Changes in spastic muscle tone increase in patients with spinal cord injury using functional electrical stimulation and passive leg movements.

OBJECTIVE: Comparison of cycling interventions to reduce spastic muscle tone increase in patients with spinal cord injury. SETTING: Neuroprosthetic outpatient clinic in a university hospital. METHODS: Five patients with spinal cord injury took part in a crossover study in which the lower limbs (1) were stimulated by functional neuromuscular electrical stimulation (FES) to induce leg cycling movements and (2) were passively moved by an ergometer machine. Patients sat in a comfortable chair fastened to the ergometer while FES was done to induce leg cycling (active session). During the passive leg movement session the ergometer moved their legs for the same period of time at the same velocity and frequency. MAIN OUTCOME MEASURES: The change in spastic muscle tone increase before and after each training session was tested with the modified Ashworth Scale and the pendulum test of spasticity (relaxation index and peak velocity). RESULTS: The averaged data of the relaxation index increased after FES by about 68%. Compared with the slight increase after the passive movement training of 12%, this is statistically significant (P = 0.01). Peak velocity increased after FES by around 50%, while it was nearly unchanged after the passive intervention (1%); this is also significant (P = 0.01). This was similar with the peak velocity and the modified Ashworth Scale. CONCLUSION: The study presents further interesting aspects of the usefulness of FES in patients with spinal cord injury to reduce spastic muscle tone.

Peripheral repetitive magnetic stimulation induces intracortical inhibition in healthy subjects.

OBJECTIVE: Repetitive magnetic stimulation (rMS) is mainly used in transcranial applications. Only a few works have described its potential peripheral use. The aim of this investigation was to determine if conditioning peripheral (paravertebral) rMS of the cervical nerve roots in a group of healthy subjects induces changes in motor cortical excitability. METHODS: This was measured by means of motor evoked potentials (MEP), motor recruitment curves (RC), intracortical inhibition (ICI) and facilitation, as well as the cortical silent period (CSP) before and after repetitive stimulation. rMS was carried out by applying ten series of stimulation at 120% of resting motor threshold, each lasting 10 seconds with a frequency of 20 Hz. The nerve roots (C7/C8) of the right hand innervating the target muscles (the first dorsal interosseous) were systematically stimulated. RESULTS: This conditioning rMS caused a significantly longer CSP (p=0.001), increased MEP amplitudes (with a tendency to significance of p=0.06) and raised ICI (p<0.05). These changes were absent on the contralateral side, as well as in the course of RC. In conclusion, previously published results that described a prolonged CSP and increased MEP amplitudes led us to speculate that conditioning peripheral rMS is, like electrical stimulation, capable of influencing motor cortical excitability. SIGNIFICANCE: rMS might therefore be used in rehabilitative strategies for spasticity, pain or central paresis.

FES cycling reduces spastic muscle tone in a patient with multiple sclerosis.

We report on a multiple sclerosis patient who received functional electrical stimulation to reduce spastic muscle tone of the lower limbs. Stimulation by means of surface electrodes applied to the thigh muscles induced cycling leg movements. Spastic muscle tone was measured clinically using the modified Ashworth scale and semiautomatically by pendulum testing of spasticity. This was done before and directly after stimulation. The patient was able to endure the stimulation for ca. 30 minutes; there was a significant reduction of spasticity after each stimulation session. We conclude, that this type of stimulation could be another potential treatment modality for multiple sclerosis patients, especially those with a high score in the expanded disability Status scale.

Botulinum toxin type-A therapy in cluster headache: an open study.

The objective of this open single-centre study was to evaluate the efficacy and tolerability of botulinum toxin type-A (BTX-A) as add-on in the prophylactic treatment of cluster headache (CH). Twelve male patients with episodic (n=3) or chronic (n=9) CH, unresponsive to common prophylactic medications, were treated with a cumulative dose of 50 International Units (IU) BTX-A according to a standardised injection scheme into the ipsilateral pericranial muscles. One patient with chronic CH experienced a total cessation of attacks and in 2 patients attack intensity and frequency improved. In another patient with chronic CH typical attacks were not influenced, but an ipsilateral continuous occipital headache significantly improved. Patients with episodic CH did not benefit from BTX-A treatment. Tolerability was excellent. These findings provide evidence that BTX-A may be beneficial as an add-on prophylactic therapy for a limited number of patients with chronic CH.

Functional output improvement in FES cycling by means of forced smooth pedaling.

PURPOSE: Investigation of the influence of forced smooth and normal (nonsmooth) pedaling on the functional output of outdoor functional neuromuscular electrical stimulation (FES)-propelled cycling of spinal cord-injured subjects. SUBJECTS: Twelve subjects with complete spinal cord injury (T4-T12) and limited previous FES training. METHOD: Each subject participated in two separate outdoor sessions: once while pedaling a tricycle in a fixed gear, and a second time while free pedaling the same tricycle; both times with FES. Data on distance covered until exhaustion, cadence, and pedal forces were collected. Energy balance calculations led to evaluations of jerk loss and joint-related concentric/eccentric work. RESULTS: First-trial and total session distances were 68 and 103% longer, respectively, in the forced smooth cycling session than in the free cycling session (P < 0.001). Significantly more additional crank work (accompanied by increased concentric work production) was generated in nonsteady cycling phases to overcome increased jerk losses during free than during fixed-gear pedaling. During fixed-gear pedaling, timing and joint location of muscle work generation were more similar to the cycling of able-bodied subjects than during freewheel pedaling, because most work was generated by knee extensors in the power phase during the former pedaling mode. CONCLUSIONS: The superiority of forced smooth cycling to free cycling, as regards functional output distance, is based on less energy expenditure (less jerk loss and muscle tension) and on more efficient production of energy (more efficient timing and joint location of work production). Some energetic mechanisms that are advantageous for fixed-gear cycling act predominantly in unsteady phases; others work continuously during all phases of cycling.

Low-frequency rectangular pulse is superior to middle frequency alternating current stimulation in cycling of people with spinal cord injury.

OBJECTIVE: To determine the efficacy of using modulated middle frequency alternating current (MFAC) muscle stimulation for functional electric stimulation-propelled cycling by people with spinal cord injury (SCI) compared with the conventional method of using standard low-frequency rectangular pulses (LFRP). DESIGN: Repeated-measures. SETTING: Laboratory setting. PARTICIPANTS: Eleven otherwise healthy volunteer subjects with SCI (8 with American Spinal Injury Association [ASIA] grade A, 3 with ASIA grade B). INTERVENTIONS: To evaluate cycling-relevant differences between LFRP and modulated MFAC stimulation, we exposed participants to isometric measurements and cycling experiments performed during both 20 Hz LFRP and 4 KHz modulated with 50 Hz MFAC. MAIN OUTCOME MEASURES: We recorded maximal isometric torque, maximal dynamic work during 20 minutes of ergometer cycling, and perceived discomfort for each of the 2 stimulation patterns. RESULTS: Both the isometric torque (P<.02) and work generated (P<.001) during MFAC stimulation were significantly lower than during standard LFRP stimulation. Four participants reported discomfort and 1 of them also developed skin burns during MFAC stimulation. CONCLUSIONS: Our findings suggest that in SCI subjects, stimulated cycling with low frequency is generally more effective than cycling with modulated MFAC in terms of torque, work, and pain sensation.

TMS motor cortical brain mapping in patients with complex regional pain syndrome type I.

OBJECTIVE: The motor cortical representation in patients with complex regional pain syndrome type I (CRPS I) was determined under the assumption that the motor cortex undergoes representational adaptations in the course of CRPS. METHODS: A total of 14 patients with CRPS I and a group of healthy subjects without any known neurological symptoms participated in the study. The motor cortical representation, i.e. the size of representation (cm2), motor-evoked potentials (MEP), the calculated volume (cm2 mV), and the center of gravity (CoG) were measured by transcranial magnetic stimulation. Recordings were made of the long extensor muscles of the forearm of the affected and unaffected hand. RESULTS: Analyses of the results revealed a significant asymmetry between the two hemispheres: the motor cortical representation corresponding to the unaffected hand was significantly larger. While the CoG data did not differ statistically between the two hemispheres, the CoG coordinates corresponding to the affected hand indicated a larger variability. CONCLUSIONS: The presence of pain and other CRPS symptoms may induce lasting changes in motor cortical plasticity, as it also does in the sensory cortex. SIGNIFICANCE: This could be of importance in rehabilitative strategies for the sensory motor system in CRPS I patients.

Effects of conditioning peripheral repetitive magnetic stimulation in patients with complex regional pain syndrome.

OBJECTIVES: We tested whether repetitive magnetic stimulation (rMS) induces an afferent input to the spinocerebral tract in patients with complex regional pain syndrome (CRPS). METHODS: Cortical and spinal motor evoked potentials (cMEP and sMEP), as well as the contra- and ipsilateral silent period (cCSP and iCSP), were recorded in patients with CRPS type I before and after conditioning rMS, applied at cervical nerve roots innervating affected muscles. Patients were compared with a group of healthy subjects. RESULTS: In the group of patients we found that cMEP amplitudes were always significantly smaller for both hemispheres. In the group of healthy subjects we found a significant prolongation of the cCSP and iCSP after rMS. This was absent in patients. SMEP were always unchanged in both groups. DISCUSSION: This led us to the explanation that the afferent input to the motor cortical system in CRPS patients is less effective than in healthy subjects.

Reduction of spastic tone increase induced by peripheral repetitive magnetic stimulation is frequency-independent.

Repetitive magnetic stimulation is able to reduce spastic tone increase after applying it at the spinal cord. It was also found to induce frequency-dependent changes in H-reflex. In a small pilot investigation we stimulated a patient with severe spasticity of the lower limbs and applied different stimulation frequencies. The aim was to look for a clinical measurable effect of spastic reduction depending on the applied frequency. We were unable to show such a dependency, but could confirm the spastic-reducing effects of a peripheral repetitive magnetic stimulation using supratheshold intensities.