Interhemispheric and Corticothalamic White-Matter Dysfunction Underlies Affective Morbidity and Impaired Pain...

Area of Science:

• Neuroimaging
• Pain Medicine
• Neurology

Background:

• Patients with chronic pain display impaired endogenous pain modulation.
• Cerebral networks responsible for pain modulation require anatomical delineation.
• Diffusion tensor imaging (DTI) can reveal white-matter alterations in chronic pain.

Purpose of the Study:

• To investigate white-matter alterations in chronic pain patients using DTI.
• To measure thermal pain modulatory responses using the offset analgesia (OA) paradigm.
• To correlate white-matter indices with pain perception and psychophysical parameters.
• To assess the potential of white-matter indices as diagnostic biomarkers for chronic pain.

Main Methods:

• 26 chronic pain patients and 18 healthy controls underwent DTI and OA measurement.
• Whole-brain DTI was performed using a 3 Tesla MRI scanner.
• Fractional anisotropy (FA) and radial diffusivity (RD) were computed using FSL.
• Correlations were analyzed between white-matter indices, pain responses, and psychophysical parameters.
• Receiver operating characteristic analysis was used to distinguish patients from controls.

Main Results:

• Patients demonstrated altered temporal dynamics in pain perception during OA.
• Reduced mean FA and increased mean RD were observed in patients' white matter, particularly in the corpus callosum and anterior thalamic radiation.
• FA in the splenium of the corpus callosum correlated with pain latency measures.
• Pain catastrophizing scores negatively correlated with FA in specific white-matter areas.
• White-matter metrics and OA parameters effectively distinguished patients from controls.

Conclusions:

• Chronic pain is associated with white-matter dysfunction affecting interhemispheric communication and descending pain modulation.
• Altered temporal dynamics of pain perception and affective morbidity are linked to these white-matter changes.
• Impaired interhemispheric pain modulation via the corpus callosum may represent a novel mechanism in the chronification of pain.