[Oral dantrolene in a parturient with myotonic dystrophy and susceptibility to malignant hyperthermia].

A 33 year old woman, with myotonia atrophica and a known susceptibility to malignant hyperthermia, presented during her second pregnancy with multiple episodes of hyperthermia. They were associated with a rapid rise in the serum creatine phosphokinase (CPK) level, and not with infection or a myotonic crisis. Because of the obstetric conditions, caesarean section was planned. Preoperative oral dantrolene was used as prophylaxis. Six days after the start of this treatment, CPK and serum myoglobin levels were back within the normal range. There were no side-effects for the mother nor for the foetus. There were no further increases in either CPK or serum myoglobin levels during surgery or afterwards, but the rectal temperature remained markedly raised for 48 h after the delivery. Oral dantrolene was given during the first nine postoperative days. The occurrence of episodes of high fever during pregnancy linked to MHS and myotonia atrophica is discussed, as well as the anaesthetic management of such a patient. Side-effects of dantrolene for the mother or the foetus are also considered, especially as foetal levels of this drug would seem not to reach therapeutic levels. It would appear interesting to measure maternal dantrolene blood levels, especially if high doses are administered, to avoid reaching therapeutic levels in the foetus.