Neurology：中脑脑桥比诊断进行性核上性麻痹敏感性及特异性均较高

进行性核上性麻痹的诊断一直是临床的难点之一，来自伦敦的Luke A. Massey等医生发现之前利用MRI检查工具诊断的进行性核上性麻痹（PSP）往往缺乏病理证实，而且MRI诊断PSP也有难度。故希望能在组织学证实的PSP患者中寻找一种简便易行的方法在矢状位MRI图像上识别PSP。研究发现中脑脑桥比诊断进行性核上性麻痹敏感性及特异性均较高，结果发表在2013年5月14日的Neurology杂志上。
该研究利用诊断明确的PSP（12例）、帕金森病（2例）、多系统萎缩（7例）和对照组（8例）患者的脑磁共振正中矢状位T1图像，通过比较测量的脑桥与中脑数据来验证诊断。使用受试者工作特征曲线方法，分析临床诊断明确的PSP（21例）、帕金森病（10例）、多系统萎缩（10例）和对照组（21例）共62例患者人群的截尾值。
研究发现在PSP患者相对其他患者，中脑的平均测量值为8.1mm，明显下降(p < 0.001)；中脑脑桥比亦下降（PSP患者小于MSA患者，p < 0.001）。对照组人群中，中脑的宽度平均为脑桥的三分之二，而在PSP患者中为52%，MSA患者的中脑比脑桥超过三分之二。对PSP患者来说，中脑宽度小于9.35mm，中脑脑桥比小于0.52用来诊断PSP的特异性为100%.21例临床确诊的PSP患者组中，有19例(90.5%)中脑宽度小于9.35 mm。
该研究在病理证实的患者中发现了一种简单可信的诊断方法，用来诊断PSP的敏感性及特异性均较高，有望成为临床诊断的有利工具。 

The midbrain to pons ratio: A simple and specific MRI sign of progressive supranuclear palsy.
OBJECTIVES
MRI-based measurements used to diagnose progressive supranuclear palsy (PSP) typically lack pathologic verification and are not easy to use routinely. We aimed to develop in histologically proven disease a simple measure of the midbrain and pons on sagittal MRI to identify PSP.
METHODS
Measurements of the midbrain and pontine base on midsagittal T1-weighted MRI were performed in confirmed PSP (n = 12), Parkinson disease (n = 2), and multiple system atrophy (MSA) (n = 7), and in controls (n = 8). Using receiver operating characteristic curve analysis, cutoff values were applied to a clinically diagnosed cohort of 62 subjects that included PSP (n = 21), Parkinson disease (n = 10), MSA (n = 10), and controls (n = 21).
RESULTS
The mean midbrain measurement of 8.1 mm was reduced in PSP (p < 0.001) with reduction in the midbrain to pons ratio (PSP smaller than MSA; p < 0.001). In controls, the mean midbrain ratio was approximately two-thirds of the pontine base, in PSP it was <52%, and in MSA the ratio was greater than two-thirds. A midbrain measurement of <9.35 mm and ratio of 0.52 had 100% specificity for PSP. In the clinically defined group, 19 of 21 PSP cases (90.5%) had a midbrain measurement of <9.35 mm.
CONCLUSIONS
We have developed a simple and reliable measurement in pathologically confirmed disease based on the topography of atrophy in PSP with high sensitivity and specificity that may be a useful tool in the clinic.