Structural abnormalities of the cricopharyngeus muscle in patients with pharyngeal (Zenker's) diverticulum

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Abstract
Recent manometric and radiological studies suggest that the upper oesophageal sphincter has poor compliance in patients with a pharyngeal (Zenker's) diverticulum. To test the hypothesis that this phenomenon is related to structural changes within the cricopharyngeus muscle we examined, histologically, muscle strips from 14 patients with a Zenker's diverticulum and compared them with control tissue obtained at autopsy from 10 non‐dysphagic individuals. The cricopharyngeus muscle from patients and controls differed from inferior constrictor muscle by virtue of type 1 fibre predominance and greater fibre size variability. Ragged red fibres and nemaline bodies are a normal finding in the cricopharyngeus. Marked differences were observed in the cricopharyngeus muscle of Zenker's patients which demonstrated fibro‐adipose tissue replacement and fibre degeneration. It is concluded that these structural changes may account for the observed diminished upper oesophageal sphincter opening and dysphagia in patients with Zenker's diverticulum.