HZ occurs due to reactivation of latent Varicella Zoster Virus in the dorsal root of ganglion following an attack of varicella. Many triggers have been suggested, including old age, physical stress, pressure on nerve roots by surgery, radiotherapy, immune suppression, etc.

SYMPTOMS:

• HZ begins with a prodrome of tingling, hyperesthesia, and severe pain localized to one or more dermatome.
• The eruption of unilateral painful grouped vesicles on an erythematous base in a dermatomal pattern with midline demarcation occurs.
• Two or more contiguous dermatomes may be involved, common being thoracic, cervical, trigeminal, and lumbar.
• The lesions begin as macules and papules and evolve into vesicles, bullae, and pustules.
• They eventually dry and form a crust in 7-10 days. The crusts disappear in 2-3 weeks.
• Herpes zoster ophthalmicus: The lesions are seen in the distribution of the ophthalmic branch of the trigeminal nerve on the forehead with midline demarcation, from the level of the eye to the scalp.
• Herpes zoster oticus: The lesions involve external auditory meatus, tympanic membrane, tonsillar fossa, and soft palate. Facial palsy with or without tinnitus, vertigo, and deafness can occur.
• Postherpetic neuralgia: Postherpetic neuralgia (PHN) is the persistence or recurrence of pain for more than 120 days. It can be allodynia, constant burning pain, or intermittent shooting pain.