Dopamine transporter imaging in clinically unclear cases of parkinsonism and the importance of Scans Without Evidence of Dopaminergic Deficit (SWEDDs)

Utiumi, Marco Antônio Takashi; Felı́cio, André Carvalho; Borges, Conrado Regis; Braatz, Vera; Rezende, Sheyla A. S.; Munhoz, Renato P.; Bressan, Rodrigo A.; Ferraz, Henrique Ballalai; Teive, Hélio Afonso Ghizoni

doi:10.1590/s0004-282x2012000900004

Cited by 23 publications

(16 citation statements)

References 26 publications

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“…However, assessments taken in combination allow a greater sensitivity for determination of nigro-striatal impairment. In previous studies, an incorrect initial diagnosis of degenerative parkinsonism seems to account for a significant proportion of SWEDDs [12,13,23] and, in those studies where a second, follow-up scan has been performed, conversion from normal to abnormal was rather uncommon (8.3% in Ref. [13] and 12.5% in Ref.…”

Section: Discussionmentioning

confidence: 92%

Scan without evidence of dopaminergic deficit: A 10-year retrospective study

Nicastro

Garibotto

Badoud

et al. 2016

Parkinsonism & Related Disorders

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Introduction: 123 I-ioflupane SPECT is a powerful method to assess nigrostriatal dopamine system integrity. Several independent studies have shown that 1e15% of patients with suspected degenerative parkinsonism, mainly PD, have scans without evidence of dopaminergic deficit (SWEDD). It has been proposed that most SWEDD patients either present with a non-degenerative condition mimicking PD, such as atypical tremor or dystonia, or demonstrate an abnormal scan when repeated later. We here hypothesized that scan interpretation methods may also play a crucial yet underestimated role in this issue. Methods: We previously established age-dependent reference values of striatal uptake by analyzing scans from a cohort of patients with non-degenerative conditions. We then studied a large population with well-established degenerative parkinsonism (N ¼ 410, 80% with PD), using identical imaging protocol, to evaluate the prevalence of patients with normal scans based on routine visual assessment. Each scan was eventually reassessed using the same automated method as for controls and a detailed 3D analysis. Results: Ten potential SWEDD cases (2.4%) were identified. However, both reassessment methods independently showed that these scans were all outside reference limits and/or visually abnormal when reexamined carefully, except for one case (0.2%) with corticobasal syndrome. Conclusion: SPECT misinterpretation emerges as an important contributor to the SWEDD population, suggesting that suspected SWEDD cases should prompt not only a serious diagnosis challenge but, equally important, a detailed scan reassessment. True SWEDD cases seem extremely rare in degenerative parkinsonism. We propose that the very concept of SWEDD is more confusing than helpful and should be definitely abandoned.

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Section: Discussionmentioning

confidence: 92%

Scan without evidence of dopaminergic deficit: A 10-year retrospective study

Nicastro

Garibotto

Badoud

et al. 2016

Parkinsonism & Related Disorders

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“…SPECT or PET using DAT radioligands are relevant methods to identify conditions associated with loss of dopaminergic nigrostriatal nerve terminals, such as PD, multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and dementia with Lewy bodies (DLB); this means that DAT imaging can distinguish patients with and without impairment of the nigrostriatal dopaminergic system. Therefore, in cases of parkinsonism and tremor disorders, normal striatal DAT density highlights the possibility of conditions, such as essential tremor (ET), psychogenic, vascular and drug-induced parkinsonism, as well as dystonic tremor [1,3,13]. To differentiate PD from ET, the sensitivity of SPECT using DAT tracers has been reported to be around 90% [14,15].…”

Section: Discussionmentioning

confidence: 99%

Dopamine Transporter Imaging Using 99mTc-TRODAT-1 SPECT in Parkinson’s Disease

Ferraz

2014

Med Sci Monit

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BackgroundAlthough the decrease in striatal dopamine transporter (DAT) density has been described in North American, European, and Asian Parkinson’s disease (PD) patients, studies on this issue are required in the rest of the world. This study examined the diagnostic utility of DAT imaging in Brazilian PD patients.Material/MethodsTwenty PD patients (13 males, 7 females, median age: 62 years, median age at disease onset: 56 years, median disease duration: 5 years, and median UPDRS-III score: 29) and 9 age- and sex-matched healthy subjects underwent single-photon emission computerized tomography (SPECT) using 99mTc-TRODAT-1.ResultsPD patients showed a significant decrease in the striatum, caudate nucleus, and putamen DAT densities compared with data from healthy subjects. Striatal 99mTc-TRODAT-1 bindings had the highest diagnostic accuracy compared to those estimates from caudate nucleus and putamen. For the diagnosis of PD, a striatal 99mTc-TRODAT-1 binding cut-off value of 0.90 was associated with a sensitivity of 100% and a specificity of 89%. There was no significant difference between striatal 99mTc-TRODAT-1 binding values provided by different readers, contrary to 99mTc-TRODAT-1 binding estimates in the caudate nucleus.ConclusionsStriatal DAT imaging using 99mTc-TRODAT-1 can be considered a marker for differentiating PD patients from healthy individuals, with a good interobserver reproducibility.

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“…Furthermore, re-emergent tremor and highest amplitude of resting tremor were more frequent in PD than in SWEDD. In some cases the PD diagnosis has been revised and attributed to dystonic tremor, vascular parkinsonism, anxiety disorder, depression, or musculoskeletal diseases [7,[25][26][27].…”

Section: Discussionmentioning

confidence: 99%

Screening for dopa-responsive dystonia in patients with scans without evidence of dopaminergic deficiency (SWEDD)

Rosa

Carducci

et al. 2014

J Neurol

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The clinical diagnosis of Parkinson's Disease (PD) is not supported by Single Photon Emission Computed Tomography (SPECT) using dopamine transporter radioligand in 4-15 % of patients. It has been hypothesized that this phenomenon, named "Scans Without Evidence of Dopaminergic Deficiency" (SWEDD), may be an adult-onset dystonia. We investigated the hypothesis that these patients might be affected by Dopa-Responsive Dystonia (DRD). We enrolled eleven unrelated patients (8 F and 3 M) with clinical parkinsonism and normal [(123)I]FP-CIT SPECT. The GTP-cyclohydrolase1 (GCH1) gene was sequenced in all patients; urine biopterin and neopterin analysis was carried out in nine and oral phenylalanine (Phe) loading in seven. Neurological examination showed bradykinesia and resting/postural tremor in all patients, and rigidity in ten, suggesting a clinical diagnosis of PD. We detected mild dystonic signs in eight cases. In particular, five of them presented cranial dyskinesias. No mutation of the GCH1 gene was found. The results of the urine biopterin and neopterin analysis and the oral Phe loading did not reveal biochemical abnormalities suggestive of reduced GCH1 activity. We confirm that some clinical features, namely the presence of focal or segmental dystonia, suggest an adult-onset dystonia in SWEDD cases. However, we exclude DRD caused by GCH1 gene mutations in the present series.

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Dopamine transporter imaging in clinically unclear cases of parkinsonism and the importance of Scans Without Evidence of Dopaminergic Deficit (SWEDDs)

Cited by 23 publications

References 26 publications

Scan without evidence of dopaminergic deficit: A 10-year retrospective study

Scan without evidence of dopaminergic deficit: A 10-year retrospective study

Dopamine Transporter Imaging Using 99mTc-TRODAT-1 SPECT in Parkinson’s Disease

Screening for dopa-responsive dystonia in patients with scans without evidence of dopaminergic deficiency (SWEDD)

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