Jaw-opening dystonia (oromandibular dystonia with jaw-opening; Brueghelʼs syndrome) is a rare condition, and only a limited number of cases have been reported in the literature. However, many patients may remain undiscovered or misdiagnosed, like a patient described previously. A case (40-year-old man) of jaw-opening dystonia (oromandibular dystonia with jaw-opening; Brueghelʼs syndrome) is reported. In this case, brain anomalies, cavum septi pellucidi and Vergaʼs ventricle, were observed on magnetic resonance imaging of the brain. This case and a review of the literature indicate the presence of organic factors in the etiology of Brueghelʼs syndrome. The etiological relationship of brain anomalies in Bruegelʼs syndrome is discussed.