Herpes zoster (HZ) is commonly known as “herpes zoster”. It is a painful disease characterized by herpes virus invading the nerves and causing pain and skin herpes in the innervated area. It occurs mostly in the chest, followed by the jaws and face, and can also involve the lower back and legs. Acute herpes zoster is defined as postherpetic neuralgia (PHN) if the pain persists for more than 1 month after clinical cure, and is one of the intractable pains that plague the middle-aged and elderly, with a short duration of 1 to 2 years, or even more than 10 years in long cases, and a general history of up to 3 to 5 years if there is no effective pain control method. Patients suffer from chronic pain, which not only leads to depression and low quality of life, but also reduces or even loses the ability to work and socialize. In addition, unlike acute herpes zoster, patients with postherpetic neuralgia often have a combination of abnormal psychological factors. Due to the long-term severe pain torment, patients have a heavy psychological burden, depression, loss of confidence in life, and most have suicidal tendencies.
I. Mechanism of occurrence
The pathogenesis of postherpetic neuralgia is not fully understood. It has been found that there is degeneration of thick nerve fibers in the early stage and degeneration of fine nerve fibers in the later stage, and the total number of local nerve fibers is reduced, and the reduction of thick nerve fibers is most obvious. neuronal excitation is increased in an epileptiform discharge. It may also be related to untimely treatment, extremely low resistance or immunity of the patient, the patient’s idiosyncratic constitution, degeneration of damaged nerve cells, and exposure to chronic stimulation.
Clinical manifestations and diagnostic points
(A) Clinical manifestations
1. persistent or episodic severe pain in the affected area 1 month after clinical cure of acute herpes zoster; obvious pigmentation changes are visible within the affected area.
2, the affected area has obvious sensory and tactile abnormalities, most patients are characterized by hypersensitivity to nociception, which can produce severe and unbearable pain with gentle touch; some patients are characterized by hyperalgesia, with obvious tactile pain.
3. Nature of pain The spontaneous slash-like or lightning-like attack pain or continuous burning pain is the main cause, and most patients have severe and difficult pain to endure. Very few patients lack the typical neuralgia.
4.Because of the fear of severe pain, patients have a heavy psychological burden, depression, and even lose confidence in life and have suicidal tendency.
(II) Diagnostic points
1.Persistent pain for more than 1 month after clinical cure of acute herpes zoster or previous history of acute herpes zoster.
2. There are obvious sensory, nociceptive and tactile abnormalities distributed according to the innervation area, and there may be local pigmentation changes.
3. The nature of the pain is spontaneous slash-like or lightning-like episodic pain or persistent burning pain or tight bundle-like pain.
4. There are obvious sequelae of nerve injury in the affected area, such as itchiness, tightness, ankylosis, twitching or other discomfort.
5.Patients have heavy psychological burden, depression, or even loss of confidence in life and suicidal tendency.
(III) Typing
The diagnosis of clinical subtypes can be made according to the nature of the patient’s pain and clinical manifestations.
The clinical manifestation is characterized by hypersensitivity to pain, which can produce severe and unbearable pain by gentle touch.
2.Paralytic pain type Clinical manifestations are characterized by hyperalgesia and nociceptive sensitivity, accompanied by tenderness.
3. Central integrated pain type The clinical manifestation can be part of the above two types or the main manifestation, and is characterized by abnormal changes in central secondary sensitization.
III. Clinical treatment
First of all, it should be emphasized that the clinical treatment and outcome of postherpetic neuralgia is very complex and variable, and so far there is still no single method that can satisfactorily relieve the pain. Only by using reasonable and comprehensive treatment methods can we effectively relieve patients’ severe pain and improve their survival quality in clinical practice.
(A) Drug treatment
1.Neurotoxin is a newer and more effective drug for the treatment of postherpetic neuralgia. It is a purified and refined solution from the skin tissue of rabbits inoculated with cowpox vaccine, which not only has a facilitating effect on the repair of cellular functions of the nervous system and immune system, but also has an analgesic effect. It can be applied orally and intravenously. Intravenous drip: 3.75U, 2 times/d, for 14d; orally 8U, 2 times/d, discontinued after the pain disappears.
2.B vitamins The commonly used ones are vitamin B1 and B12, which can be applied for a long time.
3.Antidepressants Patients with postherpetic neuralgia mostly have irritability, anxiety and depressive symptoms, and the application of antidepressants can often reduce pain. Tricyclic antidepressants are commonly used, such as amytriptyline 10-20 mg, 2-3 times/d or 50-75 mg per night, 1 time dose, the maximum dose is 150 mg/d. When the effect is not good, it can be combined with phenothiazines or fluphenazine (1 mg, 2-3 times/d). Long-term application of such drugs should pay attention to the liver, kidney and blood system damage, and occasionally may induce epilepsy, need to be noted.
4, phenothiazines have a mild analgesic effect, its analgesic effect may be related to its ability to reduce the activation of the reticular structure upward, sedation, antihistamine and reduce muscle tone. For example, chlorpromazine 100-150 mg/d (note: when chlorpromazine is applied in small doses, it can only increase pain and produce depressive symptoms, and only moderate doses have analgesic effects). It is reported that high dose short course application of chlorprothixene can make the pain lifted for a long time, the method is 200mg/d, continuous application for 5d.
5.Analgesics Commonly used central analgesics, such as Tramadol or Chimantin 0.05-0.2, 1 time/12h, the maximum dose should not exceed 0.4 per day; non-steroidal anti-inflammatory drugs, such as aspirin 50mg, 2 times/d; Mobic 7.5 mg, 1 time/d; can also try Doregis.
6. Glucocorticoids Local application of hydrocortisone in the painful area is effective in some patients. Dexamethasone epidural interstitial application is effective in some young patients.
7.Other phenytoin sodium 0.1, 3 times/d, the maximum dose does not exceed 0.6/d; carbamazepine 0.2g, 3 times/d; or combined with antidepressants. Central muscle relaxant chlorambucil 45-100 mg/d; antipsychotic permethrin 1-8 mg/d; in addition, 0.1%-0.2% procaine saline 500 ml intravenous drip is also effective.
(ii) Nerve destruction treatment
It is suitable for patients with intractable postherpetic neuralgia who have failed to respond to conservative treatment. Depending on the site of pain, the painful afferent nerves can be selectively destroyed to achieve long-term pain relief. Commonly used nerve destruction drugs include: anhydrous ethanol, 5%-8% phenol glycerol; treatment methods include: peripheral nerve destruction treatment, sympathetic nerve destruction treatment and sympathetic nerve destruction treatment.
1. Peripheral nerve destruction is applicable to postherpetic neuralgia in the chest and abdomen. Intercostal nerve and thoracic paravertebral spinal nerve root destruction is mainly performed.
Peripheral nerve disruption can be applied to a wide range of patients with poor physical condition and those who cannot tolerate posterior spinal nerve root disruption treatment. However, it is contraindicated in patients with infection at or near the block site or allergy to local anesthetics. This treatment may cause pneumothorax, local hematoma, total spinal anesthesia, local anesthetic poisoning, and blood pressure drop, so it should be performed with caution.
2. Posterior spinal nerve root disruption is indicated for patients with intractable postherpetic neuralgia who have been ineffective with common treatment, are in good health, and can tolerate subarachnoid space block. The puncture gap is determined by the site of pain complicated by herpes zoster. When anhydrous ethanol block is used, the patient is placed in the healthy side; when phenol glycerol block is used, the patient is placed in the affected side.
Because of the presence of cervical and lumbar bulge, there is a risk of injury to the anterior root causing paralysis of one upper or lower extremity during treatment, so the benefits and harms should be explained to the patient and his family and a surgical consent form should be signed before treatment. At the same time, the following patients should be contraindicated or should be used with caution: ① those with poor general condition and cannot tolerate subarachnoid space block. ②Patients whose pain can be relieved by drugs or other methods. (3) Patients whose pain is particularly widespread.
3. Hemilunar ganglion dissection is suitable for patients with intractable postherpetic neuralgia of the face. When there is cerebrospinal fluid flow from the puncture needle, inject contrast agent for trigeminal nerve pool development or take X-ray film for localization, and confirm that the tip of the puncture needle is exactly located in the foramen ovale, the successful puncture can be confirmed, and after no blood is retrieved, a test injection is first performed, followed by anhydrous ethanol or 5% to 8% glycerol.
The total dose of phenol glycerin used varies depending on the nerve being destroyed, and the specific dose is usually determined according to the blocking effect. There is no uniform standard for the maximum dose of phenol glycerin injection in the trigeminal pool, but Arias believes that 0.1 ml for destruction of the ophthalmic branch of the trigeminal nerve, 0.25 ml for destruction of both the ophthalmic and maxillary branches, 0.3 ml for destruction of both the maxillary and mandibular branches, and 0.4 ml for simultaneous destruction of all three branches of the block.
Since the treatment of hemispheric ganglion destruction has caused sensory loss or abnormality in the blocked area, vertigo, difficulty in mastication, 3rd, 4th, 6th, and 7th cerebral nerve injury, the treatment of hemispheric ganglion destruction has caused sensory loss or abnormality in the blocked area.
4, 6, 7 cerebral nerve injury and ipsilateral blindness, the following points should be noted before, during and after the block: ①Pre-operatively, the patient and his family should be informed of the possible intraoperative and post-operative conditions and sign the surgical consent form. ②After determining the successful puncture, the position of the puncture needle tip should be kept fixed, otherwise it may cause poor results or serious adverse consequences. ③Patients whose pain can be relieved by using other treatments, who have mental disorders or who cannot cooperate should be contraindicated or used with caution. ④A period of observation should be made at the end of the treatment before leaving the hospital to avoid outside occurrence.
(iv) Sympathetic nerve disruption
It is suitable for postherpetic neuralgia with obvious sympathetic neuralgic pain.
IV. Psychotherapy
Psychotherapy in a broad sense includes the improvement of the patient’s environment and living conditions, the role of language of the surrounding people, special arrangements and specialized psychotherapeutic techniques implemented by the psychiatrist. In a narrower sense, psychotherapy refers to the psychological treatment techniques and measures implemented by a specialist physician. Patients with postherpetic neuralgia can have varying degrees of psychological disorders, such as anxiety, nervousness, depression, abnormal personality traits and even suicidal tendencies, and only with effective psychotherapy can they achieve their clinical goals. Commonly used psychotherapeutic measures are.
(i) Suggestive therapy
Including: supportive suggestion therapy and explanatory suggestion therapy.
(B) behavior therapy
Also known as corrective therapy, is a clinician specially designed special treatment procedures to eliminate or correct the patient’s abnormal behavior or physiological function. Commonly used are systematic desensitization, aversion therapy, behavioral plasticity and self-adjustment methods.
(iii) Biofeedback
With the help of instruments, patients can know the functional changes that are occurring in their own bodies and carry out regulation methods to improve the functional state of organs and systems, correct inappropriate reactions to stress, and benefit the mind and body health.
V. Other treatment methods
(A) Physical therapy
Such as laser, ultra-laser pain treatment instrument, etc., to irradiate the pain site and the corresponding lesion nerve trunk or ganglion. Sometimes unexpected effects can be achieved.
(B) electrophysiological treatment
Some common electrophysiological methods have also been used for the treatment of postherpetic neuralgia, such as transdermal electrical stimulation (TENS), trans-spinal electrical stimulation (DCS), trans-hypothalamic electrical stimulation (DBS) analgesia, and so on. In recent years, China has also made a rapid start, especially with the “HANS” instrument (DD wave, stimulation intensity 5-20mA, 30min/time, 2 times/d, 10d as a course of treatment) as the representative instrument in the treatment began to apply. Since postherpetic neuralgia belongs to a special category of pain, further research is needed on how to achieve orderly and long-lasting treatment by using electrophysiological treatment, and how to give full play to the internal analgesic regulating mechanism of the body to achieve clinical therapeutic effects.
(iii) Local treatment
For patients with obvious symptoms of local skin irritation, i.e. irritation and tenderness type postherpetic neuralgia, topical lidocaine, aspirin, capsaicin and NSAIDs emulsions or creams can be used, all of which can achieve certain therapeutic effects.
(iv) Comprehensive treatment
The commonly used comprehensive treatment measures in China include Chinese herbal medicine, acupuncture, physiotherapy and other therapeutic measures, which can sometimes effectively relieve the pain of patients.
(E) Treatment of sequelae in the affected area
The sequelae of the affected area are the symptoms of postherpetic neuralgia patients in the innervated area other than pain, such as abnormal sensation, ankylosis, itching, tightness, numbness or irregular twitching and other uncomfortable sensations, etc. Some patients sometimes report that it is more unbearable than pain, and the clinical course of the disease often coexists with pain symptoms, and the vast majority of patients are longer than the painful period, which is clinically troublesome to deal with, because in addition to peripheral In addition to peripheral nerve damage, the involvement of central abnormal integration mechanisms is also a major factor. Sympathetic nerve block can sometimes relieve symptoms, but some of the symptoms can be lifelong, which is still an important and difficult topic to continue to explore.