Cerebral cortical thickness in chronic pain due to knee osteoarthritis: the effect of pain duration and pain densitization

Objective This study investigates associations between cortical thickness and pain duration, and central sensitization as markers of pain progression in painful knee osteoarthritis. Methods Whole brain cortical thickness and pressure pain thresholds were assessed in 70 participants; 40 patients with chronic painful knee osteoarthritis (age = 66.1± 8.5 years, 21 females, mean duration of pain = 8.5 years), and 30 healthy controls (age = 62.7± 7.4, 17 females). Results Cortical thickness negatively correlated with pain duration mainly in fronto-temporal areas outside of classical pain processing areas (p<0.05, age-controlled, FDR corrected). Pain sensitivity was unrelated to cortical thickness. Patients showed lower cortical thickness in the right anterior insula (p<0.001, uncorrected) with no changes surviving multiple test correction. Conclusion With increasing number of years of suffering from chronic arthritis pain we found increasing cortical thinning in extended cerebral cortical regions beyond recognised pain-processing areas. While the mechanisms of cortical thinning remain to be elucidated, we show that pain progression indexed by central sensitization does not play a major role

Characteristics of study participants.

<p>Characteristics of study participants.</p

Cortical surface maps showing thinner cortex with log-transformed longer pain duration (right hemisphere; top, and left hemisphere; bottom).

<p>Significance at p<0.05 FDR-corrected for multiple comparisons and controlled for age.</p

Demographic data and pain characteristics of short vs. long pain duration groups.

<p>Demographic data and pain characteristics of short vs. long pain duration groups.</p

Cerebral Cortical Thickness in Chronic Pain Due to Knee Osteoarthritis: The Effect of Pain Duration and Pain Sensitization - Fig 2

<p>Scatter plots showing negative correlations of cortical thickness with log-transformed pain duration for four regions showing strongest associations (a-d; right pars orbitalis and inferior parietal, and left rostral middle frontal and frontal pole, respectively).</p

Clusters of significant negative correlation with pain duration reported at the peak coordinates, (Rt. & Lt. hemispheres).

<p>Clusters of significant negative correlation with pain duration reported at the peak coordinates, (Rt. & Lt. hemispheres).</p