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Cyclic vomiting syndrome (CVS) shares many features with migraine headache, including auras, photophobia, and antimigrainous treatment response being traditionally viewed as a migraine variant. Aims. To determine whether CVS is associated with the same disorders as migraine headache, and compare these associations to those in healthy control subjects. Methods. Cross-sectional study of patients utilizing the ODYSA instrument, evaluating the probability of 12 functional/autonomic diagnoses, CVS, migraine, orthostatic intolerance (OI), reflex syncope, interstitial cystitis, Raynaud's syndrome, complex regional pain syndrome (CRPS), irritable bowel syndrome, functional dyspepsia, functional abdominal pain, fibromyalgia, and chronic fatigue syndrome. Control subjects were age-matched gender-matched friends. Patients had to fulfill criteria for CVS or migraine, while control subjects could not. Results. 103 subjects were studied, 21 with CVS, 46 with migraine and 36 healthy controls. CVS and migraine did not differ in the relative frequencies of fibromyalgia, OI, syncope, and functional dyspepsia. However, CVS patients did demonstrate a significantly elevated frequency of CRPS. Conclusions. Although CVS and migraine clearly share many of the same comorbidities, they do differ in one important association, suggesting that they may not be identical in pathophysiology. Since OI is common in CVS, treatment strategies could also target this abnormality.

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A higher proportion of autonomic dysfunction was present in women compared to men. In addition, these comorbid autonomic conditions were especially prominent during the female reproductive age.

Enhanced sympathetic activity causes an exaggerated heart rate response to standing in the postural tachycardia syndrome (POTS). All patients describe symptoms of orthostatic intolerance such as dizziness, blurred vision, shortness of breath, palpitations, tremulousness, chest discomfort, headache, lightheadedness and nausea, but only one third suffer loss of consciousness. We report four patients with POTS, who had long ventricular pauses (i.e. asystole) and syncope during head-up tilt test. This suggests that a subset of patients with POTS can have a surge in parasympathetic outflow that precedes vasovagal syncope.

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Although thermoregulatory sweat testing is commonly used to assess the autonomic nervous system, the power of this stimulus to induce sweating has not been studied. In 8 healthy male subjects, the authors quantitated sweat rates, core temperature, heart rate, and blood pressure during clinical thermoregulatory sweat testing, a separate exercise protocol, and with exercise added to thermal conditions. The authors found that (1) the addition of exercise to the thermal environment produced no further increase in sweat rate (3,841+/-948 versus 3,888+/-866 nl/mn - cm2); (2) maximum sweat rates closely corresponded to the theoretical maximum (6,000 nl/mn - cm2) derived from single gland studies; (3) sweat rates vary across subjects, but are similar across sites in any one individual; (4) core temperature rise is a major determinant of cardiovascular load in both thermal and exercise settings; (5) blood pressure decreased 28/11 mm Hg during thermal load, but increased 26/10 mm Hg with exercise, in agreement with current understanding of muscle and skin vascular physiology. The authors conclude that clinical thermoregulatory testing conditions produce maximum sweat rates in humans.

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