Acute Levodopa Challenge in Atypical Parkinsonism: Comprehensive Analysis of Individual Motor Responses

The acute levodopa challenge is widely used to distinguish Parkinson's disease (PD) from atypical parkinsonian syndromes (APSs) such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). In APSs, very few patients present a clinically relevant response to levodopa. The aim of this study was to determine whether patients with atypical parkinsonism benefit from levodopa in any aspect of their multiple motor deficits despite the generally poor response. This retrospective study analyzed individual motor responses to the acute levodopa challenge using the MDS-UPDRS III in 47 PSP, 26 MSA, and 71 PD patients at Hannover Medical School. Despite the generally poor levodopa response in both PSP and MSA patients, bradykinesia and rigidity were the symptoms most notably affected by levodopa in PSP patients, while MSA patients experienced significant improvements in bradykinesia and action tremor. These findings underscore the variability in levodopa response among PSP and MSA patients and highlight the need for personalized treatment approaches in atypical parkinsonism.

Revised criteria for diagnosis and staging of Alzheimer's disease: Alzheimer's Association Workgroup

The National Institute on Aging and the Alzheimer's Association convened three separate work groups in 2011 and single work groups in 2012 and 2018 to create recommendations for the diagnosis and characterization of Alzheimer's disease (AD). The present document updates the 2018 research framework in response to several recent developments. Defining diseases biologically, rather than based on syndromic presentation, has long been standard in many areas of medicine (e.g., oncology), and is becoming a unifying concept common to all neurodegenerative diseases, not just AD. The present document is consistent with this principle. Our intent is to present objective criteria for diagnosis and staging AD, incorporating recent advances in biomarkers, to serve as a bridge between research and clinical care. These criteria are not intended to provide step-by-step clinical practice guidelines for clinical workflow or specific treatment protocols, but rather serve as general principles to inform diagnosis and staging of AD that reflect current science. HIGHLIGHTS: We define Alzheimer's disease (AD) to be a biological process that begins with the appearance of AD neuropathologic change (ADNPC) while people are asymptomatic. Progression of the neuropathologic burden leads to the later appearance and progression of clinical symptoms. Early-changing Core 1 biomarkers (amyloid positron emission tomography [PET], approved cerebrospinal fluid biomarkers, and accurate plasma biomarkers [especially phosphorylated tau 217]) map onto either the amyloid beta or AD tauopathy pathway; however, these reflect the presence of ADNPC more generally (i.e., both neuritic plaques and tangles). An abnormal Core 1 biomarker result is sufficient to establish a diagnosis of AD and to inform clinical decision making throughout the disease continuum. Later-changing Core 2 biomarkers (biofluid and tau PET) can provide prognostic information, and when abnormal, will increase confidence that AD is contributing to symptoms. An integrated biological and clinical staging scheme is described that accommodates the fact that common copathologies, cognitive reserve, and resistance may modify relationships between clinical and biological AD stages.

Neuropathologic Validation and Diagnostic Accuracy of Presynaptic Dopaminergic Imaging in the Diagnosis of Parkinsonism

BACKGROUND AND OBJECTIVES

Degeneration of the presynaptic nigrostriatal dopaminergic system is one of the main biological features of Parkinson disease (PD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), which can be measured using single-photon emission CT imaging for diagnostic purposes. Despite its widespread use in clinical practice and research, the diagnostic properties of presynaptic nigrostriatal dopaminergic (DAT) imaging in parkinsonism have never been evaluated against the diagnostic gold standard of neuropathology. The aim of this study was to evaluate the diagnostic parameters of DAT imaging compared with pathologic diagnosis in patients with parkinsonism.

METHODS

Retrospective cohort study of patients with DAT imaging for the investigation of a clinically uncertain parkinsonism with brain donation between 2010 and 2021 to the Queen Square Brain Bank (London). Patients with DAT imaging for investigation of pure ataxia or dementia syndromes without parkinsonism were excluded. Those with a pathologic diagnosis of PD, MSA, PSP, or CBD were considered presynaptic dopaminergic parkinsonism, and other pathologies were considered postsynaptic for the analysis. DAT imaging was performed in routine clinical practice and visually classified by hospital nuclear medicine specialists as normal or abnormal. The results were correlated with neuropathologic diagnosis to calculate diagnostic accuracy parameters for the diagnosis of presynaptic dopaminergic parkinsonism.

RESULTS

All of 47 patients with PD, 41 of 42 with MSA, 68 of 73 with PSP, and 6 of 10 with CBD (sensitivity 100%, 97.6%, 93.2%, and 60%, respectively) had abnormal presynaptic dopaminergic imaging. Eight of 17 patients with presumed postsynaptic parkinsonism had abnormal scans (specificity 52.9%).

DISCUSSION

DAT imaging has very high sensitivity and negative predictive value for the diagnosis of presynaptic dopaminergic parkinsonism, particularly for PD. However, patients with CBD, and to a lesser extent PSP (of various phenotypes) and MSA (with predominant ataxia), can show normal DAT imaging. A range of other neurodegenerative disorders may have abnormal DAT scans with low specificity in the differential diagnosis of parkinsonism. DAT imaging is a useful diagnostic tool in the differential diagnosis of parkinsonism, although clinicians should be aware of its diagnostic properties and limitations.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that DAT imaging does not accurately distinguish between presynaptic dopaminergic parkinsonism and non-presynaptic dopaminergic parkinsonism.

Neuroimaging Techniques in Differentiating Parkinson's Disease from Drug-Induced Parkinsonism: A Comprehensive Review

Neuroimaging can provide significant benefits in evaluating patients with movement disorders associated with drugs. This literature review describes neuroimaging techniques performed to distinguish Parkinson's disease from drug-induced parkinsonism. The dopaminergic radiotracers already reported to assess patients with drug-induced parkinsonism are [123I]-FP-CIT, [123I]-β-CIT, [99mTc]-TRODAT-1, [18F]-DOPA, [18F]-AV-133, and [18F]-FP-CIT. The most studied one and the one with the highest number of publications is [123I]-FP-CIT. Fludeoxyglucose (18F) revealed a specific pattern that could predict individuals susceptible to developing drug-induced parkinsonism. Another scintigraphy method is [123I]-MIBG cardiac imaging, in which a relationship between abnormal cardiac imaging and normal dopamine transporter imaging was associated with a progression to degenerative disease in individuals with drug-induced parkinsonism. Structural brain magnetic resonance imaging can be used to assess the striatal region. A transcranial ultrasound is a non-invasive method with significant benefits regarding costs and availability. Optic coherence tomography only showed abnormalities in the late phase of Parkinson's disease, so no benefit in distinguishing early-phase Parkinson's disease and drug-induced parkinsonism was found. Most methods demonstrated a high specificity in differentiating degenerative from non-degenerative conditions, but the sensitivity widely varied in the studies. An algorithm was designed based on clinical manifestations, neuroimaging, and drug dose adjustment to assist in the management of patients with drug-induced parkinsonism.

Drug-Induced Movement Disorders

Drug-induced movement disorders (DIMDs) are most commonly associated with typical and atypical antipsychotics. However, other drugs such as antidepressants, antihistamines, antiepileptics, antiarrhythmics, and gastrointestinal drugs can also cause abnormal involuntary movements. Different types of movement disorders can also occur because of adverse drug reactions. Therefore, the important key to diagnosing DIMDs is a causal relationship between potential offending drugs and the occurrence of abnormal movements. The pathophysiology of DIMDs is not clearly understood; however, many cases of DIMDs are thought to exert adverse mechanisms of action in the basal ganglia. The treatment of some DIMDs is quite challenging, and removing the offending drugs may not be possible in some conditions such as withdrawing antipsychotics in the patient with partially or uncontrollable neuropsychiatric conditions. Future research is needed to understand the mechanism of DIMDs and the development of drugs with better side-effect profiles. This article reviews the phenomenology, diagnostic criteria, pathophysiology, and management of DIMDs.

Multimodality imaging of neurodegenerative disorders with a focus on multiparametric magnetic resonance and molecular imaging

Neurodegenerative diseases afflict a large number of persons worldwide, with the prevalence and incidence of dementia rapidly increasing. Despite their prevalence, clinical diagnosis of dementia syndromes remains imperfect with limited specificity. Conventional structural-based imaging techniques also lack the accuracy necessary for confident diagnosis. Multiparametric magnetic resonance imaging and molecular imaging provide the promise of improving specificity and sensitivity in the diagnosis of neurodegenerative disease as well as therapeutic monitoring of monoclonal antibody therapy. This educational review will briefly focus on the epidemiology, clinical presentation, and pathologic findings of common and uncommon neurodegenerative diseases. Imaging features of each disease spanning from conventional magnetic resonance sequences to advanced multiparametric methods such as resting-state functional magnetic resonance imaging and arterial spin labeling imaging will be described in detail. Additionally, the review will explore the findings of each diagnosis on molecular imaging including single-photon emission computed tomography and positron emission tomography with a variety of clinically used and experimental radiotracers. The literature and clinical cases provided demonstrate the power of advanced magnetic resonance imaging and molecular techniques in the diagnosis of neurodegenerative diseases and areas of future and ongoing research. With the advent of combined positron emission tomography/magnetic resonance imaging scanners, hybrid protocols utilizing both techniques are an attractive option for improving the evaluation of neurodegenerative diseases.

Shining Damaged Hearts: Immunotherapy-Related Cardiotoxicity in the Spotlight of Nuclear Cardiology

The emerging use of immunotherapies in cancer treatment increases the risk of immunotherapy-related cardiotoxicity. In contrast to conventional chemotherapy, these novel therapies have expanded the forms and presentations of cardiovascular damage to a broad spectrum from asymptomatic changes to fulminant short- and long-term complications in terms of cardiomyopathy, arrythmia, and vascular disease. In cancer patients and, particularly, cancer patients undergoing (immune-)therapy, cardio-oncological monitoring is a complex interplay between pretherapeutic risk assessment, identification of impending cardiotoxicity, and post-therapeutic surveillance. For these purposes, the cardio-oncologist can revert to a broad spectrum of nuclear cardiological diagnostic workup. The most promising commonly used nuclear medicine imaging techniques in relation to immunotherapy will be discussed in this review article with a special focus on the continuous development of highly specific molecular markers and steadily improving methods of image generation. The review closes with an outlook on possible new developments of molecular imaging and advanced image evaluation techniques in this exciting and increasingly growing field of immunotherapy-related cardiotoxicity.

The role of neuroimaging in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder that affects millions of people worldwide. Two hallmarks of PD are the accumulation of alpha-synuclein and the loss of dopaminergic neurons in the brain. There is no cure for PD, and all existing treatments focus on alleviating the symptoms. PD diagnosis is also based on the symptoms, such as abnormalities of movement, mood, and cognition observed in the patients. Molecular imaging methods such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) can detect objective alterations in the neurochemical machinery of the brain and help diagnose and study neurodegenerative diseases. This review addresses the application of functional MRI, PET, and SPECT in PD patients. We provide an overview of the imaging targets, discuss the rationale behind target selection, the agents (tracers) with which the imaging can be performed, and the main findings regarding each target's state in PD. Molecular imaging has proven itself effective in supporting clinical diagnosis of PD and has helped reveal that PD is a heterogeneous disorder, which has important implications for the development of future therapies. However, the application of molecular imaging for early diagnosis of PD or for differentiation between PD and atypical parkinsonisms has remained challenging. The final section of the review is dedicated to new imaging targets with which one can detect the PD-related pathological changes upstream from dopaminergic degeneration. The foremost of those targets is alpha-synuclein. We discuss the progress of tracer development achieved so far and challenges on the path toward alpha-synuclein imaging in humans.

[Progressive supranuclear palsy]

Progressive supranuclear palsy (PSP) is a heterogeneous progressive neurodegenerative disease characterized by onset after 50 years old, Parkinson's syndrome, early development of postural instability, absence or transient reaction to levodopa drugs, neuropsychological disorders, dysphagia and dysarthria and eye movement disorders. The review provides an analysis of modern data on etiology, clinical presentation, differential diagnosis of the disease. The morphological picture and neuroimaging features, as well as modern ideas about treatment, are described. A great clinical polymorphism of the disease, as well as its similarity to other neurodegenerative diseases, manifested by Parkinson's syndrome, complicates the diagnosis of PSP. Establishing an accurate diagnosis makes it possible to determine the prognosis and further tactics of patient management.

Recognition and Management of Antipsychotic-Induced Parkinsonism in Older Adults: A Narrative Review

Background: Parkinsonism is a common side-effect of antipsychotic drugs especially in older adults, who also present with a higher frequency of neurodegenerative disorders like Idiopathic Parkinson’s disease (IPD). Distinguishing between antipsychotic-induced parkinsonism (AIP) and IPD is challenging due to clinical similarities. Up to 20% of older adults may suffer from persisting parkinsonism months after discontinuation of antipsychotics, suggesting underlying neurodegeneration. A review of the literature on AIP in older adults is presented, focusing on epidemiology, clinical aspects, and management. Methods: A literature search was undertaken on EMBASE, MEDLINE and PsycINFO, for articles on parkinsonism induced by antipsychotic drugs or other dopamine 2 receptor antagonists in subjects aged 65 or older. Results: AIP in older adults is the second most common cause of parkinsonism after IPD. Older age, female gender, exposure to high-potency first generation antipsychotics, and antipsychotic dosage are the main risk factors. The clinical presentation of AIP resembles that of IPD, but is more symmetrical, affects upper limbs more, and tends to have associated motor phenomena such as orofacial dyskinesias and akathisia. Presence of olfactory dysfunction in AIP suggests neurodegeneration. Imaging of striatal dopamine transporters is widely used in IPD diagnosis and could help to distinguish it from AIP. There is little evidence base for recommending pharmacological interventions for AIP, the best options being dose-reduction/withdrawal, or switching to a second-generation drug. Conclusions: AIP is a common occurrence in older adults and it is possible to differentiate it from IPD. Further research is needed into its pathophysiology and on its treatment.

Molecular Imaging of Extrapyramidal Movement Disorders With Dementia: The 4R Tauopathies

Two pathologically distinct neurodegenerative conditions, progressive supranuclear palsy and corticobasal degeneration, share in common deposits of tau proteins that differ both molecularly and ultrastructurally from the common tau deposits diagnostic of Alzheimer disease. The proteinopathy in these disorders is characterized by fibrillary aggregates of 4R tau proteins. The clinical presentations of progressive supranuclear palsy and of corticobasal degeneration are often confused with more common disorders such as Parkinson disease or subtypes of frontotemporal lobar degeneration. Neither of these 4R tau disorders has effective therapy, and while there are emerging molecular imaging approaches to identify patients earlier in the course of disease, there are as yet no reliably sensitive and specific approaches to diagnoses in life. In this review, aspects of the clinical syndromes, neuropathology, and molecular biomarker imaging studies applicable to progressive supranuclear palsy and to corticobasal degeneration will be presented. Future development of more accurate molecular imaging approaches is proposed.

Neuroimaging Biomarkers of Chronic Traumatic Encephalopathy: Targets for the Academic Memory Disorders Clinic

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts, such as those from contact sports. The pathognomonic lesion for CTE is the perivascular accumulation of hyper-phosphorylated tau in neurons and other cell process at the depths of sulci. CTE cannot be diagnosed during life at this time, limiting research on risk factors, mechanisms, epidemiology, and treatment. There is an urgent need for in vivo biomarkers that can accurately detect CTE and differentiate it from other neurological disorders. Neuroimaging is an integral component of the clinical evaluation of neurodegenerative diseases and will likely aid in diagnosing CTE during life. In this qualitative review, we present the current evidence on neuroimaging biomarkers for CTE with a focus on molecular, structural, and functional modalities routinely used as part of a dementia evaluation. Supporting imaging-pathological correlation studies are also presented. We targeted neuroimaging studies of living participants at high risk for CTE (e.g., aging former elite American football players, fighters). We conclude that an optimal tau PET radiotracer with high affinity for the 3R/4R neurofibrillary tangles in CTE has not yet been identified. Amyloid PET scans have tended to be negative. Converging structural and functional imaging evidence together with neuropathological evidence show frontotemporal and medial temporal lobe neurodegeneration, and increased likelihood for a cavum septum pellucidum. The literature offers promising neuroimaging biomarker targets of CTE, but it is limited by cross-sectional studies of small samples where the presence of underlying CTE is unknown. Imaging-pathological correlation studies will be important for the development and validation of neuroimaging biomarkers of CTE.

Nuclear Imaging in the Diagnosis of Clinically Uncertain Parkinsonian Syndromes

BACKGROUND

Parkinsonian syndromes are classified by etiology mainly on clinical grounds, that is, on the basis of the clinical manifestations and with the aid of conventional ancillary studies. In most cases, the clinical diagnosis is clear. In up to 30% of cases, however, the etiological classification remains uncertain after completion of the basic clinical diagnostic evaluation, and additional investigation with nuclear imaging may be indicated. In particular, cerebral single-photon emission computed tomography (SPECT) with dopamine transporter (DAT) ligands may be helpful. DAT-SPECT can be used to demonstrate or rule out nigrostriatal degeneration and thereby differentiate neurodegenerative parkinsonian syndromes from symptomatic parkinsonian syndromes and other differential diagnoses. Positron emission tomography (PET) with the glucose analogue [18F]fluorodeoxyglucose (FDG) can be used to identify disease-specific patterns of neuronal dysfunction/degeneration in order to differentiate the various neurodegenerative parkinsonian syndromes from one another.

METHODS

In this review, we summarize the current state of the evidence on DAT-SPECT and FDG-PET for the indications mentioned above on the basis of a selective review of the literature.

RESULTS

DAT-SPECT has been adequately validated as an in vivo marker for nigrostriatal degeneration. Studies using the clinical diagnosis of a movement disorders specialist over the course of the disease as a reference have shown that DAT- SPECT is 78-100% sensitive (median, 93%) and 70-100% specific (median, 89%) for the differentiation of neurodegenerative parkinsonian syndromes from symptomatic parkinsonism and other differential diagnoses in clinically unclear cases. DAT- SPECT scanning led to a change of diagnosis in 27-56% of patients (median, 43%) and to a change of treatment in 33-72% (median, 43%). FDG-PET enables the differentiation of atypical neurodegenerative parkinsonian syndromes from the idiopathic parkinsonian syndrome (i.e., Parkinson's disease proper) with high sensitivity and specificity (both approximately 90%), when the clinical diagnosis by a movement disorders specialist over the course of the disease is used as a reference.

CONCLUSION

DAT-SPECT has been well documented to be highly diagnostically accurate and to have a relevant influence on the diagnosis and treatment of patients with clinically uncertain parkinsonian or tremor syndrome. It has not yet been shown to improve patient-relevant endpoints such as mortality, morbidity, and health-related quality of life; proof of this will probably have to await the introduction of neuroprotective treatments. The current evidence for the high differential diagnostic accuracy of FDG-PET in neurodegenerative parkinsonian syndromes needs to be reinforced by prospective studies with neuropathological verification of the diagnosis.

Confirmation of 123I-FP-CIT SPECT Quantification Methods in Dementia with Lewy Bodies and Other Neurodegenerative Disorders

Our rationale was to conduct a retrospective study comparing 3 ¹²³I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane (¹²³I-FP-CIT) SPECT quantitative methods in patients with neurodegenerative syndromes as referenced to neuropathologic findings. Methods: ¹²³I-FP-CIT-SPECT and neuropathologic findings among patients with neurodegenerative syndromes from the Mayo Alzheimer Disease Research Center and Mayo Clinic Study of Aging were examined. Three ¹²³I-FP-CIT SPECT quantitative assessment methods-MIMneuro, DaTQUANT, and manual region-of-interest creation on a workstation-were compared with neuropathologic findings describing the presence or absence of Lewy body disease (LBD). Striatum-to-background ratios (SBRs) generated by DaTQUANT were compared with the calculated SBRs of the manual method and MIMneuro. The left and right SBRs for caudate, putamen, and striatum were evaluated with the manual method. For DaTQUANT and MIMneuro, the left, right, total, and average SBRs and z scores for whole striatum, caudate, putamen, anterior putamen, and posterior putamen were calculated. Results: The cohort included 24 patients (20 [83%] male, mean age for all patients at death, 75.4 ± 10.0 y). The antemortem clinical diagnoses were Alzheimer disease dementia (n = 6), probable dementia with Lewy bodies (n = 12), mixed Alzheimer disease dementia and probable dementia with Lewy bodies (n = 1), Parkinson disease with mild cognitive impairment (n = 2), corticobasal syndrome (n = 1), idiopathic rapid-eye-movement sleep behavior disorder (n = 1), and behavioral-variant frontotemporal dementia (n = 1). Seventeen (71%) had LBD. All 3 ¹²³I-FP-CIT SPECT quantitative methods had an area under the receiver-operating-characteristics curve ranging from more than 0.93 to up to 1.000 (P < 0.001) and showed excellent discrimination between LBD and non-LBD patients in each region assessed (P < 0.001). There was no significant difference between the accuracy of the regions in discriminating the 2 groups, with good discrimination for both caudate and putamen. Conclusion: All 3 ¹²³I-FP-CIT SPECT quantitative methods showed excellent discrimination between LBD and non-LBD patients in each region assessed, using both SBRs and z scores.

What a neurologist should know about PET and SPECT functional imaging for parkinsonism: A practical perspective

The diagnosis of a parkinsonian syndrome based on clinical criteria remains sometimes difficult, especially at disease onset. Brain or heart molecular imaging techniques (SPECT or PET) can provide a major help to improve and speed up diagnosis, influencing treatment strategies. Presynaptic dopaminergic imaging using either [¹⁸F]-Dopa PET or ¹²³I -2β-Carbomethoxy-3β-(4-Iodophenyl)- N-(3-Fluoropropyl) Nortropane ([¹²³I]-Ioflupane)SPECT demonstrates or rules out the presence of a dopaminergic degenerative process. This allows to distinguish Parkinson's disease, Parkinson "plus" syndromes and dementia with Lewy bodies (reduced radiotracers binding) from essential tremor, psychogenic, post-neuroleptic or vascular parkinsonisms, dopa-responsive dystonia and Alzheimer's disease (normal radiotracers binding). For differential diagnosis between Parkinson's disease and Parkinson "plus" syndromes, brain molecular imaging with [¹⁸F]-Fluorodeoxyglucose ([¹⁸F]-FDG) PET or ^99mTc-HMPAO SPECT can provide useful information, whereas [¹⁸F]-Dopa PET or [¹²³I]-Ioflupane does not separate these entities. Finally, sympathetic cardiac [¹²³I]-Metaiodobenzylguanidine ([¹²³I]-MIBG) scintigraphy or SPECT can help distinguishing Parkinson's disease and dementia with Lew bodies (decreased binding) from multiple system atrophy and progressive supranuclear palsy (normal binding). New radiotracers notably those targeting the pathological process itself such as Tau aggregates are under development and may provide interesting informations to delineate the different Parkinson "plus" syndromes.

Sensitivity and specificity of cardiac metaiodobenzylguanidine scintigraphy in the early diagnosis of Parkinson's disease

PURPOSE

Metaiodobenylguanidine (MIBG) scintigraphy has been shown to enhance the probability of correct diagnosis in patients with parkinsonian syndromes (PS). Thus far, studies of the clinical usefulness of MIBG have been confined to cross-sectional assessments, which are inevitably associated with diagnostic uncertainty during the early stages of these syndromes. In this study, the initial clinical diagnosis was reevaluated longitudinally to assess the sensitivity and specificity of clinical and MIBG parameters in the early diagnosis of PS.

METHODS

167 patients with PS (age 67.03 ± 8.92 years (mean ± standard deviation), duration of symptoms 2.48 ± 5.27 years, median Hoehn and Yahr score 2) underwent an initial clinical assessment and MIBG scintigraphy. Eighty seven of those patients (56 with Parkinson's disease (PD), 1 with multiple system atrophy (MSA), 23 with atypical PS, 7 with tremor syndrome) were clinically reevaluated a mean of 3 years later in order to verify their initial diagnosis.

RESULTS

The use of a lower limit of normal value of 1.74 for the heart-to-mediastinum ratio (HMR) achieved the best discrimination between PD and other PS. The sensitivity of MIBG scintigraphy to PD was 94%; it also had a specificity of 65%, a positive predictive value of 88%, and a negative predictive value of 79%. MIBG scintigraphy was better than initial clinical diagnosis alone (sensitivity 83%, specificity 39%) or levodopa responsiveness (sensitivity 92%, specificity 10%). However, a combination of clinical diagnosis and MIBG scintigraphy was found to be especially clinically useful (specificity 95%, sensitivity 83%, positive predictive value 95%, negative predictive value 83%).

CONCLUSION

MIBG scintigraphy was demonstrated to be a reliable tool for the diagnosis of early PD. The best diagnostic accuracy was achieved by combining a clinical examination with MIBG scintigraphy.

Cerebrospinal fluid biomarkers for the diagnosis and prognosis of Parkinson's disease: protocol for a systematic review and individual participant data meta-analysis

INTRODUCTION

Idiopathic Parkinson's disease (PD) is a progressive neurodegenerative disorder related to α-synuclein misfolding and aggregation. For this reason, it belongs to the family of 'synucleinopathies', which also includes some other neurological diseases. Although imaging and ancillary investigations may be helpful in the diagnostic workup, the diagnosis of PD mostly relies on the clinician's expertise. Furthermore, there is a need today for markers that can track the disease progression in PD that might improve the evaluation of novel disease-modifying therapies. The cerebrospinal fluid (CSF) has been widely investigated with the purpose of finding useful diagnostic and prognostic biomarkers for PD.

METHODS AND ANALYSIS

This systematic review protocol has been developed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses Protocol 2015 statement and was registered on the PROSPERO international prospective register of systematic reviews. An international collaboration will be established. We will search the Cochrane Library, Web of Science, Medline and Embase from inception, using appropriate search strategies. Individual participant data from all included studies will be merged into a single database. We will include any study assessing the diagnostic and prognostic role of CSF biomarkers in PD. To evaluate the risk of bias and applicability of primary diagnostic accuracy studies, we will use Quality Assessment of Diagnostic Accuracy Studies-2 and Quality in Prognostic Studies. We will use standard meta-analytic procedures. We will first explore the utility of each CSF biomarker in turn. For each biomarker, we will assess its diagnostic and prognostic utility by means of receiver operating characteristic analysis and regression models. We will then move towards a multivariate approach considering different panels of biomarkers.

ETHICS AND DISSEMINATION

Our study will not include confidential data, and no intervention will be involved, so ethical approval is not required. The results of the study will be reported in international peer-reviewed journals.

Establishing On-Site Reference Values for (123)I-FP-CIT SPECT (DaTSCAN®) Using a Cohort of Individuals with Non-Degenerative Conditions

PURPOSE

To overcome the issue of reference values for DaTSCAN® requiring healthy controls, we propose an original approach using scans from individuals with non-degenerative conditions performed at one single center following the same acquisition protocol.

PROCEDURES

From a cohort of 970 consecutive patients, we identified 182 patients with a clinical diagnosis of non-degenerative parkinsonism or tremor and a visually normal DATSCAN®. Caudate nucleus (C), putamen (P), and striatum (S) uptake values, C/P ratios, and asymmetry indexes (AI) were calculated using semi-quantitative methods. Outcomes were assessed according to age and gender, and reference limits were established using the percentile approach.

RESULTS

A significant negative linear effect of age was found upon striatal nuclei uptake of 0.21-0.22 per decade (6.8%/decade for striatum), whereas a potential gender influence proved unclear. Inferior reference limits were established at the 5th percentile. C/P ratios and AIs were not influenced by age or gender, and superior reference limits were set at the 95th percentile.

CONCLUSIONS

We here propose a convenient approach to calculate site-specific reference limits for DaTSCAN® outcomes not requiring scanning healthy controls. The method appears to yield robust values that range within nearly identical limits as those obtained in healthy subjects.

Persistent Drug-Induced Parkinsonism in Patients with Normal Dopamine Transporter Imaging

Functional neuroimaging for the dopamine transporter (DAT) is used to distinguish drug-induced parkinsonism (DIP) from subclinical Parkinson’s disease (PD). Although DIP patients who show a normal DAT image are expected to recover completely, some do not. We investigated whether these patients showed changes in striatal DAT activity using semi-quantitative analysis of ¹⁸F-FP-CIT PET data. DIP patients with visually normal DAT images were selected from medical records. The subjects were classified as patients who recovered partially (PR) or completely within 12 months (CR). The ¹⁸F-FP-CIT uptake in each striatal subregion was compared between the CR and the PR groups. In total, 41 and 9 patients of the CR and PR groups were assessed, respectively. The two patient groups were comparable in terms of clinical characteristics including age, sex, and severity of parkinsonism. From semi-quantitative analysis of the PET image, the PR patients showed a relatively lower ligand uptake in the ventral striatum, the anterior putamen and the posterior putamen compared with the CR patients. This result suggests that persistent DIP in patients with visually normal DAT imaging may be associated with subtle decrement of DAT activity.

Impact of Reimbursement Cuts on the Sustainability and Accessibility of Dopamine Transporter Imaging

PURPOSE

Dopamine transporter single-photon emission computed tomography imaging utilizing iodine-123 ioflupane is accurate for differentiation of Parkinson disease from essential tremor. This study evaluates how reimbursement for I-123 ioflupane imaging changed between 2011 (year of FDA approval) and 2014 (year after loss of pass-through status for hospital-based outpatient imaging from CMS).

METHODS

I-123 ioflupane reimbursement data for our institution's hospital-based imaging were compared between two periods: (1) July 2011 to October 2012, and (2) 2014. For each time period separately and in combination, averages and ranges of reimbursement for private insurance and CMS were analyzed and compared. A model to ensure recouping of radiopharmaceutical costs was developed.

RESULTS

Review yielded 247 studies from July 2011 to October 2012 and 94 studies from 2014. Average reimbursement per study fell from $2,469 (US dollars) in 2011 to 2012 to $1,657 in 2014. CMS reduced average reimbursement by $1,148 in 2014 because of loss of radiopharmaceutical pass-through status. Average reimbursements from CMS versus private payors markedly differed in 2011 to 2012 at $2,266 versus $2,861, respectively, and in 2014 at $1,118 versus $3,470, respectively. Between 2011 to 2012 and 2014, the CMS percentage increased from 54% to 78%. Assuming that I-123 ioflupane cost $2,000, our model based on 2014 data predicts a practice with greater than 60% CMS patients would no longer recover radiopharmaceutical costs.

CONCLUSIONS

Reimbursement levels, payor mix, scanner location, and radiopharmaceutical costs are all critical, variable factors for modeling the financial viability of I-123 ioflupane imaging and, by extrapolation, future radiopharmaceuticals.

[(123)I]-Ioflupane SPECT in combination with MIBG myocardial scintigraphy in Parkinson's disease: a case series study

Metaiodobenzylguanidine (MIBG) myocardial scintigraphy is widely accepted as a beneficial tool for differentiating Parkinson's disease (PD) from other Parkinson-related disorders (PRD). In Japan, dopamine transporter (DAT) imaging, which can evaluate presynaptic degeneration of dopamine neurons, has been applied in clinics since 2014. The present study investigated the utility of [(123)I]-Ioflupane single photon emission computed tomography (SPECT) combined with MIBG myocardial scintigraphy for the diagnosis of PD. We performed [(123)I]-Ioflupane SPECT and MIBG myocardial scintigraphy in 63 PD patients, 8 PRD patients and 1 essential tremor patient, and obtained the specific binding ratio (SBR [cut-off: 4.5]) and the heart-to-mediastinum ratio (H/M [cut-off: 2.2]). In 70% of the PD patients, both parameters were significantly reduced. In 22% of the PD patients, the SBR was smaller than 4.5 with normal H/M, and H/M was less than 2.2 with normal SBR in 5% of all subjects. Either the SBR or H/M was significantly reduced in 97% of the study population. The SBR showed low disease specificity to PD (11%), and the SBR and H/M negatively correlated with disease duration. These findings indicate that [(123)I]-Ioflupane SPECT combined with MIBG myocardial scintigraphy can improve the detection rate of PD. However, careful interpretation of these results is required because [(123)I]-Ioflupane SPECT poorly differentiates PD from PRD. Progression of PD may reflect the gradual reduction of isotope accumulation, hence, both [(123)I]-Ioflupane SPECT and MIBG myocardial scintigraphy should be tested repeatedly even in clinically suspected PD cases showing negative results.

What do patients with scans without evidence of dopaminergic deficit (SWEDD) have? New evidence and continuing controversies

The term SWEDD (scans without evidence for dopaminergic deficit) refers to the absence, rather than the presence, of an imaging abnormality in patients clinically presumed to have Parkinson's disease (PD). However, such a term has since been widely used in the medical literature, even as a diagnostic label. While many authors have suggested that different disorders of PD lookalikes may account for a proportion of SWEDD cases, others have claimed that some of them may have a benign subtype of PD. Thus, there has been ensuing controversy and confusion and the use of this term continues without clarity of what it represents. We have systematically reviewed all the studies involving patients with SWEDD with the aim of shedding light on what these patients actually have. It becomes clear from this systematic review that while most 'SWEDD' cases are due to a clinical misdiagnosis of PD, there exists a small proportion of patients with SWEDD who may have PD on the basis of a positive levodopa response, clinical progression, imaging and/or genetic evidence. The latter challenge the seemingly incontrovertible relationship between dopaminergic tracer binding and the diagnosis of nigrostriatal parkinsonism, particularly PD. Patients with SWEDD are unlikely to reflect a single clinical entity and we suggest that the term SWEDD should be abandoned.

Drug-induced movement disorders

INTRODUCTION

Drug-induced movement disorders (DIMDs) can be elicited by several kinds of pharmaceutical agents. The major groups of offending drugs include antidepressants, antipsychotics, antiepileptics, antimicrobials, antiarrhythmics, mood stabilisers and gastrointestinal drugs among others.

AREAS COVERED

This paper reviews literature covering each movement disorder induced by commercially available pharmaceuticals. Considering the magnitude of the topic, only the most prominent examples of offending agents were reported in each paragraph paying a special attention to the brief description of the pathomechanism and therapeutic options if available.

EXPERT OPINION

As the treatment of some DIMDs is quite challenging, a preventive approach is preferable. Accordingly, the use of the offending agents should be strictly limited to appropriate indications and they should be applied in as low doses and as short duration as the patient's condition allows. As most of DIMDs are related to an unspecific adverse action of medications in the basal ganglia and the cerebellum, future research should focus on better characterisation of the neurochemical profile of the affected functional systems, in addition to the development of drugs with higher selectivity and better side-effect profile.

A scan without evidence is not evidence of absence: Scans without evidence of dopaminergic deficit in a symptomatic leucine-rich repeat kinase 2 mutation carrier

INTRODUCTION

The basis for SWEDD is unclear, with most cases representing PD mimics but some later developing PD with a dopaminergic deficit.

METHODS

We studied a patient initially diagnosed with SWEDD (based on (18)F-dopa PET) who developed unequivocal PD associated with a leucine-rich repeat kinase 2 p.G2019S mutation. Repeat multitracer PET was performed at 17 years' disease duration, including (+)[11C]dihydrotetrabenazine, [11C](N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine (which binds the serotonin transporter), and (18)F-dopa.

RESULTS

The patient showed bilateral striatal dopaminergic denervation (right putamen 28% of age-matched normal, left putamen 33%). (18)F-dopa uptake was decreased, particularly on the left (mean 31% of normal vs. 45% on the more affected right side). Serotonin transporter binding was relatively preserved in the putamen (right mean 90% of normal, left 81%) and several cortical regions.

CONCLUSIONS

SWEDD can occur in genetically determined PD and may, in some cases, be the result of compensatory nondopaminergic mechanisms operating in early disease.

Structural and functional imaging in parkinsonian syndromes

Movement disorders with parkinsonian features are common, and in recent years imaging has assumed a greater role in diagnosis and management. Thus, it is important that radiologists become familiar with the most common imaging patterns of parkinsonism, especially given the significant clinical overlap and diagnostic difficulty associated with these disorders. The authors review the most common magnetic resonance (MR) and molecular imaging patterns of idiopathic Parkinson disease and atypical parkinsonian syndromes. They also discuss the interpretation of clinically available molecular imaging studies, including assessment of cerebral metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET), cortical amyloid deposition with carbon 11 ((11)C) Pittsburgh compound B and fluorine 18 ((18)F) florbetapir PET, and dopaminergic activity with iodine 123 ((123)I) ioflupane single photon emission computed tomography (SPECT). Although no single imaging test is diagnostic, a combination of tests may help narrow the differential diagnosis. Findings at (123)I ioflupane SPECT can confirm the loss of dopaminergic neurons in patients with parkinsonism and help distinguish these syndromes from treatable conditions, including essential tremor and drug-induced parkinsonism. FDG PET uptake can demonstrate patterns of neuronal dysfunction that are specific to a particular parkinsonian syndrome. Although MR imaging findings are typically nonspecific in parkinsonian syndromes, classic patterns of T2 signal change can be seen in multiple system atrophy and progressive supranuclear palsy. Finally, positive amyloid-binding PET findings can support the diagnosis of dementia with Lewy bodies. Combined with a thorough clinical evaluation, multimodality imaging information can afford accurate diagnosis, allow selection of appropriate therapy, and provide important prognostic information.

Patient Survey on Satisfaction and Impact of 123I-Ioflupane Dopamine Transporter Imaging

Patients were surveyed to assess the impact of dopamine transporter imaging on diagnostic confidence, change in treatment plan, effect on medication compliance, and subjective well-being. Surveys were sent to 140 patients who completed dopamine transporter imaging an average of 18 months prior. Sixty-five surveys from patients (46%) were returned. Questions assessed patients’ perceived impact of the imaging on their care. Increased diagnostic confidence following imaging was reported by 69% of patients. Changes to treatment plan from imaging were reported by 24% of patients. Overall satisfaction with the study and its impact was reported by 70% of patients. Dopamine transporter imaging increased diagnostic confidence among patients and overall patient satisfaction with the impact of imaging on clinical care was high.

Atypical parkinsonism: diagnosis and treatment

Atypical parkinsonism comprises typically progressive supranuclear palsy, corticobasal degeneration, and mutilple system atrophy, which are distinct pathologic entities; despite ongoing research, their cause and pathophysiology are still unknown, and there are no biomarkers or effective treatments available. The expanding phenotypic spectrum of these disorders as well as the expanding pathologic spectrum of their classic phenotypes makes the early differential diagnosis challenging for the clinician. Here, clinical features and investigations that may help to diagnose these conditions and the existing limited treatment options are discussed.

The diagnostic value of dopamine transporter imaging and olfactory testing in patients with parkinsonian syndromes

The aim of the study was to compare the efficacy of olfactory testing and presynaptic dopamine imaging in diagnosing Parkinson's disease (PD) and atypical parkinsonian syndromes (APS); to evaluate if the combination of these two diagnostic tools can improve their diagnostic value. A prospective investigation of 24 PD patients, 16 APS patients and 15 patients with non-parkinsonian syndromes was performed during an 18-month period. Single photon emission computed tomography with the presynaptic radioligand (123)I-FP-CIT (DaTSCAN(®)) and olfactory testing with the Brief 12-item Smell Identification Test (B-SIT) were performed in all patients. DaTSCAN was analysed semi-quantitatively, by calculating two different striatal uptake ratios, and visually according to a predefined ranking scale. B-SIT score was significantly lower for PD patients, but not significantly different between APS and non-parkinsonism. The visual assessment of DaTSCAN had higher sensitivity, specificity and diagnostic accuracy compared to olfactory testing. Most PD patients (75%) had visually predominant dopamine depletion in putamen, while most APS patients (56%) had visually severe dopamine depletion both in putamen and in caudate nucleus. The combination of DaTSCAN and B-SIT led to a higher rate of correctly classified patients. Olfactory testing can distinguish PD from non-parkinsonism, but not PD from APS or APS from non-parkinsonism. DaTSCAN is more efficient than olfactory testing and can be valuable in differentiating PD from APS. However, combining olfactory testing and DaTSCAN imaging has a higher predictive value than these two methods separately.

The diagnostic accuracy of dopamine transporter SPECT imaging to detect nigrostriatal cell loss in patients with Parkinson's disease or clinically uncertain parkinsonism: a systematic review

In specialized movement disorder centers, Parkinson's disease (PD) is wrongly diagnosed in 6 to 25% of cases. To improve the accuracy of the clinical diagnosis, it is necessary to have a reliable and practical reference standard. Dopamine transporter single-photon emission computed tomography (DAT SPECT) imaging might have the potential (high diagnostic accuracy and practical to use) to act as reference standard in detecting nigrostriatal cell loss in patients with (early stage) parkinsonism. We performed a systematic review to evaluate if DAT SPECT imaging can be used as such. Relevant studies were searched in the MEDLINE and EMBASE databases. Studies were selected when they met the following criteria: (1) all patients were adults with a clinical diagnosis of PD or clinically uncertain parkinsonism and (2) the study reported original data. In addition, studies needed to fulfill one of the two following criteria: (1) patients underwent at least one DAT SPECT and had a neuropathological confirmed diagnosis and (2) patients underwent at least two DAT SPECT scans, performed at least 2 years apart. The search identified 1,649 articles. Eight studies fulfilled our selection criteria and were included in this review. There was only one study including patients with diagnostic uncertainty. Sensitivity and specificity of DAT SPECT imaging to detect nigrostriatal cell loss were 98%. The other studies included patients with a diagnosis of PD in whom there was no uncertainty. In these studies, sensitivity was 100%. Our systematic review indicates that DAT SPECT imaging seems to be accurate to detect nigrostriatal cell loss in patients with parkinsonism.

Methcathinone "Kitchen Chemistry" and Permanent Neurological Damage

Methcathinone abuse is a significant cause of parkinsonism among young patients in the Eastern European countries. The drug is synthesized from over-the-counter cold remedies containing ephedrine or pseudoephedrine. The final mixture contains a high concentration of manganese if potassium permanganate is used as the oxidant agent. Though manganese is an essential trace element and its homeostasis is well maintained, exposure to a high level of manganese is neurotoxic. The use of manganese-contaminated methcathinone may cause permanent neurological damage and severe disability. Drug users develop a distinctive extrapyramidal syndrome that resembles classic manganese intoxication. Methcathinone could have additive neurotoxic effect to the progression of parkinsonism. The most prevalent symptoms are symmetrical bradykinesia, dystonias, and early postural, gait, and speech impairment. After cessation of exposure, the syndrome is generally irreversible and can even progress.

Update on SPECT and PET in parkinsonism - part 1: imaging for differential diagnosis

PURPOSE OF REVIEW

To give an update on recent findings concerning the use of single-photon emission computed tomography (SPECT) and positron emission tomography (PET) for differential diagnosis and prognosis of neurodegenerative parkinsonism and related disorders.

RECENT FINDINGS

Several studies confirmed the very high diagnostic accuracy and clinical impact of imaging nigrostriatal function (most notably with [I]FP-CIT-SPECT) for diagnosing neurodegenerative parkinsonism and dementia with Lewy bodies. Accurate differential diagnosis of neurodegenerative parkinsonism can be achieved by imaging disease-specific patterns of cerebral glucose metabolism with [18F]fluorodeoxyglucose-PET, which surpasses the diagnostic accuracy of other currently available radionuclide imaging techniques.

SUMMARY

SPECT and PET are established methods for the differential diagnosis of parkinsonism with significant therapeutic and prognostic impact. Given the limited accuracy of the clinical diagnosis as the reference standard, future studies with post-mortem verification are needed for validation of diagnostic imaging pattern, particularly in tauopathies.

Transcranial sonography and (123)I-FP-CIT single photon emission computed tomography in movement disorders

Diagnosis of Parkinson's disease (PD) can be difficult in the early stages of the disease. The aim of the study described here was to assess the correlation between transcranial sonography (TCS) and (123)I-FP-CIT ([(123)I]ioflupane, N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-[(123)I]iodophenyl)nortropane) SPECT (single photon emission computed tomography) findings and the diagnosis of PD. A total of 49 patients were enrolled in the study: 29 patients with PD, 7 patients with other parkinsonian syndromes, 11 patients with essential tremor and 2 with psychogenic movement disorder. Substantia nigra echogenicity was measured using TCS. SPECT was performed using DaTSCAN ([(123)I]ioflupane). TCS and SPECT findings were correlated in 84% of patients, with κ = 0.62 (95% confidence interval: 0.38-0.86). TCS-measured substantia nigra echogenicity and SPECT-measured striatal binding ratio were negatively correlated (r = -0.326, p = 0.003). TCS/SPECT sensitivity, specificity and positive and negative predictive values for the diagnosis of PD were 89.7%/96.6%, 60.0%/70.0%, 76.5%/82.4% and 80.0%/93.3%, respectively. Both positive TCS and SPECT findings correlated significantly with the diagnosis of PD (κ = 0.52, 95% confidence interval: 0.27-0.76, and κ = 0.69, 95% confidence interval: 0.49-0.90, respectively).

Is ioflupane I123 injection diagnostically effective in patients with movement disorders and dementia? Pooled analysis of four clinical trials

OBJECTIVES

To pool clinical trials of similar design to assess overall sensitivity and specificity of ioflupane I123 injection (DaTSCAN or ioflupane ((123)I)) to detect or exclude a striatal dopaminergic deficit disorder (SDDD), such as parkinsonian syndrome and dementia with Lewy bodies.

DESIGN

Pooled analysis of three phase 3 and one phase 4 clinical trials. These four trials were selected because they were the four studies used for the US new drug application to the Food and Drug Administration (FDA).

SETTING

Multicentre, open-label, non-randomised.

PARTICIPANTS

Patients with either a movement disorder or dementia, and healthy volunteers.

INTERVENTIONS

Ioflupane ((123)I) was administered.

OUTCOME MEASURES

Images were assessed by panels of 3-5 blinded experts and/or on-site nuclear medicine physicians, classified as normal or abnormal and compared with clinical diagnosis (reference standard) to determine sensitivity and specificity.

RESULTS

Pooling the four studies, 928 participants were enrolled, 849 were dosed and 764 completed their study. Across all studies, when images were assessed by on-site readers, ioflupane ((123)I) diagnostic effectiveness had an overall (95% CI) sensitivity of 91.9% (88.7% to 94.5%) and specificity of 83.6% (78.7% to 87.9%). When reads were conducted blindly by a panel of independent experts, the overall sensitivity was 88.7% (86.8% to 90.4%) and specificity was 91.2% (89.0% to 93.0%).

CONCLUSIONS

In this pooled analysis, the visual assessment of ioflupane ((123)I) images provided high levels of sensitivity and specificity in detecting the presence/absence of an SDDD. Ioflupane ((123)I) imaging has the potential to improve diagnostic accuracy in patients with signs and symptoms of a movement disorder and/or dementia.

TRIAL REGISTRATION NUMBER

NCT00209456.

The utility of neuroimaging in the differential diagnosis of parkinsonian syndromes

The differential diagnosis of parkinsonian syndromes can be challenging, particularly in early disease stages. However, prognosis and therapeutic regimes are not alike in Parkinson disease and atypical parkinsonism, and thus a correct diagnosis at the earliest possible stage is desirable. Over the past two decades, magnetic resonance imaging and radiotracer-based imaging techniques have proven to be helpful tools to enhance the accuracy of clinical diagnosis in these disorders. Here, we review recent advances in neuroimaging for the differential diagnosis of parkinsonian syndromes.

The role of functional dopamine-transporter SPECT imaging in parkinsonian syndromes, part 2

SUMMARY

The functional imaging technique most widely used in European clinics to differentiate a true parkinsonian syndrome from vascular parkinsonism, drug-induced changes, or essential tremor is dopamine-transporter SPECT. This technique commonly reports dopamine-transporter function, with decreasing striatal uptake demonstrating increasingly severe disease. The strength of dopamine-transporter SPECT is that nigrostriatal degeneration is observed in both clinically inconclusive parkinsonism and early, even premotor, disease. In this clinical review (Part 2), we present the dopamine-transporter SPECT findings in a variety of neurodegenerative diseases, including multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, and dementia with Lewy bodies. The findings in vascular parkinsonism, drug-induced parkinsonism, and essential tremor are also described. It is hoped that this technique will be the forerunner of a range of routinely used, process-specific ligands that can identify early degenerative disease and subsequently guide disease-modifying interventions.

Differentiating drug-induced parkinsonism from Parkinson's disease: an update on non-motor symptoms and investigations

Drug-induced parkinsonism is the second most common cause of parkinsonism after Parkinson's disease and their distinction has crucial implications in terms of management and prognosis. However, differentiating between these conditions can be challenging on a clinical ground, especially in the early stages. We therefore performed a review to ascertain whether assessment of non-motor symptoms, or use of ancillary investigations, namely dopamine transporter imaging, transcranial sonography of the substantia nigra, and scintigraphy for myocardial sympathetic innervation, can be recommended to distinguish between these conditions. Among non-motor symptoms, there is evidence that hyposmia can differentiate between patients with "pure" drug-induced parkinsonism and those with degenerative parkinsonism unmasked by an anti-dopaminergic drug. However, several issues, including smoking history and cognitive functions, can influence smell function assessment. Higher diagnostic accuracy has been demonstrated for dopamine transporter imaging. Finally, preliminary evidence exists for sympathetic cardiac scintigraphy to predict dopaminergic pathway abnormalities and to differentiate between drug-induced parkinsonism and Parkinson's disease. Imaging of the dopaminergic pathway seems to be the only, reasonably available, technique to aid the differential diagnosis between drug-induced parkinsonism and Parkinson's disease.

[¹²³I]FP-CIT SPECT (DaTSCAN) may be a useful tool to differentiate between Parkinson's disease and vascular or drug-induced parkinsonisms: a meta-analysis

BACKGROUND AND PURPOSE

Differentiating idiopathic Parkinson's disease from secondary parkinsonian syndromes is crucial since their management and prognosis differ considerably. Functional imaging of the dopaminergic pathway by means of [¹²³I]FP-CIT SPECT (DaTSCAN) might be useful in this regard, but its role is still controversial. The accuracy of DaTSCAN in the differential diagnosis between Parkinson's disease and vascular or drug-induced parkinsonism was therefore systematically reviewed.

METHODS

MEDLINE and CENTRAL were searched for studies aiming to determine accuracy measures (sensitivity, specificity, diagnostic odds ratio, positive and negative likelihood ratios) of DaTSCAN in differentiating between Parkinson's disease and vascular or drug-induced parkinsonism.

RESULTS

Five studies were included. Pooled accuracy measures in differentiating between Parkinson's disease and vascular or drug-induced parkinsonism were relatively high, with sensitivity and specificity values above 85% and 80%, respectively.

CONCLUSIONS

DaTSCAN might accurately differentiate between early Parkinson's disease and secondary parkinsonian conditions, namely vascular or drug-induced, in patients with clinically unclear parkinsonism. However, all the studies reviewed here show several methodological limits, which prevent definitive conclusions on the role of DaTSCAN being drawn in this context. Further studies are needed to confirm our results and definitely evaluate the utility of DaTSCAN in differentiating between Parkinson's disease and vascular or drug-induced parkinsonism.

Diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT: a clinical follow up study

The [¹²³I]ioflupane—a dopamine transporter radioligand—SPECT (DaT-SPECT) has proven to be useful in the differential diagnosis of tremor. Here, we investigate the diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT. Therefore, 30 patients with tremor and normal DaT-SPECT were followed up for 2 years. In 18 cases we were able to make a diagnosis. The residual 12 patients underwent a second DaT-SPECT, were then followed for additional 12 months and thereafter the diagnosis was reconsidered again. The final diagnoses included cases of essential tremor, dystonic tremor, multisystem atrophy, vascular parkinsonism, progressive supranuclear palsy, corticobasal degeneration, fragile X–associated tremor ataxia syndrome, psychogenic parkinsonism, iatrogenic parkinsonism and Parkinson's disease. However, for 6 patients the diagnosis remained uncertain. Larger series are needed to better establish the relative frequency of the different conditions behind these cases.

Submandibular gland needle biopsy for the diagnosis of Parkinson disease

OBJECTIVE

This study investigates salivary gland biopsies in living patients with Parkinson disease (PD).

METHODS

Patients with PD for ≥5 years underwent outpatient transcutaneous needle core biopsies (18-gauge or 16-gauge) of 1 submandibular gland. Minor salivary glands were removed via a small incision in the lower lip. Tissue was fixed in formalin and serial 6-µm paraffin sections were immunohistochemically stained for phosphorylated α-synuclein and reviewed for evidence of Lewy type α-synucleinopathy (LTS).

RESULTS

Fifteen patients with PD were biopsied: 9 female/6 male, mean age 68.7 years, mean PD duration 11.8 years. Twelve of the needle core biopsies had microscopically evident submandibular gland tissue to assess and 9/12 (75%) had LTS. Only 1/15 (6.7%) minor salivary gland biopsies were positive for LTS. Five patients had an adverse event; all were minor and transient.

CONCLUSIONS

This study demonstrates the feasibility of performing needle core biopsies of the submandibular gland in living patients with PD to assess LTS. Although this was a small study, this tissue biopsy method may be important for tissue confirmation of PD in patients being considered for invasive procedures and in research studies of other PD biomarkers.