RT Book, Section
A1 Yaksh, Tony L.
A2 Warfield, Carol A.
A2 Bajwa, Zahid H.
SR Print(0)
ID 3410000
T1 Chapter 1. Molecular Biology of Pain
T2 Principles & Practice of Pain Medicine, 2e
YR 2004
FD 2004
PB The McGraw-Hill Companies
PP New York, NY
SN 9780071443494
LK accessanesthesiology.mhmedical.com/content.aspx?aid=3410000
RD 2024/04/19
AB The  acute  activation  of  small  sensory  afferent  axons  by  high-intensity  thermal  and  mechanical  stimuli  evokes  locally  organized  spinal  motor  reflexes  (nociceptive  reflexes),  autonomic  responses,  and  pain  behavior  in  animals  and  humans.  This  effect  is  mediated  by  the  local  encoding  of  afferent  input  at  the  level  of  the  dorsal  horn  and  the  activation  of  spinofugal  projection  neurons.  These  projection  systems  travel  both  ipsilaterally  and  contralaterally  in  the  ventrolateral  aspect  of  the  spinal  cord,  projecting  supraspinally  into  the  medulla,  mesencephalon,  and  diencephalon.  Medullary  projections  serve  to  activate  spinobulbospinal  reflexes  that  influence  autonomic  tone.  Other  projections  into  the  mesencephalon  and  thalamus  are  assumed  to  contribute  to  the  perceptual  and  complex  emotive  and  discriminative  components  of  the  pain  state.  It  is  important  to  appreciate  that  the  encoding  by  the  sensory  afferent  and  the  spinal  dorsal  horn  of  the  nociceptive  stimulus  is  the  first  step  in  nociceptive  processing,  and  this  encoding  process  contributes  properties  that  are  important  to  the  understanding  of  the  behavioral  correlates  of  nociception.  The  following  sections  consider  aspects  of  the  mechanisms  whereby  injury  leads  to  an  ongoing  pain  state  from  the  perspective  of  the  organization  of  the  sensory  afferents  and  the  spinal  dorsal  horn.  Of  particular  importance  is  the  appreciation  that  these  linkages  have  distinct  pharmacologies  and  that  these  systems  can  be  regulated  to  display  prominent  increases  (hyperalgesia)  and  decreases  (analgesia)  in  the  input-output  function.