Evaluation of the correlation of dorsal root ganglia and spinal nerves with clinical symptoms in patients with postherpetic neuralgia using magnetic resonance neurography

PURPOSE: To assess changes of dorsal root ganglia (DRG) and spinal nerves in patients with postherpetic neuralgia (PHN), and investigate the correlation between DRG morphology and clinical symptoms in PHN patients using magnetic resonance neurography (MRN). METHODS: In this case-control study, forty-nine lesioned DRG in 30 patients and 49 normal DRG in 30 well-matched (age, sex, height, weight) healthy controls were assessed. Clinical symptoms of patients (pain, allodynia, itching, and numbness) were assessed. MRN features (DRG volume (V(DRG)), the largest diameter (D(max)) of spinal nerves, signal intensity of DRG and spinal nerves (M-value)) were measured in all participants. Multilinear regression analysis was used to evaluate the relationship between the DRG morphology and clinical symptoms in patients. RESULTS: The volume and relative M-value of lesioned DRG in patients were significantly higher than those on the same side of healthy controls (p = 0.013, p < 0.001, respectively). The mean D(max) and relative M-value of spinal nerves on the lesioned side were significantly higher than those on the contralateral and same side of healthy controls (p < 0.0001, p = 0.0001, p = 0.0011, p = 0.0053, respectively). No difference was found between the mean V(DRG) of the lesioned and contralateral sides. Multiple linear regression analysis revealed that disease duration was independent risk factor for the maximum rate of V(DRG) differences (p = 0.013). CONCLUSIONS: DRG and spinal nerves on the lesioned side are swollen during PHN. Disease duration is an independent risk factor for morphological differences in the lesioned DRG of PHN patients. This study provides important guidance for individualized treatments of PHN.