The following is a summary of “Peripheral Pain Captured Centrally: Altered Brain Morphology on MRI in Small Fiber Neuropathy Patients With and Without an SCN9A Gene Variant,” published in the November 2023 issue of Pain by Gool et al. 

Researchers performed a retrospective study to compare brain morphology of pain in small fiber neuropathy (SFN) patients with and without an SCN9A gain-of-function variant to healthy controls. 

The Neuropathic Pain Scale assessed pain phenotype in idiopathic SFN (N= 20) and SCN9A-associated SFN (N =12) patients. T1-weighted structural MRI data were gathered from patients and healthy controls (N = 21) to compare cortical thickness and subcortical volumes and analyze the relationship between pain severity, quality, and duration with morphological properties. SCN9A-associated SFN patients exhibited significantly higher cortical thickness in sensorimotor regions (P< .017, Bonferroni corrected) when compared to idiopathic SFN patients. In comparison, lower cortical thickness was observed in more functionally diverse regions (e.g., posterior cingulate cortex).

The result demonstrated that in SFN patient groups, there were significant correlations between itch sensations (Neuropathic Pain Scale-7) and the thickness of the left precentral gyrus and midcingulate cortices (Spearman’s ρ = .44–.55, P = .005–.049). Notable associations were also observed between thalamic volumes and pain duration (left: ρ = -0.37, P = .043; right: ρ = -0.40, P = .025). No significant relationships were identified between morphological properties and other pain qualities. 

The study found that patients with SCN9A-associated SFN had more severe brain changes in the pain matrix, which correlated with the duration of their itch and pain. They also found a link between itch sensations and sensorimotor and midcingulate structures, which offers a new perspective on the neurobiology of itch in SFN.

Source: jpain.org/article/S1526-5900(23)00576-X/fulltext