Object: Postherpetic neuralgia (PHN) is pain that persists for 1-3 months after herpes zoster onset. It is the most common complication of herpes zoster and occurs in 15-40% of patients with herpes zoster. PHN has been suggested to be related with the lesion of doral root ganglion (DRG). However, the studies are almost limited to autopsies and animals , and the mechanism of PHN is still unclear. This study was conducted to investigate morphological and metabolic changes of DRG and sympathetic ganglion in patients with postherpetic neuralgia on MRI. Method: 30 patients diagnosed as PHN were recruited. The volume and fractional anisotropy of DRG of lesion dermatomes were measured under MRI, and compared with contralateral and adjacent DRG. The volume and fractional anisotropy of sympathetic ganglion of lesion dermatomes were also measured under MRI, and compared with contralateral and adjacent sympathetic ganglion.Then, the association between clinical phenotypes and DRG changes were analyzed.

Patients with the following conditions were excluded: psychiatric diseases or communication disorders; contraindications to MRI;DRG radiofrequency therapy, spinal cord electrical stimulation and other direct intervention treatments for DRG were performed before examination.

Inclusion Criteria:

• aged more than 18 herpes zoster in cervical, thoracic,lumbar or sacral regions agree to participate to the research

Exclusion Criteria:

• can not cooperate to MRI for mental disease contraindication for MRI treatments for DRG such as radiaofrequency therapy, spinal cord electircal stimulation were performed before examination. disagree to participate to the research

patients with herpes zoster in cervical, thoracic,lumbar or sacral regions