Clinical Reasoning: A 67-Year-Old Woman With Progressive Tingling Sensations and Imbalance.

A 67-year-old woman presented with 4 months of progressive numbness, tingling, and weakness in her hands and feet symmetrically with gait imbalance. Symptoms started in her upper and lower extremities at approximately the same time. She denied skin changes, tremors, weight loss, autonomic symptoms, or other systemic symptoms. She did not have a family history of a neuromuscular disorder. Her initial neurologic examination was notable for proximal and distal weakness (Medical Research Council [MRC] scale shoulder abduction 4+/5; elbow flexion, elbow extension, wrist flexion, wrist extension finger extension, finger flexion 4/5; finger abduction 4+/5; hip flexion 4−/5; knee extension 4+/5; and knee flexion, dorsiflexion, plantarflexion, toe extension, toe flexion 5/5 bilaterally). Sensation to pinprick, vibration, and temperature were decreased in the distal hands and feet below the levels of the wrists and ankles, respectively. Proprioception was impaired at the toes but intact at the ankles. Her reflexes were 1 in the upper extremities and absent in the lower extremities. She did not have pes cavus.