[Rare causes of stroke-a frequent stroke etiology].

As a whole, rare stroke causes represent a frequent stroke etiology. Since rare stroke causes affect primarily young patients, early diagnosis and treatment are of high socioeconomic relevance. In our everyday clinical practice, cervical artery dissection, which is the most common stroke etiology among patients < 45 years, and vasculitis are particularly important. In the case of vasculitis, devastating disease courses and potentially harmful treatment options complicate clinical decision-making. Non-vasculitic vasculopathies, infections, hematological disorders, coagulation disorders, metabolic disorders and malignancies are further rare causes of stroke with variable clinical manifestations, thus impeding an early diagnosis. If eligible, patients with rare stroke causes should be considered for thrombectomy. Except for infective endocarditis, most rare stroke causes are not per se a contraindication to thrombolysis, so that eligible patients should also be considered for thrombolysis. Evidence based recommendations for the secondary prevention of most rare stroke causes are still missing. In many cases, treatment regimens are adapted to the patients' individual risk of stroke recurrence and bleeding complications.