[Tubular aggregate congenital myopathy associated with neuromuscular block]

Various myopathies are described associated with tubular aggregates. However, in several cases tubular aggregates constitute the main structural feature allowing to consider myopathy with tubular aggregates as a distinct entity. A 50-year-old woman whose parents were consanguinous, presented frequent falls. She walked only after 18 months of age and did poorly in gymnastics. The weakness, which has myasthenic feature, involved predominantly the pelvis girdle. The serum creatine kinase was 206 UI/L (normal < 110 UI/L). Electromyogram showed a myogenic pattern in proximal muscles. Repetitive stimulation on the trapezius revealed 50 p. cent decrementing response. Muscle biopsy showed numerous tubular aggregates in type II fibers. Anti-acetylcholine receptor (AChR) antibodies were absent. There was no thymoma. The neostigmine test was negative. Clinical and electrical myasthenic features characterize one of the numerous forms of myopathy with tubular aggregates. In our case, the lack of AChR antibodies and the negative response to neostigmine argue in favor of a dysfunction of the AChR. This unusual observation highlights the therapeutic difficulties in this myopathy with neuromuscular block.