Abstract
BackgroundDopamine transporter (DAT) imaging may enable clinicians to discriminate idiopathic normal pressure hydrocephalus (iNPH) from other parkinsonian disorders. However, a specific pattern of dopaminergic loss in DAT imaging of iNPH patients remains to be further elucidated.MethodsIn this preliminary study, 11 patients with iNPH in our hospital between March 2017 and February 2019 were finally enrolled. A diagnosis of iNPH was made according to the two established criteria. For visual analysis of DAT imaging, a striatum was divided into five domains. A semi-quantitative visual assessment was performed with a consensus between a nuclear medicine specialist and an experienced neurologist who were blinded to the clinical diagnosis.ResultsStriatal dopaminergic deficits were abnormal in 90.9% (10/11) of patients with iNPH. The degree of dopaminergic reduction was mild and heterogeneous. However, a tendency of preferential striatal DAT loss in the caudate nucleus (90.9%, 10/11) than in the putamen (72.7%, 8/11) was observed, whereas ventral portion (9.1%, 1/11) was relatively preserved.ConclusionStriatal dopaminergic depletion might be mild and heterogeneous in patients with iNPH. These dopaminergic deficits were more common in the caudate nucleus than in the putamen, suggesting a pattern different from other degenerative parkinsonian disorders.
Highlights
Dopamine transporter (DAT) imaging may enable clinicians to discriminate idiopathic normal pressure hydrocephalus from other parkinsonian disorders
Ouchi et al [4] reported that presynaptic dopaminergic depletion was not observed in patients with idiopathic normal pressure hydrocephalus (iNPH), not every iNPH patients showed normal DAT imaging in recent studies
All of the followings were required for the diagnosis of iNPH: gait disturbance plus at least one of the other symptoms including cognitive impairment, urinary incontinence, or both; ventricular enlargement (Evans’ index > 0.3); narrowing of the sulci and subarachnoid spaces over the high convexity/midline surface on brain magnetic resonance imaging (MRI); cerebrospinal fluid opening pressure lower than 200 mmH2O measured with a lumbar puncture or a comparable procedure; and the absence of severe medical illness or preceding diseases that could cause secondary NPH
Summary
Dopamine transporter (DAT) imaging may enable clinicians to discriminate idiopathic normal pressure hydrocephalus (iNPH) from other parkinsonian disorders. Various degrees of parkinsonism and the cardinal symptom triad of gait disturbance, cognitive decline, and urinary incontinence are commonly observed in patients with idiopathic normal pressure hydrocephalus (iNPH). These symptoms of iNPH can be relieved by surgical interventions. According to a previous study, PD and Parkinson-plus syndrome showed different subregional patterns of striatal DAT loss in 18F-N-(3-fluoropropyl)-2β-carboxymethoxy-3β(4-iodophenyl) nortropane (FP-CIT) positron emission tomography (PET) images. Ouchi et al [4] reported that presynaptic dopaminergic depletion was not observed in patients with iNPH, not every iNPH patients showed normal DAT imaging in recent studies. A specific pattern of dopaminergic loss in DAT imaging of iNPH patients has not been reported yet
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