The study transcranial sonography on Parkinson' s disease and essential tremor

Abstract

Objective To determine the validity of transcranial sonography (TCS) in the differential diagnosis of Parkinson's disease (PD) and essential tremor (ET). Methods TCS was performed in 100 patients with PD, 33 patients with ET and 100 normal controls in a blind manner. The echo signal intensity of the substantia nigra was classified into grade Ⅰ-Ⅴ for semi-quantitative analysis. When the echo intensity was grade Ⅲ or more, it was deemed as abnormal and the area of the substantia nigra hyperechogenicity would be measured and its ratio to the area of the whole midbrain ( S/M ) would be calculated. Results ( 1 ) Semi-quantitative analysis: the ratio of the persons whose echo intensity of the substantia nigra was grade Ⅲ or more was greater (76. 00％ ,76/100) in PD than ET (9. 09％, 3/33) and normal controls ( 13.00％, 13/100; x2 = 130. 622, P ＜0. 01 ). However, there was no difference between ET and controls. (2) Quantitative analysis: the median and quartile range of the area of substantia nigra hyperechogenicity and S/M were greater in PD patients ( O. 54 ( 0. 57 ), 11.03 ( 9. 00 ) ) than ET ( 0. 00(0.04), 0.00(1.55),H= 42.39,42.19, both P＜0. 01, respectively) and normal controls (0.00(0. 00), 0. 00 (0. 00 ), H = 121.86,121.47, both P ＜ 0. 01, respectively), and there was no difference between ET and controls. (3) Using the area of hyperechogenicity ≥0. 20 cm2 or S/M ≥ 7％ as a cut off for predicting PD, the sensitivity, specificity and accuracy were 85.39％, 78. 38％ and 81.50％ or 86. 02％,81.31％ and 83.50％ ,respectively. But there was no significant difference for the accuracy (Z = 0. 683,P ＞ 0. 05). Conclusion TCS might find the specific hyperechogenicity of substantia nigra in PD patients,providing useful information to distinguish PD from ET. Key words: Ultrasonography, doppler, transcranial; Substantia nigra; Parkinson disease; Essential tremor