Measuring and controlling pain

The simplest and most common method is to record pain intensity using rank scales. There is a numerical rank scale (NRS) consisting of a sequential series of numbers from 1 to 5 or up to 10. The patient must select a number reflecting the intensity of the pain experienced. The verbal rank scale (VRS) contains a set of pain descriptor words reflecting the degree of pain increase, sequentially numbered from lesser to greater severity: none (0), mild pain (1), moderate pain (2), severe pain (3), very severe pain (4), unbearable (unbearable) pain (5). The visual analogue scale (VAS) is a straight line 100 mm long with or without millimetre divisions applied to it. The starting point of the line means no pain, the end point means unbearable pain. The patient is required to mark the level of pain with a dot on the proposed line. For patients who have difficulty abstracting and representing pain as a number or a point on a line, a facial (facial pain scale) can be used.

The simplicity and high sensitivity of rank scale assessment methods make them very useful and sometimes irreplaceable in clinical practice, but they also have a number of disadvantages. The mathematical analysis of the results is based on the unlikely assumption that each rank is an equal psychological unit of measurement. Pain is assessed unambiguously - by intensity, as a simple sensation that differs only quantitatively, whereas it has qualitative differences. Analog, numerical and verbal scales provide a single, generalized assessment that reflects the almost completely unstudied process of integrating multidimensional pain experience.

For multidimensional pain assessment R. Melzack and W. S. Orgerson (1971) proposed a questionnaire called the McGill Pain Questionnaire. Also known is the method of multidimensional semantic description of pain, which is based on the extended McGill questionnaire (Melzack R... 1975). The extended questionnaire contains 78 pain descriptor words entered into 20 subclasses (subscales) according to the principle of semantic meaning and forming three main classes (scales): sensory, affective and evaluative. The survey results can serve as a criterion for the mental state of patients. Numerous studies have verified the adequacy of the method for assessing pain, analgesia and diagnostics; at present, it has become a standard examination method abroad.

Similar work has been done in our country. V.V. Kuzmenko, V.A. Fokin, E.R. Mattis and co-authors (1986), based on the McGill questionnaire, developed an original questionnaire in the Russian language and proposed a method for analyzing its results. In this questionnaire, each subclass consists of words similar in their semantic meaning, but differing in the intensity of the pain sensation they convey. The subclasses form three main classes (scales): sensory, affective and evaluative. Descriptors of the sensory scale (subclasses 1-13) characterize pain in terms of mechanical or thermal effects, changes in spatial or temporal parameters. The affective scale (subclasses 14-19) reflects the emotional side of pain in terms of tension, fear, anger or vegetative manifestations. The evaluation scale (20 subclasses) consists of five words expressing the patient's subjective assessment of pain intensity and is a variant of the verbal ranking scale. When filling in the questionnaire, the patient selects words corresponding to his sensations at the moment in any of the 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 is reduced to determining two indicators: the index of the number of selected descriptors (INSD), which is the number (sum) of the selected words, and the rank index of pain (RIP), which is the sum of the ordinal numbers of the descriptors in the subclasses. Both indicators are calculated for the sensory and effective scales separately and together (sum index).

McGill Pain Questionnaire

Щ What words can you use to describe your pain? (sensory scale)
1. Pulsating Gripping Twitching Quilting Pounding Pounding	2. Similar: Electric discharge, Electric shock, Shot	3. Stitching Digging in Drilling Drilling Punching
4. Acute Cutting Rinsing	5. Pressing Squeezing Aching Squeezing Crushing	6. Pulling Twisting Tearing out
7. Hot Burning Scalding Scorching	8. Itchy Pinching Corrosive Stinging	9. Dumb Aching Brain-cracking Breaking Splitting
10. Bursting Stretching Heartbreaking Tearing	11. Spilled Spreading Penetrating Penetrating	12. Scratching Sore The one who tears Sawing Gnawing
	13. Mute Reducing Chilling

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

14. It's tiring It's exhausting	15. Calls: Feeling of nausea, Choking	16. Evokes the feeling: Anxiety, Fear. Horror
17. Depressing Annoys Angry It makes me furious It drives me to despair	18. It's exhausting It's blinding	19. Pain is a hindrance Pain is annoyance Pain is suffering Pain is torment Pain is torture

How do you rate your pain? (evaluative scale)

20. Weak Moderate Strong The strongest Unbearable

According to the definition of the International Association for the Study of Pain, "the pain threshold (PT) is the minimum pain sensation that can be perceived." Another informative characteristic is the level of pain tolerance (the pain tolerance threshold - PT), defined as "the highest level of pain that can be tolerated." The name of the method of quantitative study of pain sensitivity is formed from the name of the algogenic stimulus used in it: mechano-algometry, thermo-algometry, electro-algometry.

Most often, pressure is used as a mechanical effect, and then the method is called tensoalgometry (dolorimetry). In tensoalgometry, PB is expressed in units of pressure force related to a unit of area (kg/cm2 ⁾. Depending on the localization, replaceable attachments are used for measurements: in the head and distal extremities with a diameter of 1.5 mm, and in the area of massive skeletal muscles - 5 mm. Tensoalgometry is carried out by smoothly or stepwise increasing the pressure on the tested area of the body. Pain occurs at the moment when the pressure force reaches values sufficient to excite the Ab-mechanoreceptors and C-polymodal nociceptors.

Determination of PP and PPB can provide important clinical information. Decreased PP indicates the presence of allodynia, and decreased PPB is a sign of hyperesthesia (hyperalgesia). Peripheral sensitization of nociceptors is accompanied by both allodynia and hyperalgesia, and central sensitization is manifested mainly by hyperalgesia without concomitant allodynia.

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