Unique Anatomical Imaging Findings in Patients With Patulous Eustachian Tube.

Approximately 40%–85% of individuals with Parkinson's disease (PD) experience pain that negatively affects their quality of life , . Despite the prevalence and burden on daily living, pain in PD is often under-reported and inadequately assessed due to the lack of validated PD-specific pain scales, leading to suboptimal management . The Parkinson's Disease Pain Classification System (PD-PCS), developed in 2021 by pain specialists and movement-disorder experts to address mechanism-based pain diagnoses and management, was validated in an international multicenter study with a retest step . The PD-PCS distinguishes PD-related pain from PD-unrelated pain based on the pain's association with PD manifestations, and it incorporates clinical and pathophysiological descriptors (neuropathic, nociceptive, and nociplastic pain) in agreement with the International Association for the Study of Pain classification . Nociceptive pain results from an activation of nociceptors by mechanical or thermal stimuli related to an actual or potential tissue injury. Neuropathic pain arises from a lesion or disease of the peripheral or central somatosensory systems, with specific qualities (tingling, burning, or electric-shock-like) and a neurologically plausible distribution. Nociplastic pain comprises conditions in which the nociceptive system is overactive without a somatosensory lesion or peripheral nociceptor activation. Applying these general pain subtype definitions in the context of PD can be challenging, as pain in patients with PD often intertwines with diverse motor and non-motor symptoms. PD-related nociplastic pain is thought to occur in the context of the non-motor off state, restless legs syndrome (RLS), dopamine agonist withdrawal syndrome (DAWS), dopamine dysregulation syndrome (DDS), and other neuropsychiatric manifestations . However, given the heterogeneity of nociplastic pain and incomplete understanding of its neuroanatomical basis in PD, its characterization remains to be clarified , . The application of the mechanism-based PD-PCS together with supplementary MRI assessments was hypothesized to reveal distinct clinical and structural characteristics of PD-related pain subtypes, particularly aiding characterization of nociplastic pain. To test this hypothesis, PD patients underwent PD-PCS-based evaluations integrating multiple motor and non-motor indicators with supplementary MRI assessments.