Effect of Air-Splint Application on Soleus Muscle Motoneuron Reflex Excitability in Nondisabled Subjects and Subjects with Cerebrovascular Accidents

Abstract

We investigated the effect of air-splint pressure on soleus muscle motoneuron reflex excitability in 18 nondisabled subjects with no history of neurological disease and 8 subjects with cerebrovascular accidents (CVAs). Motoneuron reflex excitability was assessed by measuring the percentage of amplitude (peak-to-peak measurement) change in the Hoffman reflex (H-reflex). Pressure was applied for 5 minutes, after which the air-splint was deflated. Ten H-reflexes were recorded and averaged for each subject before pressure application to obtain a baseline value. H-reflexes were also recorded at set intervals during and after pressure application. Two-way analyses of variance for repeated measures were used to compare each group's pressure and postpressure measurements with the baseline value. Significant F tests were followed by post hoc t tests. Analyses of variance were used to compare the nondisabled subjects' H-reflex recordings with those obtained for the subjects with CVAs. The nondisabled subjects demonstrated reductions of 55% at 1 minute, 52% at 3 minutes, and 40% at the fifth minute of pressure application. The postpressure measurements showed increases in the reflex amplitude at 1 and 3 minutes postpressure; however, by the fifth minute, the amplitude was not different from the baseline value. The subjects with CVAs demonstrated reductions of 41% at 1 minute, 48% at 3 minutes, and 52% at 5 minutes of pressure application. None of the postpressure measurements, however, were statistically different from the baseline value. A statistically significant difference was demonstrated between the nondisabled subjects and the subjects with CVAs at the first minute of pressure release.(ABSTRACT TRUNCATED AT 250 WORDS)

Circumferential pressure’s inhibitory effects on soleus H-reflex

“…The main finding of this study showed that Previous studies investigating CP around the calf suggested that muscle stretch is a likely cause [5][6][7]. The compressive forces created by the air splint would seemingly cause a minimal amount of stretch to all of the muscle fibers beneath the splint.…”

“…As can be seen from to baseline pre-pressure levels in all subjects (p>0.05). This rapid return to pre-pressure levels is likely due to CP's short-lasting effect [6,7].…”

“…Circumferential pressure (CP) application and its effects on muscle activity in both the upper and lower limbs has been extensively studied [1][2][3][4][5][6][7][8]. Initial investigations examined the effect CP had on soleus monosynaptic reflexes in subjects without neurological deficits and compared them to subjects with cerebral vascular accidents [2,6].…”

“…Initial investigations examined the effect CP had on soleus monosynaptic reflexes in subjects without neurological deficits and compared them to subjects with cerebral vascular accidents [2,6]. A significant decrease in the soleus H-reflex amplitude and the soleus stretch reflex occurred throughout the pressure application.…”

Enfoques del ejercicio terapéutico sobre la espasticidad en miembro inferior post-Enfermedad Cerebro Vascular: revisión sistemática

“…Otro hallazgo que se encuentra relacionado con la reducción de la excitabilidad refleja de las motoneuronas alfa después de una intervención es la disminución del tono muscular, ya que el incremento de la excitabilidad de dichas motoneuronas es un factor que contribuye a la espasticidad 69 , sin embargo, la evaluación del tono muscular es una medición menos sensible debido a la subjetividad y falta de estandarización en su aplicación 4,70 .…”