Background Chronic spontaneous pain is a clinically relevant non‐motor symptom in multiple system atrophy (MSA) and Parkinson's disease (PD). Experimental pain sensitivity, reflecting the mechanisms of nociception and pain perception leading to clinical pain, is known to be enhanced in both diseases at advanced stages. Also, this study aimed at investigating experimental pain sensitivity already at an early stage (i.e. symptom duration ≤5 years). Methods Experimental pain sensitivity was assessed by investigating the nociceptive flexion reflex (NFR, reflecting spinal nociception) and heat and electrical pain thresholds. ‘Off‐drug’ MSA (n = 11) and PD (n = 14) patients selected at an early stage of the disease were compared to healthy controls (HC, n = 27). MSA patients had either parkinsonian (MSA‐P, n = 5) or cerebellar (MSA‐C, n = 6) subtypes. Results Compared to HC, MSA patients had lower heat pain sensitivity, whereas PD patients had reduced NFR threshold. MSA and PD patients did not differ from HC regarding other variables. MSA‐P and MSA‐C patients did not differ, either. Conclusions Impaired sensory discrimination and attention deficits could contribute to the reduced perception of heat pain in MSA, whereas in PD, local changes in spinal excitability or a diminished dopaminergic descending inhibition might impact on the motor efference of the NFR to reduce its threshold to nociceptive afferent information. What does this study add? This study investigated experimental pain sensitivity at an early stage in MSA and PD.

Rate augmentation factor improves initial rate response in the early stages of exercise. Fast response gives an improved time to initial rate increase and shortens the duration of inappropriate postexercise tachycardia. These features improve the pattern of response of the minute ventilation sensor.

Bronchial hyperresponsiveness in adults is characterized by an increased sensitivity as well as an elevated maximal response to inhaled bronchoconstrictors. In children, however, it is unknown whether the maximal response increases with increasing sensitivity. We investigated the maximal degree of airway narrowing to methacholine in nonasthmatic and asthmatic children (7-12 yrs), and compared it to that in adults. Nineteen children (9 normals, 10 asthmatics) and 19 adults (8 normals, 11 asthmatics) were selected in order to cover a wide distribution of bronchial responsiveness. All subjects underwent 2 methacholine challenge tests on separate days, by inhaling doubling doses using a standardized dosimeter technique (up to a noncumulative dose of 59 mumol). The response was measured by forced expiratory volume in one second (FEV1) and expressed as a percentage fall from baseline value. The complete dose-response curves were characterized by their position (PD20, the provocative dose causing a 20% fall in FEV1) and maximal response (MFEV1, the mean response on the plateau, defined as greater than or equal to 2 points within a 5% response range). Plateaus were observed in 13 children and 9 adults, the coefficient of repeatability of MFEV1 being 10.8 and 10.4% fall, respectively. There was an inverse relationship between log PD20 and MFEV1, which did not differ between children and adults (p greater than 0.15). In most of the asthmatic children and adults the plateau could not be measured (exceeding 50% fall in FEV1) if PD20 was less than 1 mumol. We conclude that, for a given bronchial sensitivity, the maximal response to inhaled methacholine is similar between children and adults.(ABSTRACT TRUNCATED AT 250 WORDS)