The relation between cerebral blood flow, pain attenuation and autonomic parameters in rest, during and after exercise in patients with the chronic fatigue syndrome.

Besides the characteristic fatigue, patients with Chronic Fatigue Syndrome
(CFS) often suffer from chronic widespread and persistent pain. A
population-based study revealed that 94 % of the persons diagnosed with CFS
report muscle pain, and 84 % report joint pain.
Previous research has shown that altered central pain processing and altered
pain inhibition mechanismens play a role in the increased pain perception of
CFS patients. It has been shown also that the normal inhibition of pain by
exercise is diminished or absent in CFS patients.
The underlying mechanism for these altered pain sensations in CFS is mostly
unclear. In fibromyalgia patients a relation with the impaired autonomic
functions has been demonstrated, mainly by measuring heart rate variability
(HRV). HRV data in CFS patients are limited and data are inconsistent. The
relation of impaired autonomic function and altered pain sensation in CFS
patients is unknown.
Heart rate variabiliyt and baroreflex sensiivity seem to play a role in pain
sensation and cardiovascular responses to pain.
To the best of our knowledge, studies examining the relation between ANS and
pain in CFS are lacking. Likewise, studies investigating CBF in CFS are rare.
Also in healthy controls, studies examining exercise induced analgesia in
relation to autonomic function and CBF in response to exercise are lacking. On
the other hand, it has been demonstrated that the baroreflex sensitivity is
decreased in CFS patient. But also the relation between the decrease of the
baroreflex sensitivity and altered pain perception is not known.
Moreover it is unknown, also in healthy volunteers, to which magnitude the
baroreflex and the stress of the exercise indipendently contribute to the
decreased pain sensation after exercise. Similar, this is also unknown in CFS
patients.
Finally, there are limited studies which investigated cerebral blood flow at
rest in CFS. There are no studies of the changes in cerebral blood flow during
exercise and therefore also studies are lacking which related the
exercise-induced analgesia with autonomic function tests and with changes in
cerebral blood flow during and after exercise.

Therefore the aim of the study is to determine the relation between cerebral
blood flow during and after exercise, the altered pain sensation after exercise
and autonomic functions (HRV and baroreflex sensitivity) in response to
exercise in patients with CFS. These relations will be compared to those of
healthy controls. Furthermore, the altered pain response to exercise will be
compared to that of an non exercise test: tilt table test. Finally, the changes
of cerebral blood flow during a Valsalva manoeuvre will be determined as well
as the effect of the Valsalva manoeuver on pain thresholds.

Participants are randomized to either the submaximal bicycle exercise test, or
to the emotional stressor. Prior to the first test, questionnaires will be
filled in to make an inventarisation of the pain, physical condition,
complaints of fatigue and general well being. After measuring pain thresholds,
a Valsalva manoeuvre will be performed, cerebral blood flow will be measured
and the HRV and baroreflex data will be recorded. Thereafter patients will be
randomized to either the emotional stressor or to the exercise. During the
exercise test oxygen uptake (VO2) will be measured: spiro-ergometry.The week
thereafter the other test will be performed. During both tests cerebral blood
flow will be measured and autonomic function data collected and after the test
pain thresholds will be measured.

As already answered in question E9 risks are low as is the burden of
participation.