昏厥指的是因為可逆性的腦血流不足造成短暫的意識喪失。神經系統疾病是導致昏厥重要的原因之一，常見的病因包括神經調節反射性昏厥(neutrally mediated reflex syncope)，中枢或者周邊的自律神經系統病變以及腦血管疾病等。另外，神經系統疾病相關的昏厥也必須與心因性昏厥，常見的神經科疾病如癲癇，顱内高壓等或者精神性病因導致的意識障礙做鑑別診斷。臨床醫師應從病史詢問，理學及神經學檢查，並配合相關的檢查，如心電圖監測，傾斜床測試，神經電生理，神經影像等得知造成昏厥的原因並給予適當的防治。本文將介紹及討論上述幾種疾病的臨床表現及鑑別診斷，提供一般臨床醫師參考與實際應用。

Syncope was defined as a sudden loss of consciousness, related to transient global brain ischemia, followed by spontaneous recovery. A variety of neurological disorders may cause syncope, such as neurally mediated reflex syncope, central or peripheral autonomic nervous system dysfunction, cerebrovascular diseases, etc. Besides, neurological disorders causing syncope should be differentiated from cardiogenic syncope, psychogenic disorders and other neurological diseases such as seizure, stroke, increased intracranial pressure, etc. To establish the diagnosis and cause of syncope, clinicians should perform history taking, physical and neurological examinations, and related tests such as electrocardiography Holter, tilting table test, electrophysiology studies, and neuroimaging to make correct diagnosis and proper management for subjects with suspected syncope. This article will introduce and discuss the clinical characteristics and differential diagnosis of the aforementioned disorders as reference and clinical application for general practitioner.