Abstract
A 14-year-old male presented with the chief complaint of bilateral progressive ptosis, which began approximately two years ago. He gradually felt weakness in his limbs. Initially, there were some differential diagnoses, such as spinal muscular atrophy (SMA) with bulbar involvement, neuromuscular junction problems, and some myopathies like myotonic with proximal predilection (proximal myotonic myopathy). With electrodiagnostic study, we ruled out these diagnoses. Kearns-Sayre syndrome (KSS) is a rare myopathy and usually presents with other systemic signs and symptoms, which should be considered as a differential diagnosis in all cases with myopathy and ptosis.