Detailed visual assessment of striatal dopaminergic depletion in patients with idiopathic normal pressure hydrocephalus: unremarkable or not?

Abstract

Background: Dopamine 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. Methods: In 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. Results: Striatal 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. Conclusion: Striatal 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.

Olfactory Dysfunction, an Often Neglected Symptom of Hydrocephalus: Experience from a Case of Late-Onset Idiopathic Aqueductal Stenosis

“…We initially suspected the coexistence of PD; however, most symptoms disappeared after the ETV, LIAS was finally conducted as the primary pathophysiology. Although the exact reason for slightly decreased presynaptic dopamine transporter density remains unclear in this patient, this finding is commonly observed in patients with idiopathic NPH [5].…”

Pearls & Oy-sters: Idiopathic Normal Pressure Hydrocephalus With Synucleinopathy

“…7 DAT imaging studies also indicated that the caudate nucleus was affected more than the putamen in patients with iNPH. 7,8 Regarding comorbidities, Espay et al investigated the outcome 3 years after shunt surgery, and none of the 8 patients with iNPH who had additional neurological diseases had persistent improvement, whereas 10 (43.5%) of 23 patients without concomitant neurological diseases had persistent improvement. 4 In addition, a case with iNPH comorbid with progressive parkinsonism was found to have concomitant synucleinopathy with REM sleep behavior disorder (RBD) and decreased DAT binding in the striatum 3 years after shunt surgery.…”

Update on the Cognitive Presentations of iNPH for Clinicians

“…In the shunt responsive iNPH patient neurodegenerative co-pathology seems to modify the clinical phenotype ( 17 ). Abnormal DaT imaging is proof of impaired dopaminergic function in the basal ganglia but is aetiologically non-specific and has also been described in iNPH ( 18 , 19 ). CSF tau species in PSP and CBD have yielded conflicting results ( 20 ), CSF RT-QuIC of alpha-synuclein in LBD and tau in PSP and CBD ( 21 ) may be more promising.…”