilateral EA (0.3-0.5 mA, 2 Hz) at P 5-6 using similar durations of stimulation similarly inhibited the response (35%). The inhibitory effects of EA occurred earlier and were marginally longer (20 min) than magnetic stimulation. Magnetic stimulation at Guangming-Xuanzhong acupoints (gallbladder meridian, GB 37-39) overlying the superficial peroneal nerve on the hindlimb did not attenuate the reflex. Intravenous naloxone immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex, suggesting involvement of the opioid system. Also, intrathecal injection of delta- and kappa-opioid receptors antagonists, ICI174,864 (n=7) and nor-binaltorphimine (n=6) immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex. In contrast, the mu-opioid antagonist CTOP (n=7) failed to alter the cardiovascular reflex. The endogenous neurotransmitters for delta- and kappa-opioid receptors, enkephalins and dynorphin but not beta-endorphin, therefore appear to play significant roles in the spinal cord in mediating magnetic stimulation-induced modulation of cardiovascular reflex responses.     

Effect of electrical stimulation of the olfactory tract and the caudal spinal cord on the Dahlgren cells in Clarias batrachus L.

Electrical stimuli applied to the olfactory tract for one minute caused partial depletion, but for two to five minutes resulted in complete depletion of the neurosecretory material (NSM) from the Dahlgren cells as well as from the urophysis. However, if similar stimuli were directly applied to the caudal spinal cord for one minute, the NSM was completely depleted. The neurosecretory granules were reaccumulated in the neurons within fifteen minutes after the stimuli were cut of A rapid depletion of the NSM from the caudal neurons was correlated with their electrical properties and rapid transduction of nervous information into the hormonal message. The immediate response of the caudal neurons to the olfactory tract stimulation suggested that the former are synaptically controlled by a center in the brain.