RESUMEN

Nav1.4 channelopathies due to SCN4A mutations can present with episodic attacks of myotonia triggered by fluctuation in the potassium level (potassium-aggravated myotonia). We report a case of potassium-aggravated myotonia due to Nav1.4-M1592V channelopathy with severe and long-lasting focal attacks of myotonia resembling dystonic posturing with diffuse muscle edema in the affected muscles in magnetic resonance imaging and almost constant presence of myotonic discharges in electromyography that can best be described as focal "status myotonicus".

Asunto(s)

Canalopatías/complicaciones , Canalopatías/genética , Miotonía/diagnóstico , Miotonía/etiología , Canal de Sodio Activado por Voltaje NAV1.4/genética , Adulto , Electromiografía , Femenino , Humanos , Imagen por Resonancia Magnética

RESUMEN

BACKGROUND: Sodium-channel myotonia (SCM) is a nondystrophic myotonia, characterized by pure myotonia without muscle weakness or paramyotonia. The prevalence of skeletal muscle channelopathies is approximately 1 in 100,000, and the prevalence of SCM is much lower. To our knowledge, this is the first report on anesthetic management of a patient with SCM. CASE PRESENTATION: A 23-year-old woman with congenital nasal dysplasia and SCM was scheduled to undergo rhinoplasty with autologous costal cartilage. Total intravenous anesthesia without muscle relaxants was administered followed by continuous intercostal nerve block. Although transient elevation of potassium level in the blood was observed during surgery, the patient did not show exacerbation of myotonic or paralytic symptoms in the postoperative period. CONCLUSION: Total intravenous anesthesia and peripheral nerve block can be administered safely to a patient with SCM. However, careful monitoring of the symptoms and electrolytes is recommended.