TGI Friday! Our weekly round-up of recently published research abstracts | 10 October 2014

From the Journal of Applied Physiology, 2 October 2014

Phenylephrine Alteration of Cerebral Blood Flow During Orthostasis; Effect on N-Back Performance in Chronic Fatigue Syndrome.

Medow MS(1), Sood S(2), Messer ZR(2), Dzogbeta S(2), Terilli C(2), Stewart JM(2).
1) New York Medical College marvin_medow@nymc.edu.
2) New York Medical College.

Abstract

Chronic Fatigue Syndrome (CFS), with orthostatic intolerance is characterized by neurocognitive deficits, impaired working memory, concentration, and information processing. In CFS, upright tilting (HUT) caused decreased cerebral blood flow velocity (CBFv) related to hyperpnea/hypocapnia and impaired cerebral autoregulation; increasing orthostatic stress resulted in decreased neurocognition.

We loaded the baroreflex with phenylephrine to prevent hyperpnea, and performed N-Back, neurocognition testing in 11 controls and 15 CFS patients. HUT caused a significant increase in HR (109.4±3.9 vs. 77.2±1.6 bpm, p<0.05) and respiratory rate (20.9±vs. 14.2±1.2 bpm, p<0.05) and decrease in ETCO2 (42.8±vs. 33.9±1.1 Torr, p<0.05) in CFS vs. control. HUT caused CBFv to decrease 8.7% in controls, but fell 22.5% in CFS. In CFS, phenylephrine prevented the HUT-induced hyperpnea/hypocapnia and the significant drop in CBFv with HUT (-8.1% vs. -22.5% untreated). There was no difference in control subject N-Back normalized response time (nRT) comparing supine to HUT (106.1±6.9 vs. 97.6±7.1 msec at n=4), and no difference comparing control to CFS while supine (97.1±7.1 vs 96.5±3.9 msec at n=4). However, HUT of CFS subjects caused a significant increase in nRT (148.0±9.3 vs. 96.4±6.0 msec at n=4) compared to supine. Phenylephrine significantly reduced the HUT-induced increase in nRT in CFS to levels similar to supine (114.6±7.1 vs 114.6±9.3 at n=4). CONCLUSIONS: Compared to control, CFS subjects are both more sensitive to orthostatic challenge and to baroreflex/chemoreflex-mediated interventions. Increasing BP with phenylephrine can alter CBFv. In CFS subjects, mitigation of the HUT-induced CBFv decrease with phenylephrine has a beneficial effect on N-Back outcome.


From BMJ Open, 6 October 2014.

Paediatrics
Pain and pressure pain thresholds in adolescents with chronic fatigue syndrome and healthy controls: a cross-sectional study

Anette Winger(1), Gunnvald Kvarstein(2), Vegard Bruun Wyller(3,4,5), Dag Sulheim(4,6), Even Fagermoen(3), Milada Cvancarova Småstuen(1), Sølvi Helseth(1)
1) Faculty of Health Sciences, Institute of Nursing, Oslo and Akershus University College of Applied Sciences, Oslo, Norway
2) Department of Clinical Medicine, University of Tromsø, The Arctic University of Norway, Tromsø, Norway
3) Medical Faculty, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
4) Department of Pediatrics, Oslo University Hospital, Norway
5) Department of Pediatrics, Akershus University Hospital, Norway
6) Department of Pediatrics, Lillehammer County Hospital, Lillehammer, Norway.
Correspondence to Anette Winger; anette.winger@hioa.no

Abstract

OBJECTIVES

Although pain is a significant symptom in chronic fatigue syndrome (CFS), pain is poorly understood in adolescents with CFS. The aim of this study was to explore pain distribution and prevalence, pain intensity and its functional interference in everyday life, as well as pressure pain thresholds (PPT) in adolescents with CFS and compare this with a control group of healthy adolescents (HC).

METHODS

This is a case–control, cross-sectional study on pain including 120 adolescents with CFS and 39 HCs, aged 12–18 years. We measured pain frequency, pain severity and pain interference using self-reporting questionnaires. PPT was measured using pressure algometry. Data were collected from March 2010 until October 2012 as part of the Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial.

RESULTS

Adolescents with CFS had significantly lower PPTs compared with HCs (p<0.001). The Pain Severity Score and the Pain Interference Score were significantly higher in adolescents with CFS compared with HCs (p<0.001). Almost all adolescents with CFS experienced headache, abdominal pain and/or pain in muscles and joints. Moreover, in all sites, the pain intensity levels were significantly higher than in HCs (p<0.001). CONCLUSIONS We found a higher prevalence of severe pain among adolescents with CFS and lowered pain thresholds compared with HCs. The mechanisms, however, are still obscure. Large longitudinal population surveys are warranted measuring pain thresholds prior to the onset of CFS. Trial registration number Clinical Trials, NCT01040429; The Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial (NorCAPITAL) http://www.clinicaltrials.gov.


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