100 - Paroxysmal Extreme Pain Disorder

Abstract

Paroxysmal extreme pain disorder is an uncommon cause of severe, episodic, burning rectal, perineal, ocular, and mandibular pain. Also known as familial rectal pain syndrome, paroxysmal extreme pain disorder is caused by autosomal dominant abnormalities in the voltage-gated sodium channel NaV1.7 which are induced by mutations of the gene SCN9A. These mutations cause impairment of the ability of these specific sodium channels to inactivate causing prolonged action potentials resulting in increased pain sensation and sympathetic nervous system activity. Paroxysmal extreme pain disorder manifests itself clinical in infancy, with paroxysms of severe pain triggered by defecation, teething, eating, micturition, sexual intercourse, and painful stimuli. Painful attacks can be triggered in some patients suffering from paroxysmal extreme pain disorder simply by the thought of a physical trigger. Fear of triggers may condition some patients to avoid painful triggers at all costs, leading to physical consequences such as constipation. Attacks last between seconds to a few hours. Between attacks, the patient is pain free. Associated symptoms include tonic, nonepileptic seizures, apnea, tachycardia, asystole, and harlequin skin changes and cutaneous flushing of skin in the painful areas.