Neural strain

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Neural strain from biomechanical stress can cause profound metabolic changes in the affected tissue due to alterations in the morphology of the cell membrane and decreased blood flow[1][2][3][4][5][6][7][8] causing hypoxia. Injury can result from tensile, compressive, or shear stress or as a combination of stresses.[1] Metabolic changes include a shift to anaerobic metabolism, resulting in increased lactate dehydrogenase[9] and reduced ATP production,[10] and changes in electrolyte balance, including an increase in intracellular calcium in a dose-dependent manner.[11][12][9]

Tension[edit | edit source]

In animal models, stretching or tension of nerves results in substantially reduced blood flow.[1][2][3][4][5][6][7][8] Tension impairs nerve regeneration.[13]

Tethered cord syndrome[edit | edit source]

Tethered cord syndrome, a condition where tissue attachments limit the movement of the spinal cord within the spinal column, is associated with impaired glucose metabolism in spinal cord tissue,[14] changes in the reduction/oxidation ratio of cytochrome oxidase.[15] and reduced ATP production.[10] Energy loss due to neural membrane stretching contributes to leakage of sodium, potassium and calcium.[16]

A study of energy cost of walking in adolescents with tethered cord, as measured by oxygen uptake, found that “energy cost per metre during walking at preferred speed and physical strain were higher than in peers without disability.”[17]

People with tethered cord syndrome have reduced blood flow to the spinal cord.[18]

“Traction on the caudal cord results in decreased blood flow causing metabolic derangements that culminate in motor, sensory, and urinary neurological deficits. The untethering operation restores blood flow and reverses the clinical picture in most symptomatic cases.”[19]

In a study of five children undergoing surgery for tethered cord syndrome group, spinal cord blood flow prior to untethering was a mean of 12.6 ml/min per 100 g of tissue. It increased in all cases after release to a mean of 29.4 ml/min per 100 g of tissue.[20]

Compression[edit | edit source]

Compression of nerves can result in changes in microcirculation and ischemia,[21] changes in vascular permeability, edema, axonal damage, and has been associated with demyelination.[1][22][23][24]

Prologned compression can result in inflammation and activation of endoneurial fibroblasts, mast cells, and macrophages.[25]

Neurobiology of stretch injury[edit | edit source]

Stretching a neuron causes clumping and loss of microtubules and neurofilaments inside the axons, which results in the the axons being sheared off the cell body to form axon retraction balls. In experiments, stretching a mouse optic nerve by just 20% of its length results in the appearance of axon retraction balls a few days later; a week later apoptosis of the neuron occurs. Stretching a nerve causes an opening of the sodium channels, which floods the cell with sodium. The sodium then depolarizes the voltage-gated calcium channels, leading to an influx of calcium, which is very harmful to the nerve cell. Stretching a neuron also causes an upregulation of NMDA receptors, which make the neuron more vulnerable to free radical species.[26]

Diagnoses[edit | edit source]

Diagnoses associated with tension, compressive and shear stress:

ME/CFS[edit | edit source]

In a study of neuromuscular strain in ME/CFS, 60 people with ME/CFS and 20 healthy controls randomly were assigned to undergo a neuromuscular strain maneuver or sham maneuver. Those with ME/CFS in the strain condition group had significantly increased symptoms for up to 24 hours.[27]

References[edit | edit source]

  1. 1.01.11.21.3 Boyd, Benjamin S.; Topp, Kimberly S. (Jan 1, 2006). "Structure and Biomechanics of Peripheral Nerves: Nerve Responses to Physical Stresses and Implications for Physical Therapist Practice". Physical Therapy. 86 (1): 92–109. doi:10.1093/ptj/86.1.92. ISSN 0031-9023. 
  2. 2.02.1 Clark, William L.; Trumble, Thomas E.; Swiontkowski, Mark F.; Tencer, Allan F. (Jul 1, 1992). "Nerve tension and blood flow in a rat model of immediate and delayed repairs". The Journal of Hand Surgery. 17 (4): 677–687. doi:10.1016/0363-5023(92)90316-H. ISSN 0363-5023. 
  3. 3.03.1 Clark, William L.; Trumble, Thomas E.; Swiontkowski, Mark F.; Tencer, Allan F. (Jul 1, 1992). "Nerve tension and blood flow in a rat model of immediate and delayed repairs". The Journal of Hand Surgery. 17 (4): 677–687. doi:10.1016/0363-5023(92)90316-H. ISSN 0363-5023. 
  4. 4.04.1 Driscoll, Peter J.; Glasby, Michael A.; Lawson, Graham M. (2002). "An in vivo study of peripheral nerves in continuity: biomechanical and physiological responses to elongation". Journal of Orthopaedic Research. 20 (2): 370–375. doi:10.1016/S0736-0266(01)00104-8. ISSN 1554-527X. 
  5. 5.05.1 Clark, William L.; Trumble, Thomas E.; Swiontkowski, Mark F.; Tencer, Allan F. (Jul 1, 1992). "Nerve tension and blood flow in a rat model of immediate and delayed repairs". The Journal of Hand Surgery. 17 (4): 677–687. doi:10.1016/0363-5023(92)90316-H. ISSN 0363-5023. 
  6. 6.06.1 Tanoue, M.; Yamaga, M.; Ide, J.; Takagi, K. (Jun 1996). "Acute stretching of peripheral nerves inhibits retrograde axonal transport". Journal of Hand Surgery (Edinburgh, Scotland). 21 (3): 358–363. ISSN 0266-7681. PMID 8771477. 
  7. 7.07.1 Ogata, K.; Naito, M. (Feb 1986). "Blood flow of peripheral nerve effects of dissection, stretching and compression". Journal of Hand Surgery (Edinburgh, Scotland). 11 (1): 10–14. ISSN 0266-7681. PMID 3958526. 
  8. 8.08.1 Jou, I. M.; Lai, K. A.; Shen, C. L.; Yamano, Y. (Jan 2000). "Changes in conduction, blood flow, histology, and neurological status following acute nerve-stretch injury induced by femoral lengthening". Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society. 18 (1): 149–155. doi:10.1002/jor.1100180121. ISSN 0736-0266. PMID 10716291. 
  9. 9.09.1 Laplaca, Michelle C.; Lee, Virginia M.-Y.; Thibault, Lawrence E. (Jun 1, 1997). "An In Vitro Model of Traumatic Neuronal Injury: Loading Rate-Dependent Changes in Acute Cytosolic Calcium and Lactate Dehydrogenase Release". Journal of Neurotrauma. 14 (6): 355–368. doi:10.1089/neu.1997.14.355. ISSN 0897-7151. 
  10. 10.010.1 Sullivan, Stephen; Park, Paul; Stetler, William R. (Jul 1, 2010). "Pathophysiology of adult tethered cord syndrome: review of the literature". Neurosurgical Focus. 29 (1): E2. doi:10.3171/2010.3.FOCUS1080. ISSN 1092-0684. 
  11. Cargill, Robert S.; Geddes, Donna M. (Jun 1, 2001). "An in Vitro Model of Neural Trauma: Device Characterization and Calcium Response to Mechanical Stretch". Journal of Biomechanical Engineering. 123 (3): 247–255. doi:10.1115/1.1374201. ISSN 0148-0731. 
  12. Cargill, Robert S.; Thibault, Lawrence E. (Jul 1, 1996). "Acute Alterations in [Ca2+]i in NG108-15 Cells Subjected to High Strain Rate Deformation and Chemical Hypoxia: An in Vitro Model for Neural Trauma". Journal of Neurotrauma. 13 (7): 395–407. doi:10.1089/neu.1996.13.395. ISSN 0897-7151. 
  13. Sunderland, Ian R. P.; Brenner, Michael J.; Singham, Janakie; Rickman, Susan R.; Hunter, Daniel A.; Mackinnon, Susan E. (Oct 2004). "Effect of Tension on Nerve Regeneration in Rat Sciatic Nerve Transection Model". Annals of Plastic Surgery. 53 (4): 382. doi:10.1097/01.sap.0000125502.63302.47. ISSN 0148-7043. 
  14. Colohan, Austin R. T.; Zouros, Alexander; Siddiqi, Javed; Yamada, Shoko M.; Yamada, Brian S.; Pezeshkpour, Gholam; Won, Daniel J.; Yamada, Shokei (Aug 1, 2007). "Pathophysiology of tethered cord syndrome and similar complex disorders". Neurosurgical Focus. 23 (2): 1–10. doi:10.3171/FOC-07/08/E6. ISSN 1092-0684. 
  15. Yamada, Shoko M.; Won, Daniel J.; Yamada, Shokei (Feb 1, 2004). "Pathophysiology of tethered cord syndrome: correlation with symptomatology". Neurosurgical Focus. 16 (2): 1–5. doi:10.3171/foc.2004.16.2.7. ISSN 1092-0684. 
  16. Yamada, Shokei; Iacono, Robert P.; Andrade, Terry; Mandybur, George; Yamada, Brian S. (Apr 1, 1995). "Pathophysiology of Tethered Cord Syndrome". Neurosurgery Clinics of North America. Spinal Dysraphism. 6 (2): 311–323. doi:10.1016/S1042-3680(18)30465-0. ISSN 1042-3680. 
  17. Bruinings, A. L.; Berg‐Emons, H. J. G. Van Den; Buffart, L. M.; Heijden‐Maessen, H. C. M. Van Der; Roebroeck, M. E.; Stam, H. J. (2007). "Energy cost and physical strain of daily activities in adolescents and young adults with myelomeningocele". Developmental Medicine & Child Neurology. 49 (9): 672–677. doi:10.1111/j.1469-8749.2007.00672.x. ISSN 1469-8749. 
  18. Colohan, Austin R. T.; Zouros, Alexander; Siddiqi, Javed; Yamada, Shoko M.; Yamada, Brian S.; Pezeshkpour, Gholam; Won, Daniel J.; Yamada, Shokei (Aug 1, 2007). "Pathophysiology of tethered cord syndrome and similar complex disorders". Neurosurgical Focus. 23 (2): 1–10. doi:10.3171/FOC-07/08/E6. ISSN 1092-0684. 
  19. Rekate, Harold L.; Theodore, Nicholas; Kalani, M. Yashar; Filippidis, Aristotelis S. (Jul 1, 2010). "Spinal cord traction, vascular compromise, hypoxia, and metabolic derangements in the pathophysiology of tethered cord syndrome". Neurosurgical Focus. 29 (1): E9. doi:10.3171/2010.3.FOCUS1085. ISSN 1092-0684. 
  20. Danto, Joseph; Greenberg, Burt M.; Rosenthal, Alan D.; Schneider, Steven J. (Feb 1, 1993). "A Preliminary Report on the Use of Laser-Doppler Flowmetry during Tethered Spinal Cord Release". Neurosurgery. 32 (2): 214–218. doi:10.1227/00006123-199302000-00010. ISSN 0148-396X. 
  21. Rydevik, B.; Lundborg, G.; Bagge, U. (Jan 1, 1981). "Effects of graded compression on intraneural blood flow: An in vivo study on rabbit tibial nerve". The Journal of Hand Surgery. 6 (1): 3–12. doi:10.1016/S0363-5023(81)80003-2. ISSN 0363-5023. 
  22. Myers, R. R.; Powell, H. C. (Jul 1986). "Pathology of experimental nerve compression". Laboratory investigation; a journal of technical methods and pathology. 55 (1): 91–100. ISSN 0023-6837. PMID 3724067. 
  23. Dahlin, L. B.; Lundborg, G. (Jun 1992). "The pathophysiology of nerve compression". Hand clinics. 8 (2): 215–227. ISSN 0749-0712. PMID 1613031. 
  24. Dahlin, L. B.; Lundborg, G. (May 1996). "Anatomy, function, and pathophysiology of peripheral nerves and nerve compression". Hand clinics. 12 (2): 185–193. ISSN 0749-0712. PMID 8724572. 
  25. Powell, H. C.; Myers, R. R. (Jul 1986). "Pathology of experimental nerve compression". Laboratory Investigation; a Journal of Technical Methods and Pathology. 55 (1): 91–100. ISSN 0023-6837. PMID 3724067. 
  26. Henderson, Fraser. "Presentation at the ILC Ehlers Danlos & Chronic Pain Foundation. Timecode 10:46". 
  27. Violand, Richard L.; Thompson, Carol B.; Moni, Malini; Marden, Colleen L.; Jasion, Samantha E.; Lauver, Megan; Fontaine, Kevin R.; Rowe, Peter C. (Jul 18, 2016). "Neuromuscular Strain Increases Symptom Intensity in Chronic Fatigue Syndrome". PLOS ONE. 11 (7): e0159386. doi:10.1371/journal.pone.0159386. ISSN 1932-6203. 

Myalgic encephalomyelitis or chronic fatigue syndrome


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From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history