Benign congenital hypotonia with uniform type 1 fibers and aspecific ultrastructural changes in the muscle: a case with esophagus involvement.

We report the case of a child with congenital neuromuscular disease characterized by neonatal onset of symptoms, a floppy syndrome with marked weakness of facial muscles, palsy of the velum pendulum and hypomotility of the esophagus. EMG was inconclusive. Serum enzyme levels were within the normal range. Muscle biopsy specimen showed uniform type 1 fibers, smallness of the occasionally observed type 2 fibers and slight ultrastructural changes in many fibers. On the basis of the clinical and morphological features we have included the present case among the group of non-progressive congenital neuromuscular diseases.