Stomach motility disorders

(Dysmotility of the stomach)

Normal anatomy

• Proximal stomach -> receptive relaxation, mediated by vagus nerve, when food enters. Presence of amino acids initiates a slow tonic contraction of proximal stomach, which increases the intraluminal pressure, mediating gastric emptying.

Gastric emptying studies

• Radionucleotide scan
  • Nuclear scintigraphy study - meal of radiolabelled food
  • Scans immediately after the meal and at 1, 2 and 4 hours
  • At 4 hours, retention of 10%-15% is mild, 15-35% is moderate, and >35% is severe
  • Can do it with clear liquids only to identify patients with normal solid food emptying and delayed liquid emptying
• Barium swallow with upper GI series
  • May reveal mechanical causes contributing to delay
• Electrogastrogram or antroduodenal motility study
  • Assesses for nerve and muscle abnormalities
  • Doesn't address functional significance
• Wireless motility capsules
  • Can measure pH, temperature and pressure during transit

Gastroparesis

• Background
  • Syndrome of delayed gastric emptying in the absence of mechanical obstruction
• Aetiology
  • Vagal damage
  • Prior gastric or bariatric surgery (Roux en Y, gastric resections, anti-reflux fundoplication, pancreaticoduodenectomy)
  • Chronic illness
    • Diabetes (type I and II)
      • Can occur both with and without insulin
      • Impaired neural control via vagal nerve, myenteric nervous system, interstitial cells of Cajal, and the underlying smooth muscle
      • Hyperglycaemia itself decreases contractility of the antrum and increases contractility in the pylorus
      • Hyperinsulinaemia may also play a role in suppressing migrating myoelectric complex activity
    • Hypothyroidism
    • Neurological disease - Parkinsonism, amyloidosis, paraneoplastic disease
    • Autoimmune disorders
  • Post-viral gastroparesis (look for recent viral prodrome)
  • Medications
    • Narcotics
    • Anticholinergics
    • GLP-1 inhibitors
  • Mesenteric ischaemia
  • Idiopathic - this is actually the most common, especially in young/middle-aged women
• Presentation
  • Epigastric fullness/pain (but this is non-specific)
    • Pain is often nocturnal , induced by eating, and interferes with sleep
  • Early satiety, mostly to solids
  • Delayed vomiting - especially if it occurs a day later, with undigested food
  • Anorexia, dehydration, weight loss, malnutrition
• Diagnosis
  • Symptoms of gastroparesis, absence of gastric outlet obstruction, and delay in gastric emptying (solids at 4 hours on scintigraphy)
• Workup
  • Exclude mechanical bowel obstruction - efferent limb syndrome, anastomotic stricture, intussusception
    • XRAY
  • Evaluate for metabolic derangements
    • Albumin takes a month to drop - consider ordering pre-albumin
  • Consider gastroscopy
    • If gastric reservoir is large and distended, vagal issue is unlikely - since vagus mediates distension!
  • Gastric emptying studies
• Differential diagnosis
  • Gastric outlet obstruction
  • Gastritis, especially secondary to H pylori
  • Peptic ulcer disease
  • Functional dyspepsia
  • Consider gastroparesis in setting of treatment-resistant GORD
• Treatment
  • Resuscitation
    • Restore fluids and electrolytes
    • Consider nutritional support - TPN/nasojejunal feeding tube
      • Indication for NJT is unintentional weight loss >10% over 3-6 months, or repeated hospitalisations
      • Obviously NJT is preferable to TPN
  • Lifestyle
    • Modify diet - focus on liquids (as liquid emptying is often normal), smaller and more frequent meals, low-residue diet, lower fat content. Minimise acidic and spicy foods, carbonated drinks, alcohol and tobacco.
  • Medical
    • Treat contributing factors, especially labile sugars in the acute setting
    • Prokinetics
      • Metoclopramide first-line
        • Dopamine antagonist
        • Stimulates antral contractions
        • Decreases post-prandial fundus relaxation
      • Domperidone (note that this takes effect in antrum - may not help in some patients)
        • Dopamine antagonist
        • Needs baseline ECG and ongoing ECGs due to prolonging of QT
        • Trial if metoclopramide is not tolerated or doesn't help
      • Erythromycin (IV or oral, but tachyphylaxis develops to oral)
        • Motilin agents - stimulate fundal contraction
        • Second-line therapy
        • Azithromycin can also be used via the same mechanism
  • Surgical
    • Indication: refractory symptoms despite maximal medical therapy
    • Pyloromyotomy/pyloroplasty - lower outflow resistance at the pylorus
    • Gastric POEM - under investigation
    • People have tried total gastrectomy for patients with vagal dysfunction-mediated delayed emptying, but it's very controversial
    • Implantation of gastric stimulator
      • Helps with n/v but do not increase emptying
    • Venting gastrostomy - palliative
    • Pyloric dilation and stenting could be considered in certain circumstances
    • Intra-pyloric botox doesn't work

Rapid gastric emptying/dumping

• See 'gastrectomy' complications