Pathogenesis
Herpes zoster is characterized by clustered vesicles that are distributed in clusters along one peripheral nerve, often accompanied by significant neuralgia. The virus enters the bloodstream through the respiratory mucosa to form viremia, and varicella or occult infection occurs, after which the virus can be latent in the posterior root ganglion of the spinal cord or in the sensory ganglion of the cranial nerve for a long time.
When the body is stimulated (e.g. trauma, fatigue, malignant tumor or post-illness weakness), the latent virus is activated and replicates along the axon of the sensory nerve to the skin of the area innervated by the nerve, and at the same time, the affected nerve becomes inflamed and necrotic, resulting in neuralgia. The disease is usually not recurrent because of the long-lasting immunity after healing.
Typical manifestations
The rash may be preceded by systemic symptoms such as mild malaise, low-grade fever, and poor circulation, and the affected skin may have a burning sensation or neuralgia, with significant pain sensitivity to touch, lasting 1 to 3 days. The most common sites are the intercostal nerve, cervical nerve, trigeminal nerve and lumbosacral nerve innervation areas. The affected area often first appears as a flushed spot, followed by corn- to soybean-sized papules, which are distributed in clusters without fusion, and then rapidly turn into blisters with tense and shiny walls and clarified fluid, surrounded by a red halo, with normal skin between the clusters of blisters; the lesions are arranged in a band along a peripheral nerve, mostly on one side of the body, and generally do not exceed the midline.
Neuralgia is one of the characteristics of the disease and can occur before the onset of the disease or with the lesions, and is often more intense in older patients. The duration of the disease is usually 2 to 3 weeks, or 3 to 4 weeks in the elderly, with temporary pale erythema or hyperpigmentation after the blisters dry up and the crusts fall off. The disease occurs in adults and is more common in spring and autumn. The incidence of the disease increases significantly with age.
How to diagnose shingles before the onset of the disease
(1) The pain is on one side of the body;
②The pain is a throbbing tingling pain;
(3) The pain is not fixed;
④There is a feeling of heat in the painful area;
(5) The pain may increase at night from 12:00 to 3:00 a.m., because the herpes virus is “time-sensitive”.
Special manifestations
(1) Ocular herpes zoster: the virus invades the ophthalmic branch of the trigeminal nerve, mostly in the elderly, with severe pain, and may involve the cornea to form ulcerative keratitis.
(2) Ear herpes zoster: It is caused by the virus invading the facial nerve and the auditory nerve, and manifests as herpes of the external auditory canal or tympanic membrane. When the geniculate ganglion is involved and the motor and sensory nerve fibers of the facial nerve are also invaded, a triad of facial palsy, otalgia and herpes in the external ear canal can occur, called Ramsay-Hunt syndrome.
(3) Postherpetic neuralgia: Herpes zoster is often accompanied by neuralgia, which can be present before the onset of the rash, during the onset of the rash, and after the lesions have healed, but mostly disappears after the lesions have completely resolved or within 1 month, and in a small number of patients the neuralgia can persist for more than 1 month.
(4) Other atypical herpes zoster: it is associated with differences in the resistance of the patient’s organism and can manifest as strophic (no lesions but only neuralgia), incomplete (only erythema, papules without blistering that regresses), maculopapular, hemorrhagic, gangrenous and generalized (involving more than 2 ganglia at the same time to produce lesions in multiple areas contralateral or ipsilateral); the virus can occasionally spread through the bloodstream to produce a widespread varicella-like rash and invade The virus may occasionally spread through the bloodstream to produce a widespread varicella-like rash and invade organs such as the lungs and brain.
What diseases can be complicated by herpes zoster?
(1) Herpes zoster may be complicated by bacterial infection after local breakage
Herpes zoster can have serious consequences if the lesions occur in specific areas, such as the eyes. If a bacterial infection develops secondary to herpes zoster, it can lead to full ophthalmoplegia or even meningitis; after the disease, sequelae such as loss of vision, blindness and facial paralysis can occur. 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.
(2) May induce keratitis, corneal ulcers, and conjunctivitis
Herpes zoster can occur in the trigeminal nerve segment of the face. The patient may suffer from photophobia, lacrimation, eye pain, resulting in vision loss, or in severe cases, total ophthalmoplegia leading to blindness. When the herpes virus infects the motor nerve fibers in the facial nerve, facial palsy can occur, with the eyes on the affected side unable to close, dull facial expressions on the affected side, skewed corners of the mouth to the healthy side, and inability to do blowing movements.
(3) Causes inner ear dysfunction
Herpes zoster that occurs in the auricle and ear canal can cause symptoms of inner ear dysfunction. Patients show dizziness, nausea, vomiting, hearing impairment, nystagmus, etc.
(4) Causes viral encephalitis and meningitis
Viral encephalitis and meningitis occur when the herpes virus invades the central nervous system, i.e., the human brain parenchyma and meninges, from the nerve roots at the spinal cord upward, manifesting as severe headache, jet-like vomiting, convulsions, limb convulsions, and life-threatening confusion and coma.
(5) Causes internal disorders
Herpes virus can cause acute gastroenteritis, cystitis, prostatitis, abdominal cramps, difficulty urinating, and urinary retention when the nerve roots in the spinal cord invade the visceral nerve fibers in the body.
The main characteristics of herpes zoster
1. It can develop in both young and old, but is more common in adults and has more severe symptoms.
2. The disease can develop in all seasons, with spring and autumn and humid days being the most common.
3. Herpes can appear on any part of the body, with the trunk and face being the most common.
4. The onset of herpes is accompanied by pain, and some patients will continue to have pain after the herpes has crusted over.
5. Blisters and lesions are mostly distributed along a certain peripheral nerve and arranged in bands on one side of the body, not exceeding the midline of the torso.
Hazards
During the onset of the disease, patients will experience a variety of uncomfortable symptoms, the nerve pain is the most obvious, making it difficult for people to sleep and eat. If not treated properly or due to a number of factors, herpes zoster can turn into “postherpetic neuralgia”, which can last for years and can be painful for a long time. There are also special types of herpes zoster: ocular herpes, ear herpes, visceral herpes, herpetic meningitis, and herpes zoster without herpes. These herpes are both specific and seriously harmful, some of them can cause blindness, deafness, and even death.