[Congenital myasthenia gravis. Presentation of a case with dysphagia as the only clinical manifestation].

Myasthenia gravis is an infrequent disease seen at the neonatal stage. Two main groups are identified: a) one with a genetic origin which can be secondary to pre- or postsynaptic defects and b) of an acquired origin, as transitory neonatal myasthenia seen in 10-15% of those children with myasthenic mothers. Few cases with a genetic origin have been reported in the literature; the most common symptoms being bilateral eyelid ptosis, ophtalmoparesis, easy fatigability, respiratory and feeding difficulties. This is a report of a genetic neonatal case of myasthenia gravis with dysphagia as the only clinical manifestation seen since the first days of the child's life, confirming the diagnosis using a repetitive supramaximal stimulation test and obtaining excellent results with pyridostigmine. We conclude that, although this a rare form of the disease, genetic neonatal myasthenia gravis should be considered in the differential diagnosis of newborns with difficulties to swallow. The repetitive supramaximal stimulation test is the diagnostic procedure of first choice to be used in the neonatal period.