case 1

A 78 year old woman was admitted in February 1991 because of immobility and constipation secondary to longstanding Parkinson’s disease. She was treated with chloral hydrate 500 mg at night for insomnia. In June 1992, she presented with a three month history of intermittent diarrhoea. Flexible sigmoidoscopy suggested mild ulcerative colitis (not confirmed on biopsy) and simultaneous barium enema showed extensive inflammatory polyps up to the proximal transverse colon, with a malignant stricture in the distal sigmoid colon. At laparotomy, no tumour was detected but gas filled cysts were noted in the bowel wall, confirmed at peroperative colonoscopy. Oxygen therapy was considered but not administered, as her diarrhoea remained mild and intermittent. She remained on chloral hydrate for insomnia until she died of ischaemic heart disease in November 1994.

case 2

A 45 year old man with chronic anxiety, atypical depression and benzodiazepine dependence was referred in January 1998; his complaint was of a five year history of intermittent severe right iliac fossa pain and the passage of watery green motions twice daily with leakage of bloody discharge up to thrice daily. Having suffered from constipation as a child, he presented with right flank pain in 1979; this recurred with intermittent diarrhoea in 1989. Sigmoidoscopy and rectal biopsy were normal, but he failed to attend for a barium enema. In 1990 colonoscopy to the hepatic flexure was normal, apart from mild diverticular disease. His current drug regimen was chlorpromazine, diazepam, fluoxetine, beconase inhaler for mild asthma, and intermittent fluconazole for recurrent oral candidiasis. Examination revealed that he was overweight with a distended abdomen tender on the right side. Flexible sigmoidoscopy identified submucosal cysts proximal to the rectosigmoid junction. Barium enema confirmed multiple cysts in the sigmoid and ascending colons and at the hepatic flexure. Subsequent enquiry of the patient and his general practitioner established that he had first been prescribed chloral hydrate in 1994; in the year before presentation, he had been taking chloral betaine (Welldorm), two tablets at night.

It is tempting to speculate that the cause of the abdominal symptoms diagnosed as PCC in these two patients was chloral hydrate, in the light of Dr Florin’s observations and experiments. Underwood et al in 1978 described two cases of PCC in one family1: the mother was taking chloral hydrate and the son was a chronic schizophrenic. The only other evidence to support the association is the epidemiological description2 of an outbreak of PCC in those exposed to trichloroethylene in Japan. The Committee on Safety of Medicines has to date received only one report of PCC in a patient taking chloral hydrate.

In both the patients described here, constipation had been a feature of the previous history. Case 1 suffered from longstanding Parkinson’s disease and had been treated with L-dopa and orphenadrine, all of which may induce constipation. Case 2 had a history of constipation since childhood and had been on phenothiazines and tricyclic antidepressants for many years. Both patients described by Underwood et alwere taking nortryp- tiline.1 Of Dr Florin’s patients, at least three of the six were taking psychotropic drugs that may induce constipation. Patients with PCC have normal or slow colonic transit times.3 It may be that the combination of chloral hydrate and prolonged colonic transit is necessary to allow hydrogen accumulation in the colonic lumen and subsequently in the bowel wall.

The diagnostic difficulties of PCC, as posed by case 1, have been reported by others. Colectomy and ileorectal anastomosis for PCC simulating polyposis has been reported,4 and two sisters only avoided colectomy when the correct diagnosis was made at another hospital.5 The appearances on flexible sigmoidoscopy and barium enema in case 1 were very suggestive of a carcinoma and ulcerative colitis, and were reported by an experienced gastroenterological consultant radiologist. Thus the potential for diagnostic confusion with PCC is not to be underestimated.

It remains to be seen as to whether more reports of PCC in patients taking chloral hydrate are forthcoming in the light of Dr Florin’s observations.