A 70-year-old man presented with dizziness and unsteadiness when standing and was hospitalized in another hospital. Magnetic resonance imaging (MRI) of the brain on Day 1 showed no abnormalities. The patient developed respiratory failure on Day 1and flaccid tetraplegia on Day 3, and was transferred to our hospital. Progressive upper and lower limb weakness and bulbar symptoms suggested Guillain-Barré syndrome or its variant. Diffusion-weighted MRI on Day 6 disclosed high signal intensities in the bilateral medial portion of the medulla, and the patient was diagnosed with bilateral medial medulla infarction. Bilateral medial medulla infarction should be considered when a patient shows progressive tetraplegia, and bulbar palsy and follow-up MRI is important to confirm the diagnosis. (Received January 23, 2020; Accepted April 21, 2020; Published August 1, 2020).