Written by Sophie Hose, DC, MS, DACNB, CCSP
Pain is a universal human experience, yet its true nature remains deeply misunderstood by many. While most people associate pain with injury or damage—such as a broken bone or a sprained ankle —modern research reveals that pain can occur even when there is no visible or measurable tissue damage. This paradox challenges conventional wisdom and underscores the importance of viewing pain as a complex, multifaceted phenomenon.
In 2020, the International Association for the Study of Pain (IASP) introduced a groundbreaking redefinition of pain, framing it as:
“An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.”
This new definition reflects a critical shift in how pain is understood and treated. It emphasizes that pain is not merely a symptom of tissue injury or disease but a standalone experience shaped by biological, emotional, and cognitive factors.
One of the most striking aspects of this definition is its acknowledgment that pain does not require actual tissue damage to exist. Pain can arise from the nervous system itself, independent of any ongoing injury. This phenomenon is central to conditions like fibromyalgia, chronic regional pain syndrome (CRPS), and phantom limb pain—collectively referred to as central pain syndromes. These disorders challenge traditional paradigms of pain treatment because the source of the pain lies not in the tissues but in the brain and spinal cord.
In this post, we’ll delve into the types of pain—peripheral and central—and the neurological theories that explain their mechanisms. Using insights from chiropractic neurology, we’ll explore how understanding these pain types can help inform effective treatment strategies.
The Types of Pain: Peripheral and Central
Peripheral Pain
Peripheral pain originates from the tissues, nerves, or organs of the body and is typically associated with injury or inflammation.
- Mechanism: Nociceptors, specialized sensory receptors, detect harmful stimuli such as heat, pressure, or chemical irritation and send these signals to the spinal cord and brain.
- Acute and Protective: This pain serves an evolutionary purpose, acting as a warning system to prevent further injury. For example, the sharp pain from touching a hot stove prompts immediate withdrawal to avoid burns.
Peripheral pain is often localized and tied to a clear cause, such as a sprained joint or a cut. Treatments typically target the site of injury to reduce inflammation, promote healing, and alleviate pain.
Central Pain
Central pain, in contrast, originates in the central nervous system (CNS)—the brain and spinal cord —without direct input from peripheral nociceptors. This type of pain is far more complex and challenging to treat because it often lacks a clear external trigger.
- Mechanism: Central pain arises when the CNS becomes hypersensitive, misinterpreting normal sensory inputs or generating pain signals independently. This phenomenon, known as central sensitization, can occur after an initial injury but persist long after the tissues have healed.
- Examples of Central Pain Syndromes:
- Fibromyalgia: Widespread musculoskeletal pain without identifiable tissue damage.
- Complex Regional Pain Syndrome (CRPS): Severe, burning pain often triggered by minor injuries.
- Phantom Limb Pain: Sensations of pain in a limb that has been amputated.
These conditions illustrate that pain is not merely a “report” from the body but an experience constructed by the brain. The absence of tissue damage does not diminish the reality or severity of the pain.
The Neurology of Pain: Key Theories
1. Gate Control Theory
Developed in 1965 by Melzack and Wall, this theory proposed that pain signals are modulated at the spinal cord level before they reach the brain.
- Implications for Central Pain: In conditions of central sensitization, the “gate” becomes dysregulated, allowing excessive or inappropriate pain signals to reach the brain.
- Relevance to Treatment: Therapies like manual adjustments, electrical stimulation, and acupuncture may help “close the gate” by stimulating non-painful sensory pathways.
2. Neuromatrix Theory
This theory, an evolution of the gate control model, posits that the brain actively constructs the pain experience by integrating sensory inputs with emotional and cognitive information.
- Chronic Pain and Pain Memory: The neuromatrix explains why individuals can experience pain without ongoing injury. For example, in phantom limb pain, the brain retains a “map” of the missing limb, leading to persistent sensations.
- Chiropractic Insight: Addressing chronic pain involves “retraining” the neuromatrix, often through graded exposure, visualization techniques, and neurofeedback.
3. Central Sensitization
Central sensitization is a state in which the CNS becomes hyperactive, amplifying pain signals. It is a hallmark of many central pain syndromes.
- Mechanisms of Amplification: Changes in spinal cord neurons, a decrease in inhibitory signals, and overactive brain regions all contribute to this hypersensitivity.
- Treatment Strategies: Interventions aim to desensitize the nervous system, using techniques such as mindfulness, sensory retraining, and gradual exposure to movement.
4. Biopsychosocial Model
The biopsychosocial model views pain as the result of an interplay between biological, psychological, and social factors.
- Holistic Perspective: Addressing chronic pain requires a comprehensive approach that considers physical rehabilitation, mental health support, and social engagement.
- Role of Chiropractic Neurology: By integrating manual therapies and neurological rehabilitation with lifestyle interventions and psychological support, this model aligns with the principles of holistic care.
Central Pain Syndromes: A Closer Look
Fibromyalgia
Fibromyalgia is characterized by widespread pain, fatigue, and cognitive difficulties. Despite the lack of visible tissue damage, patients experience intense and disabling pain due to central sensitization. Treatments often focus on calming the CNS through gentle movement, stress management, and improving sleep quality.
Phantom Limb Pain
Phantom limb pain highlights the role of the brain in constructing the pain experience. Even after amputation, the brain’s “map” of the limb persists, generating sensations that feel real. Techniques like mirror therapy and graded motor imagery help reshape the neuromatrix.
Complex Regional Pain Syndrome (CRPS)
CRPS is a severe condition marked by burning pain, swelling, and temperature changes in the affected limb. The cause is believed to involve both central and peripheral mechanisms, requiring a multidisciplinary treatment approach.
Chiropractic Neurology’s Role in Pain Management
Chiropractic neurology offers a unique perspective on pain management, emphasizing the interconnectedness of the nervous system and the body. Treatments are tailored to address both peripheral and central components of pain:
- Manual Therapies: Spinal adjustments, myofascial release, and mobilizations help reduce mechanical stress and improve movement patterns, addressing peripheral contributors to pain.
- Neurological Rehabilitation: Balance exercises, sensory retraining, and neurofeedback target central sensitization, helping to recalibrate the CNS.
- Holistic Care: By integrating nutrition, exercise, and stress reduction techniques, chiropractic care supports overall nervous system health.
Conclusion
Pain is far more than a physical sensation; it is a complex, subjective experience shaped by the brain, body, and environment. The revised IASP definition reminds us that pain can exist without tissue damage, particularly in central pain syndromes. Understanding the mechanisms of pain through models like the gate control theory and neuromatrix theory offers hope for effective treatments.
Chiropractic neurology, with its focus on the nervous system and holistic care, plays a pivotal role in addressing the multifaceted nature of pain. By combining manual therapies, neurological rehabilitation, and lifestyle interventions, it empowers patients to regain control over their lives.
If you or someone you love is suffering from pain, whether chronic or not, and you would like to learn how chiropractic neurology can help, contact the team at Georgia Chiropractic Neurology Center today. We look forward to hearing from you.
References
- Malik, N.A. (2020). Revised definition of pain by ‘International Association for the Study of Pain’: Concepts, challenges and compromises. Anaesthesia, Pain & Intensive Care, 24(5), 481-483. Apicare Online ps://www.apicareonline.com/index.php/APIC/article/view/1352).
- Melzack, R. (2001). Pain and the neuromatrix in the brain. Journal of Dental Education, 65(12), 1378-1382.
- Woolf, C.J. (2011). Central sensitization: Implications for the diagnosis and treatment of pain. Pain, 152(3 Suppl), S2-S15.
- Moseley, G.L. (2007). Reconceptualizing pain according to modern pain science. Physical Therapy, 87(4), 482-493.