Term
| What is the basic 3-neuron pain arc? |
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Definition
1) Peripheral nociceptors are unmyelinated (C-fiber) or lightly myelinated (A-delta) that respond to noxious mechanical, temperature or chemical stimuli when they exceed a THRESHOLD.
2) Information travels as vagal visceral afferents (unconscious) or spinal visceral afferents (conscious) |
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Term
| How can pain information be transmitted from the viscera in the absense of dedicated pain fibers (as described by the "adequate stimulus theory")? |
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Definition
1) Frequency Coding
- High-frequency perceived as pain.
2) Silent afferents- fibers recruited following inflammation |
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Term
| What is so debilitating about Visceral hyperalgesia? |
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Definition
| IBD is a good example, where normal sensations become very painful. |
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Term
| What are 3 major co-moribidities of visceral pain? |
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Definition
1) Depression
2) Nausea- Vagal afferents to area postrema
**why you stop chemo**
3) Cachexia |
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Term
| What are the 4 major components of the Vagus nerve, their origins and projections? |
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Definition
Sensory component is NOT CONSCIOUS
1) Visceral motor output from DMN
2) Somatic motor output from NA
3) Somatic sensory neurons in superior vagal ganglion that project to trigeminal nucleus.
4) Visceral sensory neurons in inferior vagal ganglion (NODOSE) that project to nucleus tractus solitarius
**Sensory component runs with the parasympathetic pre-ganglionic fibers, but they belong to DIFFERENT functional systems |
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Term
| What aspects of the sympathetic and parasympathetic systems do spinal visceral sensory neurons "run with"? |
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Definition
Fibers original in spinal or dorsal root ganglia.
This anatomy MATTERS for nerve blocks.
1) Sympathetic
- Greater (T5-T8), lesser (T10-T11) and least (T12) splanchnic nerves, as well as lumbar splanchnics and sacral splanchnics.
2) Parasympathetic
- Run with pelvic splanchnic nerves that contain pre-ganglionic parasympathetic fibers. |
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Term
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Definition
Second order sensory neurons in dorsal horn receive visceral input as well as somatic stimulation (visceral afferent projects to large number of spinal neurons)
You feel visceral pain as if it came from the somatic structure (Left arm hurts during heart attack) |
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Term
Construct a reasonable ddx for each of the following abdominal pain locations.
1) RLQ
2) RUQ
3) Central
4) LUQ
5) LLQ |
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Definition
1) RLQ
- acute appendicitis
- mesenteric lymphadenitis
- infective distal ileitis
- crohn's
2) RUQ
- Acute cholecystitis
- Biliary colic
- Perforated duodenal ulcer
- Hepatic distension
3) Central
- Gastroenteritis
- Small intestinal colic
- Pancreatitis
4) LUQ
- Perisplenitis
- Splenic infarct
5) LLQ
- Diverticulutis
- Pyogenic sacroiliitis |
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Term
An alcoholic presents with pancreatitis and intense pain of the central abdomen.
You try NSAIDs and want to decrease his intrapancreatic pressure that may be stimulating sensory neuron excitation. To do this, you want to decrease pancreatic secretions.
How might you go about doing this? If it doesn't work, what surgical options are available? |
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Definition
1) Proton-pump inhibitors (Prilosex; Nexium) to increase duodenal pH and decrease stimulus for pancreatic excretion (safe but probably won't work).
2) Oral pancreatic enzymes- May involve feedback mechanism via a decrease in CCK release.
3) SubQ octreotide- mixed results and expensive
4) Whipple surgery to remove proximal head of pancreas |
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Term
| Why might you give a 5-HTR agonist for IBS with constipation? |
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Definition
| Increase motility and decrease Pain (Tegasrod) |
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Term
True or False:
The majority of chronic pain patients get minimal long-term relief with opioids. |
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Definition
True! Only 30%
Treat underlying disease or go for CBT, diet and exercise. |
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