Visceral pain Flashcards
1
Q
Nociception in viscera
A
- afferent nerves that run parallel wtih efferent autonomic nerves
- Unmyelinated C fibres mainly
- larger nerves within which visceral afferents run:
- vagus
- pelvis nerves
- spinal nerves
2
Q
Pathophysiology
A
- cell bodies of sensory fibres from abdominal viscera
- celiac plexus (anterior to crura of diaphram and L1)
- hypogastric plexus
- Superior (L5)
- Inferior (sacrococcygeal junction)
- carry visceral info from pelvis and left colong
- sacral plexus
- impulses proceed to dorsal horn of TL spinal cord
3
Q
Differences between anatomy of visceral nociceptive and somatosensory system
A
- innervation density MUCH lower for visceral nerves
- Visceral sensory nerves project to larger number of levels in spinal cord
- visceral nerves project to contralateral side
- one visceral sensory neuron may innervate two different visceral organs
4
Q
Visceral nociceptors types
A
- respond to distention, ischemia, electical stimulation
- Mechanosensory receptors:
- distention
- located in walls and muscles of organs
- Chemoreceptors
- mucosa and muscles
- Thermoreceptors
- mucosa and muscles
5
Q
Peripheral activation of visceral pain
A
- distention, inflammation, torsion, ischemia
- also chemicals like bradykinin, acidemia
- Cardiac ischemia:
- drop in pH –> lactate
- acid sensing ion channel and TRPV channels activated
- Gut:
- mechanosensory receptors TRPV, sodium channels
- cytokines, substance P, etc
- Pancreatic cancer:
- inflammatory perineural invasion by pancreatic cancer cells –> aroborization of sensory nerves
6
Q
Peripheral sensitization in visceral pain
A
- changes in functioning of a primary afferent nerve that may include
- reduced threshold
- spontaneous activation
- increased response
- sensitized by inflammatory or adrenergic compounds
- lasts after exposure
- bradykinin, cytokines
- visceral hyperalgesia
7
Q
Central sensitization. in visceral pain
A
- amplification of neural signalling in CNS
- allodynia, hyperpathia, hyperalgesia
- ? NMDA receptor
8
Q
Clinical aspects of visceral pain
A
- Hollow viscus:
- poorly localized
- vague, gnawing, crampy
- Solid organs, capsules
- better localized
- sharp
- stabbing
- all can have autonomic sx (nausea)
- aversive emotional reactions
9
Q
Referred pain
A
Viscerosomatic referred pain
- visceral and somatic afferent fibres converge on same lamina of spinal cord
- cortex may interpret signals as emanating from corresponding somatic site
Viscero-visceral referred pain/ cross organ sensitivity
- shared afferents for 2 different organs
- CAD and biliary tree common afferent T5
- intestive and pelvic organs common afferent T10-L1
10
Q
Patterns of visceral referral pain
A
- Thoracic region pain
- referred from cardiac or esophagus
- lung and diaphragm refers to shoulder
- Upper abdominal wall pain
- upper abdo organs (pancreas, stomach, liver)
- liver, porta hepatis : RUQ and refers to shoulder
- Pain in lower abdominal wall
* colon, bladder, uterus, kidney
11
Q
Referred pain syndrome : cervical distention
A
- pain in lower abdo and back
12
Q
Referred pain from bladder distention
A
- subprapubic
13
Q
Referred pain from thoracic injuries (cardiac, esophageal, lung)
A
- Thoracic pain
- Cardiac : L arm
- lung –> shoulder
14
Q
Referred pain from upper abdominal organs
A
- Upper abdo wall
- thoracic back
15
Q
Referred pain from abdominopelvic organs
A
- lower abdominal wall
