A 45-year-old woman presented to the neurology department with numbness and weakness of extremities, which had progressed during 3 months. The patient had tingling sensation in the left neck. Although muscle atrophy was not observed, manual muscle test revealed grade 4 weakness in bilateral deltoid muscles, right upper and left lower limbs. The patient had normal deep tendon reflex, and Babinski reflex was negative bilaterally. Laboratory blood tests showed no abnormalities. Spinal fluid examination revealed a slightly increased protein level of 56 mg/dL (normal range: 10–45 mg/dL) and no white blood cells.
