In migraine patients,
the alterations in pain thresholds were found to be modality and location
specific.
Quantitative sensory testing is
used to examine the function of both large and small nerve fibers and the
sensory perception after application of different mechanical and thermal
stimuli of controlled intensity. This method is widely in use to quantify
somatosensory function. It further points out towards the impairments or
interference in pain pathways of an individual in response to controlled
stimuli across a variety of modalities encompassing pressure and thermal.
The present meta-analysis was
conducted to evaluate 1) the differences in pain thresholds in migraine
patients and healthy controls 2) effect of stimulus modality and stimulus
location on pain thresholds.
A comprehensive search was
performed using the keywords like 'a migraine' AND ('pain,' 'threshold,'
'pressure,' 'electrical,' 'warm,' 'heat,' 'cold,' 'mechanical,' 'quantitative
sensory testing'). This meta-analysis included 14 studies to estimate the
pressure pain thresholds. However, as such no particular differences were found
between migraine patients and healthy controls (effect size 95% CI, -1.28 to
0.30, p=0.22). Subdivision based on stimulus region (head and neck area),
migraine patients were found to have a lower pressure-pain threshold (PPT) than
the control group (effect size 95% CI, -1.5 to -0.19, P=0.01). Assessment of PPT
on the outside of the head and neck region (non-local) found no significant
differences between the groups (effect size 95% CI,-2.04 to 2.74, p=0.77). To
assess heat pain thresholds (HPT), 9 studies were included. Here no evidence
was found supporting significant differences in HPT between migraine patients
and controls (effect size 95% CI, -0.33 to 0.02, p=0.09). Similarly, no
differences were noticeable on dividing data to local (effect size 95% CI,
-0.36 to 0.19, p=0.14) or non-local areas (effect size 95% CI, -0.34 to 0.08,
p=0.11).
This meta-analysis estimated
that the changes in the nociceptive processing of migraine patients were
modality and location specific. Symptoms associated with pressure sensations
were usually reported during the migraine attack. This might explain the
reasons for differences found for PPT but not HPT. As well sensory
abnormalities found to be soma topically localized to the head and neck areas
and do not seem to indicate a pattern of generalized sensitization.
The Journal of Pain
Meta-Analysis Confirms Modality and Location Specific Alterations in Pain Thresholds in Migraine Patients
H. Nahman-Averbuch et al.
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