[123I]-FP/CIT SPECT imaging for distinguishing drug-induced parkinsonism from Parkinson's disease

Exploring the Relationships Between Antipsychotic Dosage and Voice Characteristics in Relation to Extrapyramidal Symptoms

OBJECTIVE

Extrapyramidal symptoms (EPS) are common side effects of antipsychotic drugs. Despite the growing interest in exploring objective biomarkers for EPS prevention and the potential use of voice in detecting clinical disorders, no studies have demonstrated the relationships between vocal changes and EPS. Therefore, we aimed to determine the associations between voice changes and antipsychotic dosage, and further investigated whether speech characteristics could be used as predictors of EPS.

METHODS

Forty-two patients receiving or expected to receive antipsychotic drugs were recruited. Drug-induced parkinsonism of EPS was evaluated using the Simpson-Angus Scale (SAS). Participants' voice data consisted of 16 neutral sentences and 2 second-long /Ah/utterances. Thirteen voice features were extracted from the obtained voice data. Each voice feature was compared between groups categorized based on SAS total score of below and above "0.6." The associations between antipsychotic dosage and voice characteristics were examined, and vocal trait variations according to the presence of EPS were explored.

RESULTS

Significant associations were observed between specific vocal characteristics and antipsychotic dosage across both datasets of 1-16 sentences and /Ah/utterances. Notably, Mel-Frequency Cepstral Coefficients (MFCC) exhibited noteworthy variations in response to the presence of EPS. Specifically, among the 13 MFCC coefficients, MFCC1 (t=-4.47, p<0.001), MFCC8 (t=-4.49, p<0.001), and MFCC12 (t=-2.21, p=0.029) showed significant group differences in the overall statistical values.

CONCLUSION

Our results suggest that MFCC may serve as a predictor of detecting drug-induced parkinsonism of EPS. Further research should address potential confounding factors impacting the relationship between MFCC and antipsychotic dosage, possibly improving EPS detection and reducing antipsychotic medication side effects.

Optimization of [18F]-FDOPA Brain PET Acquisition Times for Assessment of Parkinsonism in the Clinical Setting

BACKGROUND AND PURPOSE

Fluorine 18-fluoro-L-dopa ([18F]-FDOPA) was approved by the FDA in 2019 and reimbursed by the Centers for Medicare & Medicaid Services in 2022 for use with PET to visualize dopaminergic nerve terminals in the striatum for evaluation of parkinsonism. We sought to determine the optimal image acquisition time for [18F]-FDOPA PET by evaluating rater-estimated FDOPA positivity and image quality across 4 time points.

MATERIALS AND METHODS

Brain PET/CT was acquired 90 minutes following injection of 185 megabecquerel (5 mCi) of [18F]-FDOPA. PET was acquired in list mode for 20 minutes, and data were replayed to represent 15-, 10-, and 5-minute acquisitions. By means of MIMneuro, PET/MR imaging or PET/CT was independently graded for FDOPA positivity and image quality by 2 readers, blinded to the clinical report and diagnosis. Expert neuroradiologist clinical reads were used as the criterion standard.

RESULTS

Twenty patients were included, average age 65.6 years, 55% women. Image-quality ratings decreased with shorter acquisition times for both readers (reader 1, ρ = 0.23, P = .044; reader 2, ρ = 0.24, P = .036), but there was no association between abnormality confidence scores and acquisition time (reader 1, ρ = -0.13, P = .250; reader 2, ρ = -0.19, P = .100). There was a high degree of consistency in intra- and interrater agreement and agreement with the expert reads when using acquisition times of ≥10 minutes (maximal confidence score consistency [ρ = 0.92] and interrater agreement [κ = 0.90] were observed at 15 minutes), while image quality was consistently rated as low and FDOPA positivity ratings were inconsistent when using a 5-minute acquisition time.

CONCLUSIONS

Our study suggests that image-quality ratings were stable after 15 minutes and that between-subject abnormality detection rates were highly consistent between the 2 readers when acquired for at least 10 and up to 20 minutes but were inconsistent at 5 minutes. Shorter [18F]-FDOPA PET acquisition times may help maximize patient comfort while increasing throughput in the clinical setting.

The role of laboratory investigations in the classification of tremors

INTRODUCTION

Tremor is the most common movement disorder. Although clinical examination plays a significant role in evaluating patients with tremor, laboratory tests are useful to classify tremors according to the recent two-axis approach proposed by the International Parkinson and Movement Disorders Society.

METHODS

In the present review, we will discuss the usefulness and applicability of the various diagnostic methods in classifying and diagnosing tremors. We will evaluate a number of techniques, including laboratory and genetic tests, neurophysiology, and neuroimaging. The role of newly introduced innovative tremor assessment methods will also be discussed.

RESULTS

Neurophysiology plays a crucial role in tremor definition and classification, and it can be useful for the identification of specific tremor syndromes. Laboratory and genetic tests and neuroimaging may be of paramount importance in identifying specific etiologies. Highly promising innovative technologies are being developed for both clinical and research purposes.

CONCLUSIONS

Overall, laboratory investigations may support clinicians in the diagnostic process of tremor. Also, combining data from different techniques can help improve understanding of the pathophysiological bases underlying tremors and guide therapeutic management.

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.

Adequate diagnosis of the cause of Parkinsonism and treatment in an elderly patient with schizophrenia: A case report

Background

Parkinsonism is frequently observed in patients with schizophrenia, and most patients are diagnosed with drug-induced parkinsonism. However, comorbidity with idiopathic Parkinson's disease or Parkinson-plus syndrome is also possible. The pathophysiology and treatment for each of these are entirely different, thus an appropriate diagnosis is required. However, distinguishing them based on clinical symptoms alone is often difficult, and many cases are misdiagnosed. Additionally, Parkinsonism is frequently mistaken for negative symptoms.

Case Description

We report a case of 68-year-old woman diagnosed with schizophrenia, who was admitted to a welfare center. At approximately age 60, the patient experienced motivation reduction, a loss of appetite, and pain in the extremities. In her mid-60s, tremor and muscle rigidity appeared; nuclear medicine testing was performed for a detailed examination, resulting in a diagnosis of levodopa-responsive Parkinson's syndrome. Notably, the patient's parkinsonism and emotional symptoms, which had been considered negative symptoms thus far, improved with levodopa treatment.

Conclusion

This case report illustrates the importance of properly diagnosing the cause of parkinsonism in patients with schizophrenia.

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.

Gait abnormalities and non-motor symptoms predict abnormal dopaminergic imaging in presumed drug-induced Parkinsonism

Drug-induced parkinsonism (DIP) can be clinically indistinguishable from degenerative parkinsonism, and bedside assessments are needed to differentiate between these conditions. We examined 34 U.S. Veterans with DIP using ¹²³I-FP-CIT (DAT-SPECT) to identify underlying nigrostriatal degeneration. Participants were 94% male with mean age of 64.5 ± 7.1 years. DAT-SPECT was abnormal in 12/34 (35%). Comparing normal and abnormal imaging groups, there were no differences in age, sex, race/ethnicity, psychiatric diagnosis, motor severity, or RBD Screening Questionnaire scores. Those with underlying neurodegeneration reported significantly more non-motor symptoms (NMS), worse olfactory function on the University of Pennsylvania Smell Identification Test, and greater turning duration/steps on the instrumented Timed Up and Go. Area under the curve (AUC) combining poor olfaction and total NMS burden was 0.84 (CI 0.71-0.97), while AUC for turn steps was 0.91 (CI 0.81-1.00). Gait impairment, hyposmia, and NMS may be useful alone and in combination to identify DIP patients with underlying dopaminergic degeneration.

Differentiating tardive dyskinesia: a video-based review of antipsychotic-induced movement disorders in clinical practice

Accurate diagnosis and appropriate treatment of tardive dyskinesia (TD) are imperative, as its symptoms can be highly disruptive to both patients and their caregivers. Misdiagnosis can lead to incorrect interventions with suboptimal or even deleterious results. To aid in the identification and differentiation of TD in the psychiatric practice setting, we review its clinical features and movement phenomenology, as well as those of other antipsychotic-induced movement disorders, with accompanying links to illustrative videos. Exposure to dopamine receptor blocking agents (DRBAs) such as antipsychotics or antiemetics is associated with a spectrum of movement disorders including TD. The differential diagnosis of TD is based on history of DRBA exposure, recent discontinuation or dose reduction of a DRBA, and movement phenomenology. Common diagnostic challenges are the abnormal behaviors and dyskinesias associated with advanced age or chronic mental illness, and other movement disorders associated with DRBA therapy, such as akathisia, parkinsonian tremor, and tremor related to use of mood stabilizing agents (eg, lithium, divalproex). Duration of exposure may help rule out acute drug-induced syndromes such as acute dystonia or acute/subacute akathisia. Another important consideration is the potential for TD to present together with other drug-induced movement disorders (eg, parkinsonism, parkinsonian tremor, and postural tremor from mood stabilizers) in the same patient, which can complicate both diagnosis and management. After documentation of the phenomenology, severity, and distribution of TD movements, treatment options should be reviewed with the patient and caregivers.

Novel case of Parkinson's disease and schizophrenia: challenges in the management

Coexistence of idiopathic Parkinson's disease (iPD) and schizophrenia can pose great diagnostic and therapeutic challenges because of their pathophysiology. Our case highlights such challenges in management. We present a case of 73-year-old man who had parkinsonism for last several years and was also diagnosed with schizophrenia. Due to lack of collateral information about the onset of symptoms and clinical course, it was difficult to distinguish iPD from neuroleptic-induced parkinsonism. Even though, certain clinical findings may help to differentiate between the two conditions, single positron emission computerized tomography/DatScan was used to confirm the diagnosis of iPD. Treatment of coexisting iPD and schizophrenia can be challenging, and a delicate pharmacologic balance must be maintained to ensure adequate symptomatic control. Current evidence suggests that clozapine is a better choice for managing psychosis in these patients due to its unique receptor profile and better safety data.

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.

Distinctive regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative Parkinsonisms

PURPOSE

This study aimed to identify regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative parkinsonisms, using dopamine transporter single-photon emission computed tomography images.

MATERIAL AND METHODS

This study included 213 consecutive participants (Parkinson's disease [n = 111], dementia with Lewy bodies [n = 64], progressive supranuclear palsy with Richardson's syndrome [n = 18], and healthy participants [n = 20]) who underwent both magnetic resonance imaging and ¹²³I-labelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane single-photon emission computed tomography/computed tomography. Using normalized specific binding ratio images, we created voxel-wise regional asymmetry index images to identify the regional specific pattern of regional asymmetries in degenerative parkinsonisms.

RESULTS

Compared with healthy controls, patients with Parkinson's disease showed a regional asymmetry index increase in the nigrostriatal dopaminergic pathway, and those with dementia with Lewy bodies showed a regional asymmetry index increase confined to the bilateral caudate. Individuals with progressive supranuclear palsy exhibited a distinct regional asymmetry index increase in the pallido-subthalamic pathway. Notably, the regional asymmetry index increase in the subthalamic nucleus was significantly greater in progressive supranuclear palsy than in Parkinson's disease.

CONCLUSION

The current study revealed distinctive regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative parkinsonisms. The present findings highlight the potential application of visual diagnosis in degenerative parkinsonisms.

Prevalence of Extrapyramidal Symptoms in In-Patients With Severe Mental Illnesses: Focus on Parkinsonism

Patients with severe mental illnesses may present extrapyramidal symptoms as part of a concomitant neurological disorder or secondary to medications. Extrapyramidal symptoms are frequently unrecognized, have negative consequences for adherence to treatment, negatively affect quality of life and can induce stigma. We estimated and correlated with demographic and clinical variables prevalence of extrapyramidal symptoms in in-patients with severe mental illnesses. Additionally we evaluated ¹²³I-FP-CIT SPECT binding to striatal dopamine transporter in subjects with clinical manifestations suggestive of Parkinson's Disease and recorded therapeutic management and clinical evolution for 6-months. Extrapyramidal symptoms were present in 144 out of 285 patients (50.5%), mainly tremor (94 patients, 33%). There were 38 patients (13.3%) with parkinsonism and they had older age, more medical comorbidities and medical treatments. In 15/38 patients striatal dopamine transporter binding was abnormal resulting in dose reduction or change of psychotropic drugs as well as combination with antiparkinson therapy. Our study confirmed the clinical and epidemiological relevance of extrapyramidal symptoms among inpatients with severe mental illnesses. A small percentage of patients with extrapyramidal symptoms had features compatible with possible diagnosis of Parkinson's Disease. ¹²³I-FP-CIT SPECT was useful to identify dopaminergic dysfunction and initiate dopamine replacement therapy.

Systematic clinical approach for diagnosing upper limb tremor

Tremor is the most common movement disorder worldwide, but diagnosis is challenging. In 2018, the task force on tremor of the International Parkinson and Movement Disorder Society published a consensus statement that proposes a tremor classification along two independent axes: a clinical tremor syndrome and its underlying aetiology. In line with this statement, we here propose a stepwise diagnostic approach that leads to the correct clinical and aetiological classification of upper limb tremor. We also describe the typical clinical signs of each clinical tremor syndrome. A key feature of our algorithm is the distinction between isolated and combined tremor syndromes, in which tremor is accompanied by bradykinesia, cerebellar signs, dystonia, peripheral neuropathy or brainstem signs. This distinction subsequently informs the selection of appropriate diagnostic tests, such as neurophysiology, laboratory testing, structural and dopaminergic imaging and genetic testing. We highlight treatable metabolic causes of tremor, as well as drugs and toxins that can provoke tremor. The stepwise approach facilitates appropriate diagnostic testing and avoids unnecessary investigations. We expect that the approach offered in this article will reduce diagnostic uncertainty and increase the diagnostic yield in patients with tremor.

Relations of clinical symptoms with dopamine transporter imaging in drug-naïve Parkinson's disease

OBJECTIVES

The aim of the present study was to determine the relations of clinical symptoms with nigrostriatal neuron loss in drug-naïve patients with Parkinson's disease (PD). We examined the severity of motor symptoms and freezing of gait (FOG), falls and overactive bladder (OAB) in PD patients and their relations with striatal dopamine transporter (DAT) binding.

PATIENTS AND METHODS

Thirty-two untreated PD patients (14 men and 18 women with a mean age of 71.4 ± 7.2 years) were included in this study. Clinical assessments were performed by using Unified Parkinson's Disease Rating Scale (UPDRS) and overactive bladder symptom score (OABSS), and striatal dopamine transporter (DAT) binding was measured by¹²³I-FP-CIT SPECT.

RESULTS

The results showed that striatal DAT availability was significantly lower in the high UPDRS motor score group, high akinetic-rigid score group, FOG group, and OAB group than in the low UPDRS motor score group, low akinetic-rigid score group, non-FOG group, and non-OAB group. However, the results also showed that there was no significant difference in striatal DAT availability between the high tremor score group and low tremor score group or between the faller group and non-faller group.

CONCLUSIONS

The severity of bradykinesia and axial symptoms and the existence of FOG and OAB in untreated PD patients are related to a decrease in striatal DAT availability. Severity of tremors and occurrence of falls are not related to a decrease in striatal DAT availability. The mechanisms underlying the clinical symptoms of PD involve not only dopaminergic pathways but also non-dopaminergic pathways.

EANM practice guideline/SNMMI procedure standard for dopaminergic imaging in Parkinsonian syndromes 1.0

Purpose

This joint practice guideline or procedure standard was developed collaboratively by the European Association of Nuclear Medicine (EANM) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI). The goal of this guideline is to assist nuclear medicine practitioners in recommending, performing, interpreting, and reporting the results of dopaminergic imaging in parkinsonian syndromes.

Methods

Currently nuclear medicine investigations can assess both presynaptic and postsynaptic function of dopaminergic synapses. To date both EANM and SNMMI have published procedural guidelines for dopamine transporter imaging with single photon emission computed tomography (SPECT) (in 2009 and 2011, respectively). An EANM guideline for D2 SPECT imaging is also available (2009). Since the publication of these previous guidelines, new lines of evidence have been made available on semiquantification, harmonization, comparison with normal datasets, and longitudinal analyses of dopamine transporter imaging with SPECT. Similarly, details on acquisition protocols and simplified quantification methods are now available for dopamine transporter imaging with PET, including recently developed fluorinated tracers. Finally, [¹⁸F]fluorodopa PET is now used in some centers for the differential diagnosis of parkinsonism, although procedural guidelines aiming to define standard procedures for [¹⁸F]fluorodopa imaging in this setting are still lacking.

Conclusion

All these emerging issues are addressed in the present procedural guidelines for dopaminergic imaging in parkinsonian syndromes.

Chronic Neuroleptic-Induced Parkinsonism Examined With Positron Emission Tomography

BACKGROUND

Neuroleptic drug-induced parkinsonism (NIP) is a leading cause of parkinsonism, particularly in aging. Based on abnormal dopamine transporter scan results, individuals displaying chronic NIP are often diagnosed with Lewy-body Parkinson's disease (PD), but this assumption needs further substantiation.

OBJECTIVE

To quantitate the profile of striatal dopaminergic nerve terminal density in NIP relative to PD.

METHODS

We used the positron emission tomography ligand [¹¹ C](+)-dihydrotetrabenazine targeting vesicular monoamine transporter type 2 (VMAT2) binding sites and collected various clinical parameters (motor ratings, olfaction, polysomnography to document rapid eye movement sleep muscle activity, quantitative sensory testing for pain thresholds) possibly predicting binding results in patients older than age 50 living with schizophrenia spectrum disorders under long-term stable antipsychotic drug treatment, with (N = 11) or without (N = 11) chart documention of chronic NIP, and compared them to healthy volunteers (N = 11) and others medicated for PD (N = 12).

RESULTS

Striatal VMAT2 binding was dichotomous in the NIP group between those with spared (N = 5) or low (N = 6) PD-like values. Striatal binding reduction in the low VMAT2-NIP group was asymmetric without the gradient of maximal involvement in the posterior putamen typical of PD. Anosmia was the only nonmotor parameter measured matching the abnormal striatal VMAT2 binding status.

CONCLUSION

These preliminary observations suggest that striatal VMAT2 binding is abnormal in a fraction of chronic NIP cases and differs in spatial distribution from PD. The possibility of a drug-induced axonopathy and resultant synaptopathy, as well as the evolution of the binding deficit, warrant further longitudinal studies in a large cohort. © 2020 International Parkinson and Movement Disorder Society.

Impaired functional connectivity of sensorimotor network predicts recovery in drug-induced parkinsonism

OBJECTIVE

In a substantial portion of patients with drug-induced parkinsonism (DIP), parkinsonism may persist for long periods after discontinuation of offending drugs, suggesting subtle underlying neurodegeneration. We hypothesized that patients with DIP have impaired functional connectivity (FC) of brain networks, which may determine the reversibility of parkinsonism.

METHODS

In this case-control study, we consecutively recruited 60 patients with DIP and 32 healthy controls. We used independent component analysis and dual regression of functional magnetic resonance imaging data to identify seven resting-state networks and compared FC of the networks between the DIP and control groups. Among regions where the two groups showed a significant difference in the FC with sensorimotor network, we compared the FC between patients who had completely recovered (n = 21) and those who had partially recovered (n = 39) within 3 months of cessation of the offending drugs.

RESULTS

Patients with DIP had decreased FC between the sensorimotor network and widespread brain regions, when compared to healthy controls. FC in the prefrontal regions was negatively correlated with parkinsonian motor score. Patients who partially recovered had a significantly lower FC in the prefrontal and cerebellar regions than those who recovered completely, providing a useful predictor of recovery status.

CONCLUSIONS

Patients with DIP had decreased FC of the sensorimotor network, which correlated with the severity of parkinsonism and predicted the recovery status after cessation of offending drugs. Impaired FC of the sensorimotor network can be used as a biomarker to evaluate the severity and prognosis of DIP.

Symptomatic Characteristics of Parkinson's Disease Induced by Neuroleptic Drugs, Based on a Functional Neuroimaging Diagnosis

Objective When patients take neuroleptics, the distinction between Parkinson's disease (PD) and drug-induced parkinsonism (DIP) based solely on clinical features can become difficult. At present, ¹²³I-FP-CIT SPECT (DAT-SPECT) and ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy are widely used to supplement the differential diagnosis of parkinsonism. This study assessed the clinical symptoms and neurological findings in the patients suspected of having DIP based on DAT-SPECT findings. Methods Twenty-three patients (11 men, 12 women, age: 52-81 years old) presenting with DIP were recruited. All patients underwent neurological examinations, including brain magnetic resonance imaging and DAT-SPECT. Patients who showed abnormal DAT-SPECT results underwent MIBG myocardial scintigraphy. Results Eleven patients showed a reduction in the ligand uptake on DAT-SPECT (DAT-positive group), and nine of these patients showed a low delayed heart-to-mediastinum (H/M) ratio on MIBG myocardial scintigraphy. The remaining 12 patients showed normal results on DAT-SPECT (DAT-negative group). All patients in the DAT-positive group had asymmetric motor symptoms, whereas only 4 in the DAT-negative group exhibited this clinical feature (p=0.001). A detailed medical history showed that 7 of the 11 patients in the DAT-positive group had prodromal symptoms for PD. However, only 1 patient in the DAT-negative group exhibited these symptoms (p= 0.009). Although two patients in the DAT-negative group showed poor improvement, they showed a normal H/M ratio on MIBG and no response to levodopa. Conclusion The patients in the DAT-positive group might have prodromal symptoms that were worsened by neuroleptic drugs. The results of detailed history-taking and neurological findings seem to indicate cases of compromised dopaminergic transmission before the administration of neuroleptic drugs.

Molecular Imaging of the Dopamine Transporter

Dopamine transporter (DAT) single-photon emission tomography (SPECT) with (123)Ioflupane is a widely used diagnostic tool for patients with suspected parkinsonian syndromes, as it assists with differentiating between Parkinson’s disease (PD) or atypical parkinsonisms and conditions without a presynaptic dopaminergic deficit such as essential tremor, vascular and drug-induced parkinsonisms. Recent evidence supports its utility as in vivo proof of degenerative parkinsonisms, and DAT imaging has been proposed as a potential surrogate marker for dopaminergic nigrostriatal neurons. However, the interpretation of DAT-SPECT imaging may be challenged by several factors including the loss of DAT receptor density with age and the effect of certain drugs on dopamine uptake. Furthermore, a clear, direct relationship between nigral loss and DAT decrease has been controversial so far. Striatal DAT uptake could reflect nigral neuronal loss once the loss exceeds 50%. Indeed, reduction of DAT binding seems to be already present in the prodromal stage of PD, suggesting both an early synaptic dysfunction and the activation of compensatory changes to delay the onset of symptoms. Despite a weak correlation with PD severity and progression, quantitative measurements of DAT binding at baseline could be used to predict the emergence of late-disease motor fluctuations and dyskinesias. This review addresses the possibilities and limitations of DAT-SPECT in PD and, focusing specifically on regulatory changes of DAT in surviving DA neurons, we investigate its role in diagnosis and its prognostic value for motor complications as disease progresses.

Treatment of Tardive Dyskinesia: A General Overview with Focus on the Vesicular Monoamine Transporter 2 Inhibitors

Tardive dyskinesia (TD) encompasses the spectrum of iatrogenic hyperkinetic movement disorders following exposure to dopamine receptor-blocking agents (DRBAs). Despite the advent of atypical or second- and third-generation antipsychotics with a presumably lower risk of complications, TD remains a persistent and challenging problem. Prevention is the first step in mitigating the risk of TD, but early recognition, gradual withdrawal of offending medications, and appropriate treatment are also critical. As TD is often a persistent and troublesome disorder, specific antidyskinetic therapies are often needed for symptomatic relief. The vesicular monoamine transporter 2 (VMAT2) inhibitors, which include tetrabenazine, deutetrabenazine, and valbenazine, are considered the treatment of choice for most patients with TD. Deutetrabenazine-a deuterated version of tetrabenazine-and valbenazine, the purified parent product of one of the main tetrabenazine metabolites, are novel VMAT2 inhibitors and the only drugs to receive approval from the US FDA for the treatment of TD. VMAT2 inhibitors deplete presynaptic dopamine and reduce involuntary movements in many hyperkinetic movement disorders, particularly TD, Huntington disease, and Tourette syndrome. The active metabolites of the VMAT2 inhibitors have high affinity for VMAT2 and minimal off-target binding. Compared with tetrabenazine, deutetrabenazine and valbenazine have pharmacokinetic advantages that translate into less frequent dosing and better tolerability. However, no head-to-head studies have compared the various VMAT2 inhibitors. One of the major advantages of VMAT2 inhibitors over DRBAs, which are still being used by some clinicians in the treatment of some hyperkinetic disorders, including TD, is that they are not associated with the development of TD. We also briefly discuss other treatment options for TD, including amantadine, clonazepam, Gingko biloba, zolpidem, botulinum toxin, and deep brain stimulation. Treatment of TD and other drug-induced movement disorders must be individualized and based on the severity, phenomenology, potential side effects, and other factors discussed in this review.

The role of exposure to pesticides in the etiology of Parkinson's disease: a 18F-DOPA positron emission tomography study

Susceptibility to Parkinson's disease (PD) is believed to involve an interaction between genetic and environmental factors. The role of pesticides as a risk factor of PD and neurodegeneration remains controversial. An asymmetric decrease in ligand uptake on ¹⁸F-DOPA positron emission tomography (PET), especially in the dorsal putamen, is a sensitive marker of PD. The aim of this study was to examine the pattern of ligand uptake on ¹⁸F-DOPA PET in patients with PD exposed or not exposed to pesticides. The main sample included 26 Israeli patients with PD, 13 who were exposed to pesticides and 13 who were not, matched for age and disease duration. All underwent ¹⁸F-DOPA PET imaging, and an asymmetry index of ligand uptake between the ipsilateral and contralateral caudate, putamen, and whole striatum was calculated. No significant between-group differences were found in demographic variables, clinical asymmetry index (P = 0.15), or asymmetry index of ligand uptake in the putamen (P = 0.84), caudate (P = 0.78) and striatum (P = 0.45). Comparison of the ¹⁸F-DOPA results of the Israeli cohort with those of 17 non-pesticide-exposed patients with PD from Austria yielded no significant differences, further validating our findings. Our observations suggest that although exposure to pesticides might be a risk factor for PD, it does not have an effect on the asymmetry pattern in the nigrostriatal system over non-exposure. We assume that once the disease process is initiated in pesticide-exposed patients, the pathogenic mechanism does not differ from that of idiopathic PD.

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.

Source-Based Morphometry Multivariate Approach to Analyze [123I]FP-CIT SPECT Imaging

PURPOSE

[¹²³I]FP-CIT (DaTSCAN®) single-photon emission computed tomography (SPECT) imaging is widely used to study neurodegenerative parkinsonism, by measuring presynaptic dopamine transporter (DAT) in striatal regions. Beyond DAT, [¹²³I]FP-CIT may be considered for other monoaminergic systems, in particular the serotonin transporter (SERT). Independent component analysis (ICA) implemented in source-based morphometry (SBM) could represent an alternative method to explore monoaminergic pathways, studying the relationship among voxels and grouping them into "neurotransmission" networks.

PROCEDURES

One hundred forty-three subjects [84 with Parkinson's disease (PD) and 59 control individuals (CG)] underwent DATSCAN® imaging. The [¹²³I]FP-CIT binding was evaluated by multivariate SBM approach, as well as by a whole-brain voxel-wise univariate (statistical parametric mapping, SPM) approach.

RESULTS

As compared to the univariate whole-brain approach (SPM) (only demonstrating striatal [¹²³I]FP-CIT binding reduction in PD group), SBM identified six sources of non-artefactual origin, including basal ganglia and cortical regions as well as brainstem. Among them, three sources (basal ganglia and cortical regions) presented loading scores (as index of [¹²³I]FP-CIT binding) significantly different between PD and CG. Notably, even if not significantly different between PD and CG, the remaining three non-artefactual sources were characterized by a predominant frontal, brainstem, and occipito-temporal involvement.

CONCLUSION

The concept of source blind separation by the application of ICA (as implemented in SBM) represents a feasible approach to be considered in [¹²³I]FP-CIT (DaTSCAN^®) SPECT imaging. Taking advantage of this multivariate analysis, specific patterns of variance can be identified (involving either striatal than extrastriatal regions) that could be useful in differentiating neurodegenerative parkinsonisms.

Semi-quantitative dopamine transporter standardized uptake value in comparison with conventional specific binding ratio in [123I] FP-CIT single-photon emission computed tomography (DaTscan)

PURPOSE

We developed a new analytical method to quantify the dopamine transporter (DAT) radiation dose in the striatum on [¹²³I] FP-CIT single-photon emission computed tomography (SPECT). This method is based on the dopamine transporter standardized uptake value (DaTSUV). The purpose of this study was to compare DaTSUV with the classical specific binding ratio (SBR) in the discrimination of dopaminergic neurodegenerative diseases (dNDD) from non-dNDD.

METHOD

Seventy-seven consecutive patients who underwent DaTscan were included. Patients were divided into a dNDD group (n = 44; 24 men, 20 women; median age 73 years) and a non-dNDD group (n = 33; 14 men, 19 women; median age 75 years) based on their clinical diagnoses. The relationship between each method was evaluated by Pearson's correlation coefficient. Differences in SBR and DaTSUV in each group were evaluated by t test. Pairwise comparison of receiver operating characteristic (ROC) curve analysis was performed to compare the discriminating abilities of each method according to the standard error of the area under the curve (AUC). A value of p < 0.05 was considered statistically significant.

RESULT

There was a significant strong correlation between DaTSUV and SBR (r = 0.910 [95% CI = 0.862-0.942], p < 0.001). The dNDD group showed significantly lower SBR (3.48 [1.25-7.91] vs 6.58 [3.81-11.1], p < 0.001) and DaTSUV (4.91 [1.59-13.6] vs 8.61 [2.29-15.6], p < 0.001) than the non-dNDD group. The discriminating ability of SBR (AUC = 0.918) was significantly higher than that of DaTSUV (AUC = 0.838, p = 0.0176).

CONCLUSION

DaTSUV has a good correlation with SBR, but it could not exceed SBR for discriminating dNDD from non-dNDD.

DAT-SPECT imaging in cases of drug-induced parkinsonism in a specialty movement disorders practice

OBJECTIVE

Compare clinical characteristics and outcomes in cases where DAT-SPECT imaging is used to distinguish Parkinson's disease from Drug-Induced Parkinsonsim.

BACKGROUND

Clinical uncertainty in diagnosing Parkinson's disease is common when patients are on dopamine-blocking medications. DAT-SPECT imaging can improve diagnostic certainty but little data are available on clinical characteristics and outcomes associated with normal and abnormal scan results.

METHODS

Retrospective chart review of patients seen at a movement disorders center between 2011 and 2017 where DAT-SPECT was ordered to distinguish Parkinson's disease from Drug-induced Parkinsonism. Descriptive statistics were calculated for variables of interest and compared by scan result. Chi-squared analyses was carried out for categorical variables and students' t-tests for continuous values.

RESULTS

51 patients met inclusion criteria with 36 normal scans and 15 abnormal scans. Those with greater than 2 cardinal manifestations (tremor, rigidity, akinesia, postural instability) were more likely to have an abnormal scan (63.89% vs 93.33%, p = 0.04). No other clinical characteristics assessed were associated with scan results. Atypical antipsychotics (aripiprazole 39.21%, olanzapine 31.37%) and mood stabilizers (valproic acid 33.33%, lithium 17.65%) were most commonly associated with suspected Drug-induced Parkinsonism cases. A post-scan change in management occurred in 41.18% of patients. 55.56% of patients with normal scans responded to changes in the offending medication, with 16.66% taking over 3 months to show improvement.

CONCLUSIONS

Many DAT-SPECT scans at our institution are ordered to distinguish Parkinson's disease from Drug-induced Parkinsonism because clinical characteristics alone are unreliable. DAT-SPECT results lead to changes in management and the outcomes of these changes are consistent with scan results.

Early-onset drug-induced parkinsonism after exposure to offenders implies nigrostriatal dopaminergic dysfunction

OBJECTIVES

The onset of parkinsonism in patients with drug-induced parkinsonism (DIP) exhibits extensive individual variability following exposure to offending drugs. We investigated whether the individual variations in the onset time of parkinsonism reflected the underlying subtle dopaminergic dysfunction in DIP.

METHODS

We enrolled 71 patients with DIP who had visually normal striatal dopamine transporter (DAT) availability in ¹⁸F-FP-CIT positron emission tomography scans. According to their exposure durations to the offending drugs prior to onset of the parkinsonism, the patients were divided into the early-onset group (duration ≤6 months; n=35) and delayed-onset group (duration >6 months; n=36). We performed the quantitative analysis of the DAT availability in each striatal subregion between the groups.

RESULTS

No patients with DIP had DAT availability that was more than 2 SD below the normal mean of DAT availability. Compared with the delayed-onset group, the early-onset DIP group had decreased DAT availability in the striatal subregions including the posterior putamen (p=0.018), anterior putamen (p=0.011), caudate (p=0.035) and ventral striatum (p=0.027). After adjusting for age, sex and cross-cultural smell identification test scores, a multivariate analysis revealed that the DAT availability in the striatal subregions of the patients with DIP was significantly and positively associated with the natural logarithm of the duration of drug exposure.

CONCLUSIONS

These results suggest that a short exposure to the offending drugs before the development of parkinsonism would be associated with subtle nigrostriatal dopaminergic dysfunction in patients with DIP.

Asymmetric Drug-Induced Parkinsonism and Psychopathology: A Prospective Naturalistic Study in Long-Stay Psychiatric Patients

BACKGROUND

Drug-induced parkinsonism (DIP) is the most common movement disorder induced by antipsychotics. Although DIP is mostly symmetric, asymmetric DIP is reported in a substantial part of the patients. We investigated the frequency of motor asymmetry in DIP and its relationship to the severity of psychopathology in long-stay psychiatric patients.

METHODS

We obtained data from a cohort study of 207 long-stay psychiatric patients on the frequency and risk factors of tardive dyskinesia, akathisia, tardive dystonia, and DIP. From July 2003 to May 2007 (mean follow-up, 1.1 year) drug-induced movement disorders were assessed at least two times in each patient, with a frequency of persistent DIP of 56.2%. All patients who had at least one time parkinsonism in the upper/lower limb(s) were included for analyses (190 patients, 79 women; mean age, 48.0 ± 12.9 years). The Unified Parkinson Disease Rating Scale motor scale was used to calculate the frequency of asymmetric parkinsonism. Multilevel mixed models were built to explore the relationship between asymmetry in parkinsonism and the severity of psychopathology, measured on the Clinical Global Impression-Schizophrenia scale severity index (CGI-SCH SI).

RESULTS

The frequency of asymmetric parkinsonism was 20.8%. Asymmetry in parkinsonism was associated with symptom severity on all CGI-SCH SI scales (β range, 0.37-3.74) and significantly associated with the positive symptom scale (β, 3.74; 95% CI, 0.35-7.31).

CONCLUSION

DIP is asymmetric in a substantial part of patients. Asymmetric presentation of DIP is of clinical relevance as it is related to the severity of psychopathology and may alert the clinician of more severe psychopathology. Future research is recommended to provide insight into the neuropsychopathology and clinical value of asymmetric parkinsonism for psychiatric patients.

Microstructural white matter alterations in patients with drug induced parkinsonism

Drug-induced parkinsonism (DIP) is the second most common etiology of parkinsonism. And yet, there is little information on structural imaging in DIP to elucidate the accurate underlying pathomechanisms. To investigate microstructural white matter (WM) in patients with DIP using diffusion tensor image and to determine its relationship to severity of parkinsonian motor symptoms and cognitive function. A total of 42 patients with DIP, 65 with Parkinson's disease, and 33 control subjects were recruited from a movement disorders outpatient clinic. We performed comparative analysis of fractional anisotropy (FA) and mean diffusivity (MD) values among groups using tract-based spatial statistics. Correlation analysis between WM integrity and parkinsonian motor symptoms and cognitive performance was also performed in DIP patients using voxel-wise statistical analysis. DIP patients had significantly lower FA and higher MD values over widespread WM areas than control subjects. The patients with DIP had poor cognitive performance relative to control subjects, which correlated well with WM properties. Additionally, the parkinsonian motor symptoms were negatively correlated with FA values. In contrast, exposure time to the offending drugs prior to the development of parkinsonism or duration of parkinsonism showed no significant association with FA or MD values. The present study demonstrates that disruption of the WM microstructure is extensive in patients with DIP, and it is correlated with clinical parameters of parkinsonism and cognitive performance. This suggests that DIP may be reflective of underlying abnormality of microstructural WM. Hum Brain Mapp 38:6043-6052, 2017. © 2017 Wiley Periodicals, Inc.

Drug-Induced Dyskinesia, Part 2: Treatment of Tardive Dyskinesia

Dyskinesias encompass a variety of different hyperkinetic phenomenologies, particularly chorea, dystonia, stereotypies, and akathisia. The main types of drug-induced dyskinesias include levodopa-induced dyskinesia (LID) in patients with Parkinson's disease and tardive syndrome (TS), typically present in patients with psychiatric or gastrointenstinal disorders treated with dopamine receptor blocking drugs, also referred to as neuroleptics. Besides preventive measures (i.e., avoiding the use of the offending drugs), general treatment strategies include slow taper of the offending agent and use of dopamine-depleting agents like tetrabenazine. Botulinum toxin may be helpful for wearing off focal dystonia and some forms of tardive dystonia. Deep brain stimulation is usually reserved for patients with disabling motor fluctuations, LID, and for severe TS that cannot be managed medically.

Clinical Features Indicating Nigrostriatal Dopaminergic Degeneration in Drug-Induced Parkinsonism

OBJECTIVE

Patients with drug-induced parkinsonism (DIP) may have nigrostriatal dopaminergic degeneration. We studied the clinical features that may indicate nigrostriatal dopaminergic degeneration in patients with DIP.

METHODS

Forty-one DIP patients were classified into normal and abnormal [¹⁸F] FP-CIT scan groups. Differences in 32 clinical features and drug withdrawal effects were studied.

RESULTS

Twenty-eight patients had normal (Group I) and 13 patients had abnormal (Group II) scans. Eight patients of Group I, but none of Group II, had taken calcium channel blockers (p = 0.040). Three patients of Group I and six of Group II had hyposmia (p = 0.018). After drug withdrawal, Group I showed greater improvement in Unified Parkinson's Disease Rating Scale total motor scores and subscores for bradykinesia and tremors than Group II. Only hyposmia was an independent factor associated with abnormal scans, but it had suboptimal sensitivity.

CONCLUSION

None of the clinical features were practical indicators of nigrostriatal dopaminergic degeneration in patients with DIP.

Parkinsonian axial signs in schizophrenia

INTRODUCTION

We have recently demonstrated evidence of nigro-striatal denervation, disease progression and response to levodopa in a subgroup of patients with schizophrenia who developed parkinsonism.

OBJECTIVE

In the present study, we investigated whether axial parkinsonian signs might be an early manifestation of parkinsonism in schizophrenia not necessarily related to chronic administration of antipsychotic drugs (AP) drugs.

METHODS

From a baseline cohort of 299 schizophrenic patients who did not satisfy the diagnostic criteria for parkinsonism (presence of at least two of the following appendicular signs: bradykinesia, tremor, rigidity), we identified a group of patients who manifested two out of three axial parkinsonian signs (abnormality of trunk posture, hypomimia and short-step gait). Accordingly, we obtained two sub-groups of patients with schizophrenia, with (Schiz-Axial, N = 26), and without parkinsonian axial signs (Schiz-NO-Axial, N = 273). Clinical and demographical variables were compared between groups. The motor section of the Unified Parkinson's disease rating scale (UPDRS) was employed to measure motor disability.

RESULTS

Schiz-Axial patients were significantly older (p = 0.007) and had longer disease duration (p = 0.04) compared to Schiz-NO-Axial. The two groups did not differ for variables related to AP treatment. Total UPDRS motor score (p < 0.0001) as well as limb (p < 0.0001) and axial (p < 0.0001) UPDRS sub-scores were increased in Schiz-Axial patients compared to Schiz-NO-Axial.

CONCLUSIONS

Our findings provide evidence that axial parkinsonian signs might be an early manifestation of parkinsonism in schizophrenia associated to older age and longer disease duration.

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.

Molecular imaging of dopamine transporters

The dopamine transporter (DAT) is responsible for clearance of dopamine from the synaptic cleft after its release. Imaging DAT availability provides a measure of dopamine terminal function and a method for detecting the striatal dopamine terminal dysfunction present in idiopathic Parkinson's disease (PD) and atypical neurodegenerative parkinsonian disorders such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). DAT imaging with positron emission tomography (PET) or single photon emission computed tomography (SPECT) can be used to support or refute a diagnosis of dopamine deficient parkinsonism in cases where this is unclear and rationalise a trial of dopamine replacement agents as therapy. It can also detect subclinical dopaminergic dysfunction when present in subjects at risk for PD such as relatives of patients, susceptibility gene mutation carriers, and subjects with late onset hyposmia or sleep disorders. The presence of normal DAT availability on imaging can help categorise "subjects without evidence of dopamine deficiency" (SWEDDs) who on occasion mimic PD and include dystonic tremors, drug-induced and psychogenic parkinsonism in their ranks. Reduced levels of baseline striatal DAT availability on PET or SPECT scanning, however, should be regarded as supportive rather than diagnostic of dopamine deficient parkinsonism.

Neuroimaging of Freezing of Gait

Functional brain imaging techniques appear ideally suited to explore the pathophysiology of freezing of gait (FOG). In the last two decades, techniques based on magnetic resonance or nuclear medicine imaging have found a number of structural changes and functional disconnections between subcortical and cortical regions of the locomotor network in patients with FOG. FOG seems to be related in part to disruptions in the "executive-attention" network along with regional tissue loss including the premotor area, inferior frontal gyrus, precentral gyrus, the parietal and occipital areas involved in visuospatial functions of the right hemisphere. Several subcortical structures have been also involved in the etiology of FOG, principally the caudate nucleus and the locomotor centers in the brainstem. Maladaptive neural compensation may present transiently in the presence of acute conflicting motor, cognitive or emotional stimulus processing, thus causing acute network overload and resulting in episodic impairment of stepping.In this review we will summarize the state of the art of neuroimaging research for FOG. We will also discuss the limitations of current approaches and delineate the next steps of neuroimaging research to unravel the pathophysiology of this mysterious motor phenomenon.

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.

Neuroleptic-induced Parkinsonism: Clinicopathological study

BACKGROUND

Drug-induced parkinsonism is a well-known complication of several different drugs--the most common being neuroleptic-induced parkinsonism. However, very few autopsies have been reported in such cases.

METHODS

Patients assessed at Movement Disorders Clinic Saskatchewan are offered brain autopsy. Detailed clinical records are kept.

RESULTS

Brains were obtained from 7 drug-induced parkinsonism patients with parkinsonian symptom onset coinciding with use of drugs known to produce parkinsonism. Six were on antipsychotics and 1 was on metoclopramide. Three cases were treated with levodopa for parkinsonism. In two cases, parkinsonian features reversed after stopping the offending agent. Both had autopsy evidence of preclinical PD. In 4 of the remaining 5, dopamine-blocking drugs were continued until death. In 4 of those 5, brain histology revealed no cause for the parkinsonism, but 1 had mild SN neuronal loss without Lewy bodies.

CONCLUSION

This study shows that reversal of parkinsonism after discontinuing offending drugs does not indicate absence of underlying pathology. Neuroleptics can unmask preclinical PD in patients with insufficient SN damage for the disease to manifest clinically. Though the mechanism of sustained parkinsonian features after discontinuing neuroleptics remains to be established, it is unlikely that dopamine receptor block leads to retrograde SN neuronal degeneration. Furthermore, L-dopa does not appear to be toxic to SN.

Tremor pattern differentiates drug-induced resting tremor from Parkinson disease

OBJECTIVE

DAT-SPECT, is a well-established procedure for distinguishing drug-induced parkinsonism from Parkinson's disease (PD). We investigated the usefulness of blink reflex recovery cycle (BRrc) and of electromyographic parameters of resting tremor for the differentiation of patients with drug-induced parkinsonism with resting tremor (rDIP) from those with resting tremor due to PD.

METHODS

This was a cross-sectional study. In 16 patients with rDIP and 18 patients with PD we analysed electrophysiological parameters (amplitude, duration, burst and pattern) of resting tremor. BRrc at interstimulus intervals (ISI) of 100, 150, 200, 300, 400, 500 and 750 msec was also analysed in patients with rDIP, patients with PD and healthy controls. All patients and controls underwent DAT-SPECT.

RESULTS

Rest tremor amplitude was higher in PD patients than in rDIP patients (p < 0.001), while frequency and burst duration were higher in rDIP than in PD (p < 0.001, p < 0.003, respectively). Resting tremor showed a synchronous pattern in all patients with rDIP, whereas it had an alternating pattern in all PD patients (p < 0.001). DAT-SPECT was normal in rDIP patients while it was markedly abnormal in patients with PD.

CONCLUSIONS

In the absence of DAT-SPECT, the pattern of resting tremor can be considered a useful investigation for differentiating rDIP from PD.

Movement disorders

Movement disorders can be hypokinetic (e.g., parkinsonism), hyperkinetic, or dystonic in nature and commonly arise from altered function in nuclei of the basal ganglia or their connections. As obvious structural changes are often limited, standard imaging plays less of a role than in other neurologic disorders. However, structural imaging is indicated where clinical presentation is atypical, particularly if the disorder is abrupt in onset or remains strictly unilateral. More recent advances in magnetic resonance imaging (MRI) may allow for differentiation between Parkinson's disease and atypical forms of parkinsonism. Functional imaging can assess regional cerebral blood flow (functional MRI (fMRI), positron emission tomography (PET), or single-photon emission computed tomography (SPECT)), cerebral glucose metabolism (PET), neurochemical and neuroreceptor status (PET and SPECT), and pathologic processes such as inflammation or abnormal protein deposition (PET) (Table 49.1). Cerebral blood flow can be assessed at rest, during the performance of motor or cognitive tasks, or in response to a variety of stimuli. In appropriate situations, the correct imaging modality and/or combination of modalities can be used to detect early disease or even preclinical disease, and to monitor disease progression and the effects of disease-modifying interventions. Various approaches are reviewed here.

Drug-induced Parkinsonism versus Idiopathic Parkinson Disease: Utility of Nigrosome 1 with 3-T Imaging

Purpose To explore the utility of nigrosome 1 with 3-T magnetic resonance (MR) imaging to differentiate idiopathic Parkinson disease (IPD) from drug-induced parkinsonism (DIP). Materials and Methods The institutional review board approved this study, and participants gave informed consent. This study enrolled patients with DIP (n = 20) and IPD (n = 29) who underwent N-3-fluoropropyl-2-β-carbomethoxy-3-β-(4-iodophenyl)nortropane ((18)F-FP-CIT) positron emission tomography (PET) and healthy participants (n = 20). All participants underwent 0.5 × 0.5 × 1.0 mm(3) oblique axial three-dimensional multiecho-data image combination imaging to view the nigrosome 1 with 3-T imaging. Two reviewers independently assessed the nigrosome 1 without clinical information. DIP was diagnosed when no abnormality was seen at (18)F-FP-CIT PET. Diagnostic sensitivity, specificity, and accuracy of the nigrosome 1 imaging were evaluated between the IPD and DIP patients and between the IPD patients and healthy participants. Interrater agreement was assessed with Cohen κ. Results Both reviewers agreed in 63 of 69 participants (91.3%) for the presence of any abnormality on either side of the nigrosome 1 (κ = 0.825). Findings in all 29 IPD patients (100%) and three of 20 DIP patients (15%) were rated as abnormal and in 17 of 20 DIP patients (85%) they were interpreted as normal on the basis of imaging of the nitgrosome 1 (sensitivity, 100% (29 of 29); specificity, 85.0% (17 of 20); accuracy, 93.9% (46 of 49) between IPD and DIP patients). Findings in 3 of 20 healthy participants (15.0%) were interpreted as abnormal on the basis of imaging the nigrosome 1 while in the other 17 of 20 healthy participants (85.0%) they were rated as normal (sensitivity, 100% [29 of 29]; specificity, 85.0% [17 of 20]; accuracy, 93.9% [46 of 49] between IPD patients and healthy participants [κ = 0.831]). Conclusion The imaging of nigrosome 1 with 3-T imaging can differentiate DIP from IPD with high accuracy and may help to screen patients who need dopamine transporter imaging in those suspected of having DIP. (©) RSNA, 2015 Online supplemental material is available for this article.