Herpes zoster is an acute infectious skin disease caused by the varicella-zoster virus. Chickenpox occurs when children who are not immune to this virus are infected. Some patients become infected with the virus without developing symptoms. Because the virus is neurophilic, it can be latent in the neurons of the posterior root ganglion of the spinal nerve for a long time after infection. When the resistance is low or when you are tired, infected, or have a cold, the virus can grow and multiply again and move along the nerve fibers to the skin, causing intense inflammation of the invaded nerves and skin. The rash is usually unilateral and distributed by nerve segments, with clusters of herpes consisting of pain; the older the age, the more severe the neuralgia. The disease occurs in adults and is more common in the spring and fall. The incidence of the disease increases significantly with age. Complications 1. Complicated bacterial infections If herpes zoster lesions occur in specific areas, such as the eye, they may lead to serious consequences. If a bacterial infection develops secondary to herpes zoster, it can lead to full ophthalmoplegia or even meningitis, with sequelae such as vision loss, blindness, and facial paralysis. 2. Post-herpetic neuralgia Herpes zoster in the head is mostly found in the anterior part of the head, the first branch of the trigeminal nerve, which can cause hair loss and permanent scarring. Pain can persist for some time after the herpes zoster skin damage has healed. Some elderly patients with neuralgia can last for months or years, which can seriously affect sleep and emotions, and the heavier pain level and longer duration can lead to mental anxiety and depression. Herpes zoster can occur in the trigeminal nerve segment of the face. There is a nerve fiber in the trigeminal nerve, the ophthalmic nerve fiber, and some of the nerve fibers are distributed in the cornea and conjunctiva of the human eye as well as the whole eye. Patients may experience photophobia, lacrimation, eye pain, resulting in vision loss, or in severe cases, total uveitis leading to blindness. When the herpes virus infects the motor nerve fibers in the facial nerve, facial palsy can occur, resulting in the inability to close the eyes on the affected side, dull facial expressions on the affected side, skewed corners of the mouth to the healthy side, and inability to do blowing movements. 4. Triggering inner ear dysfunction Herpes zoster that occurs in the earwax and ear canal can cause symptoms of inner ear dysfunction. Patients show dizziness, nausea, vomiting, hearing impairment, nystagmus, etc. 5. Viral encephalitis and meningitis occur when the herpes virus invades the central nervous system, i.e., the brain parenchyma and meninges of the human body, from the nerve roots at the spinal cord upward, manifesting as severe headache, jet-like vomiting, convulsions, twitching of limbs, and life-threatening confusion and coma. When the herpes virus invades the visceral nerve fibers from the nerve roots at the spinal cord to the body, it can cause acute gastroenteritis, cystitis, and prostatitis, manifesting as abdominal cramps, difficulty urinating, and urinary retention.