Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

A cerebrovascular accident may affect the somatosensory areas of the cortex and hence cutaneous sensibility. One component of cutaneous sensibility is the ability to detect sinusoidal vibrations applied to the skin, dependent on activation of at least two separate classes of afferent fibres associated with different receptor classes. The ability to detect high frequency (60-1000 Hz) vibrations depends on inputs arising from Pacinian corpuscles (PC) and their associated afferent fibres, whereas the Meissner's corpuscles in the glabrous skin and the hair follicle receptors in the hairy skin, associated with rapidly adapting (RA) afferents, are responsible for signalling low frequency (2-100 Hz) vibrations. To investigate any changes in vibration detection thresholds that may occur as a consequence of cerebrovascular accident we tested a group of elderly adults (57 to 90 years old) at three weeks and ten weeks post-vascular event and a group of elderly (55 to 90 years old) healthy subjects. Detection thresholds were assessed at eight body regions (bilateral middle fingertip, forearm, shoulder and face) for three frequencies (30, 80 and 200 Hz) allowing separate (30 and 200 Hz) and concurrent (80 Hz) activation of the PC and RA classes of afferent fibres. The vibrotactile stimuli were delivered via a mechanical stimulator and the amplitude of the mechanical sinusoids generated by a computer could be altered instantaneously. A method of limits was employed and the mean value of six measures of threshold was calculated. The results indicate that for each of the body regions, except the face, detection thresholds for all frequencies tested were significantly elevated on the sites contralateral to the vascular lesion, when compared to the thresholds of elderly healthy subjects. Follow-up testing indicated a lowering of the elevated detection thresholds at all sites; in some subjects follow-up thresholds were within the range of healthy age matched controls.

Back to the top.
Poster Number PAstuart0678
Keywords: vibration, threshold, mechanoreception, stroke, psychophysics