Shingles pain
Acute herpes zoster (AHZ) is a disease characterized by severe pain caused by Varicella zoster virus (VZV), although the incidence varies according to age. Most of the cases reported by domestic and foreign scholars are in middle-aged and older people, especially the elderly and those with reduced immunity. However, in recent years, we have also found cases in young people (20-25 years old) one after another. Due to the continuous development and expansion of the field of clinical anesthesiology, many anesthesiologists have become more involved in clinical analgesic treatment, especially some refractory herpes pains are often referred to the pain clinic of anesthesiology or the pain department of anesthesiology by specialists, and they can achieve better pain relief. Hou Mingming, Department of Pain, Guilin People’s Hospital
Acute herpes zoster
AHZ has a long history, both in Chinese traditional medicine and in Western medicine, but in the early days people did not know what herpes zoster was all about, and it was not until the latter part of the nineteenth century that the medical profession figured out that it was a viral disease; thanks to modern medicine, we now know that VZV is a virus with neurophilic and dermatophilic properties, and its form is rectangular It invades the body through the sensory nerve endings of the skin or the nasal mucosa, invades the nervous system through retrograde axonal operation, and then enters the ganglion of the posterior spinal nerve or the ganglion cells of the cerebral nerve for a long period of time, in a dormant state, without any symptoms, when the internal environment of the body changes, especially when the normal immune defense mechanism is damaged or suppressed, When the internal environment of the body is changed, especially when the normal immune defense mechanism is damaged or suppressed, VZV is activated and grows and multiplies in the affected ganglion, causing acute inflammation, hemorrhage, necrosis and disease.
Incidence and prevalence
The incidence of AHZ varies slightly depending on the species cluster and population or region, and there are few official publications in China. The incidence in the general population according to Loeser [3] was about 125/100,000/year, with large differences between ages, such as 0.074% in the 1-9 years group, 0.13% in the 10-19 years group, 0.258% in the 20-29 years group, 0.229% in the 30-39 years group, 0.292% in the 40-49 years group, and 0.509% in the 50-59 years group. 0.509% in the group of 50-59 years, 0.679% in the group of 60-69 years, 0.642% in the group of 70-79 years, and 1.01% in the group of 80-89 years; in addition, according to the prevalence and proportion of AHZ: 15% in the head and face, 12% in the neck and collar, 55% in the chest and back, 14% in the lumbar abdomen, 3% in the sacrococcygeal region, and 1% in the systemic region, respectively.
Nature and clinical course of pain
More than 90% of patients with AHZ have pain, which is more clinically characteristic than other types of pain, i.e., it is severe. Most of the patients have spontaneous cut-like or lightning-like episodes of pain accompanied by continuous burning pain, or only episodic pain; some patients may have pinprick-like pain or continuous burning pain, and the patients’ daily life is obviously affected, especially sleep disturbance at night, although the degree of pain may vary, but most patients are suffering. Although the degree of pain may vary, most patients suffer. Very few patients have only persistent soreness and lack typical neuralgia.
The prodromal phase is the aforementioned general and local abnormal sensory symptoms, which vary in severity and duration from patient to patient, generally 1-6 days; followed by the herpetic phase, in which irregular erythema or corn-like papules and small herpes appear on the local skin, which can turn into shiny blisters surrounded by a red halo and distributed along the nerve distribution area. Herpes on the back of the abdomen often occur in batches from near to far, occasionally at the same time, early herpes can be distributed independently, and later sometimes can be fused into large lesions, improperly handled mixed infection, the lesions are more obvious, this period is about 2-3 weeks. The recovery period varies according to the condition of the body, generally 1-6 weeks, if the body is more resistant, the herpes group is limited and the scope is small, the recovery can be short term, often after the herpes is mature that gradually fade, crust and fall off, while the main symptoms disappear, leaving only local pigmentation changes; on the contrary or in addition to the occurrence of mixed secondary infection, the recovery time is naturally prolonged. Most patients undergo timely and reasonable treatment, and after about 10 weeks of recovery, pain and other discomfort gradually disappear, reaching the goal of clinical cure, while some patients enter the post-pain phase,
The diagnosis of acute herpes zoster is relatively easy based on the characteristic pain and the typical clinical features of herpes distribution, but the diagnosis is sometimes difficult in the prodromal phase and preherpetic phase, which sometimes needs to be clinically distinguished from herpes simplex, which mostly occurs at the junction of skin and mucous membranes, with no obvious pattern of distribution and, most importantly, no significant pain. In the case of microdermatitis and herpes zoster, the diagnosis is more difficult.
Clinical treatment
1. Principles of drug therapy
Anti-viral drugs: for the etiology of treatment selected, such as Ara-C, Ara-A, interferon, AMP and oral Chinese and Western drugs can inhibit the virus to varying degrees, to promote the recovery of patients, timely and effective doses of drugs can sometimes reduce the incidence of post-pain, such as a comparative study in 1982, the use of AMP intramuscular injection treatment to a group of human AHZ to obtain more satisfactory results, inhibiting the In a comparative study in 1982, for example, treatment with AMP intramuscularly gave satisfactory results in a group of human AHZ, inhibiting the propagation of the virus, promoting the healing of the lesions and also relieving pain.
Adjuvant drugs: Adjuvant drugs include glucocorticoids, immune adjuvants, vitamins and antibiotics, such as dexamethasone, prednisone, polymyxin, levamisole, etc.
2.Light therapy
Light can produce many beneficial effects on the human body, so it can play a therapeutic role in some diseases. The light therapy currently used is an example of successful application, clinically used infrared, ultraviolet light and laser, their common effect on the human body are mainly through the form of photochemical action and heat, light therapy so that cells absorb light energy and local heat production, so that the affected area blood supply increases, and promote the metabolism of cells.
3.Epidural cavity drug injection
The epidural space is a potential gap between the ligamentum flavum and the dura mater, filled with connective tissue, blood vessels, nerve roots and fat. The injection of drugs can directly affect the affected tissues and nerves of AHZ patients, which can achieve timely and satisfactory clinical pain relief, shorten the course of the disease and promote the recovery of AHZ.
4.Paravertebral drug injection and sympathetic nerve block
By injecting therapeutic drugs around the nerve roots in the paravertebral foramina or using the corresponding sympathetic nerve segment block can also be used in the clinical treatment of AHZ, and the effect is also satisfactory, as long as the site is accurate, the same effect as the epidural injection can be achieved, but the clinical technical requirements are also high, so be careful to prevent complications.
5.VZV serum antibody and vaccine
The prospect of an inactivated varicella vaccine, which is said to be very popular, is encouraging and may significantly reduce the incidence of AHZ, but it is unlikely to be commonly used in clinical practice in the near future. In addition, serum antibodies from patients recovering from AHZ may effectively inhibit the proliferation of VZV, alleviate the disease and promote the recovery of patients.
Postherpetic neuralgia (PHN)
PHN is defined as postherpetic neuralgia (PHN) after clinical cure of AHZ. PHN is one of the most persistent pain disorders in the middle-aged and elderly population, with a short duration of 1-2 years and a long duration of more than 10 years, and a general history of 3-5 years if there is no effective pain control method. Patients suffer from pain for a long time, which not only leads to depression and poor quality of life, but also reduces or even loses their ability to work and socialize.
Disease course and pathological changes
The pathological changes of PHN are not yet fully understood. Although the pain of PHN is related to AHZ, there are still different views on whether it is simply a temporal continuation of AHZ or a different type of pain. Most scholars tend to believe that they are two different types of pain, with some suggesting atrophy and sensory ganglion lesions on the infected side of the dorsal horn in patients with PHN, but no such changes in patients with AHZ []. In addition, chronic inflammatory cell infiltration can be found in the posterior root ganglion. In addition, they suggest that central mechanisms are involved in the pain of PHN. Based on the results of the efficacy analysis of a group of clinical cases we observed, it is suggested that the sites involved in the production of pain may be dominated by the intervertebral foramina and paravertebral space regions [6]. In addition, unlike acute herpes zoster, the psychological factors involved in patients with PHN are significantly higher. Due to long-term severe pain, patients are psychologically burdened, depressed, and lose confidence in life, and most of them have suicidal tendencies, which should be given special attention.
Morbidity
In general, the incidence of PHN is proportional to the age. Morages once counted a group of cases in which the incidence was 4% in 10-19 years, 2% in 20-29 years, 15% in 30-39 years, 33% in 40-49 years, 49% in 50-59 years, 65% in 60-69 years, and 74% in 70-79 years; and the possibility of pain lasting >1 year in 4-10% in the 10-49 years group, 18-48% in the 50-79 years group, and up to 10 years or more in individual patients [3].
Clinical staging of PHN
Rowbotham (1999)[5] suggested that the pain of PHN can be clinically classified into three subtypes, i.e., agitated tenderness, paresthesia and centrally integrated pain. The different subtypes are clinically significant and should be treated differently, but there are few published reports on the cases and clinical treatment.
Modern treatment
1. Principles of drug treatment
PHN’s responsiveness to drugs is clinically different from that of AHZ, so many commonly used analgesic drugs are not effective, but the commonly used narcotic analgesics, antidepressants, anticonvulsants, hormones and some NSAID drugs are effective in relieving pain in some patients.
(1) Narcotic analgesics
Narcotic analgesics are less effective in the analgesic treatment of PHN patients than in other areas of pain. There are still clinical attempts to use narcotic analgesics abroad, but since the exact mechanism of PHN is still unknown, further clinical studies and observations are needed to reach a conclusion.
(2) Antidepressants
Antidepressants are used in the adjuvant analgesic treatment of PHN patients with certain effect, and the commonly used ones are amitriptyline (25-100 mg/day), doxorubicin (25-150 mg/day), and sellett (25-75 mg/day), etc. They can be used routinely, but care should be taken to start with small doses and gradually increase them to prevent significant side effects.
(3) Anti-epileptic drugs
The effect of antiepileptic drugs alone is not obvious, the combination of antidepressants can improve the efficacy, the commonly used clinically are carbamazepine (200-300 mg / day) and phenytoin sodium (200-300 mg / day), the use process should pay attention to liver and kidney function.
(4) NSAIDs
NSAIDs can sometimes be used as adjuvant therapy for early PHN patients, especially when the inflammatory reaction of peripheral nerve roots is predominant, and can be used together with other drugs, such as diclofenac sodium and clozoxazone, etc. Clinical use should pay attention to gastrointestinal side effects.
(5) Topical medication
For patients with obvious symptoms of local skin irritation, i.e. irritable and painful PHN, foreign reports have shown that the use of lidocaine, aspirin, capsaicin and other NSAIDs emulsions or creams can achieve certain therapeutic effects.
(6) Immunomodulators
Although we do not know the exact connection between immune factors on the occurrence and prognosis of PHN, it is recognized that the occurrence of acute herpes zoster is closely related to the decrease of the body’s immunity, so immunomodulatory therapy should be one of the directions, and polyinosinic acid and nucleotide are commonly used in early clinical practice.
Since most of the patients with PHN have severe pain, the clinical response to drug therapy varies greatly among individuals, and a reasonable combination of drugs should be selected according to the length of medical history, the nature of pain and previous medication history to achieve the purpose of pain relief.
2.Comprehensive treatment
At present, the comprehensive treatment of PHN commonly used in China and abroad includes acupuncture, physiotherapy, topical application or ointment with electrophysiological and pharmacological treatment can make some patients’ pain relieved or temporarily reduced, but from the clinical point of view, a longer period of continuous treatment is needed to achieve the ideal effect.
3.Regional nerve block and sympathetic nerve block and evaluation
According to our preliminary clinical experience, regional nerve or nerve root injection is the most effective method to relieve severe pain in patients with PHN, especially for patients with disease duration <6 months. Regional nerve block for PHN includes local infiltration drug injection, nerve trunk block, paravertebral nerve root and sympathetic ganglion and local intravenous drug injection, etc. Generally speaking, some regional analgesic treatment has good efficacy for patients with paralytic PHN, but it is necessary to achieve clear diagnosis, accurate positioning and technical operation in order to ensure the effect.
4.Intravertebral drug injection
Intradural injection is the epidural injection, and its effect is not exact in the treatment of PHN, and many patients can only get temporary relief (probably related to the pathological changes of PHN, the inflammatory process in the spinal cord and its surrounding tissues basically subsides during this period); some patients may respond to epidural injection treatment in the clinical process, and most patients often have difficulty in achieving long-term pain relief, but it may cause other complications. In our study, we observed a group of paralytic pains. The preliminary results of a group of paralytic clinical cases we observed showed that the effect of using epidural injection as a control data was far less than that of the peripheral nerve root injection group.
5.Electrophysiological treatment
Electrophysiological treatment for pain relief of PHN is more common in foreign countries, such as transdermal (TENS), transspinal (DCS), and transhypothalamic (DBS) electrical stimulation for pain relief, etc. The basic principle is based on the traditional method of acupuncture for pain relief in China; in the past 20 years, China has also started faster, and many instruments have been put into clinical use, especially those represented by HANS in the near future. In the near future, HANS will definitely play an active role in the treatment of PHN. Since PHN is a special kind of pain, it should be orderly and lasting in the process of using electrophysiological treatment, giving full play to the internal regulatory mechanism of the body and focusing on activating the endogenous analgesic system in order to achieve the clinical treatment effect.
6.The use of special drugs
In the treatment of PHN, sometimes the use of conventional drugs cannot effectively control the pain, and special drugs such as ethanol and phenols are needed to achieve the purpose of chemically cutting off the nerves and long-term pain relief. However, we must remind you that these drugs are very corrosive and irritating, and the clinical use of these drugs should be done with sufficient technical level, or they will not only cause tissue destruction but also cause pain.
7.Freezing for pain relief
Since the anatomical continuity of peripheral nerves is not cut off, it should be said that freezing analgesia only “temporarily” interrupts or weakens the transmission of pain information, and relies on the regenerative ability of peripheral nerves themselves to eventually restore their inherent function of conveying information, These characteristics are the material basis for the ability of freezing to analgesia without affecting the function of peripheral nerves and the vegetative nervous system. In the past 10 years or so, there has been a rapid development in China, especially in the PLA Orthopedic Medical Center under the leadership of Professor Shao Zhenhai, in the range of -20 to -180 degrees with different temperature gradients, a systematic and comprehensive study of the effect of peripheral nerves, and the creation of percutaneous puncture freezing of the posterior branch of the spinal nerve for the treatment of low back pain, for clinical pain This has provided another important method for clinical pain management. There is not much information on the use of cryopreservation in the treatment of PHN, but it is expected that as long as the method is accurately mastered, cryoanalgesia will play a role in the treatment of PHN.
8.Psychotherapy
Psychotherapy plays a significant role in the treatment of pain, and is especially important in the treatment of PHN. It is known that pain is accompanied by significant emotional changes, and the so-called psychotherapy, in a broad sense, includes the improvement of the patient’s environment and living conditions, the role of the language of the surrounding people, special arrangements and specialized psychotherapy techniques implemented by physicians. In a narrow sense, psychotherapy refers to the psychological treatment techniques and measures implemented by specialists. From the clinical point of view, PHN are accompanied by varying degrees of psychological disorders, such as anxiety, tension, depression, abnormal personality characteristics and even suicidal tendencies, if drug treatment or nerve block alone, there is no significant effect on this type of pain, must be supplemented with the corresponding effective psychotherapy.
9. Treatment of sequelae
The sequelae of the affected area refers to the symptoms of PHN patients, such as abnormal sensation, ankylosis, itchiness, tightness, numbness or irregular twitching and other uncomfortable sensations in the innervated area, because the affected nerve has been severely damaged by the virus, and the clinical course of the disease is often coexisting with painful symptoms. Sympathetic nerve block can sometimes relieve the symptoms, but some of the symptoms can be lifelong, and the complete solution depends on the nerve repair process.
Microdermatomal and anaplastic herpes zoster
In a very few cases of AHZ, the patient only has severe pain without typical herpes, which can be called zoster sine herpete (ZSH), and some patients only have microscopic herpes in the affected area, which we call mini-herpes zoster (MHZ), ZSH and MHZ are two special and rare clinical types. ZSH and MHZ are two special and rare clinical types, because the symptoms are not typical or no herpes is visible, the diagnosis is difficult when clinical attention is not paid, and both doctors and patients are troubled. Therefore, the existence of ZSH was even suspected in the early days of pain monographs, but now the existence of such patients has been noticed.
Typical cases
1. Zhang ×, female, 60 years old, retired cadre, complained of persistent pain in the left calf for 10 days, which was not relieved by various treatments. The pain was persistent, with paroxysmal tearing pain, and it was often difficult to sleep or wake up at night. On physical examination, there were no abnormal signs in the spine and lumbosacral region, and the left sciatic nerve point showed light pressure pain. No local pressure point was found in the left calf, and there was no significant abnormality in the X-ray and related examinations, and the movement and walking of the left lower limb were mildly restricted. He went to several hospitals to receive traditional Chinese medicine, acupuncture, topical application and pain medication, but could not significantly relieve the pain. The initial diagnosis was ZSH (sciatic nerve involvement) of the left lower limb, and the pain was controlled after antiviral treatment, vitamin supplementation and sciatic nerve block treatment once, and the pain disappeared completely in about 10 days after the second treatment.
2. Zhou xx, male, 72 years old, had persistent pain in the left eye, forehead and head with lightning-like episodes for one week, and took painkillers ineffectively. After careful examination, a cluster of small blisters with a total of 5 blisters and an area of about 0.2 cm2 was found in the near hairline area of the head.
Diagnosis
The diagnosis of herpes zoster without herpes is currently based on clinical symptoms and signs and laboratory techniques.
1.According to the nature and characteristics of clinical pain, especially the characteristics of segmental regional pain and abnormal changes of sensation without localization pain, the degree of more intense;
2.Serum antibody determination: serum IgM and A antibodies can determine primary infection, while IgG and A antibodies can appear when VZV is reactivated. (Because VZV has only one serotype, IgG and A are often elevated in the serum during reactivation [8].) In this group, serum IgG was elevated while IgA was basically normal.
3, VZV culture isolation and DNA analysis: by laboratory culture or using the multiplex enzyme chain reaction (PCR) technique.
Treatment
Once the diagnosis was established, the patients in this group were treated with a comprehensive treatment method based on nerve root injection, such as antiviral drugs, vitamin supplementation and nerve trunk or nerve root injection, all of which rapidly relieved or controlled the pain in about one week, and none of the 12 patients in this group had residual neuralgia, but the dysfunction generally recovered more slowly, and still did not fully recover after >6 months of follow-up. According to our clinical statistics, MHZ and ZSH account for about 3.48% of acute herpes zoster, with MHZ about 2% and ZSH about 1.3%.