Both ipsilateral and contralateral localized vibratory stimulations modulated pain-related sensory thresholds on the foot in mice and humans

Purpose

This study was aimed to investigate the effect of localized vibration on sensory thresholds in mice and humans using a novel quantitative method.

Participants and methods

The sensory thresholds of 7-week-old male C57BL/6J mice were measured with four sine-wave electrostimulation frequencies (5, 50, 250, and 2,000 Hz) before and after applying 2-minute vibration to the plantar side of the foot in mice. In human participants (16 males and 16 females; mean age, 21.0±0.8 years), the sensory threshold was measured at 50 Hz before and after applying 2-minute and 5-minute vibrations to the dorsal side of the foot.

Results

Application of a 2-minute vibration at either the ipsilateral or contralateral side modulated the sensory thresholds elicited by a 5- or 50-Hz right electrostimulation in mice. In human participants, application of a 5-minute vibration at either the ipsilateral or contralateral side modulated the sensory threshold elicited by 50-Hz right electrostimulation, but had no effect on local skin temperature. These results suggest that the right side of pain-related Aδ fibers (50 Hz) or C fibers (5 Hz) was modulated by the localized ipsilateral or contralateral side of vibratory stimuli, respectively, in mice and humans.

Conclusion

The ability of contralateral vibration to modify the right sensory thresholds suggests possible involvement of the central nervous system in vibratory modulation.

Breathlessness--current and emerging mechanisms, measurement and management: a discussion from an European Association of Palliative Care workshop

BACKGROUND

A pre-conference workshop at the 2012 European Association of Palliative Care meeting discussed the current scientific and clinical aspects of breathlessness.

AIM

To describe a current overview of clinically relevant science in breathlessness.

DESIGN

A collation of workshop presentations and discussions.

DATA SOURCES

Narrative review.

RESULTS

The mismatch between the drive to breathe and the ability to breathe underlies the major theories of breathlessness unifying central processing of peripheral inputs including more recent recognition of the importance of peripheral muscles in mediating efferent inputs, supporting reduction of breathlessness with muscle conditioning. Key questions are whether there is a 'final common pathway' for breathlessness? Are the central nervous system targets for reducing breathlessness identical irrespective of underlying aetiology? Central nervous system functional imaging confirms an ability to differentiate severity (intensity) from affective components (unpleasantness). Breathlessness generates suffering across the community for patients and their caregivers often for long periods. The exertional nature of breathlessness means that reduction rather than elimination of the symptom is the therapeutic goal. No single intervention is likely to relieve chronic refractory breathlessness, but interventions made up of several components may provide incremental relief. Having optimally treated any underlying reversible components, the resultant chronic refractory breathlessness can be treated with pharmacological, psychological and physical therapies to reduce the sensation and its impacts.

CONCLUSION

Ensuring optimal delivery of interventions for breathlessness, whose design is underpinned by improving the understanding in the aetiology and maintenance of breathlessness, is the subject of ongoing controlled clinical trials.