Quantitative Sensory Testing (QST) - Does assessing ... - TI Pharma

4. QST and neuropathic pain mechanisms
Abstract
Quantitative sensory testing (QST) allows the somatosensory profiling of patients with
neuropathic pain. The ultimate goal of identifying differences in the responsiveness
to sensory stimuli is the identification of differences in the mechanisms responsible
for generating sensory abnormalities and their subsequent mechanism-based therapy.
Recently, it was shown that distinct somatosensory patterns using a battery of QST
tests are present in the different clinical entities of neuropathic pain. Until now, it has
not been investigated whether the responsiveness to a single QST parameter would
reveal different patient subgroups. Thus, we studied patients with neuropathic pain
for their responsiveness to a single QST parameter “Mechanical Pain Sensitivity”
(MPS). Abnormal MPS score reflects hypersensitivity for mechanical stimulation,
which occurs in ~30% of the neuropathic pain patient population. The MPS test obtains
stimulus-response function to seven pinprick devices exerting forces between 8-512mN
to identify abnormalities for pinprick pain. In this study we found that patients with
MPS abnormalities showed two distinctive patterns of altered stimulus-response
function to pinpricks. 40% of patients reported a stimulus dependent pain response
whereas 60% of patients did not show such stimulus dependent behaviour and rated
all pinprick intensities equally painful. Both types of responses were found within
different clinical entities of neuropathic pain. Hence, we show that even a single QST
parameter can reveal additional, more detailed information of sensory abnormalities in
neuropathic pain. Further evaluation might lead to the identification of differences in
the mechanisms responsible for these distinct MPS abnormalities.