EFFECTS OF INHOMOGENEOUS STATIC MAGNETIC FIELD ON HUMAN THERMAL PAIN THRESHOLD Zsfia KovcsBlint1, rp

1
EFFECTS OF INHOMOGENEOUS STATIC MAGNETIC FIELD ON
HUMAN THERMAL PAIN THRESHOLDZsófia
Kovács-Bálint1, Árpád Csathó2, Orsolya Pachner3,
János László4, Péter Juhász5, István
Hernádi11Department of Experimental Zoology and
Neurobiology, University of Pécs, Pécs, Hungary
2Institute of Behavioral Sciences, University of
Pécs, Pécs, Hungary 3Institute of Psychology,
University of Pécs, Pécs, Hungary4Section for
Mathematics, Hungarian Academy of Sciences,
Budapest, Hungary5Department of Non-ionizing
Radiation, National Frederic Joliot-Curie
Research Institute for Radiobiology and
Radiohygiene, Budapest, Hungary
University of PécsInstitute of Biology

• Results
• Thermal-pain threshold (in C) was recorded for
  each trial. Figure 1 shows the average threshold
  data as a function of Sets. A cyclic tendency
  dominates the pattern of results the TPT data
  shows a linear increase within each of the
  Blocks, but drops between the Blocks. While this
  cyclic tendency is highly salient for the SHAM
  session, it is much more modest for the SMF
  session.
• For the Device-blocks, there was a significant
  main effect of Session F(1,14) 7.82, p
  0.014. For the Control-block, the analysis
  yielded a non-significant main effect of Session
  F(1,13) 0.09, p 0.76.

• Introduction
• In the present experiment the effect of a single
  30 min SMF exposure on heat ramp evoked thermal
  pain threshold (TPT) was examined in young
  healthy human volunteers.
• Various effects of static magnetic fields (SMF)
  have been reported on nociceptive processes in
  the literature 1,2. Many studies addressed the
  question of potential adverse side effects
  induced by SMFs, especially that of magnetic
  resonance imaging (MRI) scanners 3,4, but less
  attention was paid to point out potential
  beneficial effects of such magnetic fields.

• Method
• Heating devices
• Thermal stimuli were randomly delivered through
  four computer-controlled miniature piezoelectric
  heating pads (designed by IH, patent pending)
  equipped with a movement detector attached to the
  inner surface of each fingertip of one hand
  excluding the thumb. Stimuli were delivered in a
  randomised order with approximately 20 s delay.
  The participants task was to indicate their TPT
  to a ramp of increasing temperature (35-55C).
• SMF exposure system
• The SMF exposure system used in the experiments
  consisted of a metal frame that held two
  magnetically coupled ferrous matrices facing each
  other. The matrices contained cylindrical magnet
  blocks. This layout generated a magnetic field
  that was strongly inhomogeneous in both lateral
  directions. Neighboring blocks were distributed
  with alternating poles. The distance between the
  two matrices was set by the metal frame, and it
  was held constant at 50 mm. The matrices thus
  formed a treatment chamber big enough for a human
  palm, the thumb remained outside the device. The
  active volume of the chamber was
  140 x 100 x 50 mm 5.
• A single block contained an axially
  magnetized cylindrical permanent magnet made of
  N50 grade neodymium-iron- boron (NdFeB,
  Br  1.47 T), co-axially surrounded by two
  ring shaped magnets made of the same
  material, similar magnetization.
• Arrangement
• All participants took part in four consecutive
  recording blocks per session on two sessions
  separated one week apart. After a block of
  practicing trials, the participants non-dominant
  hand was exposed to either genuine SMF or SHAM
  exposure for 30 min in three consecutive blocks
  (blocks A, B, C) in a double blind design. In
  each session, the fourth block (block D) was a
  control measurement at 30 min post-exposure time.
• After each block the subjects filled out a visual
  analogue rating scale (VAS), on which they marked
  how painful the stimuli were.

Discussion The present results demonstrate that
exposure to inhomogeneous SMF increases objective
pain threshold (measured in C), but leaves
subjective pain perception unchanged. In
addition, within each experimental block, an
ongoing habituation was observed for pain
threshold only in the SHAM condition, which was
completely absent in the SMF condition.
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imaging a review. Med Lav 2008 99 16-28. 4
Patel M, Williamsom RA, Dorevitch S, Buchanan S.
Pilot study investigating the effect of the
static magnetic field from a 9.4-T MRI on the
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