Postherpetic Neuralgiaเกิ�ดกิ�บคนที่�เป็ นโรคงู�สวั�ดหายดแล้�วัตั้��งูแตั้� 3 เด�อนขึ้!�นไป็ แตั้�ย�งูมีอากิารป็วัดแสบป็วัด

ร�อนบร�เวัณที่�เคยเป็ นงู�สวั�ดน��น

Pathogenesis of PHN-Damage to neurons in the spinal cord and ganglion, and to the peripheral nerve.

-Fibrosis is noted at the dorsal root ganglion, nerve root and peripheral nerve upon resolution of the acute stage.

-Damaged primary afferent nerves may become spontaneously active and hypersensitive to peripheral stimuli.

Pathogenesis of PHN-Excessive nociceptor activity and ectopic impulse generation may, in turn,

sensitize CNS neurons, augmenting and prolonging central responses to innocuous as well as noxious stimuli(ภาวัะที่างูจิ�ตั้ใจิหร�อพฤตั้�กิรรมีที่�ตั้อบสนองูตั้�อตั้�วักิระตั้+�นควัามีเจิ,บป็วัด).

-Clinically, these mechanisms result in allodynia (pain and/or unpleasant sensations elicited by stimuli that are normally not painful, e.g., light touch) with little or no sensory loss.

Pathogenesis of PHN

(19)The transient receptor potential cation channel subfamily V member 1 (TrpV1) known as the capsaicin receptor and the vanilloid receptor 1, is a protein that encoded by the TRPV1 gene. The function of TRPV1 is detection and regulation of body temperature. Additionally, TRPV1 provides sensation of scalding heat and pain (nociception).

Incidence

PHN commonly affects the thoracic dermatomes, followed in frequency by cervical, trigeminal and lumbosacral regions.

10-20% of patients with AHZ develop PHN.

ผู้��หญิ�งูมีโอกิาสเกิ�ด post herpetic neuralgia คนอาย+ 80 ป็0เป็ นงู�สวั�ด 30% อย�างูน�อยจิะเป็ น

PHNคนอาย+ 60-65 ป็0 20% จิะมี PHN

พบ PHN ได�น�อยในคนที่�มีอาย+น�อยกิวั�า 50 ป็0 แตั้�พบบ�อยในคนไขึ้�ที่�เป็ น immunocompromised

Reference

1.Fitzpatrick's Dermatology in General Medicine, 8e. Chapter 194. Varicella and Herpes Zoster.

2. Neuropathic pain of Postherpetic Neuralgia. University of New York.

3.http://58.137.211.174/news/journal/myfile/67175029bd97ad720_P.16-P.24%20Herpes%20zoster%20(Mark).pdf