From Tissue Injury to Nerve Hyperexcitability: Understanding the Shifting Nature of Pain
Overloaded tissues often cause new back pains. However, in persistent pain, even when tissues have healed, discomfort lingers. Chronic pain may be less about damage or arthritis and more about a hypersensitive nervous system.
Pain hypersensitivity is not just a symptom; it can be a standalone diagnosis, highlighting the body's heightened protective response to stimuli.
Learned pain hypersensitivities can become as automatic as playing an instrument or driving a familiar route, shifting its triggers from sensitised tissues to overprotective nerves. With back pain's long-term nature, recognising how pains evolve over time helps demystify why hurt does not necessarily mean harm, especially when symptoms last longer than twelve weeks.
Tissue Dominant Pain
Mechanical pain arises when potentially harmful stimuli trigger normal functioning neurons. It alerts us when our tissue tolerance is exceeded, guiding us to rest or adjust our actions.
Pain is localised to sensitised anatomical structures.
Symptoms are comparable with mechanical stress and dissipate quickly after removing the trigger.
Tissue-dominant pain retains its protective link to physical damage. Therefore, things that should hurt after injury often cause pain, but typically harmless stimuli, such as touch or temperature, do not trigger discomfort.
Temporarily reducing mechanical stress can ease symptoms, guiding people in how to self-manage their pain, even when its exact cause is unclear.
Symptom modification allows individuals with functional pain triggers to stay active while sensitised tissues heal and strengthen.
As symptoms ease, we can slowly resume activities once deemed painful. This gradual reintroduction strengthens the spine via adaptation, empowering us to manage episodic pain and continue to enjoy valued activities.
Nerve Dominant Pain
The longer our back pain lasts, the more overprotective our nervous system becomes, altering the way we experience pain.
Influenced by genetics, frequent exposure to painful stimuli can make nerves more sensitive to stimulation, strengthening their pathways.
This turns our pain volume up, making specific postures and actions more threatening to our brain.
This results in the first symptom of an overprotective nervous system:
Hyperalgesia: stimuli that were previously painful now hurt even more.
This heightened sensitivity makes the pain more widespread, unpredictable, longer-lasting, and harder to diagnose.
Over time, hypersensitive nerves begin to malfunction. Instead of detecting potentially dangerous energies only, they can misinterpret harmless stimuli as threats. This results in the second symptom of an overprotective nervous system:
Allodynia: safe stimuli, such as touch or temperature, cause unpleasant discomfort.
Such pain loses its protective relationship with physical injury, underscoring that hurt does not always signify harm.
In some cases, an excess of ion channels in our neurons can produce a 'leaky' current, resulting in spontaneous, rhythmic pains. Unlike typical pains linked to injuries, these operate with an automaticity similar to heart pacemakers. It is therefore important to appreciate the factors that cause pain may be very different from the factors that maintain it.
When pain is driven more by an overprotective nervous system than by tissue damage, treatment should shift from passive pain relief to supported self-management.
Recognising pain hypersensitivity as a distinct diagnosis allows clinicians and patients to move away from the endless search for an elusive tissue disorder to "fix." Instead, they can embrace sustainable and person-centred approaches that build resilience.
While we cannot always change pain, reframing it addresses unhelpful thoughts and behaviours that may be hindering recovery, freeing individuals to challenge activities they once avoided due to anxiety.
Once our nervous system learns pain, various harmless biopsychosocial factors can influence it, affecting its timing, severity, and duration.
Factors such as emotional distress, negative beliefs, poor sleep, long work hours, inactivity, family issues, and unhealthy lifestyles can turn our pain volume up. This complexity shows pain correlates poorly with damage and highlights various health and lifestyle adjustments to turn our pain volume down.
This empowers individuals to develop new coping strategies, overcome barriers, and better manage ongoing discomfort. The goal is to steadily reduce pain volume and restore lost function, choosing not to let pain dictate their quality of life.
