Do patients with functional chest pain have neuroplastic reorganization of the pain matrix? A diffusion tensor imaging study

• Central hyperexcitability is believed to play a role in functional chest pain.
• Microstructural reorganization of the pain neuromatrix was assessed.
• Microstructural changes were not present in functional chest pain patients.
• This challenges the hypothesis that visceral hypersensitivity is due to central changes.

Background and aimsIn functional chest pain (FCP) of presumed esophageal origin central nervous system hyperexcitability is generally believed to play an important role in pain pathogenesis. However, this theory has recently been challenged. Using magnetic resonance diffusion tensor imaging, the aim was to characterize any microstructural reorganization of the pain neuromatrix in FCP patients.Methods13 FCP patients and 20 matched healthy controls were studied in a 3T MR scanner. Inclusion criteria were relevant chest pain, normal coronary angiogram and normal upper gastrointestinal evaluation. Apparent diffusion coefficient (ADC) (i.e. mean diffusivity of water) and fractional anisotropy (FA) (i.e. directionality of water diffusion as a measure of fiber organization) values were assessed in the secondary sensory cortex, cingulate cortex, insula, prefrontal cortex, and amygdala.ResultsOverall, including all regions, no difference in ADC and FA values was found between the patients and controls (P = 0.79 and P = 0.23, respectively). Post-hoc tests revealed no difference in ADC and FA values of the individual regions. However, a trend of patients having increased ADC in the mid insula grey matter and increased FA in the mid insula white matter was observed (both P = 0.065).ConclusionsThis explorative study suggests that microstructural reorganization of the central pain neuromatrix may not be present in well-characterized FCP patients.ImplicationsThis finding, together with recent neurophysiologal evidence, challenges the theory of visceral hypersensitivity due to changes in the central nervous system in FCP patients.