静脉回流障碍与短暂性全面遗忘症的相关性

Obstruction of Venous Drainage Linked to Transient Global Amnesia

背景颈静脉回流异常被认为是短暂性全面遗忘症(transient global amnesia,TGA)的病因。既往研究报道,Valsalva动作(Valsalva maneuver,VM)期间短暂增高的胸内压或者腹内压主要是通过椎静脉系统上传及通过颈内静脉(internal jugular vein,IJV)下传,所以通畅的颈内静脉对短暂增高的颅内压力的释放及脑静脉的回流非常重要。我们假设颈内静脉受压导致的静脉回流障碍是TGA发病机制中的决定性因素。方法本研究是病例对照研究,研究对象为45例TGA者及性别/年龄相匹配的45例健康对照组。利用磁共振成像(magnetic resonance imaging,MRI),包括应用造影剂的增强轴向T1加权成像(contrastenhanced axial T1-weighted imaging,Contrast T1)与时间分辨对比剂动态成像(time-resolved imaging of contrast kinetics,TRICKS)及未应用造影剂的磁共振静脉血管成像(magnetic resonance venography,MRV),评估双侧颈内静脉与左侧头臂静脉(brachiocephalic vein,BCV)的形态及横窦(transverse sinus,TS)的不对称性,其中颈内静脉被分成上、中及下段。结果相对于对照组,TGA者双侧颈内静脉上段(左侧:37.8%vs 17.8%,P=0.0393;右侧:57.8%vs 15.6%,P<0.0012)及左侧头臂静脉(60%vs 8.9%,P<0.0004)中、重度狭窄/闭塞及横窦发育不良(53.3%vs 31.1%,P=0.0405)的比例显著高。病例组静脉回流的任一部位狭窄/闭塞(包括颈内静脉或者左侧头臂静脉狭窄/闭塞)的比例显著高于对照组(91.1%vs 33.3%,P<0.0004)。MRV显示病例组左侧横窦的管径与对照组相比显著小([0.31±0.21)cm vs(0.41±0.19)cm,P=0.0290],而Contrast T1显示病例组左侧横窦的管径与对照组无显著差异,此结果与回流静脉存在近心端狭窄/闭塞相符。结论头颈静脉回流障碍是TGA的重要发病机制;双侧颈内静脉和(或)左侧头臂静脉狭窄/闭塞及横窦发育不良是导致头颈静脉回流障碍的重要因素。

Abnormal extracranial venous drainage modality has been considered an etiology of transient global amnesia（TGA）. Evidence suggests that the transmission of the intrathoracic/intraabdominal pressure during a Valsalva maneuver（VM） is mainly through the vertebral venous system, and patency of internal jugular vein（IJV） is essential for venous drainage and pressure releasing. We hypothesize that obstruction of IJV venous drainage is a contributing factor in TGA pathogenesis. A magnetic resonance imaging（MRI） protocol was used in 45 TGA patients and 45 age- and sex-matched controls to assess the morphologies of IJV, brachiocephalic vein（BCV） and asymmetry of transverse sinus（TS）. The IJV was divided into the upper- and middle-IJV segments. Compared to the controls, TGA patients had significantly higher rates of moderate and severe compression/stenosis at the bilateral upper-IJV segment（left： 37.8% vs 17.8%, P =0.0393; right： 57.8% vs 15.6%, P〈0.0012）, in left BCV（60% vs 8.9%, P〈0.0004）, and in TS hypoplasia（53.3% vs 31.1%, P =0.0405）. The prevalence of at least one site of venous compression/stenosis in IJV or BCV was significantly higher in patients than in controls（91.1% vs 33.3%, P〈0.0004）. The diameter of the left TS in MRV, but not in T1 contrast imaging, was significantly smaller in TGA patients than in controls（0.31±0.21 vs 0.41±0.19, P=0.0290）, which was compatible with downstream venous stenosis/obstruction. TGA patients have a higher prevalence of compression/stenosis of the bilateral IJV and the left BCV and TS hypoplasia, which is new evidence that supports the role of extracranial veins in TGA pathogenesis.