Visual analogue pain scale (VAS).

With this simple test you will be able to assess the severity somewhat more objectively pain syndrome and its dynamics as a result of the treatment, as well as obtain simple recommendations that will help you cope with back and joint pain.

Test instructions:

  • Sit back and relax.
  • Below is a visual analog pain scale. At the top are images demonstrating pain, and below them are descriptions of pain. Click on the image that corresponds to your pain sensations (in the back and joints) on at the moment. Write down or remember the pain level in points. When re-evaluating, compare this indicator with the pain severity indicator before treatment.
  • Read on for tips to help you cope with back and/or joint pain.
  • No pain
  • Mild pain
  • Moderate pain
  • Severe pain
  • Intolerable
    pain

No pain

Your joints and back are in good condition. It is recommended to eat foods that are good for your joints and perform daily physical exercise, helping to keep your back and joints healthy. More detailed information can be found in our articles and useful tips.

Mild pain

Recommended local therapy using drugs (Viprosal B® ointment, Capsicam®, Valusal® gel) for the treatment of back and joint pain (1-2 times a day, up to a maximum of 2 weeks), daily implementation of the complex therapeutic exercises for the back and joints. More detailed information can be found in our articles and useful tips.

Moderate pain

It is recommended to regularly use local medications with analgesic and anti-inflammatory effects (Viprosal B® ointment or Capsicam® ointment or Valusal® gel) 2-3 times a day for 10-14 days. If the effect is insufficient, change the external drug (repeated course for 10-14 days). Will help you decide on a remedy

It is recommended to consult a specialist who may prescribe you a short course (5-7 days) of non-steroidal anti-inflammatory drugs for oral administration (diclofenac, ibuprofen, nimesulide, etc.) or select comprehensive scheme treatment.

Severe pain

Depending on the location of the pain: if back pain - Capsicam® ointment (2-3 times a day for up to 10 days), if muscle pain - Valusal® gel (2-3 times a day for up to 10 days), if joint pain - Viprosal B® ointment (1-2 times a day for up to 14 days). Will help you decide on a remedy

As an “ambulance”, you can take an anesthetic tablet orally, available from a pharmacy without a doctor’s prescription.

A consultation with a specialist is indicated, who may prescribe you a short course (5-7 days) of non-steroidal anti-inflammatory drugs for oral administration (diclofenac, ibuprofen, nimesulide, etc.) and select a comprehensive treatment regimen.

A doctor's help is needed.

Before the doctor arrives, take horizontal position in order to . You may need bed rest within 2-3 days.

Depending on the location of the pain: if back pain - Capsicam® ointment (2-3 times a day for up to 10 days), if muscle pain - Valusal® gel (2-3 times a day for up to 10 days), if joint pain - Viprosal B® ointment (1-2 times a day for up to 14 days). It will help you decide on the product.

As an “ambulance”, you can take an anesthetic tablet orally, available from a pharmacy without a doctor’s prescription (up to 2-3 times a day).

Complex therapy and optimal course of treatment using various drugs pharmacological groups can only be prescribed by your attending physician.

Everyone Have a good day. We are with you in lately very often we talk about remission, a decrease in disease activity, about activity in general, activity indices, etc.

Today and tomorrow we’ll talk about how to measure this activity and how to interpret the result. Let's look at it using an example; if you are interested in other activity indices, just let us know.

So, today we will look at the pain scale, which is often used by rheumatologists and is used to calculate disease activity indices. Pain rating scales are designed to determine the intensity of pain (for any disease). These scales allow you to assess the subjective pain experienced by the patient at the time of the study. The Visual Analogue Scale (VAS) was introduced by Huskisson in 1974.


This method of subjective pain assessment involves asking the patient to mark a point on a non-graduated 10 cm line that corresponds to the severity of pain. The left border of the line corresponds to the definition of “no pain at all,” the right border corresponds to “the most intense pain imaginable.” As a rule, a paper, cardboard or plastic ruler 10 cm long is used. C reverse side centimeter divisions are marked on the ruler, according to which the doctor notes the obtained value and enters it into the medical history or outpatient card. Also, to assess the intensity of pain, you can use a modified visual analogue scale, in which the intensity of pain is also determined by different shades of colors.

The undoubted advantages of this scale include its simplicity and convenience, and the ability to monitor the effectiveness of therapy.

During dynamic assessment, an objective and significant difference is the difference between the VAS value and the previous one by more than 13 mm.

  • The disadvantage of the VAS is its one-dimensionality, i.e., on this scale the patient notes only the intensity of pain.
  • The emotional component of the pain syndrome introduces significant errors into the VAS score.
  • The subjectivity of the VAS is also its main drawback. The patient, in pursuit of his goals, may deliberately underestimate or overestimate the values. When? For example, the patient does not want to offend (stress, bother) his doctor, and even in the absence of a result and the pain syndrome remains at the same level, he underestimates the value. Yes, there are such things) Or the patient wants to get a disability, wants to become a candidate for expensive treatment, etc., and deliberately sets the score significantly higher than the previous result. Well, don’t forget that we are all different: some will endure and even smile, while others with the same pain will not even be able to get out of bed.

Plus, the doctor also needs to be attentive and actively communicate (no, don’t push!!!) with the patient. For example, offering him options for comparison. Let's say a woman walks into the office quite cheerfully, but on a scale she puts it at 10 out of 10, all accompanied by a story about how terrible she feels. You ask: “Have you given birth? Does it hurt as much? “Oh, no, doctor, when I gave birth, did you think I was going to die?” After this, the value decreases to 5. That is why VAS is only one of the tools for calculating the activity index by the doctor himself, who uses objective methods for assessing the patient’s condition. Here you can remember Dr. House and his ironclad “Everyone lies,” but you and I are well-mannered people and will not express ourselves so categorically😄

In conclusion, I just want to say one thing: please be honest with your doctor. If you feel better, talk about it, if you feel worse, again tell the doctor about it. There is no need to deliberately fake or hide anything. If the doctor doesn’t hear you, doesn’t want to hear you, then it’s simply not your doctor. Tomorrow we will discuss DAS-28 and what is considered remission.

Visual Analog Scale (VAS)

Using the VAS method, on a straight line 10 cm long, the patient notes the intensity of pain. The beginning of the line on the left corresponds to the absence of pain, the end of the segment on the right corresponds to unbearable pain. For convenience of quantitative processing, divisions are applied on the segment every centimeter. Numerical scales are more varied: on some, the intensity of pain is indicated by numbers from 0 to 10, on others - as a percentage from 0 to 100. The patient must indicate the intensity of pain, knowing that zero corresponds to the absence of pain, and the final number of the scale indicates the most severe pain, which the patient has ever experienced in his life.

The method of descriptive definitions is that the patient is offered definitions of pain: “mild”, “moderate”, “tolerable”, “strong” and “unbearable” (usually no more than 10 definitions). The patient must choose a definition and underline it. Comparative studies have shown that most patients prefer a descriptive scale, since the intensity of pain is expressed by adjectives, rather than abstract marks on a line, not numbers and percentages.

A multidimensional assessment of pain is possible using the McGill Pain Questionnaire, which in the Russian version consists of 78 descriptor words (words that define pain), combined into 20 subclasses (subscales), forming three main classes (scales): sensory, affective and evaluative . In each subclass, descriptors are arranged in increasing intensity; the subject must choose one of them that most matches his feelings. The patient is asked to describe the pain by selecting certain descriptors in any (not necessarily each) of the 20 subscales, but only one of the descriptors in the corresponding subscale. Data processing comes down to determining three indicators:

  1. The number of selected descriptors index is the total number of selected words.
  2. Rank pain index (RIPI) is the sum of the ordinal numbers of subdescriptors in a given subscale from top to bottom.
  3. The intensity of pain is determined by counting words describing pain during the study period (at the time of presentation of the questionnaire).

Each indicator can be calculated for all scales entirely or separately for each scale.

Electrometric technique

Using the presentation of single electrical stimuli, thresholds are determined pain sensitivity. The threshold of pain sensitivity is taken to be the parameters (amplitude) of the minimum electrical stimulus accompanied by the appearance of pain. The use of this method allows for a quantitative assessment of pain sensitivity thresholds, comparison of data on the diseased and healthy sides, etc. By measuring pain thresholds, a comparison of the sensation of pain in the so-called actual (in the area of ​​pain localization) and neutral zones has also been proposed. In the actual zone, pain thresholds are most often reduced.

Quality of life questionnaires

In order to assess the intensity of pain, its impact on life, and determine the effectiveness of the painkillers used, a study of the patient’s degree of vital activity is also carried out. There are several quality of life questionnaires. With their help, the degree of activity, performance, feeling of fatigue, mood changes, the effectiveness of the activity performed, emotionality (fear, anxiety, apathy, agitation, anger, frustration, etc.), the duration of these states, and their correlation with the degree of pain are assessed. All this allows us to indirectly judge the severity of pain. If a more thorough analysis of the emotional and personal sphere of patients is necessary, especially with chronic pain syndromes, special psychological testing is carried out: a multifaceted personality study (MIL), determination of the level of reactive and personal anxiety according to the Spielberger test, assessment of depression according to the Beck test, the Hamilton scale, etc. These studies are absolutely adequate, since the close relationship between the algic phenomenon, depression and anxiety has been proven.

Algometry

The algometry method consists of quantitative measurement of the subjective report of pain when presenting painful stimuli of increasing intensity. There are various types algometers, including mechanical type is the most common. The researcher uses an algometer (a device in the form of a metal rod with a spring and a sensor) to press on certain points of the body. The pressure force is reflected by a digital indicator. When feeling unbearable pain, the patient, by pressing a special button, records a digital value corresponding to the strength mechanical pressure which caused the pain. Typically, many points are examined, which makes it possible to assess the zones of localization of maximum pain. Found this method greatest application in the study of myofascial pain of various localizations.

Trousseau-Bonsdorff test

To assess pain, the Trousseau-Bonsdorff test is also used: a pneumatic cuff is placed on the patient’s shoulder, maintaining its pressure above 10-15 mm Hg for 10 minutes. Art., then hyperventilation is carried out for 5 minutes: forced breathing (frequency 18-20 per minute). Ischemia and hyperventilation cause a complex of algic, sensory and vegetative manifestations. To assess pain, every minute during the test the patient marks the degree of pain experienced on a visual analogue scale.

Verbal Rating Scale

The verbal rating scale allows you to assess the intensity of pain through a qualitative verbal assessment. Pain intensity is described in specific terms ranging from 0 (no pain) to 4 (worst pain). severe pain). From the proposed verbal characteristics, patients choose the one that best reflects the pain they experience.

One of the features of verbal rating scales is that verbal characteristics of the pain description can be presented to patients in a random order. This encourages the patient to select a pain grade that is based on semantic content.

Verbal Descriptive Pain Rating Scale

Verbal Descriptor Scale (Gaston-Johansson F., Albert M., Fagan E. et al., 1990)

When using a verbal descriptive scale, you need to find out if the patient is experiencing any pain right now. If there is no pain, then his condition is assessed as 0 points. If painful sensations are observed, it is necessary to ask: “Would you say that the pain has gotten worse, or the pain is unimaginable, or is this the worst pain you have ever experienced?” If this is the case, then the highest score of 10 points is recorded. If there is neither the first nor the second option, then you need to further clarify: “Can you say that your pain is weak, average (moderate, tolerable, not strong), strong (sharp) or very (especially, excessively) strong (acute) "

Thus, there are six possible pain assessment options:

  • 0 - no pain;
  • 2 - mild pain;
  • 4 - moderate pain;
  • 6 - severe pain;
  • 8 - very severe pain;
  • 10 - unbearable pain.

If the patient experiences pain that cannot be characterized by the proposed characteristics, for example, between moderate (4 points) and severe pain (6 points), then the pain is rated as an odd number that is between these values ​​(5 points).

The Verbal Descriptive Pain Rating Scale can also be used in children over seven years of age who are able to understand and use it. This scale can be useful for assessing both chronic and acute pain.

The scale is equally reliable for younger children school age, and older age groups. In addition, this scale is effective in various ethnic and cultural groups, as well as in adults with Not significant violations cognitive abilities.

Faces Pain Scale (Bien, D. et al., 1990)

The facial pain scale was created in 1990 by Bieri D. et al. (1990).

The authors developed a scale to optimize the child's assessment of pain intensity by using changes in facial expression depending on the degree of pain experienced. The scale is represented by pictures of seven faces, with the first face having a neutral expression. The next six faces depict increasing pain. The child should choose the face that he thinks best demonstrates the level of pain he is experiencing.

The Facial Pain Scale has several features compared to other facial pain rating scales. Firstly, she's in to a greater extent is a proportional scale, not an ordinal one. In addition, the advantage of the scale is that it is easier for children to correlate their own pain with a drawing of a face presented on the scale than with a photograph of a face. The simplicity and ease of use of the scale make it possible to use it widely clinical application. The scale has not been validated for use with preschool children.

The Faces Pain Scale-Revised (FPS-R)

(Von Baeyer C. L. et al., 2001)

Carl von Baeyer and students from the University of Saskatchewan (Canada), in collaboration with the Pain Research Unit, modified the facial pain scale, which was called the modified facial pain scale. The authors, instead of seven faces in their version of the scale, left six, while maintaining a neutral facial expression. Each of the images presented in the scale received a digital rating ranging from 0 to 10 points.

Instructions for using the scale:

“Look carefully at this picture, where the faces are drawn, which show how much pain you can have. This face (show the leftmost one) shows a person who is not in pain at all. These faces (show each face from left to right) show people whose pain is increasing, increasing. The face on the right shows a person in unbearable pain. Now show me a face that indicates how much you are hurting at the moment.”

Visual Analog Scale (VAS)

Visual Analogue Scale (VAS) (Huskisson E. S., 1974)

This method of subjective pain assessment involves asking the patient to mark a point on a non-graduated 10 cm line that corresponds to the severity of pain. The left border of the line corresponds to the definition of “no pain,” the right border corresponds to “the worst pain imaginable.” As a rule, a paper, cardboard or plastic ruler 10 cm long is used.

On the reverse side of the ruler there are centimeter divisions, according to which the doctor (and in foreign clinics this is the responsibility of the nursing staff) notes the obtained value and enters it into the observation sheet. The undoubted advantages of this scale include its simplicity and convenience.

Also, to assess the intensity of pain, you can use a modified visual analogue scale, in which the intensity of pain is also determined by different shades of colors.

The disadvantage of the VAS is its one-dimensionality, i.e., on this scale the patient notes only the intensity of pain. The emotional component of the pain syndrome introduces significant errors into the VAS score.

During dynamic assessment, a change in pain intensity is considered objective and significant if the current VAS value differs from the previous one by more than 13 mm.

Numerical Pain Scale (NPS)

Numeric Pain Scale (NPS) (McCaffery M., Beebe A., 1993)

Based on the principle stated above, another scale was built - a numerical pain scale. The ten-centimeter segment is divided by marks corresponding to centimeters. According to it, it is easier for the patient, in contrast to the VAS, to assess pain in digital terms; he determines its intensity on the scale much faster. However, it turned out that during repeated tests the patient, remembering the numerical value of the previous measurement, subconsciously reproduces an intensity that does not actually exist

pain, but tends to remain in the region of the previously mentioned values. Even with a feeling of relief, the patient tries to recognize a higher intensity, so as not to provoke the doctor to reduce the dose of opioids, etc. - the so-called symptom of fear of repeated pain. Hence the desire of clinicians to move away from digital values ​​and replace them verbal characteristics pain intensity.

Pain scale by Bloechle et al.

Pain scale of Bloechle et al. (Bloechle C., Izbicki J. R. et al., 1995)

The scale was developed to assess pain intensity in patients with chronic pancreatitis. It includes four criteria:

  1. Frequency of pain attacks.
  2. Pain intensity (pain rating on a VAS scale from 0 to 100).
  3. The need for analgesics to eliminate pain (the maximum severity is the need for morphine).
  4. Lack of performance.

NB!: The scale does not include such characteristics as the duration of the pain attack.

When using more than one analgesic, the analgesic requirement for pain relief is equal to 100 (maximum score).

If there is continuous pain, it is also assessed at 100 points.

The rating on the scale is made by summing the ratings for all four characteristics. The pain index is calculated using the formula:

Overall scale rating/4.

The minimum score on the scale is 0, and the maximum is 100 points.

The higher the score, the more intense pain and its impact on the patient.

Observational ICU Pain Rating Scale

Critical Care Pain Observation Tool (CPOT) (Gelinas S., Fortier M. et al., 2004)

The CPOT scale can be used to assess pain in adult patients in the ICU. It includes four signs, which are presented below:

  1. Facial expression.
  2. Motor reactions.
  3. Muscle tension in the upper limbs.
  4. Speech reactions (in non-intubated) or resistance to the ventilator (in intubated) patients.

... objectification of pain is one of the intractable problems in the clinical practice of doctors of various specialties.

Currently, to assess the presence, degree, and location of pain in the clinic, they are used (1) psychological, (2) psychophysiological and (3) neurophysiological methods. Most of them are based on a subjective assessment of their feelings by the patient himself.

Most in simple ways quantitative characteristics of pain are the ranking scale (Bonica J.J., 1990).

Numerical ranking scale consists of a sequential series of numbers from 0 to 10. Patients are asked to rate their pain sensations with numbers from 0 (no pain) to 10 (maximum possible pain). Patients can easily learn to use this scale. The scale is simple, visual and easy to fill out and can be used quite often during treatment. This allows you to obtain information about the dynamics of pain: by comparing previous and subsequent indicators of pain, you can judge the effectiveness of the treatment.

Verbal ranking scale consists of a set of words characterizing the intensity of pain. The words are arranged in a row, reflecting the degree of increase in pain, and are numbered sequentially from less severe to greater. Most often used next row descriptors: no pain (0), mild pain (1), moderate pain (2), severe pain (3), very severe (4), and intolerable (unbearable) pain (5). The patient chooses the word that most closely matches his feelings. The scale is easy to use, adequately reflects the patient's pain intensity and can be used to monitor the effectiveness of pain relief. The verbal rating scale data compares well with the results of pain intensity measurements using other scales.

Visual analogue scale(VAS) is a straight line 10 cm long, the beginning of which corresponds to the absence of pain - “no pain.” The end point on the scale reflects excruciating, unbearable pain—“unbearable pain.” The line can be either horizontal or vertical. The patient is asked to make a mark on this line that corresponds to the intensity of the pain he is experiencing at the moment. The distance between the beginning of the line (“no pain”) and the mark made by the patient is measured in centimeters and rounded to the nearest whole. Each centimeter on the visual analogue scale corresponds to 1 point. As a rule, all patients, including children over 5 years of age, easily learn the visual analogue scale and use it correctly.

The visual analogue scale is a fairly sensitive method for quantification pain, and data obtained using the VAS correlate well with other methods of measuring pain intensity.

McGill Pain Questionnaire(McGill Pain Questionnaire). Pain is a complex, multidimensional feeling, which simultaneously reflects the intensity of pain, its sensory and emotional components, therefore, when using one-dimensional ranking scales, the doctor evaluates pain only quantitatively, without taking into account the qualitative features of pain. In the early 70s of the 20th century, R. Melzack developed the McGill Pain Questionnaire, in which all words (descriptors) describing the qualitative characteristics of pain are divided into 20 subclasses (Melzack R., 1975). The McGill Pain Questionnaire has been translated into many languages ​​of the world and has proven its effectiveness high efficiency in multidimensional pain assessment.

In our country, there are several versions of the questionnaire in Russian, but the most successful is the version prepared by employees of the Russian State Medical University, Moscow State University. M.V. Lomonosov and CITO named after. N.N. Priorov (Kuzmenko V.V. et al., 1986), which is given below.

MCGILL PAIN QUESTIONNAIRE

Please read all the definition words and mark only those that most accurately describe your pain. You can mark only one word in any of the 20 columns (rows), but not necessarily in each column (row).

What words can you use to describe your pain? (sensory scale)

(1) 1. pulsating, 2. grasping, 3. jerking, 4. constricting, 5. pounding, 6. gouging.
(2) similar to: 1. electric discharge, 2. electric shock, 3. shot.
(3) 1. stabbing, 2. biting, 3 drilling, 4. drilling, 5. piercing.
(4) 1. sharp, 2. cutting, 3. striping.
(5) 1. pressing, 2. squeezing, 3. pinching, 4. squeezing, 5. crushing.
(6) 1. pulling, 2. twisting, 3. tearing out.
(7) 1. hot, 2. burning, 3. scalding, 4. scorching.
(8) 1. itchy, 2. pinching, 3. corrosive, 4. stinging.
(9) 1. dull, 2. aching, 3. brainy, 4. aching, 5. splitting.
(10) 1. bursting, 2. stretching, 3. tearing, 4. tearing.
(11) 1. diffuse, 2. spreading, 3. penetrating, 4. penetrating.
(12) 1. scratching, 2. raw, 3. tearing, 4. sawing, 5. gnawing.
(13) 1. mute, 2. cramping, 3. chilling.

What feeling does pain cause, what effect does it have on the psyche? (affective scale)

(14) 1. tires, 2. exhausts.
(15) causes a feeling of: 1. nausea, 2. suffocation.
(16) causes feelings of: 1. anxiety, 2. fear, 3. horror.
(17) 1. depresses, 2. irritates, 3. angers, 4. infuriates, 5. drives into despair.
(18) 1. weakens, 2. blinds.
(19) 1. pain-interference, 2. pain-annoyance, 3. pain-suffering, 4. pain-torture, 5. pain-torture.

How do you rate your pain? (evaluative scale)

(20) 1. weak, 2. moderate, 3. strong, 4. strongest, 5. unbearable.

Each subclass consisted of words that were similar in their semantic meaning, but differed in the intensity of the pain sensation they conveyed. The subclasses formed three main classes: a sensory scale, an affective scale and an evaluative (evaluative) scale. Sensory scale descriptors (subclasses 1–13) characterize pain in terms of mechanical or thermal effects, changes in spatial or temporal parameters. The affective scale (14 – 19 subclasses) reflects emotional side pain in terms of tension, fear, anger or vegetative manifestations. The evaluative scale (20th subclass) consists of 5 words expressing the patient’s subjective assessment of pain intensity.

When filling out the questionnaire, the patient selects words that correspond to his feelings at the moment in any of 20 subclasses (not necessarily in each, but only one word in a subclass). Each selected word has a numerical indicator corresponding to the ordinal number of the word in the subclass. The calculation comes down to determining two indicators: (1) index of the number of selected descriptors, which is the sum of the selected words, and (2) pain rank index– the sum of the ordinal numbers of descriptors in subclasses. Both measures can be scored for the sensory and affective scales separately or together. The evaluative scale is essentially a verbal ranking scale in which the selected word corresponds to a certain rank. The obtained data is entered into a table and can be presented in the form of a diagram.

McGill Questionnaire allows you to characterize in dynamics not only the intensity of pain, but also its sensory and emotional components, which can be used in differential diagnosis diseases.

Age factor in assessing pain in children. Children aged 8 years and older can use the same visual analogue scales as adults to assess pain severity - this scale is plotted on a ruler, which should be positioned horizontally.

For children from 3 to 8 years old, when self-assessing the severity of pain, you can use either facial scales (faces in photographs or drawings are lined up in a row, in which the facial expressions of distress gradually intensify) or scales with a color analogy (rulers with increasing brightness of red color, indicating the severity of pain) . Reported high degree similarities in pain severity parameters obtained using the photographic portrait scale and the color analogy scale in children aged 3 to 7 years after surgery.

The use of child behavior scales is the main method for assessing pain in newborns, infants and children aged 1 to 4 years, as well as in children with developmental disorders. In such scales, pain is assessed by facial expression, motor responses of the limbs and trunk, verbal responses, or a combination of behavioral and autonomic changes. In some similar techniques The term "distress" reflects not only pain, but also fear and anxiety. Behavioral scales may underestimate the severity of long-term pain when compared with self-report measures.

During the surgical operations and in conditions intensive care It is advisable to document physiological responses to pain, although these responses may be nonspecific. For example, tachycardia can be caused not only by pain, but also by hypovolemia or hypoxemia. Hence, ( !!! ) it can be difficult to assess the severity of pain in newborns, infants and children aged 1 to 4 years, as well as in children with significant developmental disorders. If clinical picture does not allow certain conclusions to be drawn, one should resort to the use of stress-levelling measures, which include creating comfort, nutrition and analgesia, and the cause of distress can be judged by the effect.

Quantitative assessment of pain sensitivity refers to integrative indicators reflecting general condition body and its response to physiological or psycho-emotional stress, so measuring pain thresholds is very useful method V comprehensive examination patients. The threshold of pain sensitivity is taken to be the minimum value of the stimulus that is perceived by the test subject as a painful sensation.

Pain threshold determined using instrumental methods, in which various mechanical, thermal or electrical stimuli are used as stimuli (Vasilenko A.M., 1997). The threshold of pain sensitivity is expressed in (1) units of stimulus strength when using methods with increasing intensity, or in (2) units of time when exposed to a stimulus constant force. For example, when measuring pain sensitivity using a strain gauge, which provides a gradual increase in pressure on the skin, the pain threshold is expressed in units of the ratio of pressure force to tip area (kg/cm2). During thermoalgometry with constant temperature thermode, the threshold of pain sensitivity is expressed in seconds - the time from the beginning of exposure to the appearance of pain.

Using methods for quantitative assessment of pain sensitivity, it is possible to (1) detect zones of hyperalgesia in pathology internal organs, (2) trigger points for myofascial pain syndromes, (3) monitor the effectiveness of analgesics, and in some cases (for example, with psychogenic pain syndromes) (4) determine therapeutic tactics.

Electrophysiological methods. To assess patients' pain sensitivity and monitor the effectiveness of pain relief in clinical studies Electrophysiological methods are also used. Most widespread received a technique for recording the nociceptive withdrawal reflex, or RIII reflex.

Nociceptive withdrawal reflex(NRO), or nociceptive flexor reflex, is a typical defensive reflex. for the first time this type protective reflexes that arise in both animals and humans in response to painful irritation, was described by Sherrington in 1910 and has been used clinically since 1960 to objectify pain (Kugekberg E. et al., 1960). Most often, NRO is recorded in response to electrical stimulation of n. suralis or plantar surface of the foot (Vein A.M., 2001; Skljarevski V., Ramadan N.M., 2002). At the same time, NPO can be recorded during painful stimulation of the fingers (Gnezdilova A.V. et al., 1998) and even with heterosegmental stimulation (Syrovegina A.V. et al., 2000).

When recording NPO, two components are distinguished in EMG activity – RII and RIII responses. The RII response has a latent period of 40–60 ms and its appearance is associated with the activation of thick low-threshold A-fibers, while the RIII response occurs with a latent period of 90–130 ms at an intensity of stimulation exceeding the excitation threshold of thin A-fibers. It is believed that the NRO is polysynaptic, the reflex arc of which closes at the level spinal cord.

However, there is evidence indicating the possibility of involvement of supraspinal structures in the mechanisms of occurrence of NRA. Direct confirmation of this is studies that compared the characteristics of changes in NPO in intact and spinal rats (Gozariu M. et al., 1997; Weng H.R., Schouenborg J., 2000). In the first study, the authors found that in intact rats, the preservation of supraspinal pain control mechanisms counteracts the development of an increase in NPO amplitude under conditions of prolonged painful stimulation, in contrast to spinal animals. The second paper provides evidence of an increase in NPO inhibitory reactions to heterotopic nociceptive stimuli under conditions of spinalization of animals.

Understanding the fact that supraspinal structures of the brain are involved in the formation of NPO not only expands the diagnostic capabilities of the method, but also makes it possible to use it in the clinic for an objective assessment of the severity of pain not only during homotopic stimulation, but also during heterosegmental pain stimulation.

Method of exteroceptive suppression of voluntary muscle activity in m. masseter. To study the mechanisms of development of headaches and facial pain, the clinic also uses the method of exteroceptive suppression of voluntary muscle activity in the m. masseter (Vein A.M. et al., 1999; Andersen O.K. et al., 1998; Godaux E., Desmendt J.E., 1975; Hansen P.O. et al., 1999). This method is essentially a type of nociceptive withdrawal reflex.

It has been established that perioral electrical stimulation causes two successive periods of inhibition in the tonic EMG activity of the masticatory muscles, designated ES1 and ES2 (exteroceptive suppression). Early period inhibition (ES1) occurs with a latency of 10 -15 ms, late (ES2) - has a latency period of 25 - 55 ms. The degree of exteroceptive suppression in masticatory muscles is enhanced by homotopic nociceptive activity in trigeminal afferents, which is used clinically to quantify pain in patients with headaches and facial pain.

The exact mechanisms of development of ES1 and ES2 are unknown. It is believed that ES1 is associated with oligosynaptic activation by trigeminal afferents of interneurons of the nuclei of the trigeminal complex, which have an inhibitory effect on motoneurons of the masticatory muscles, while ES2 is mediated by polysynaptic reflex arc, involving neurons of the medullary part of the spinal trigeminal nucleus (Ongerboer de Visser et al., 1990). At the same time, there is evidence that ES2 can be recorded during heterotopic pain stimulation, and electrical stimulation of the fingers reduces ES2 in the masticatory muscles (Kukushkin M.L. et al., 2003). This suggests that the mechanisms of ES2 development are more complex and are realized with the participation of supraspinal centers through the spinocorticospinal recurrent loop.

Method for recording somatosensory evoked potentials. Over the past two decades, somatosensory evoked potentials (SSEPs) have been widely used to measure clinical and experimental pain in humans. There is extensive research material on this issue, summarized in a number of review articles (Zenkov L.R., Ronkin M.A., 1991; Bromm B., 1985; Chen A.C.N., 1993). It is believed that the early SSEP components (N65-P120) reflect the intensity of the physical stimulus used to evoke pain, while the amplitude of the late SSEP components (N140-P300) correlates with the subjective perception of pain.

The idea that the amplitude of late SSEP components may reflect the subjective perception of pain was based on studies that showed a positive relationship between a decrease in the amplitude of the N140-P300 SSEP components and the administration of various analgesics. At the same time, the variability of the amplitude of late SSEP components is well known, which depends on a number of psychological factors such as attention, memory, emotional state(Kostandov E.A., Zakharova N.N., 1992), which can be significantly changed not only by analgesics, but also by the research procedure itself. In addition, recent publications on this problem (Syrovegin A.V. et al., 2000; Zaslansky R. et al., 1996) indicate a low connection between subjective pain perception and the amplitude of late SSEP components.

!!! The most reliable among electrophysiological methods for monitoring the magnitude of subjective pain sensation remains the nociceptive withdrawal reflex (NRE).

Functional mapping of neuronal activity brain structures . Recently in clinical practice methods of functional mapping of neuronal activity of brain structures during acute and chronic pain(Coghill R.C., et al., 2000; Rainville P. et al., 2000). The most famous of them are: (1) positron emission tomography and method (2) functional magnetic resonance. All functional mapping methods are based on recording a local hemodynamic reaction in brain structures, which has a positive correlation with the electrical activity of neuron populations.

Using functional mapping methods, it is possible to visualize in three-dimensional spatial coordinates (millimeters in humans and micrometers in animals) changes in neuronal activity in response to presented nociceptive influences, which makes it possible to study the neurophysiological and neuropsychological mechanisms of pain.