Congenital Myasthenia Gravis

This report of a case of congenital myasthenia gravis and a study of the patient's family are presented not only because of their intrinsic interest, but also because they may help to elucidate this rare condition and to establish it as a disorder of infancy. The accounts of myasthenia gravis in the textbooks do not usually include references to the condition in infancy. The maximal incidence is in young adults, but many articles have reviewed the cases known to have occurred in childhood. The condition has, however, only rarely been reported in infants. Levin (1949) described congenital myasthenia gravis in two siblings, and reviewed previous case reports. From these he deduced certain clinical principles concerning the behaviour of myasthenia gravis in young infants. The case reports can be analysed in three groups. The first group may be classified as transitory neonatal myasthenia occurring in infants whose mothers suffer from myasthenia gravis. They all show signs of a myasthenic state: general feebleness, poor sucking and swallowing reflexes, drooping eyelids, a mask-like facies, and sometimes sudden, fatal collapse. When such infants were treated for the first two weeks of life with prostigmine, survival and recovery were usual. If prostigmine was not continued, the infants usually died, some after a sudden collapse. Strickroot, Schaeffer, and Bergo (1942) reported such an infant who developed symptoms on the third day, and in whom 3 *75 mg. of prostigmine bromide, given orally, produced a dramatic response. Omission of the treatment on the fifth day caused a relapse, and although some recovery followed the administration of a double dose, the baby suddenly collapsed and died. At necropsy there was evidence of cerebral congestion and oedema, atelectasis, suprarenal haemorrhages, and diffuse cloudy swelling of other organs with mild hyperplasia of the thymus including hypertrophy of Hassall's corpuscles. Wilson and Stoner (1944) reported two probable cases born to a woman with myasthenia gravis; the first died soon after birth, while the mother was not receiving treatment; the second survived after some initial difficulties, while the mother was having regular maintenance treatment with prostigmine. Neither infant received prostigmine as treatment. Stone and Rider (1949) reported a similar case in which the infant was treated with neostigmine for 14 days, and who survived as a normal child. LaBranche and Jefferson (1949) described a child who responded to prostigmine therapy which was continued for four months. At this age the child's condition was reported as satisfactory, while treatment continued. F. R. Ford reported to Levin, in a personal communication, a baby born with a myasthenic state, who was treated for one week and survived as a normal infant. The various authors imply that this type of myasthenia is due to the transplacental passage of a curare-like substance which affects the baby at birth, but which is destroyed in some manner, and leaves the child unaffected in later life. In the second group, three cases of congenital myasthenia gravis have been reported in which the accepted clinical picture of myasthenia gravis was present from birth. The mothers were not affected. Bowman (1948) described a child in whom the condition had been present from birth, and who was well maintained on prostigmine. Two cases were described by Levin in the paper quoted. The first was a boy whose symptoms were present from birth as progressive weakness, bilateral ptosis, and limited ocular movements. He responded well to prostigmine therapy, but treatment was discontinued during an acute respiratory infection, and he died. The second case was the boy's younger sister whose condition was suspected in the antenatal period, because the mother felt that foetal movements were not sufficiently strong. Myasthenia gravis was diagnosed at birth, and treatment started at once. Treatment was continuous, and the response satisfactory. The mother was not affected, and no latent myasthenic state could be demonstrated even after large doses of quinine. Although no other cases of congenital myasthenia gravis have been reported, Levin states certain principles concerning the condition. He suggests