Abnormalities of neuromuscular anatomy in diverticular disease.

The pathogenesis of diverticular disease is still poorly understood and considered to be multifactorial. Whereas classical pathogenetic concepts have focused on risk factors including increasing age, low-fiber diet and connective tissue disorders, novel concepts take into account that patients with diverticular disease exhibit disturbed intestinal motility patterns (that may result in functional obstruction and painful sensations) therefore postulating an underlying enteric neuro-/myopathy. Recent studies including quantitative evaluations of the enteric nervous system (ENS) in diverticular disease yielded hypoganglionic conditions of both myenteric and submucosal plexus as well as a nerve tissue remodeling in chronic diverticular disease. The disturbed neuromuscular communication was proven by demonstrating alterations in several enteric neurotransmitter systems, exemplified for the cholinergic, serotonergic, nitrergic system as well as for vasointestinal peptide, galanin and tachykinins. Novel lines of evidence have added the involvement of neurotrophic factors such as glial cell line-derived neurotrophic factor which is supposed to regulate ENS development and maintenance and which is downregulated in patients with diverticular disease. Consistent with the hypothesis of an enteric myopathy, deficits in smooth muscle integrity and composition such as hypertrophy, fibrotic transformation and gene expression deficits could be delineated. Taken together, the structural and functional findings on alterations of the ENS and the enteric musculature in diverticular disease provide evidence to strengthen the hypothesis that an enteric neuro-/myopathy may contribute to the development of colonic diverticula and the generation of symptoms in the course of the disease.