RESUMEN
BACKGROUND: Hereditary polyglucosan inclusion body myopathy of the internal anal sphincter is a rare cause of proctalgia fugax and constipation. Treatment options are explored. CASE PRESENTATION: A 61 year-old Caucasian woman presented with an 18-year history of severe anal pain and constipation. She had no response to medical treatment which included amitriptyline and topically administered diltiazem. Endoscopy revealed no abnormalities, whereas endoanal ultrasound showed an abnormally thick internal anal sphincter (> 5 mm) and anal manometry showed intermittent episodes of very high resting pressures in excess of 200 mmHg that resolved spontaneously after 2 minutes. She had no relief of her symptoms after receiving an injection of botulinum toxin to the internal anal sphincter. She subsequently underwent a lateral internal anal sphincterotomy which led to complete resolution of her symptoms. CONCLUSIONS: Hereditary polyglucosan inclusion body myopathy of the internal anal sphincter should be considered in the differential diagnosis of a patient presenting with severe anal pain and constipation in the absence of an anal fissure or sepsis. If medical therapy with calcium antagonists fails to provide symptom relief, lateral internal sphincterotomy should be considered rather than botulinum toxin injection.