A Child with Paroxysmal Extreme Pain Disorder and Erythromelalgia: Challenges in Hypertension Treatment

Paroxysmal extreme pain disorder (PEPD) and inherited erythromelalgia (IEM) are two distinct syndromes caused by pathogenic mutations in the SCN9A gene. Still, they can be part of a clinical continuum manifesting in the same patient. The main clinical characteristics are painful attacks accompanied by various autonomic nervous system symptoms, the most severe being apnea, bradycardia and asystole. Arterial hypertension has also been reported, especially in secondary erythromelalgia, however, its pathomechanism is still not well understood. Some suggest that hypertension results from severe painful episodes that activate the sympathetic nervous system. Other hypotheses include autoimmune and inflammatory etiologies and dysfunctional nitrous oxide pathways causing non-apparent vasoconstriction. Currently, there are no specific guidelines for hypertension management in pediatric patients with IEM, making trial-and-error the most common therapeutic approach. Treatment is especially challenging in patients with PEPD who manifest with bradycardia and asystole and usually take several medications for controlling neuropathic pain. We report the clinical course of a patient with PEPD and IEM who was diagnosed with systolic-diastolic hypertension at the age of nine, which was successfully managed with low-dose doxazosin.