Non-atherosclerotic, Uncommon Diseases

Atherosclerosis is not the only cause of posterior circulation arterial disease. Arterial dissection, dolichoectasia, moyamoya disease, vasculitis, vasospasm, and immunologic disorders are less common yet important causes of posterior circulation stroke. Identification of the correct etiology is important in establishing treatment strategies and assessing the prognosis. Careful history taking and appropriate laboratory and imaging testings are essential. Although catheter angiography remains the most important diagnostic tool to examine various posterior circulation arterial diseases, other more convenient and less risky diagnostic modalities such as CT angiogram and MR angiogram are nowadays widely used. High-resolution vessel wall MRI can also assist us in making a correct diagnosis as this technique can give us information regarding vessel wall pathology. Diseases such as infectious vasculopathy and moyamoya disease are more prevalent in certain parts of the world, and physicians practicing in these regions should pay attention to these disorders. In this chapter, these non-atherosclerotic posterior circulation arterial diseases are described.