Autonomic neuroscience : basic & clinical
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Chemically-induced quantitative sudomotor axon reflex test (QSART) and quantitative sensory testing (QST) are established clinical tools to assess thin fiber function in humans. We investigated stimulus-response functions to transcutaneous electrical stimuli of different current intensity (3.75 to 10mA) and pulse frequency (5 to 100Hz) comparing sweat output (ml/h/m(2)) and pain intensity (numeric rating scale [NRS], 0-10). Efferent sudomotor and afferent nociceptive responses were recorded after a 30s electrical stimulation period of distal (hand and foot) and proximal (forearm and thorax) body sites with 3 repetitive measures per body site. ⋯ Sudomotor activity, but not pain ratings, was significantly different between the body sites (p<0.05, ANOVA) with maximum sweat responses obtained at the ventral forearm. Varying response patterns for higher stimulation frequencies between sweating (peak maximum at 20Hz) and pain (maximum at 100Hz) might indicate differential axonal properties of sympathetic efferent and nociceptive afferent fibers. Electrically induced QSART could be a useful explorative and clinical method to indirectly study characteristics of frequency-dependent axonal excitability changes of sudomotor fibers.
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Iontophoresis of α(1)-adrenoceptor agonists in the human forearm evoke axon reflex vasodilatation, possibly due to an accumulation of inflammatory agents at the site of iontophoresis. To investigate this possibility, skin sites in the forearm of healthy participants were treated with an anti-inflammatory gel containing ibuprofen 5% before the iontophoresis of the α(1)-adrenoceptor agonist phenylephrine (350μA for 3min). Red cell flux was measured with laser Doppler flowmetry at the site of iontophoresis and 8mm away in the region of axon reflex vasodilatation. ⋯ Axon reflex vasodilatation to phenylephrine was unaffected by variations in blood flow at the site of phenylephrine iontophoresis, but was reduced by ibuprofen pretreatment and abolished by local anaesthetic pretreatment. These findings suggest that prostaglandin synthesis at the site of iontophoresis contributes to but does not account entirely for axon reflex vasodilatation to phenylephrine. Alpha-1 adrenoceptor mediation of axon reflexes could play a role in aberrant sensory-sympathetic coupling in neuro-inflammatory diseases.
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This study compared verum acupuncture (VA) and sham acupuncture (SA) stimulation by assessing autonomic and subjective responses. Autonomic responses such as skin conductance response (SCR) and heart rate (HR) were measured. Subjective pain ratings were collected and evaluated. ⋯ Subjective responses were different for VA and SA. The SCR changes correlated with subjective responses for VA, but not SA. The present results suggest that VA and SA do not fundamentally differ in their autonomic response patterns.
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Acupuncture has become a popular complementary treatment in oncology, particularly as patients seek non-pharmacological alternatives to provide symptom control. A considerable body of evidence suggests that acupuncture modulates neurological processes to bring about its effects. This basic research is supported by an increasing number of positive clinical studies of varying quality. ⋯ Acupuncture is safe with minimal side-effects, and is clinically effective for the management of these symptoms. Continuing research using validated methodology is essential. In the interim, health professionals should be open to explore the use of acupuncture with their cancer patients.
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Salivary alpha amylase levels were measured to investigate sympathetic nervous system activity in migraine patients during attack, post-attack and interval periods of headache since salivary alpha amylase levels have been suggested as a potential indirect marker of sympatho-adrenal medullary activity in recent studies. ⋯ This is the first study showing the dynamic nature of sympathetic nervous system activity by evaluating the salivary alpha amylase levels-a noninvasive, reliable and an easy method-in different periods of migraine headache.