How much do you know about postherpetic neuralgia?

Shingles, commonly known as "herpes zoster", is an acute infectious skin disease caused by the varicella-zoster virus. The virus will lurk in the ganglia. When the immune system is weakened, the virus will be activated and migrate along the nerve fibers to the skin, causing severe pain and rash. Postherpetic neuralgia (PHN) is the most common complication of herpes zoster.

1. What is postherpetic neuralgia?

When the pain persists for 1 month or more after the shingles rash heals, it is called postherpetic neuralgia. This pain is often a manifestation of nerve damage, and the degree of pain varies, seriously affecting the patient's quality of life. The location of the pain is mostly in the unilateral chest (accounting for 50%), and the trigeminal nerve (mainly the ophthalmic branch) (accounting for 10-20%), and the rest are in the neck (accounting for 10-20%), waist (accounting for 10%~20%), sacrum (accounting for 2%~8%) and other parts (<1%). The pain feels like burning, electric shock, knife cutting, needle pricking or tearing pain. Some patients even describe that the slightest touch of the skin will cause severe pain, as if being tortured.

Common types of pain include:

Spontaneous pain: pain is felt even without any external stimulation. Allodynia: slight touch, such as friction from clothing, can cause severe pain. Paresthesia: abnormal sensations such as numbness, tingling, and itching may occur on the skin.

2. Who are the susceptible groups?

• Middle-aged and elderly people : As they age, their immunity declines, making it easier for viruses to invade their nerves. The incidence rate in people over 50 years old increases significantly, and the degree and duration of pain may become more severe as they age.

• People with weakened immune systems : People with AIDS, malignant tumors, long-term use of immunosuppressants, or receiving chemotherapy and radiotherapy have weak immune systems to fight viruses, and are at higher risk of developing post-herpetic neuralgia. For example, when diabetic patients have poor blood sugar control, the virus can easily invade the nerves, and once they develop herpes zoster, the chance of developing post-herpetic neuralgia will also increase.

3. How to treat postherpetic neuralgia?

• Drug treatment : Common ones include calcium channel modulators, such as pregabalin, which can regulate the release of neurotransmitters and relieve pain; antidepressants such as amitriptyline, which relieve pain by improving neurotransmitter disorders; topical lidocaine patches, which can anesthetically treat local pain and relieve the patient's pain. Drug treatment should be carried out under the guidance of a doctor, and the appropriate drug and dosage should be selected according to the degree of pain and individual differences. Drug treatment should be used throughout the course of treatment to avoid premature discontinuation of medication, which may lead to pain sensitization.

• Minimally invasive interventional therapy : For patients who do not respond well to drug therapy, nerve block therapy can be considered. The drug is injected around the diseased nerve to eliminate the aseptic inflammation caused by damage to the myelin sheath of the nerve fibers, block the transmission of pain signals, and accelerate nerve repair.

• Radiofrequency therapy : Regulating nerve function through pulsed radiofrequency current can reduce nerve sensitivity, or destroying some nerve fibers through radiofrequency ablation to achieve the purpose of relieving pain. These treatment methods can accurately act on diseased nerves and reduce damage to surrounding tissues.

Low-temperature plasma : After accurately locating the diseased nerves, the energy generated by the low-temperature plasma field regulates the nerves, reduces nerve sensitivity, and thus relieves severe pain symptoms such as allodynia.

Spinal cord stimulation : It is one of the more mainstream methods of treating postherpetic neuralgia. By implanting electrodes into the dorsal horn of the spinal cord, a mild current signal is generated to interfere with the pain signal and create rest time for the nerves. After 2-3 weeks of treatment, the pain symptoms of most patients can be controlled.

4. How to prevent it?

• Vaccination : The vaccine against herpes zoster can effectively reduce the risk of developing the disease, thereby reducing the chance of postherpetic neuralgia. Vaccination is recommended for middle-aged and elderly people and people with weakened immune systems, as it is a key step in prevention.

• Enhance immunity : Maintain a regular schedule, ensure adequate sleep, and avoid staying up late; moderate exercise, such as walking, Tai Chi and other aerobic exercises, can enhance the body's resistance; eat a balanced diet and consume more foods rich in vitamins and protein, such as fresh fruits and vegetables, lean meat, fish, eggs, etc., which can help maintain the normal function of the immune system and resist viral invasion.

Kind tips

Postherpetic neuralgia is a chronic disease that requires patience and confidence to treat. Patients should actively cooperate with the doctor's treatment and maintain an optimistic attitude to get rid of the pain as soon as possible. Source: Pain Department, Xuanwu Hospital

Author: Ma Hongmei, Guo Yuna