[Three cases of small brain infarction in the lateral wall of the fourth ventricle presenting with paroxysmal positional vertigo and vomiting].

A lesion responsible for central paroxysmal positional vertigo (PPV) is often found in the dorsolateral wall of the fourth ventricle. A relatively large tumor or hemorrhage in the dorsolateral wall of the fourth ventricle usually causes central PPV, but small brain infarction has hardly been reported to cause central PPV. We report three cases of a small brain infarction in the lateral wall of the fourth ventricle presenting with central PPV. All of the cases showed similar clinical features in which a given recumbent position and a sitting position caused a dizziness associated with nausea and vomiting over an acute period. The symptom lasted one to two months after the onset. In two of our cases, no neurological abnormal signs, except nystagmus, were observed, and initial differentiation of central PPV from peripheral PPV was difficult. Interruption of the vestibular nuclei-archicerebellar loop seems to be responsible for the central PPV. Recognition of the clinical features of central PPV and diffusion-weighted MRI images are important for a precise local diagnosis in small brain infarction showing PPV.