Clinical Reasoning: A 64-year-old woman with progressive leg weakness and ophthalmoplegia

A 64-year-old woman with type 2 diabetes (HbA1C: 6.6%) experienced pain radiating down her right leg with intermittent numbness and tingling in her feet, followed by right leg weakness and recurrent falls. Two months after onset, she required a walker to ambulate long distances. Over the next 5 months, she experienced slow and progressive right leg weakness. Her neurologic examination revealed normal cranial nerves, fasciculations in the right leg, and nonpyramidal weakness in the right L3-S1 myotomes. She had intact strength elsewhere. Reflexes were pathologically brisk (3+), except for absent right patellar and bilateral Achilles reflexes. Plantar responses were flexor. There was mild length-dependent distal sensory loss in both lower extremities.