Abstract:

Congenital neuromuscular disease with uniform type 1 fiber (CNMDU1) is a rare type of congenital myopathy. It is characterized by early onset of symptoms, mild proximal muscle weakness, hyporeflexia or areflexia, normal serum creatine kinase (CK) levels and myopathic electromyography finding, uniform type 1 fibers, and nonprogression. We report a 2-year-old boy who presented with congenital hypotonia, breathing and feeding difficulty, myopathic facies, proximal muscle weakness, ptosis, total external ophthalmoplegia and delayed motor developmental
milestones. Normal serum muscle enzyme and short duration of motor unit potentials on electromyography were noted. Muscle biopsy showed uniformity of type 1 fibers (greater than 99%) and moderate variation in fiber size without specific structural abnormality. Total external ophthalmoplegia may be one of the important clinical manifestations of CNMDU1. It is important to recognize this disorder because it is nonprogressive in nature.

日本語要旨:

CNMDU1は非常にまれな先天性ミオパチーであり、近位筋の筋力低下、腱反射の低下または消失、筋電図で筋原性変化を認め、病理所見ではタイプ1線維優位を呈する非進行性の疾患である。症例は筋緊張低下、呼吸障害、経口摂取困難、ミオパチー様顔貌、近位筋筋力低下、眼瞼下垂、外眼筋麻痺を呈する2歳男児で、筋生検では筋線維の大小不同がありほぼ全てタイプ1線維だった。全方位の外眼筋麻痺はCNMDU1の臨床所見として特徴的で、また外眼筋麻痺は重度であるが、非進行性の疾患であることを認識しておくことは重要である。