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

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 u2018new generationu2019 tool to depict an individualu2019s 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 u00b1 11.4, F=27) underwent psychophysical assessment within 72hafter the MVC, and provided head and neck pain scores at 6 monthspost-accident.The psychophysical assessment consisted of conditioned painmodulation (CPM) paradigm which measures the difference betweenpain scores to 30 brief contact heat test-stimuli (forearm) given asstand-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 correspondingevent related potentials. CPM was considered efficient if test-painrating reduced under the conditioning stimulus (negative CPM score).Chronic clinical pain score was the average of head and neck painscores 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 assessedduring 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 painchronification 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 preventpain chronification.