Gattuso, Jennifer May; (1997) Clinical and patho-physiological studies of idiopathic megacolon and megarectum. Doctoral thesis (M.D), UCL (University College London).

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Abstract

Constipation associated with dilatation of the rectum and/or colon, in the absence of demonstrable organic disease, is an uncommon and poorly characterised condition. The aim of the work reported in this thesis was to characterise idiopathic megarectum and megacolon clinically and to investigate the pathophysiology of this condition. Idiopathic megarectum (with or without more proximal colonic dilatation) has been shown to be clinically and epidemiologically distinguishable from idiopathic megacolon (where the rectum is of normal diameter). A small number of patients had spinal dysraphism which may be of aetiological importance. Upper and lower gastrointestinal radiology and transit studies were used to determine if there was a panenteric disorder. There was no upper gut dilatation. There were abnormalities of late gastric emptying, but small bowel transit was unremarkable and delay in colonic transit was mainly confined to the regions of dilated gut. There was no intrinsic abnormality of the internal or external anal sphincters in patients with idiopathic megarectum or idiopathic megacolon. However, manual disimpaction under general anaesthetic was associated with iatrogenic sphincter damage. The use and adverse effects of drugs used in the management of constipation have been reviewed. Some patients require a colostomy in their management. I investigated physiologically the value of different irrigation techniques. Archive (formalin fixed and processed into paraffin wax) and fresh frozen tissue were studied using a variety of histological techniques, including immunohistochemistry with antibodies raised against neural tissue, neurotransmitters and contractile proteins. In patients with idiopathic megarectum the muscularis externa and mucosae were thickened and there was a decreased density of innervation of the longitudinal muscle. In rectal longitudinal muscle of these patients there was a decrease in nonadrenergic noncholinergic nerve fibres. Abnormalities of the smooth muscle contractile proteins have been demonstrated in one patient with idiopathic megarectum. The abnormalities of the enteric innervation in patients with idiopathic megarectum have been shown not to be attributable to the neurotropic effects of herpes viruses.

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