Deciphering Persistent Orofacial Pain - PIFP

Condition(s) studied

Study summary

Persistent non-dental orofacial pain is common yet poorly characterised, and its pathophysiology remains largely unknown. Two clinically similar entities are distinguished: post-traumatic trigeminal neuropathic pain (PTNP), in which peripheral nerve damage is demonstrable, and persistent idiopathic facial pain (PIFP), in which peripheral findings are typically absent - pointing to an altered central processing of trigeminal nociceptive input. This monocentric study characterises the peripheral and central mechanisms of PIFP by comparing PIFP patients with age- and sex-matched healthy controls using a combination of non-invasive peripheral and central approaches.

The study comprises two work packages. The peripheral work package uses quantitative sensory testing (standardised DFNS protocol) to test the hypothesis that PIFP patients retain an intact peripheral nervous system. The central work package uses functional MRI with standardised trigemino-nociceptive stimulation to characterise brainstem network dynamics, testing the hypothesis that PIFP patients exhibit a central trigeminal processing disturbance at the brainstem level. In PIFP patients, the functional MRI is repeated before and after a local-anaesthetic nerve block in the pain area, additionally distinguishing patients whose pain is completely abolished by the block from those with persistent pain despite it. The overarching aim is to characterise the pathophysiological basis of PIFP and thereby advance the mechanistic understanding of persistent orofacial pain.

Eligibility

Primary outcome measure(s)

• Difference in brain functional neuroimaging response to standardized trigemino-nociceptive stimulation between PIFP patients HC — Baseline (MRI session before local anesthesia)
  BOLD signal change (contrast estimates, arbitrary units) during standardized trigemino-nociceptive stimulation versus baseline, compared between PIFP patients and HC in a priori defined regions of interest and at whole-brain level.
• Difference in brain activation before versus after the local-anesthetic nerve block, and between complete responders and non-responders — Pre-block MRI at baseline and post-block MRI, both on the same day 1
  BOLD signal change (contrast estimates, arbitrary units) during standardized trigemino-nociceptive stimulation, compared within participants before versus after the local-anesthetic nerve block, and between participants whose pain is completely abolished by the block and those with persistent pain despite the block

Trial sites (1)

More Universitätsklinikum Hamburg-Eppendorf trials in Germany