Objective: To assess the clinical manifestation of acute herpes zoster associated pain (AHP) and postherpetic neuralgia (PHN) and nerve block effect in AHP and PHN.

Method: We assessed twenty eight patients by physical examination and pain questionairre, and nerve block effect in thirty one patients. We injected local anesthetics and triamcinolone into nerve root or trunk in study group, and saline in control group. The effect was assessed by visual analogue scale.

Result: 1. Clinical manifestation: There was high incidence in thoracic dermatome. AHP and PHN patients expressed "sharp" pain. Pain rating index of AHP and PHN were 32.9, 33.0. 2. Nerve block effect: There was no nerve block effect in AHP (p＞0.05) and PHN (p＞0.05), but four patients of PHN patients in study group had significant pain relief, who suffered from pain during 2 month, 10 month, 6 years, 8 years.

Conclusion: AHP and PHN had variable clinical manifestation but no difference between them. There was no nerve block effect in AHP and PHN but we can consider nerve block as a additive method for pain relief of PHN because some patients responded to nerve block and there was no significant complication in nerve block.

Postherpetic neuralgia(PHN) is a common complication of herpes zoster and one of most common intractable conditions in pain clinics. The PHN is defined solely by the persistence of pain after the herpes zoster. There has been no known pathophysiology for the PHN and the role of scars, local muscles, tendons and ligaments has not been addressed.

The characteristics, duration, and location of the referred pain were evaluated along with the electromyographic(EMG) examination of involved muscles. Then treatment was given under the concept of a myofascial pain syndrome till the pain was completely resolved. Most of the patients with acute or chronic pain were relieved from the pain.

This study revealed a practical and important new concept on herpes zoster related pains. In some cases of herpes zoster, acute herpes zoster seems to be an initiating factor to form an acute trigger point in the muscles of the related area. And uncomplicated trigger points neglected in an acute stage become chronic intractable problems, when they were neglected.

In conclusion, myofascial pain syndrome should be taken into account when a postherpetic neuralgia is diagnosed. The recognition of this possible relationship between PHN and myofascial pain syndrome and an early proper care can greatly reduce the suffering of patents from chronic pain.