2018 年 35 巻 4 号 p. 423-426
Brain white matter lesions are frequently observed changes in older adults. Traditionally, white matter lesions were considered to be caused by peripheral circulation disorders due to stenosis of large blood vessels. However, the discovery of small blood vessel diseases with only small blood vessels indicates that in some situations, small blood vessels are affected primarily and have a different molecular mechanism from large blood vessels. Hereditary cerebellar small vessel diseases are caused by mutations of genes ubiquitously expressed in many tissues, but the pathological changes of small vessels are different from organ to organ. This fact indicates that small blood vessels can be characterized by each organ. Furthermore, recently, cerebral small vessels have been found to function as a mechanism of excretion from the brain and as a mechanism of blood flow redistribution depending on nerve activity. The neurological symptoms which are suggested by these new mechanisms cannot be understood by the traditional concept of clinical neurology based on functional localization theory. Neurological symptoms due to cerebral small vessels should be understood from a whole new perspective. It is also suggested that there is a close relationship between dysfunction of cerebral small vessels and degenerative diseases. For this understanding, the molecular mechanism of the hereditary cerebrovascular disease is considered to be useful. Pathology of small vessels is characteristic of each cerebral small vessel disease. The affected lesions in cerebellar small vessel disease are anatomically limited to specific cells or structures in vessels. The study of cerebral small vessel diseases will open a new understanding of cerebral small vessel disease in sporadic cases and new therapeutic strategy for dementia.
