Dr. Spina discusses the concept of ‘Central sensitization’ & it’s role in perpetuating nociceptive signal in chronic pain. Also discussed is the role of Acupuncture in the treatment of central sensitization

In this clip Dr. Spina briefly outlines the concept of ‘Central Sensitization’ and its role in perpetuating nociceptive signals in the central nervous system.  He also states that preliminary acupuncture research has demonstrated strong potential for the treatment to battle the development of central sensitization.  The clip is taken from a Functional Anatomic Palpation Systems (F.A.P.)™ ‘SPINE’ seminar that was held in Midland, Ontario, Canada.

Briefly it has been shown in rat models that repetitive noxious stimulation of primary C-fiber afferents results in a ‘wind-up’ phenomenon which is characterized by an escalation of nociceptive transmission by cells in the dorsal horn.  Wind-up contributes to central sensitization via wide-dynamic range (WDR) cells resulting in the amplification and prolongation of nociceptive transmission in ascending pathways in the central nervous system. This sensitizing effect results in sensitivity to normally non-noxious mechanical and thermal stimuli (allodynia) and exaggerated responses to noxious stimuli (hyperalgesia). Central sensitization is mediated via activation of the N-methyl-D-aspartate (NMDA) glutamate receptor and is a feature of many chronic pain states.

Further animal studies have shown that acupuncture, electroacupuncture can reduce central sensitization. (1-3).  Acupuncture stimulates small myelinated A fibers in muscle and skin which synapse with interneurones in the substantia gelatinosa (SG) of the spinal cord resulting in the release of inhibitory neuromodulators such as enkephalin that reduce activity in NS and WDR neurons. (4) Reduced nociceptive transmission in the dorsal horn following A input (long-term depression) has been shown to outlast the stimulation by hours (1,2).

Further animal studies have shown that regular treatment at a low-frequency which maintains analgesia and produces a long-term depression in the dorsal horn may be achieved by stimulation of afferent A fibers using manual acupuncture alone and studies using rats have shown that this depression may last for days or weeks. Recent studies using mice have shown that manual acupuncture with bidirectional stimulation stimulates connective tissue which generates a strong afferent input to the dorsal horn and is therefore likely produce a depressing effect (5,6).  It has also been suggested that the release of oxytocin in response to non-noxious sensory stimulation such as manual acupuncture may give rise to long-term elevations in pain threshold (3).  It is therefore likely that acupuncture should help to prevent wind-up, central sensitization and the resultant allodynia and hyperalgesia.

1.  Sandkühler J. Learning and memory in pain pathways. Pain (2000) 88: 113–8.

2.  Sandkühler J, Chen JG, Cheng G. Low-frequency stimulation of afferent adelta -fibers induces long-term depression at primary afferent synapses with substantia gelatinosa neurons in the rat. J Neurosci (1997;) 17: 6483–91.

3.  Carlsson C. Acupuncture mechanisms for clinically relevant long-term effects–reconsideration and a hypothesis. Acupunct Med: J Brit Med Acupunct Soc (2002;) 20: 82–99.

4.  Thompson JW, Filshie J. Transcutaneous Electrocal Nerve Stimulation (TENS) and Acupuncture. In: Oxford Textbook of Palliative Medicine —Doyle D, Hanks G, Cherny N, Calman K, eds. (2005) 2nd. Oxford: Oxford University Press. 421–36.

5.  Langevin HM, Bouffard NA, Churchill DL, Badger GJ. Connective tissue fibroblast response to acupuncture: dose-dependent effect of bidirectional needle rotation. J Alt Comp Med ( 2007;) 13: 355–60.

6. Langevin HM, Storch KN, Cipolla MJ, White SL, Buttolph TR, Taatjes DJ. Fibroblast spreading induced by connective tissue stretch involves intracellular redistribution of alpha- and beta-actin. Histochem Cell Biol ( 2006;) 125: 487–95.

FUNCTIONAL ANATOMY SEMINARS.com