The unbearable pain of life - let you understand postherpetic neuralgia

Author: Shi Jiayu Peking Union Medical College Hospital

Reviewer: Guan Yuzhou, Chief Physician, Peking Union Medical College Hospital

Anyone who has had shingles knows that herpes itself is not terrible, but the postherpetic neuralgia that is really unbearable is the subsequent pain, medically known as "postherpetic neuralgia". The degree of this pain is so severe that it can be called "unbearable pain in life". The varicella-zoster virus is the culprit of postherpetic neuralgia. The virus is usually transmitted through droplets and contact. During the initial infection, the virus causes chickenpox; afterwards, the virus will lurk in the dorsal root ganglia of the spinal cord. When the body's immunity decreases, the latent virus will be activated and replicated in large quantities, and transferred to the skin through the sensory nerve axis, causing shingles.

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1. Why does shingles cause unbearable neuralgia?

The reason why postherpetic neuralgia is unbearable is closely related to the nerve structures invaded by the herpes zoster virus. In the acute stage of herpes zoster, the virus not only invades the skin tissue, but also the delicate sensory nerve tissue of the body, including peripheral nerves, dorsal roots and dorsal root ganglia. This invasion can lead to hemorrhagic inflammation, causing local tissue redness, swelling, pain and inflammatory response. Even if the acute inflammation subsides, the damage caused by the virus has not stopped. Fibrosis damage will occur in the dorsal root ganglia, nerve roots and peripheral nerves. Fibrotic nerve structures will have abnormal spontaneous nerve discharge activity, and these nerves will continue to generate pain signals even if there is no persistent tissue damage. The pain caused by this abnormal discharge is persistent, and patients will feel tingling, burning or electric shock-like pain, which seriously affects the quality of life.

2.Who is more likely to develop postherpetic neuralgia?

The occurrence of postherpetic neuralgia is related to many factors, among which age is the most important risk factor. It is usually more likely to occur in the elderly and people with low immunity. The probability of postherpetic neuralgia is about 50% for people over 60 years old, and it can reach 75% for people over 70 years old, and the incidence of postherpetic neuralgia increases with age. In addition, female patients, severe pain during the herpes period, widespread herpes, distribution in special parts and people with specific health problems are more likely to develop it. Understanding these risk factors and taking corresponding preventive and therapeutic measures can effectively reduce pain and improve the quality of life. I hope that every patient can pay attention to these issues and take active measures to protect their health. If herpes is distributed in special parts, such as the eyes, perineum, and brachial plexus, the incidence of postherpetic neuralgia will also increase accordingly. In addition, patients who have recently undergone surgery, malignant tumors, use immunosuppressants, and have diabetes or other chronic infectious diseases are at a higher risk of postherpetic neuralgia.

3. How to treat postherpetic neuralgia?

Once postherpetic neuralgia occurs, early multidisciplinary comprehensive treatment is critical. Drug treatment is the basis, and commonly used first-line drugs include ion channel modulators (pregabalin, gabapentin, etc.), antidepressants (amitriptyline, duloxetine, etc.) and 5% lidocaine patches. Second-line drugs include opioids and tramadol; Chinese medicine treatment can also be used as an auxiliary means to improve symptoms by conditioning the body. Vitamins that nourish the nerves are used as an auxiliary treatment and can be taken for a long time for most patients. If drug treatment alone cannot achieve the goal of rapid pain relief, minimally invasive interventional treatment can be considered, among which neurointerventional techniques include nerve blocks, selective nerve damage and intrathecal drug infusion techniques; neuromodulation techniques mainly include pulsed radiofrequency and electrical nerve stimulation.

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4. FAQs about postherpetic neuralgia

(1) How long after recovery from shingles does postherpetic neuralgia usually develop?

A: If the patient still feels persistent pain one month after the shingles rash has healed, it can be diagnosed with postherpetic neuralgia.

(2) What kind of pain is postherpetic neuralgia?

Answer: It can manifest as persistent pain, or it can reappear after a period of relief; it can feel burning, electric shock, knife cutting, needle-like or tearing; one type of pain may be predominant, or multiple pains may coexist.

(3) How to prevent postherpetic neuralgia?

A: Postherpetic neuralgia can be prevented by preventing herpes zoster. On the one hand, physical exercise and a healthy and light diet can improve immunity and enhance resistance to the herpes zoster virus; on the other hand, herpes zoster can be prevented by vaccination.

(4) Can I get the shingles vaccine if I have had chickenpox or shingles?

A: It is still recommended that people who have had chickenpox or shingles get the shingles vaccine. Because shingles itself has a certain chance of recurring, vaccination has a preventive effect regardless of whether you have had chickenpox or shingles in the past.

(5) How long after having shingles can I get the shingles vaccine?

A: Vaccination against herpes zoster is the most effective measure to control herpes zoster, but it cannot cure herpes zoster. If herpes zoster is currently occurring, you need to wait until the outbreak is over and the symptoms disappear before you can get vaccinated.

(6) Can nerve nourishing drugs be taken for a long time?

A: Nerve nutrition drugs mainly refer to methylcobalamin. The main absorption site of methylcobalamin is the lower part of the small intestine. After a single oral dose in healthy adult men, it was found that the blood concentration reached the highest value about 3 hours after taking it. Part of the drug was converted into cobalamin (DBCC) by the liver and kidneys, but most of it was excreted into the urine as methylcobalamin. In general, the drug is safe to use and can be taken for a long time according to the doctor's advice for most people.

(7) What are the adverse reactions of commonly used analgesics for postherpetic neuralgia?

A: Gabapentin is the most commonly used analgesic for postherpetic neuralgia, and patients generally tolerate gabapentin well. Common adverse reactions are drowsiness, dizziness, peripheral edema, and ataxia or gait disorders.

(8) Does herpes zoster affect the central nervous system?

Answer: Under certain special circumstances, the herpes zoster virus can extend retrogradely along the spinal ganglion cells to the central nervous system, causing meningitis and spinal meningitis.

(9) Which group of people are more likely to develop central nervous system involvement after contracting shingles?

Answer: People with weakened immunity or those with herpes affecting the head, face, and neck are more likely to have their meninges and spinal membranes affected.

(10) What are the symptoms of herpes zoster affecting the central nervous system?

A: If you experience severe headaches, nausea, vomiting, blurred vision, and other symptoms after being infected with the herpes zoster virus, you should be alert to the involvement of the meninges. If you experience the above symptoms, it is recommended that you visit the neurology emergency department in a timely manner.