Functional dyspepsia: unraveling the relation between symptoms and mechanisms PART3 (FINAL)

Part 1: http://gastroenterology-news.blogspot.com/2009/05/functional-dyspepsia-unraveling.html

Part 2: http://gastroenterology-news.blogspot.com/2009/05/functional-dyspepsia-unraveling_19.html

aritcle by G. Vantrappen

Corresponding address: G. Vantrappen, M.D. Department of Medicine University of Leuven ZU Gasthuisberg Herestraat 49 B-3000 Leuven Belgium

Tel.: +32-16-3442 25, fax: +32-16-3444 19

Visceral hypersensitivity and functional dyspepsia

The lack of a consistent relation­ship between many dyspeptic symptoms and putative physio­logical disturbances has led several investigators to study the role of alterations in visceral sensory perception in the pathophysiology of dyspeptic symptoms. Altered visceral sen­sory perception may be due to central or peripheral hypersensi­tivity to mechanical or chemical stimuli, but also to altered viscerosomatic referral patterns of central origin.

Several studies have demon­strated that many patients with functional dyspepsia have hyper­sensitivity to gastric distension (they experience discomfort and pain at lower distension volumes than normal subjects), and show altered viscerosomatic referral areas. Mertz et al. (1998) com­pared perceptual thresholds, viscerosomatic referral patterns, and psychological symptoms in 23 patients with functional dyspepsia, 10 with organic dys­pepsia, and in 15 healthy control individuals.

Patients with functional dyspepsia had clinical symptoms similar to those with organic dyspepsia (the prevalence of eight different clinical symptoms was similar in the two groups). However, only patients with functional disease reported hypersensitivity to gastric balloon distension: the volume thresholds for fullness, discom­fort, and pain in response to slow gradual balloon distension were 40-50% lower in patients with functional dyspepsia than in those with organic causes or healthy volunteers. The thresh­olds in organic dyspeptics and healthy controls were similar (Fig. 2); 65% of functional dyspeptics and no patients with organic dyspepsia had hypersen­sitivity to distension. In addition, 52% of the functional dyspepsia patients showed altered visce­rosomatic referral patterns, whereas only 20% of the organic disease patients experienced sen­sations in an aberrant location. Therefore, if abnormal sensation is defined as either aberrant referral or hypersensitivity to gastric distension, the sensitivity of abnormal sensation for functional dyspepsia is 87% and the specificity is 80%, when compared with an appropriate disease control.

There were no significant differences in psychological symptoms between functional and organic dyspeptics. Only the symptoms of severe nausea occurred more often in functional dyspepsia patients, and corre­lated with psychological distress, particularly anxiety.

In conclusion, these two papers on the relation between Symptoms and mechanisms of functional dyspepsia show that: a) impaired gastric accommoda­tion to a meal has an important role in the generation of early satiety;

b) hypersensitivity to gastric distension, with lowered thresholds for fullness, discom­fort, and pain, occurs only in patients with functional dyspep­sia, not in organic dyspeptics.