FUNCTIONAL AND MORPHOLOGICAL-STUDY OF THE CRICOPHARYNGEAL MUSCLE IN PATIENTS WITH ZENKERS DIVERTICULUM

Pharyngo-oesophageal function was investigated in 12 patients with Zen ker's diverticulum before and after cricopharyngeal myotomy with or wi thout diverticulectomy using low-compliance, high-frequency. oesophage al manometry. Nine healthy volunteers served as controls. The amount o f muscle and connective tissue in the cricopharyngeal muscle was also measured by computerized morphometry and compared with findings in cad avers with no history of dysphagia. Preoperative manometry in patients with Zenker's diverticulum showed an incomplete relaxation of the upp er oesophageal sphincter (UOS) (the residual UOS pressure at swallowin g was 7.9 (range 1-20) mmHg in patients versus 0.2 (-12.5-14) mmHg in controls; P<0.001) and increased pharyngeal intrabolus pressure (21 (r ange 0-52) versus 9 (range 0-16)mmHg; P<0.01), with no pharyngo-oesoph ageal coordination abnormalities. Both parameters significantly decrea sed after myotomy. Patients with Zenker's diverticulum had significant ly fewer muscle fibres in the cricopharyngeus and the muscle:connectiv e tissue ratio was significantly lower (0.94 (range 0.8-1.4) in patien ts versus 1.5 (1.4-3.6) in controls; P<0.05). This study supports the theory that Zenker's diverticulum is caused by an increased intraphary ngeal pressure at swallowing due to incomplete cricopharyngeal muscle relaxation resulting from localized sclerosis.