Ouch! Neuronal pathways responsible for conduction of somatosensory and visceral pain

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Presenter Last Name: 
McBride, PhD
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Pain Defined
Somatic pain

  • Sensation: pricking, burning, aching, stinging, and soreness (Basbaum AI & Jessel TM, 2000)
  • Sources: extreme temperature, acids, pinching, swelling and a variety of others (Squire LR et al, 2008; Purves et al, 2008)
  • Subjective: environment dependent (Basbaum AI & Jessel TM, 2000)

Visceral pain (Purves et al, 2008)

  • Sensation: increased pressure and damaging stretch
  • Sources: bloating, ischemia, irritating chemicals, inflammation, edema
  • Localization: sparse innervation and large receptive fields

Perception of Pain
Nociceptors sub-typed by axon

  • Aδ mechanosensitive nociceptors
  • Aδ mechanothermal nociceptors
  • Polymodal nociceptors (C-fiber)

Sodium channels role in pain

  • Dib-Hajj SD et al. Annu. Rev. Neurosci. 33:325-347. 2010 - Review of NaV1.3,NaV1.7, NaV1.8, NaV1.9 role in pain
  • Cox JJ, Reimann F et al. Nature. 444:894-898. 2006 - “An SCN9A channelopathy causes inability to experience pain”
  • Dib-Hajj SD et al. Trends in Neurosciences 30:555-563. 2007 - Review of pain disorders linked to NaV1.7

Vanilloid receptors–Caterina MJ et al. Nature. 389:816-824.1997

Who needs to feel pain?
Purpose of pain


“Living” without pain
Cox JJ, Reimann F, Nicholas AK, Thornton G et al. Nature. 444:894-898. 2006

  • Lip and tongue mutilation
  • Finger mutilation
  • Visual damage or loss of eye(s)
  • Unaware of broken bones
  • Numerous scars
  • Cuts and bruises

Anterolateral System History
Magendie, 1822

  • anterior root motor function
  • posterior root sensory function

Brown-Sequard; Schiff, 1858

  • first insight to decussation of fibers

Gowers, 1878 & 1879

  • L1 crush lead to ascending lesion
  • “anterolateral ascending tract”

Mott, 1895

  • Marchi technique tracing
  • confirmed Gowers findings

Anterolateral System
Pain, temperature & crude touch (Blumenfeld H, 2010; Haines DE, 2006)

Enter posterior horn

  • primarily synapse in laminae I & V

Target structures

  • ventral posterolateral nucleus of the thalamus
  • midline thalamic nuclei
  • reticular formation
  • periaqueductal gray matter

Visceral Pain Pathways

  • Overdistention, increased pressure, tissue damage (Haines, Purves)
  • Peripheral origin - sympathetic nerves (<20%)
  • Enter posterior horn - primarily synapse in laminae I & V
  • Target structures - anterolateral pathway to VPL
  • Gildenberg PL & Hirshberg RM, 1984 - myelotomy at T9 or T10; treatment for pelvic cancer pain
    Hirshberg RM, Al-Chaer ED et al, 1996 -medial myelotomy of posterior column at T10; human histological analysis (n=1); anterograde and retrograde tracing (rats); neurophysiology (rats)

Spinal Trigeminal Pathway
Pain, temperature & crude touch  
(Blumenfeld H, 2010; Purves D, 2008)


  • lateral pons in trigeminal sensory root

Target structures

  • ventroposteromedial & intralaminar nuclei of thalamus
  • reticular formation

Spinal Trigeminal Pathway History

  • Spitzer 1899 and Wallenberg 1901, 1904 - fibers arising from the spinal nucleus
  • Papez & Rundles 1937 - decussation of fibers ascending to thalamus–“ventral tract”
  • Kuru 1938, 1949 - confirmation in human brain
  • Walker 1939 - conclude lesion of spinal nucleus or tract result in loss of pain and temperature sensation in face


  • Blumenfeld H. Neuroanatomy through clinical cases. Sunderland. Sinauer. 2002
  • Basbaum AI & Jessell TM. In: Kandel ER, Schwartz JH, Jessell TM, eds. Principles of Neural Science.4thed. New York, NY: McGraw-Hill; 2000:473-491.
  • Dib-Hajj SD, Cummins TR, Black JA, Waxman SG. Trends in Neurosciences 30:555-563. 2007
  • Dib-Hajj SD, Cummins TR, Black JA, Waxman SG. Annu. Rev. Neuroscie. 33:325-347. 2010
  • Caterina MJ, Schumacher MA, Tominaga M et al. Nature. 389:816-824.1997
  • Chang J et al. (2008, February 22). Medical Mystery: A World Without Pain. Retrieved April 20, 2010, from http://abcnews.go.com/Health/MedicalMysteries/story?id=3679532&page=1
  • Cox JJ, Reimann F, Nicholas AK, Thornton G et al. Nature. 444:894-898. 2006
  • Haines DE. Fundamental Neuroscience for basic and clinical applications 3rd ed. Philadelphia. Churchill Livingstone, Elsevier. 2006
  • Lenz FA, Casey KL, Jones EG, Willis WD. The Human Pain System: Experimental and Clinical Perspectives. New York, NY: Cambridge University Press; 2010:1-10, 16-17.
  • Purves D et al. In: Purves D, Augustine GJ, Fitzpatrick D, Hall WC, LaMantia AS, McNamara JO, White LE, eds. Neuroscience. 4thed. Sunderland, MA: Sinauer; 2008:231-251.
  • Squire LR et al. In: Squire LR, Berg D, Bloom FE, du Lac S, Ghosh A, Spitzer NC, eds. Fundamental Neuroscience. 3rded. Burlington, MA: Academic Press, Elsevier; 2008:581-608
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