Brainstem/cerebellar infarction is known to cause various cranial nerve symptoms that may require otorhinolaryngological evaluation. Acute-phase cerebellar infarction is evaluated by MRI with diffusion-weighted imaging (MRI-DWI). However, in the acute phase, MRI-DWI may show false-negative results, because of which patients are referred to the department of otolaryngology for further evaluation of the cranial nerve symptoms. We investigated 250 cases of brainstem/cerebellar infarction in 245 patients who were admitted to our hospital between 2010 and 2015. Of the 250 cases, eight cases were diagnosed at the department of otolaryngology after detailed evaluators for dizziness or dysphagia, and three of them were false negative on initial MRI-DWI. In total, we examined 16 cases detected as false negatives upon initial MRI-DWI. Of the 16 cases, 12 were brainstem infarctions, three were cerebellar infarctions, and one was infarction of the brainstem and cerebellum. All 16 cases were evaluated by initial MRI-DWI within 12 h of onset. Careful observation of the neurological findings and follow-up MRI-DWI are useful for the detailed evaluation of patients suspected to have a cerebellar infarction.