[Congenital myasthenic syndromes. Clinical and electromyographic evaluation].

BACKGROUND

Congenital myasthenic syndromes are the more frequent group of disorders involving neuromuscular transmission in childhood. They are characterized by hypotonia, weakness and periodic apneic spells, which can be life threatening. Further elucidation of the causes of these syndromes requires sophisticated technology, which is not available in all hospitals.

OBJECTIVE

To provide evidence that clinical features and repetitive stimulation support and guide the correct diagnosis in the absence of invasive techniques.

METHODS

All the patients diagnosed with congenital myasthenic syndrome were selected. The sample consisted of four children: two with a defect in acetylcholine resynthesis and mobilization (familial infantile myasthenia), one with absence of the endplate-specific form of acetylcholinesterase and one with acetylcholine receptor deficit. The clinical and electromyographic features of these syndromes are described in detail.

CONCLUSIONS

Clinical phenotypes and repetitive stimulation can be used to classify the most common myasthenic syndromes and to avoid more aggressive techniques, predict potentially life threatening respiratory exacerbations and avoid iatrogenic effects. They can also be used in genetic counseling.