Background and Aims Herpes zoster(HZ) inflammation in the ganglia and the retrograde transport along peripheral nerves result in severe neuropathic pain and skin rash. HZ is often diagnosed based on the dermatome affected by skin rash of the ventral rami of the thoracic spinal nerves. However, the HZ rash and pain are not always accompanied by symptoms on the posterior trunk innervated by the dorsal ramus of the spinal nerve. We investigated whether zoster-associated posterior trunk pain, innervated by the dorsal ramus of the spinal nerve, contributes to the chronicity of pain.

Methods We conducted a retrospective cohort study in our department. We reviewed the medical records of 82 outpatients who had initiated treatment for thoracic zoster-associated pain within 90 days of onset. The participants were divided into two groups based on the presence or absence of posterior trunk pain at the initial visit: 51 patients with pain (+) and 31 patients without pain (-). We compared the duration of treatment and the rate of chronicity in the two groups using Excel statistics.

Results No significant differences in the background of the patients were observed between the two groups. The median (interquartile range) duration of treatment was 86 (39-157) days for the (+) group and 75 (36.5-115) days for the (-) group. There was no significant difference in the rate of chronicity or duration of treatment based on the presence or absence of pain.

Conclusions It was not possible to confirm that zoster-associated posterior trunk pain innervated by the dorsal ramus contributes to the chronification.