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. 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.
I. Etiology
The virus enters the bloodstream through the mucous membrane of the respiratory tract to form viremia, and chickenpox occurs or is recessive infection, after which the virus can be latent in the posterior root ganglion of the spinal cord or the sensory ganglion of the cranial nerve for a long time. When the body is stimulated (such as trauma, fatigue, malignant tumor or post-illness weakness), the latent virus is activated and replicates in the skin along the axon of the sensory nerve to the area innervated by the nerve to produce blisters, and at the same time the affected nerve becomes inflamed and necrotic, resulting in neuralgia.
Clinical manifestations
1. Typical manifestations
Before the onset of the rash, there may be mild malaise, low fever, poor circulation and other systemic symptoms, and the affected skin may have a burning sensation or neuralgia, with obvious 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 and do not fuse, and then rapidly turn into blisters with tense, 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 course of the disease is usually 2 to 3 weeks, and temporary pale erythema or pigmentation remains after the blisters dry up and the crusts fall off.
2.Special performance
(1) Ocular herpes zoster is a viral invasion of the ophthalmic branch of the trigeminal nerve, the rash involves the eye, the skin of the top of the forehead and part of the skin of the temporal area, mostly in the elderly, pain is intense, the nature of the pain section similar to trigeminal neuralgia, can involve the cornea to form ulcerative keratitis.
(2) Ear herpes zoster It is caused by viral invasion of the facial and auditory nerves and is manifested 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 auditory canal can occur, called Ramsay-Hunt syndrome.
(3) Postherpetic neuralgia Herpes zoster is often accompanied by neuralgia, which can occur 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 few patients the neuralgia can persist for more than 1 month. If the pain does not resolve after more than 3 months, it is called postherpetic neuralgia.
(4) Other atypical herpes zoster is associated with differences in the resistance of the patient’s organism, and can manifest as strophic (no lesions but neuralgia), incomplete (only erythema, papules without blistering that subsides), 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 The virus can occasionally spread through the bloodstream to produce a widespread varicella-like rash and invade organs such as the lungs and brain, called disseminated herpes zoster.
III. Diagnosis
1. Clusters of clusters of blisters appear on the lesioned skin and are distributed in a band along one side of the peripheral nerve.
2. There is significant neuralgia with localized lymph node enlargement.
3. The skin between the rashes is normal.
Differential diagnosis
(1) The disease sometimes needs to be distinguished from herpes simplex, which is found at the junction of skin and mucous membrane, with irregular distribution, small and easily broken blisters, and little pain, mostly in the course of fever (especially high fever), often easily recurring.
(2) Occasionally it is confused with contact dermatitis, but the latter has a history of contact, the rash is not related to the distribution of nerves, self-conscious burning, severe itching, and no neuralgia.
(3) In the prodromal phase of herpes zoster and herpes zoster without rash, neuralgia is easily misdiagnosed as intercostal neuralgia, pleurisy, and acute abdominal conditions such as acute appendicitis, and requires attention.
(4) Herpes simplex usually has a history of multiple recurrences at the same site, whereas this phenomenon does not occur in patients with herpes zoster without significant immunodeficiency. Isolation of the virus from blister fluid or detection of VZV, HSV antigen or DNA is the only reliable method for differential diagnosis.
V. Complications
1. Complicated bacterial infection
If herpes zoster lesions occur in a specific area, such as the eye, they may lead to serious consequences. In case of secondary bacterial infection, it can cause full ophthalmoplegia or even meningitis, with sequelae such as loss of vision, blindness, and facial paralysis after the disease.
2. Post-herpetic neuralgia
Herpes zoster in the head is mostly in the forehead, i.e., the first branch of the trigeminal nerve distribution area, which can cause hair loss and permanent scarring. After the herpes zoster skin damage heals, the pain can still last for some time. Some elderly patients with neuralgia can last for months or years, which can seriously affect sleep and emotions, and the heavier pain and longer duration can lead to mental anxiety, depression and other manifestations.
3. May induce keratitis, corneal ulcers, conjunctivitis
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, part of the nerve fiber distribution in the human eye cornea, conjunctiva and even the entire eye, the nerve fiber in this area if infected by the herpes virus, can occur keratitis, corneal ulcer, conjunctivitis, patients can occur photophobia, tearing, eye pain, resulting in vision loss, and in severe cases, the whole eye 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. The affected side of the eye cannot be closed, the affected side of the face has a dull expression, the corners of the mouth are skewed to the healthy side, and the patient cannot make blowing movements.
4. 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.
5. Causes viral encephalitis and meningitis
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. When the herpes virus invades visceral nerve fibers from the nerve roots at the spinal cord to the body, it can cause acute gastroenteritis, cystitis, and prostatitis, manifested as abdominal cramps, difficulty urinating, and urinary retention.
6.Treatment
1.Drug therapy
(1) Anti-viral drugs Acyclovir, valacyclovir or famciclovir can be used. It needs to be used in full and on time.
(2) Neuralgia medication
(1) Antidepressants The main drugs are amitriptyline, paroxetine (Celebrex), fluoxetine (Pepcid), etc., which are suitable for patients with localized burning pain;
②Anticonvulsants Gabapentin, pregabalin, carbamazepine, oxcarbazepine, etc., for patients with paroxysmal pain.
③Narcotic analgesics Available drugs include tramadol hydrochloride extended-release tablets (Chimantin), morphine sulfate extended-release tablets (Methocarbamol), oxycodone hydrochloride extended-release tablets, fentanyl transdermal patch (Doregis), etc.
④Non-narcotic analgesics including NSAIDs, tramadol hydrochloride extended-release tablets (Chimantin), etc.
⑤ Topical medications: Ganciclovir cream (can be made) at the beginning of herpes (but not suitable for use when large ulcers are present)
After the scabs fall off Compound lidocaine cream, fotarine cream, capsaicin ointment, etc. can be used.
(6) Adjuvant medication: Anti-vomiting reaction Gastrodia, Gastrodia orally, or Obe intravenous push
Anti-constipation reactions Constipation stop orally, Dulcolax orally
Anti-pruritus Anti-allergic drugs
Enhance the immunity of the body Thymus peptides (e.g. Ritalin)
Promote nerve repair class Micropol injection or tablet, neurotoxin intravenous use
2.Nerve block (for pain department treatment characteristics)
Paravertebral nerve or intercostal nerve block: 0.25~0.375% bupivacaine + dexamethasone 5mg + mikepro 2ml + ribavirin 2ml 2-3ml per segment, the pain should disappear completely after the block, observe the time of pain disappearance, if it exceeds the half-life of anesthetic, and the maintenance time of efficacy is prolonged after each block, it means this method is effective.
② continuous epidural analgesia: applicable to the first block approach, patients whose efficacy maintenance is not satisfactory, can be treated with the corresponding segment, epidural placement of continuous pumping of morphine and local anesthetics, but the disposable epidural catheter is left in place for no more than one week.
(iii) Subarachnoid infusion channel implantation with continuous analgesia: This method is recommended when the above therapy is effective, but the catheter needs constant replacement. It can be continuously intrathecal, pumped with morphine at 1/300 of the oral dose of the drug, with reduced side effects can be implanted high in the cervical segment and used as an injection channel for total spinal anesthesia if necessary. It can be placed for a period of 3 months.
④ Total spinal anesthesia: for patients with head, face and refractory episodic herpes zoster neuralgia
The general principle should be from superficial to deep, from simple to complex, from terminal to nerve trunk, nerve root to central.
3.Nerve destruction
Radiofrequency temperature-controlled thermocoagulation for nerve destruction can be used for herpes zoster neuralgia in the intercostal and trigeminal nerve regions.
Nerve destruction treatment also includes medial thalamus stereotactic radiation therapy (gamma knife or X-knife), surgical subdural spinal cord dorsal root destruction treatment, pituitary destruction, sympathetic trunk ganglion destruction, etc.
4.Spinal cord electrical stimulation therapy.
It is suitable for those who have persistent herpes zoster pain and have not undergone chemical destruction, but the cost is more expensive.