Data for: Sudden paraparesia in an old man

The first consideration with this presentation pattern is a spinal cord lesion, most likely anterior cord syndrome characterized by loss of motor function, pain, pinprick, and light touch below the level of the lesion . In general, pathologic processes involving the spinal cord may be divided into processes affecting the cord or its blood supply primarily and processes that compress the cord, most often originating outside the dura.The main causes of anterior cord syndrome are external compression (such as mass, discopathy, trauma) , ischemia (such as aortic surgery or involvement, aortic angiography, laceration or thrombosis of the anterior spinal artery or a major feeding vessel, severe hypotension, myocardial infarction , vasospasm),Inflammation, infection and demyelination. Note that lesions from ischemia usually are incomplete. If the physical examination does not support a cord syndrome or cauda equina syndrome (absence of UMN signs or a clear thoracic pinprick level, loss of perianal sensation and rectal tone, and urinary retention), the patient may have a peripheral neuropathy affecting the longest nerve tracts first (such as Guillain-Barré syndrome).针对该临床表现模式，首要鉴别诊断为脊髓病变（spinal cord lesion），最可能为脊髓前综合征（anterior cord syndrome），其特征为病变节段以下运动功能丧失，以及痛觉、针刺觉与轻触觉缺失。总体而言，累及脊髓的病理过程可分为两大类：一类主要累及脊髓本身及其血供，另一类则压迫脊髓，此类压迫多起源于硬脊膜（dura）外。脊髓前综合征的主要致病因素包括：外部压迫（如占位性病变、椎间盘病变（discopathy）、创伤）、缺血性损伤（如主动脉手术、主动脉受累、主动脉造影术（aortic angiography）、脊髓前动脉（anterior spinal artery）或主要滋养血管撕裂/血栓形成、重度低血压、心肌梗死（myocardial infarction）、血管痉挛（vasospasm）），以及炎症、感染及脱髓鞘（demyelination）病变。需注意，缺血所致的脊髓损伤通常为不完全性损伤。若体格检查结果不支持脊髓综合征或马尾综合征（cauda equina syndrome）的诊断——即无上运动神经元体征（UMN signs）、无明确的胸段针刺觉定位平面，且无肛周感觉丧失、直肠张力缺失及尿潴留，则患者可能罹患以最长神经束先行受累为特征的周围神经病（peripheral neuropathy），例如吉兰-巴雷综合征（Guillain-Barré syndrome）。