Myasthenia gravis in childhood and infancy. Usefulness of electrophysiologic studies
C. Vial, N. Charles, G. Chauplannaz and B. Bady
EMG Department, Hopital Neurologique, Lyon, France.
The diagnostic yield of electrodiagnostic tests was evaluated in 21
children with myasthenia gravis (MG). Twelve children had juvenile
autoimmune MG, four had neonatal MG, four had congenital MG, and one had MG
with arthrogryposis. Repetitive stimulation (RS) of the ulnar nerve was
performed in every patient, sometimes with sensitization by ischemia. When
the RS test was negative, the spinal or facial nerve was tested. In the
group with neonatal MG, the RS test disclosed a significant decrement in
75% of the patients. Among the 17 other children, the overall percentage of
positive RS tests was 88%. An ulnar nerve RS test was positive in 41% of
them. Sensitization of ulnar nerve RS by ischemia improved the diagnostic
yield to 66%. A spinal or facial nerve RS test was positive in seven of 10
patients. These results confirmed the diagnostic value of RS, with
sensitization by ischemia, when necessary, in childhood MG whenever a
careful technique is provided.
