Multi-minicore disease in pregnancy: avoiding malignant hyperpyrexia

Multi-minicore disease (minicore myopathy) is a rare form of myopathy, which usually presents in childhood, but can occasionally present later in life or early infancy. It is characterised by slowly progressive or non-progressive muscle weakness and characteristic multiple cores within the muscle fibres. Most cases of minicore myopathy are due to recessive mutations in either SEPN1 or RYR1. Individuals with mutations in the RYR1 gene are susceptible to malignant hyperthermia, which is triggered primarily by the volatile inhalational anaesthetic agents and the muscle relaxant succinylcholine, though other drugs have also been implicated as potential triggers. We report on the anaesthetic and obstetric care, and outcome of a pregnant woman diagnosed with minicore myopathy as a child, and antenatal plans put in place for delivery, which included early diagnosis and early rapid administration of dantrolene, discontinuance of triggering agents, and assistance from extra personnel.