Mechanisms of gastroparesis

Mechanisms of gastroparesis:

• gastric motility results from:
  • the integration of tonic contractions of the fundus
  • phasic contractions of the antrum
  • inhibitory forces of pyloric and duodenal contraction
• contractions require a complex interaction between gastric smooth muscle, the enteric nervous system and specialized pacemaker cells, the interstitial cells of Cajal
  • gastric accommodation enables adaptation of the proximal stomach to a liquid or solid volume load, i.e. a meal
  • antral contractions are required for grinding and transport of the meal towards the pyloric sphincter
  • pyloric relaxation enables the titration of the grinded meal (chyme) into the duodenum and requires coordination of propulsive contractions in the stomach and duodenum
    • rate of gastric emptying is influenced by the composition of the ingested meal
      • non-nutrient liquids are emptied almost immediately, whereas nutrient liquids and solids empty after a period of retention (lag phase) in a non-linear manner and linear manner respectively
        • fat rich meals show a more prolonged emptying pattern, resulting from duodenal feedback mechanisms, in particular, cholecystokinin
• motor dysfunction of the stomach may result from autonomic neuropathy, enteric neuropathy, abnormalities of ICCs, fluctuations in blood glucose and psychosomatic factors
• several mechanisms are involved in the process of gastric emptying
  • these actions are highly dependent on adequate neuronal and hormonal feedback mechanisms

Reference:

• Waseem S, Moshiree B, Draganov PV. Gastroparesis: current diagnostic challenges and management considerationsWorld J Gastroenterol. 2009 Jan 7;15(1):25-37
• Haans JJ, Masclee AA.The diagnosis and management of gastroparesis. Aliment Pharmacol Ther. 2007 Dec;26 Suppl 2:37-46.