First rib fracture and Horner's syndrome due to a motor vehicle collision: a case report.

A case of a first rib fracture and Horner's syndrome due to a motor vehicle collision is reported. Initial evaluation in a hospital emergency department and follow-up by a medical primary care physician failed to provide identification of the Horner's syndrome. Careful assessment and review of the patient's symptoms, signs and images revealed this uncommon and important neurologic case presentation. A brief discussion related to traumatic first rib fracture, Horner's syndrome and arterial dissections of the neck is provided.