Terminology in pain physiotherapy

Chronic pain is pain that lasts or recurs for more than three months and has multiple causes: biological, psychological, and social factors contribute to chronic pain. Chronic pain is considered a disease in its own right. We distinguish between:

Secondary chronic pain
Pain associated with other diseases and considered solely as a symptom (e.g., knee osteoarthritis). Even if the pain persists despite effective treatment of the disease/cause, it is still considered secondary chronic pain. (e.g., total knee replacement)

Primary chronic pain
Widespread and/or localized pain in different areas, in one or more anatomical regions, which cannot be explained by a chronic disease/cause and which is accompanied by considerable emotional distress and/or functional impairment (e.g., CRPS, “non-specific” low back pain, fibromyalgia, etc.).

It is a conscious emotional and behavioral experience of pain, usually measured using a visual analog scale (0-100 mm) or a numerical scale (0-10). Therapeutic changes are only considered clinically significant when there is a reduction of 30% (> 2 points/> 20 mm).

This is a neural process that involves encoding harmful stimuli (mechanical, thermal, chemical) into electrical signals, which may or may not cause pain. Nociception can be measured using mechanical stimuli (pressure algometer, pinprick, etc.) and thermal stimuli (thermometer, metal disc at 8°C and 45°C, etc.) that cause pain.

Hypersensitivity to painful stimuli (hyperalgesia, first-order nociceptive neurons) in response to peripheral stimulation. Peripheral sensitization is generally characterized by sensitivity to cold and/or heat (thermal hyperalgesia).

Enhancement of sensory and/or normal stimuli triggering pain originating in the periphery in the central nervous system through persistent excitability of spinal cord nerves (second-order neurons), resulting in hypersensitivity to pain. Central sensitization is characterized by nociceptive sensitivity to mechanical stimuli (mechanical hyperalgesia) in the affected surrounding tissues (secondary hyperalgesia) and/or pain sensation in response to non-painful stimuli (mechanical allodynia) and/or cumulative intensification of pain in response to repeated mechanical stimuli causing pain (wind-up phenomenon).

The mechanisms of pain are as follows processes the processing of painful stimuli, which explains how a painful experience (perception) arises from the interaction between peripheral and central neural activities. We distinguish between:

nociceptive
Pain results from the activation of pain signals, irritations causing or potentially causing tissue damage, and the processing of this activity in the somatosensory system.

neuropathic
Neuropathic pain is defined as pain resulting directly from damage or disease of the somatosensory system (e.g., nerve damage, nerve compression, brain damage, and brain disease).

noziplastic
In the case of nociceptive pain, the nociceptive system, which encompasses all stages of nociception from the harmful stimulus to perception, is hyperactive without any detectable lesion or disease of the somatosensory system or peripheral activation of nociceptive neurons due to actual or potential tissue damage.

The phenotypes of pain are as follows classifications types of pain based on their mechanisms. We distinguish between nociceptive, neuropathic, and nociceptive pain phenotypes.

This refers to motor behavior that has been modified (inappropriately) by a painful experience (perception). We distinguish between:

1. Pain-related avoidance behavior
   (non-associative, learned through sensitization: I don’t move because it hurts)
2. Fear-related avoidance behavior
   (learned through classical associative conditioning: I don’t move because I’m afraid of breaking something)
3. Perseverance behavior linked to distress with painful episodes (learned through associative operant conditioning: I must absolutely accomplish my tasks despite the pain and then suffer for it).
4. Perseverance behavior linked to eustress, with positive distraction and a sense of control (even if the activities are painful, I continue to do them because I don’t want the pain to prevent me from moving freely).

This is a specific form of physical training in which subliminal nociceptive stimuli are endured and gradually increased (in stages) while performing a set number of repetitions. There are two types:

1. Graduated activity (effort according to a program with a pace based on quotas) in cases of avoidance behavior related to pain
2. Gradual exposure (overcoming fears through movement) in cases of anxiety-related avoidance behavior
3. Gradual balance (exertion within one’s limits with pace based on pain) in case of persistence with painful flare-ups
4. Graduated motor imagery (mirror therapy) for neuropathic pain

Pacing is an active self-management strategy in which individuals learn to find an appropriate balance between periods of activity and rest in order to improve their functioning and participation in important activities.