The Effects of Non-Noxious Cutaneous Stimulation on Reflex Excitability in Neurological Intact Individuals and Patients With Spasticity Following an Upper Motor Neurone Lesion

  • Elaine M. Carruth

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Physiotherapy has a large input into the rehabilitation of patients who have suffered an upper motor neurone lesion (UMNL). Physiotherapists aim to improve movement and function in patients, both of which may be affected due to a change in muscle tone following the UMNL which can impact directly or indirectly on the patient’s ability to function.

Simple non-noxious cutaneous stimulation has been demonstrated to affect muscle tone. Cutaneous stimulation such as air splints and transcutaneous electrical nerve stimulation have been shown to decrease reflex excitability in healthy individuals and in patients with spasticity. However, the effect of different pressure magnitudes has not been investigated within a single study and few studies have considered the effect of TENS during its application. Both these forms of stimulation provide different types of cutaneous stimulation, combining them together may provide a greater effect than either stimulation alone.

Forty six neurologically intact individuals were recruited from a sample of convenience, additionally a sample of nine patients with an UMNL and spasticity in at least one lower limb were also recruited from a local neurological rehabilitation unit. Appropriate ethical approval was obtained locally and from the NHS.

The H-reflex, a frequently used measure of motoneurone excitability, was elicited by stimulating the tibial nerve in the popliteal fossa at 1. lx the H-reflex threshold. Surface EMG was recorded from the skin overlying the lateral head of the gastrocnemius muscle. Cutaneous stimulation of the lower limb was applied via circumferential pressure using a blood pressure cuff which was inflated to 20, 40, 60 and 80 mmHg for a duration of 90s - 10 minutes at each pressure. The peak-to-peak amplitude of 10 H-reflexes was obtained and recorded at baseline (before pressure), during each of the different pressure magnitudes and after the pressure was released: immediately after release and 2 minutes after release. The order of application of the different pressure magnitudes varied to determine if a time, order or pressure magnitude dependency on any changes in the H-reflex amplitude existed. TENS was applied (90 Hz; lOOps) to the skin over the triceps surae for 20 minutes. Ten Hreflexes were obtained before and every 5 minutes during TENS and again 5 minutes after the TENS had been switched off. Both pressure and TENS were then applied in combination, first to the neurologically intact individuals and finally to the patient group.

The 10 H-reflexes obtained under each condition (baseline; different pressure magnitudes / TENS stimulation periods and after release of stimulation) were averaged for each individual and these were considered as a percentage of the baseline. Statistical differences were determined using a general linear model ANOVA. Statistical significance was accepted at p < 0.05.

The application of circumferential pressure to the lower leg produced a decrease in the H-reflex amplitude down to 36% of baseline in the healthy volunteers (p < 0.05), irrespective of the order or length of time the pressure was applied. A decrease in the H-reflex amplitude down to 29% of baseline (p < 0.05) was obtained in the patient population. There was a statistically significant difference between the lower pressure magnitudes and the higher pressure magnitudes (p < 0.05). When the pressure was released, the amplitude had returned to baseline levels within 2 minutes. The decrease in the H-reflex amplitude down to 86% of baseline during TENS was also found to be statistically significant, occurred within 5 minutes of being turned on and lasting the entire 20 minutes (p < 0.05). The inhibitory effect on the H-reflex amplitude lasted less than 5 minutes after the TENS was switched off.

When the pressure and TENS were combined, the inhibitory effect of the circumferential pressure on reflex excitability continued to be evident. However in both the neurologically intact individuals and the patients with spasticity, the inhibitory effect on the amplitude of the H-reflex was no greater with the combined application of pressure and TENS than when the pressure was applied in isolation (p > 0.05).

The application of circumferential pressure had an inhibitory effect on reflex excitability in both the neurologically intact subjects and in patients with spasticity and the greater the pressure magnitude, the greater the inhibition. The application of TENS did not result in the same degree of inhibition and did not augment the inhibition of the circumferential pressure when applied in combination. Circumferential pressure would make a useful adjunct in the physiotherapy treatment of patients with spasticity to aid in improving movement and function.
Date of Award2010
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorLes Wood (Supervisor) & Joyce Nicol (Supervisor)

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