MRCP2-3116

MRCP2-3116

A 45-year-old office worker presented with a 9-month history of gradual weakness in their left hand and a 4-month history of similar weakness in their right hand. They had no significant medical history. On examination, there were fasciculations in both biceps muscles with increased tone in both arms, weakness of intrinsic hand muscles bilaterally, and brisk upper limb reflexes. Coordination and sensory examinations were unremarkable. What is the most probable diagnosis?