低颅压综合症 Intracranial hypotension.doc

低颅压综合症 Intracranial hypotension 病史：The patient is a 22-year-old woman complaining of a headache that is exacerbated while standing and while coughing, but relieved in the recumbent position since the birth of her first child 1 month ago. The delivery was uncomplicated except for difficulty establishing epidural anesthesia.影像改变：There is diffuse linear enhancement of the pachymeninges involving both the supratentorial and infratentorial compartments (arrows in Figure 1 and Figure 2).硬脑膜可见弥漫性线样强化,累及幕上及幕下The sagittal T1-weighted image demonstrates low-lying cerebellar tonsils (yellow arrow Figure 3), a slightly elongated fourth ventricle, and slight effacement of the prepontine cistern. Slight AP elongation of the mesencephalon is demonstrated on the axial T2-weighted image (yellow arrow in Figure 4).矢状位Ti显示扁桃体低位,四脑室轻度狭长,桥前池轻微狭窄,轴位T2显示中脑向前后方向轻度延伸.诊断：Intracranial hypotension低颅压综合症要点： Meningeal enhancement should be categorized as pachymeningeal or leptomeningeal to aid in the formulation of a differential diagnosis.脑膜强化应该被分为硬脑膜或软脑膜强化,以帮助鉴别诊断 The typical imaging findings of intracranial hypotension are: sagging of posterior fossa structures and diffuse pachymeningeal enhancement.颅内低压综合征的典型影像表现为:后颅窝结构下垂和弥漫性硬脑膜强化.讨论：Intracranial hypotension (ICH) is a rare cause of orthostatic headache that worsens in the upright position. ICH is thought to result from a persistent CSF leak, usually after dural compromise following a diagnostic lumbar puncture, spinal anesthesia, or myelography. Other etiologies include prior craniotomy, craniectomy, spinal surgery, or trauma. ICH may also occur spontaneously secondary to rupture of a Tarlov cyst, dehydration, hyperpnea, uremia, or diabetic coma.低颅压综合症（ICH）是体位性头痛的一种少见病因，在直立位的时候更明显，ICH被被认为是脑脊液持续性渗漏的结果，通常发生在诊断性腰穿、脊椎麻醉或脊髓造影术后。其他的病因包括既往的开颅术后、颅骨切除术、脊椎外科手术或创伤。ICH也可以继发于Tarloy囊肿破裂、脱水、深快呼吸、尿毒症或糖尿病昏迷Imaging characteristic can be subtle and nonspecific in the absence of an appropriate history. The imaging findings are characterized by sagging of the posterior fossa with low-lying cerebellar tonsils (which may be mistaken for a Chiari I malformation), elongation of the fourth ventricle, and effacement of the prepontine cistern. Additionally, diffuse smooth linear pachymeningeal enhancement is present involving both the supratentorial and infratentorial compartments. The diffuse pachymeningeal enhancement is felt to result from increased intracranial blood flow to compensate for the CSF loss in accordance with the Monro-Kellie hypothesis, particularly on the venous side of the dura. Other imaging signs of venous congestion that may be present include bilateral subdural effusions and an enlarged pituitary gland.在缺乏明确的病史时，影像表现可以是轻微的，且无特异性。其特征性的影像表现是颅后窝的下降，表现为小脑扁桃体的低位（可能被误以为是Chiari型畸形），四脑室的延长、桥前池的消失。另外，弥漫性的硬脑膜线样强化，同时累及幕上/下。依据假设，弥漫性的硬脑膜强化被认为是由于颅内血流增加以补偿脑脊液的丢失，特别是硬膜静脉。其他的静脉性充血的影像表现包括双侧硬膜下积液和增大的脑垂体。The diagnosis can be confirmed with a low CSF opening pressure, nuclear radioisotope cisternography, or myelography. Symptoms will often resolve spontaneously with conservative therapy and bed rest. If symptoms persist, an autologous epidural blood patch is a safe, effective treatment.通过降低的脑脊髓开放压、核素显像、脊髓造影可以确诊，通过保守治疗及卧床休息，临床症状可以自发的消退。假如症状持续，硬膜外腔注射自体静脉血是一种安全有效的治疗方式。 另一段资料颅内低压综合征疾病概述：正常颅内压的范围，由腰椎穿刺测定应在7.8411.8kPa（80120mmH2O）之间。一般颅脑损伤后的颅内压，常有不同程度的升高，而表现为低颅压者较少，间或有些病人伤后早期曾经有过颅内压升高，嗣后又出现颅内低压，其发生率约为5。所谓颅内低压综合征，系指病人侧卧腰穿压力在7.84kPa以下所产生的综合性症候群，临床表现与颅内压增高相类似，只因处理方法各异，必须慎加区别。造成颅内低压的原因，可能原发于伤后脑血管痉挛，使脉络丛分泌脑脊液的功能受到抑制，亦可能继发于脑脊液漏、休克、严重脱水、低血钠症、过度换气以及手术或腰穿放出过多的脑脊液等。腰穿后头疼已为人们所熟知，其机理一是腰穿本身所引起的脉络丛反射性抑制或因丘脑下部脑脊液分泌中枢发生功能紊乱；二是脑脊液容量的减少。Franksson曾指出，当颅内压为100200mmH2O时，自腰穿针孔漏入硬脊膜外间隙的脑脊液，1天就可达240ml之多，而正常情况下脑脊液总量为100160ml，分泌速率约为0.3ml/min，每天可产生400500ml，故健康人一次快速放出脑脊液20ml，即可引起头疼。Grant等（1991）认为头疼可能是因代偿性动脉扩张所致。另外，因外伤时脑脊液向椎管强力冲击，造成腰神经根袖囊撕裂亦有可能使脑脊液漏入硬脊膜外间隙，从而导致低颅压（Bell,1960）。疾病描述正常颅内压的范围，由腰椎穿刺测定应在7.8411.8kPa（80120mmH2O）之间。一般颅脑损伤后的颅内压，常有不同程度的升高，而表现为低颅压者较少，间或有些病人伤后早期曾经有过颅内压升高，嗣后又出现颅内低压，其发生率约为5。所谓颅内低压综合征，系指病人侧卧腰穿压力在7.84kPa以下所产生的综合性症候群，临床表现与颅内压增高相类似，只