Afferent stimulation inhibits abnormal cutaneous reflex activity in patients with spinal cord injury spasticity syndrome.

BACKGROUND

Tibialis Anterior (TA) cutaneous reflex (CR) activity evoked following cutaneous stimulation of the plantar (Pl) surface (Pl-TA CR) has demonstrated hyperreflexia and damage of inhibitory mechanisms in subjects with spinal cord injury (SCI) and spasticity.

OBJECTIVES

To modulate Pl-TA CR and Soleus H-reflex activity with transcutaneous electrical nerve stimulation (TENS) and vibratory stimulation of the plantar pad during rest and controlled isometric plantarflexion.

METHODS

Non-injured subjects (n = 11) and individuals with incomplete SCI with (n = 14) and without spasticity (n = 14) were recruited. The effect of TENS and vibratory stimuli on Pl-TA CR and soleus H-reflex activity were assessed during rest and controlled ramp-and-hold plantarflexion.

RESULTS

Vibration failed to inhibit H-reflex activity during rest or plantarflexoin following SCI compared to healthy subjects. In contrast, vibration-induced inhibition of Pl-TA CR was specifically detected in SCI spastic subjects during both rest and the hold phase of plantarflexion. TENS inhibited Pl-TA CR activity in the SCI spasticity group only during hold plantarflexion.

CONCLUSIONS

Plantar vibratory stimuli inhibited the pl-TA CR, but not the H reflex, during rest and controlled movement in SCI spastic subjects. Assessment of Pl-TA CR modulation should contribute to the development of modality-specific sensory stimuli programmes for the neurorehabilitation of SCI spasticity.