Background and aims: Every year millions are involved in motor vehicle collisions (MVC).Many reach full recovery in 3-6 months post-injury, however up to 50% will suffer from chronic pain. 
The lab assessment of endogenous pain inhibition is a ‘new generation’ tool to depict an individual’s pain modulation mechanism. Individuals can be positioned on the clinical nociceptive spectrum where pro-nociceptive individuals express a higher pain phenotype, resultant in higher risk of pain chronification.
Methods: Seventy-three post-MVC participants diagnosed with mTBI (age range 36.1 ± 11.4, F=27) underwent psychophysical assessment within 72h
after the MVC, and provided head and neck pain scores at 6 months
post-accident.
The psychophysical assessment consisted of conditioned pain
modulation (CPM) paradigm which measures the difference between
pain scores to 30 brief contact heat test-stimuli (forearm) given as
stand-alone, and then repeated concurrent with a conditioning stimulus
(immersion of the other hand in cold water).
Very short test-stimuli were used in order to detect corresponding
event related potentials. CPM was considered efficient if test-pain
rating reduced under the conditioning stimulus (negative CPM score).
Chronic clinical pain score was the average of head and neck pain
scores at 6 months. Patients were divided into pain group (>=20 on 0-
100 NPS, n=35) and no pain group (n=38).
Results: An association was found between (i) CPM efficiency as assessed
during the very-early acute post-MVC and (ii) chronic pain intensity.
In addition, Baseline conditioned test-pain scores linearly correlated with chronic mTBI pain.
Conclusions: Pro-nociceptive pattern of pain modulation predicts pain
chronification post-mTBI, and CPM efficiency in mTBI patients at very-early acute post-accident stage may be a bio-marker for therapeutic policy decisions on intensiveness of analgesic approach, possibly trying to prevent
pain chronification.

VERY-EARLY ACUTE PRO-NOCICEPTIVE PAIN MODULATION PREDICTS CHRONIC AREA-OF-INJURY PAIN IN MTBI PATIENTS SIX-MONTH POST INJURY