Postherpetic neuralgia

Postherpetic neuralgia is a condition that is accompanied by pain and usually follows an episode of herpes zoster. The term itself refers to the condition (pain after herpes).

Shingles (herpes zoster) - the cause is the reactivation of the varicella zoster virus, which is latent in the human body and for unknown reasons is activated and causes an episode of herpes zoster. The exact reasons for the activation of the virus are not yet known.

The reactivated virus spreads along the nerves, causing pain and rashes or small blisters on the skin. Typically, shingles rash and pain usually occur on one side of the torso or head. Most often, rashes occur in the chest area. The disease usually lasts for several weeks and goes away without leaving a trace. But sometimes the virus damages nerve fibers, which results in pain and other symptoms after the rash disappears. This is postherpetic neuralgia

Symptoms of postherpetic neuralgia vary (depending on the individual characteristics of the individual) and may include severe pain, numbness, tingling, and paresthesia in the area affected by the viral infection. Postherpetic neuralgia can have a negative impact on both daily life and ability to work. But, at present, there are quite effective ways to treat this condition (physiotherapy, drug treatment).

Risk factors

Only those who have had chickenpox can get shingles. But there are certain groups that are more susceptible to postherpetic neuralgia:

Age – the chance of postherpetic neuralgia is higher in the older age group. (30% of people over 60 years of age who have had herpes zoster subsequently develop postherpetic neuralgia) and only 10% of the younger group develop postherpetic neuralgia.
Localization of rashes - symptoms of neuralgia are more pronounced if the rashes were in the forehead or eyes.
Concomitant pathology – The presence of a suppressed immune system (after chemotherapy or taking immunosuppressants) or diseases such as AIDS.

Early treatment of herpes zoster is important. Treatment started within 2-3 days after the rash appears can help reduce symptoms and avoid the risk of postherpetic neuralgia.

Statistics

The number of cases is up to 3 diseases per 1000 people per year. According to statistics, older people are more susceptible to pathology - in people 80 years of age and older, the detection rate is already 10 cases per 1000.

If we consider the percentage distribution of pathology within age groups, we can note that people aged 60–75 years account for half of all cases, those aged 76 years and older account for three quarters.

People aged 60+ are at risk of developing constant pain for a long time - about 10% of patients note that the discomfort persisted for up to six months.

6% of people who have suffered postherpetic neuralgia experience relapses, and 10 years or more may pass from the first to the next case.

Causes

Postherpetic neuralgia has a specific pathogenesis. Nerves in their structure are similar to electrical wires that run throughout the body and conduct impulses from the central nervous system and back, with information about the state of organs and tissues. Sensory nerves transmit pain, temperature, and tactile sensations.

Postherpetic neuralgia occurs when the shingles virus damages sensory nerves. Damaged nerves begin to function poorly and send pain impulses to the central nervous system. This leads to chronic pain or sensory disturbances in certain areas of the body.

Forecast

With timely treatment, the prognosis is favorable - the vast majority of cases end in recovery. When predicting the outcome, it is important to take into account risk factors; the more there are, the higher the likelihood of transition to a chronic form.

The transition to a chronic form can be considered a complication, since intense pain significantly affects the patient’s lifestyle and quality of life.

Other possible complications include changes in skin sensitivity at the site of the rash, the addition of a secondary infection, mycosis,

Symptoms

Symptoms of postherpetic neuralgia typically occur only in the area of the body affected by shingles and include:

Pain (can be sharp, cutting, throbbing, burning),
Numbness, tingling, itching
Headaches if shingles is localized to the head or face
Rarely, muscle weakness or paralysis if the nerve supplying a particular muscle is damaged.

Sometimes patients experience allodynia. Allodynia is a reaction that is not proportionate to the stimulus (that is, the patient reacts to minor stimuli such as a slight change in temperature or the touch of clothing with severe pain).

Effective help

Specialists at the MEDICA clinic first determine the pain phenotype using special equipment. And only after that the following treatment methods are used:

Selection of drug therapy: prescription of drugs of various classes according to the identified mechanism of damage.
Qutenza patch ("Qutenza"): "MEDICA" is the only institution in the city that is ready to work with the 8% capsaicin patch Qutenza (the use of the drug is associated with a number of features).
When the effectiveness of conservative treatment is low, various types of blockades are used, that is, the introduction of drugs directly into the diseased area.
Pulsed radiofrequency ablation helps relieve pain. This method is based on the effect of ultra-high frequency electric current on nerve roots, plexuses and peripheral nerves. Due to this, the transmission of pain impulses is disrupted.
Implantation of an epidural electrode (a device is inserted under the skin that relieves pain completely or almost completely).
Botulinum therapy: this method has long been successfully used to treat many types of pain.

Diagnosis

If pain occurs after an episode of rashes or sensory disturbances, you should consult a doctor. Diagnosis is based on medical history, examination and laboratory tests (necessary to exclude other diseases). Instrumental diagnostic methods (CT, MRI, EMG, ultrasound) are prescribed only if there is a need for differential diagnosis.

Forecast

Exercise therapy, physiotherapy and drug treatment in most cases help reduce symptoms and restore quality of life. Especially if treatment is carried out in a timely manner.

Survey

If you suspect postherpetic neuralgia, it is advisable to consult a neurologist.

The diagnosis is not difficult in cases where pain occurs after the appearance or extinction of vesicles. The difficulty is presented by patients whose pain has developed before the skin manifestations of herpes. During the examination, the neurologist (in his absence, the therapist) notes the following abnormalities in the patient:

hyperalgesia - excessive pain with slight impact - pressure, gathering the skin into a fold;
allodynia – the appearance of pain from contact with irritants that normally do not cause it (touching clothes, patting with the palm of the hand);
hypoesthesia - a decrease in all types of sensitivity along the nerve fiber.

Laboratory and instrumental studies are prescribed quite rarely. To confirm the GWP, 2 main studies are carried out:

Tzanck test - scraping from a vesicle, placing the contents on a glass slide, followed by staining. In this case, multinucleated giant cells are revealed.
Blood test for antibodies to the pathogen - HerpesZoster.

A general blood test, indicating the viral nature of the disease, and a biochemical study, which determines an increase in acute-phase inflammatory proteins, are less informative.

Herpes virus infection does not always manifest as rashes. In such cases, in order to exclude other neurological pathologies, the patient may be referred for ENMG - a study that allows identifying disturbances in conduction along nerve fibers, a change in response when exposed to a stimulus.

Treatment

Drug treatment:

Analgesics such as acetaminophen (Tylenol, Panadol, Tempra), and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, naproxen, and Celebrex.
Opioids – Your doctor may prescribe opioid analgesics for severe pain that is not controlled by regular analgesics, but these medications should be used with caution due to the risk of serious side effects. For example: This group includes tramadol or oxycodone. Some studies suggest that oxycodone may also help reduce allodynia.
Antidepressants – These medications are effective in treating depression. In addition, they improve sleep (for example, amitriptyline, Cymbalta, etc.).
Anticonvulsants – Drugs in this group are intended mainly for the prevention of convulsive conditions. But sometimes they are quite effective for postherpetic neuralgia (Neurontin, Lyrica, Topamax, carbamazepine).
Blocks - Injections of corticosteroid into paravertebral points sometimes lead to a significant reduction in pain.
Local painkillers - ointments, gels containing analgesics or anesthetics (lidocaine). Helps temporarily reduce symptoms.

Epidural administration of anesthetics and steroid hormones

Spinal epidural block involves the injection of drugs into the epidural space, which leads to loss of sensation in the area of impact. This means that this procedure involves introducing the active substance directly into the source of pain. Achieving a therapeutic effect in this case is possible due to the following factors:

analgesic properties of the drug;
the maximum possible concentration in the affected area;
reflex action at all levels of the nervous system.

Prevention

Certain antiviral medications may help prevent or reduce the effects of shingles, thereby reducing the risk of postherpetic neuralgia:

Chickenpox vaccine – The varicella zoster virus vaccine (Varivax) is now a routine childhood vaccine, but may also be recommended for older children and adults who have never had chickenpox. This vaccine does not guarantee that a person will not get chickenpox or shingles, but it may reduce the duration and severity of symptoms and the risk of complications such as postherpetic neuralgia.
Shingles vaccine - (Zostavax) can be given to people over 60 years of age (who have had chickenpox but not shingles). Zostavax is not recommended for use in certain groups of people (for example, those undergoing cancer treatment or those who are immunocompromised).
Antiviral medications – Antiviral medications such as acyclovir, valocyclovir, famciclovir, when taken within the first 72 hours after the shingles rash appears, can help shorten the duration of shingles and reduce the chance of developing postherpetic neuralgia.

Physiotherapy helps reduce pain and relieve inflammation. Various techniques are used (including transcutaneous electrical stimulation).

Exercise therapy helps restore the elasticity of ligaments and muscles. Exercises can be carried out both on simulators and in the form of gymnastics.

Acupuncture. This method is quite effective in restoring conductivity and reducing pain.

Let's start with the fact that this disease is not independent, but manifests itself against the background of herpes zoster, also called herpes zoster.

The occurrence of shingles is caused by the unexpected awakening of the Varicella zoster virus, the causative agent of chickenpox in children. Like all viruses of different types of herpes, this “parasite” does not leave the body of a person who has recovered from the disease. For many years, the patient may not even suspect that he is carrying a time bomb in his nerve cells.

What causes the activation of the virus that causes shingles is still not known exactly. “Waked up” Varicella zoster quickly spreads throughout the nervous system, most often localizing in the intercostal nerve trunks and trigeminal nerve trunks. During this period, the patient feels general malaise, body temperature rises, itching and unpleasant stabbing sensations in the area of the developing rash. Then small pink swellings appear, the place of which, after 3-4 days, will be taken by compactions, quickly turning into bubbles filled with clear liquid. Often the disease is cured quite quickly, in just 3-4 weeks.

If the virus has infected the nerve cells, the person experiences severe pain and some other complications, even with a seemingly complete cure for herpes zoster (shingles). Then we can say with confidence that we are dealing with postherpetic neuralgia.

Causes of postherpetic neuralgia

We also know from biology lessons that our nerve fibers resemble the structure of wires through which electrical impulses run. And they work in exactly the same way, sending impulses to the brain and receiving responses. What happens if the system suddenly fails? That's right, we'll get a short circuit.

The same thing will happen if the Varicella zoster virus damages our nerves. The affected nerve fibers will not be able to perform their functions correctly, which will lead to pain localized in the areas of nerve damage, as well as to impaired sensitivity in the affected areas of the body.

Symptoms

Different types of pain.
Itching, numbness of the skin, tingling sensation in the affected area.
If shingles is localized in the face or head, headache.
In rare cases, paralysis and weakening of the muscles of the limb are observed.

As a rule, these symptoms appear only in those places that are affected by herpes zoster. In some cases, a patient suffering from postherpetic neuralgia may experience a condition of Allodynia. Allodynia is the occurrence of pain, sometimes even barely tolerable, in response to an irritant that in the normal state of the body would not cause the slightest inconvenience.

Risk factors

Let's say by the way that only people who have had chickenpox can become victims of herpes zoster. However, the risk zone includes several other groups of people in whom the likelihood of developing postherpetic neuralgia increases.

People over 60 who have had herpes zoster are more likely to suffer from postherpetic neuralgia than younger people.
Location of the rash. The manifestations of postherpetic neuralgia will be stronger if the rash was in the upper area of the head.
Disorders of the immune system due to radiation, chemotherapy, acquired immunodeficiency syndrome, etc.

It should be noted that the risk of developing postherpetic neuralgia can be avoided by timely treatment of the disease that precedes this condition, namely herpes zoster. Treatment should begin 2-3 days after the rash appears.

Diagnosis

If there is pain in the area of the skin where the rash appears, or loss of sensitivity in this area, you should immediately consult a doctor. After studying the medical history, a medical examination, and after taking tests, a diagnosis will be made. If the doctor deems it necessary, he can give directions for diagnostic methods such as Ultrasound examination (ultrasound), MRI or another differential diagnostic method.

Prevention

The use of special antiviral drugs helps reduce the risk of herpes zoster, thereby minimizing the possibility of postherpetic neuralgia. To prevent this disease, the following are used:

The Varivax antiviral vaccine, now widely used to vaccinate children, is also suitable for older age groups who have not had chickenpox. Of course, vaccination does not provide a 100% guarantee that a person will never get shingles or chickenpox, but, in case of infection, it reduces the chance of postherpetic neuralgia, and also helps alleviate the course of a disease such as herpes zoster.
Zostavax, used against herpes zoster, is prescribed to people over 60 who have had chickenpox but have not gotten shingles. Not recommended for cancer patients undergoing treatment or people with weak immune systems.
Antiviral drugs, which include drugs such as famciclovir, acyclovir, etc., must be taken within 72 hours after the appearance of the rash. These drugs will not only shorten the duration of the disease, but also reduce the possibility of postherpetic neuralgia.

Treatment

Treatment of this disease includes taking painkillers for oral, local and intramuscular administration.

Conventional analgesics such as Panadol, Acetaminophen and those with anti-inflammatory effects (aspirin, Celebrex, etc.).
For excruciating pain that conventional analgesics cannot cope with, it is possible to prescribe opioid analgesics. For example: oxycodone, tramadol. But such drugs have serious side effects and must be prescribed with great caution.
If depression is present, antidepressants (Novopassit, Anafranil) are prescribed to improve well-being and sleep.
Anticolvusants, such as Neurotin, Topamax, etc., have also shown themselves to be effective in the condition of postherpetic neuralgia.
Corticosteroid blockades at the affected sites, with drugs such as Dexamethasone, significantly reduce pain.
Ointments and gels, such as Fastumgel, Capsicam, Diclofenac, containing analgesics or lidocaine, help muffle the symptoms.

An important role in restoring the elasticity of ligaments and muscle tissue is played by physical therapy (physical therapy), in the form of gymnastic exercises and training on simulators.

It would also be a good idea to visit a physiotherapy room and have acupuncture sessions. The latter treatment method is especially effective in reducing pain and restoring neuronal conductivity.

And, although a lot of methods for treating this type of complications have been developed, we should not forget that it is better to take preventive measures in time than to undergo long-term treatment in the future.
Author: K.M.N., Academician of the Russian Academy of Medical Sciences M.A. Bobyr

Severe consequences of HSV infection

Along with common manifestations of infection on the lips, mouth, nose, face, buttocks and genitals, herpes can affect internal organs, meninges, nerves, causing such severe conditions as meningitis, encephalitis, neuritis, meningoencephaloradiculitis, cause bronchitis, pneumonia , damage to lymphocompetent organs: liver, spleen, pancreas and even sepsis. Some of the criteria for infectious encephalitis - inflammation of the brain - are disturbances in the mental or mental status of the patient, fever, convulsions, neurological symptoms, and changes in the ECG.