[Wallenberg's syndrome following minor neck trauma: a case associated with atlanto-axial subluxation, an anomaly of the axis, and platelet activation].

A 38-year-old man hit his forehead against a steel pipe, which made his neck hyperextended. He noticed unsteady gait and dysphagia approximately 6 hours after the accident. On the next day he was admitted. He had a Horner's syndrome, and pharyngeal and palatal weakness on the right side. There were no pyramidal tract signs. He could not balance on his right foot or gait tandemly. Sensation for cold and pin-prick was absent on his left limbs; position sense was intact. Angiography demonstrated an occlusion of the right vertebral artery at the 3rd segment. Cranial MRI demonstrated an infarction in the right lateral medulla. A radiogram demonstrated an atlanto-axial instability. There was an anomalous bone mass between the left superior articular process and the odontoid process. These abnormalities might have precipitated injury of the vertebral artery during the minor neck trauma. The plasma levels of molecular markers for coagulation and fibrinolysis were unremarkable. In contrast, beta-thromboglobulin and platelet factor 4 levels were high, suggesting activated platelet aggregation. To my knowledge, this is the first report showing evidence for platelet activation at the molecular level early in the course of vertebral artery thrombosis following a minor neck trauma.