Persistent Idiopathic Facial Pain (PIFP)

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.

Use these resources to provide understandable information about this study to patients, families, and health care providers: The present randomized clinical trial (RCT), conducted at the IRCCS Carlo Besta Neurological Institute, aims to evaluate the effectiveness of Pain Reprocessing Therapy (PRT), a form of psychological support/psychotherapy based on cognitive-behavioral therapy, which has already proven effective in the treatment of other types of primary chronic pain. Chronic Primary Orofacial Pain (CPOP) is a rare and complex form of chronic pain that predominantly affects adult women and occurs without evident lesions, yet has a significant emotional and functional impact. It was recently classified among chronic primary pain conditions in the ICD-11 and is considered a form of nociplastic pain, associated with alterations in brain connectivity. At present, pharmacological treatments have shown limited effectiveness. This randomized clinical trial (RCT), conducted at the IRCCS Carlo Besta Neurological Institute, aims to evaluate the effectiveness of Pain Reprocessing Therapy (PRT), a form of psychological support/psychotherapy based on cognitive-behavioral therapy, which has already proven effective in the treatment of other types of primary chronic pain. Sixty participants, all diagnosed with CPOP according to ICD-11 criteria, will be selected and randomly assigned to two groups: one will receive PRT, the other will receive treatment as usual (TAU). The primary outcome of the study is the assessment of pain intensity reduction. Secondary outcomes include a broad range of psychosocial variables: improvement in quality of life, reduction of anxiety-depressive symptoms, catastrophizing, and other psychopathological traits. The effects of the therapy on brain connectivity will also be analyzed using fMRI, and on pain neurophysiology through the Conditioned Pain Modulation (CPM) paradigm. The protocol provides for the evaluation of therapy effectiveness at three follow-ups (3, 6, and 12 months) in order to measure the duration of effects. Finally, through advanced statistical analysis tools and the support of artificial intelligence, the study also aims to identify specific clinical-neurofunctional profiles that may be useful for differential diagnosis and for tailoring therapeutic interventions.