Striatal D2 Receptor Availability After Shunting in Idiopathic Normal Pressure Hydrocephalus

Journal of Nuclear Medicine

Yasuomi Ouchi¹  Tatsuo Torizuka¹  Keisei Tanaka¹  Etsuji Yoshikawa¹  Genichi Sugihara¹  Teiji Nakayama¹ 

关键词: idiopathic normal pressure hydrocephalus;    D₂ receptor;    raclopride;    ventriculoperitoneal shunting;    PET;   

DOI  :  10.2967/jnumed.107.045310

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Gait disturbance in idiopathic normal pressure hydrocephalus (iNPH) is reminiscent of parkinsonism. Our recent PET study showed reduction in postsynaptic D2 receptor binding concomitant with a normality of presynaptic dopamine transporter binding. Here, we investigated the plasticity of D2 receptor in treating iNPH patients with ventriculoperitoneal (VP) shunting using PET with 11C-raclopride and discuss the contribution of D2 receptor to the pathophysiology of iNPH. Methods: Eight iNPH patients participated in this study. After evaluation of their neuropsychologic abilities, all patients underwent 3-dimensional MRI and quantitative PET measurements twice before and 1 mo after VP shunting. MRI-based morphometric analyses were performed to examine postoperative variations of the ventricles. Estimation of binding potential (BP) for 11C-raclopride was based on Logan plot analysis. Region-of-interest analysis was used to examine changes in 11C-raclopride BP in the striatum. A 2-tailed paired t test was used for evaluating changes in PET and MRI parameters between conditions, and correlation analysis was used to investigate clinicopathophysiologic relevance (clinical vs. in vivo findings). Results: Clinical evaluation revealed significant recovery in a 5-m back-and-forth navigation test and an affect test and a mild increase in Mini-Mental State Examination scores after VP shunting. Significant postoperative increases in 11C-raclopride BP were found in the nucleus accumbens and dorsal putamen, and the increases were significantly associated with emotional (Spearman rank r = 0.66, P < 0.05) and navigational improvement (r = 0.72, P < 0.05), respectively. The 11C-raclopride BP increase in the striaum as a whole correlated significantly with improvement in general cognitive ability. There was a mild ventricular shrinkage after surgery, albeit there was no correlation of its size with clinical and PET parameters. Conclusion: Striatal upregulation of D2 receptor after VP shunting is associated with amelioration of hypokinetic gait disturbance and anhedonic mentation in iNPH patients, indicating that the effect of VP shunting may reside in noninhibition of functionally suppressed D2 receptor in the striatum. D2 receptor responsiveness may indicate a mechanism for iNPH pathophysiology.

【 授权许可】

Unknown