136b - Disorders of GI Motility Flashcards
A patient presents with progressive dysphagia. Barium swallow is attached.
What is the most likely diagnosis?
What may have caused this?
Achalasia
- May be primary (idiopathic)
- If history of acute Chaga’s disease years-decades ago, may be secondary to Chagas disease
Describe the pathogenesis of systemic sclerosis small bowel
- Neuropathy; may be due to M3 antibodies. Cholinergic trsnmission is impaired
- -> Smooth muscle atrophy and fibrosis due to lack of stim
- -> Visceral myopathy
This is an example of chronic intestinal pseudo-obstruction
How is chronic intestinal pseudo-obstruction managed?
- Diet: Stick to easily digestable foods
- Rotate antibiotics
- Prokinetic agents
- Less helpful in systemic sclerosis; smooth muscle is lost :(
Surgical intervention is not indicated
What GI motility disorder is caused by failed migration of neuroblasts into the terminal bowel?
How is it cured?
Hirschprung’s disease
Surgery: resect the portion missing enteric neurons
How is achalasia treated?
Target the LES, usually surgical
- Dilation w/baloon
- Myotomy
- Basically cuts the LES open
- Botulinum toxin
- Muscle relaxants
- But pill is hard to swallow if you can’t swallow
- Stenting
- Gasrostomy tube if pt cannot tolerate surgery
Describe the clinical preserntation of Hirschpring’s disease (4)
Days old infant
- Failure to pass meconium
- Empty rectal vault
- Abdominal distension
- Vomiting
What test is used to diagnose gastroparesis?
Gastric emptying study (scintigraphy)
- Eat a radiolabeled meal
- Look for retention at 4h
- Normal = <10% of the meal is still in the stomach
Are prokinetic agents efficacious in the treatment of chronic intestinal pseudoobstruction associated with systemic sclerosis?
Not really :(
In systemic sclerosis, intestinal smooth msucle undergoes atrophy and fibrosis due to impaired cholinergic transmission (M3 autoantibodies maybe)
No smooth muscle = no contraction, even if stimulation is increased
Which test is most sensitive for the diagnosis of achalsia?
Esophageal manometry
What is the most common cause of gastroparesis?
Longstanding diabetes
-> Vagal neuropathy
How does systemic sclerosis affect the GI tract?
- Esophageal dysmotility
- Small bowel dysmotility (chronic pseudoobstruction)
In both cases, peristalsis is imparied due to loss of smooth muscle (usually 2/2 to loss of cholinergic transmission, may result from antibodies against M3 receptors)
True or false:
If you swallow a piece of gum, it will stay in your stomach for 8 years
Explain
False!
Migrating motor complexes are responsible for getting large/indigestable objects (like a wad of gum) out of the stomach
Exception: systemic sclerosis destroys smooth muscle, migrating motor complexes are ineffective :(
What causes Hirschprung’s disease?
Absense of enteric neurons in the rectum and distal colon
- Due to failed migration of neuroblasts into th eterminal bowel
(Congenital disorder)
List 3 clinical manifestations of chronic intestinal pseudo-obstruction
Ex: systemic sclerosis small bowel
- Maldigestion
- Small bowel bacterial overgrowth (due to stasis)
- -> Diarrhea, gas, B12 deficiency
- Diverticulosis
- Due to bacterial overgrowth
Describe the pathogenesis of achalasia
- Loss of ganglion cells in the myenteric (Auerbach) plexus
- -> No nitric-oxide producing neurons
- -> LES cannot relax to allow liquids or solids through
Remember, the baseline tone of the LES is under myenteric (smooth muscle) control; contracted at rest
