Clinical utility of DaTscan™ imaging in the evaluation of patients with parkinsonism: a US perspective

Practical use of DAT SPECT imaging in diagnosing dementia with Lewy bodies: a US perspective of current guidelines and future directions

Background

Diagnosing Dementia with Lewy Bodies (DLB) remains a challenge in clinical practice. The use of 123I-ioflupane (DaTscan™) SPECT imaging, which detects reduced dopamine transporter (DAT) uptake-a key biomarker in DLB diagnosis-could improve diagnostic accuracy. However, DAT imaging is underutilized despite its potential, contributing to delays and suboptimal patient management.

Methods

This review evaluates DLB diagnostic practices and challenges faced within the U.S. by synthesizing information from current literature, consensus guidelines, expert opinions, and recent updates on DaTscan FDA filings. It contrasts DAT SPECT with alternative biomarkers, provides recommendations for when DAT SPECT imaging may be indicated and discusses the potential of emerging biomarkers in enhancing diagnostic approaches.

Results

The radiopharmaceutical 123I-ioflupane for SPECT imaging was initially approved in Europe (2000) and later in the US (2011) for Parkinsonism/Essential Tremor. Its application was extended in 2022 to include the diagnosis of DLB. DaTscan's diagnostic efficacy for DLB, with its sensitivity, specificity, and predictive values, confirms its clinical utility. However, US implementation faces challenges such as insurance barriers, costs, access issues, and regional availability disparities.

Conclusion

123I-ioflupane SPECT Imaging is indicated for DLB diagnosis and differential diagnosis of Alzheimer's Disease, particularly in uncertain cases. Addressing diagnostic obstacles and enhancing physician-patient education could improve and expedite DLB diagnosis. Collaborative efforts among neurologists, geriatric psychiatrists, psychologists, and memory clinic staff are key to increasing diagnostic accuracy and care in DLB management.

Genetics in Parkinson's disease, state-of-the-art and future perspectives

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder and is clinically characterized by the presence of motor (bradykinesia, rigidity, rest tremor and postural instability) and non-motor symptoms (cognitive impairment, autonomic dysfunction, sleep disorders, depression and hyposmia). The aetiology of PD is unknown except for a small but significant contribution of monogenic forms.

SOURCES OF DATA

No new data were generated or analyzed in support of this review.

AREAS OF AGREEMENT

Up to 15% of PD patients carry pathogenic variants in PD-associated genes. Some of these genes are associated with mendelian inheritance, while others act as risk factors. Genetic background influences age of onset, disease course, prognosis and therapeutic response.

AREAS OF CONTROVERSY

Genetic testing is not routinely offered in the clinical setting, but it may have relevant implications, especially in terms of prognosis, response to therapies and inclusion in clinical trials. Widely adopted clinical guidelines on genetic testing are still lacking and open to debate. Some new genetic associations are still awaiting confirmation, and selecting the appropriate genes to be included in diagnostic panels represents a difficult task. Finally, it is still under study whether (and to which degree) specific genetic forms may influence the outcome of PD therapies.

GROWING POINTS

Polygenic Risk Scores (PRS) may represent a useful tool to genetically stratify the population in terms of disease risk, prognosis and therapeutic outcomes.

AREAS TIMELY FOR DEVELOPING RESEARCH

The application of PRS and integrated multi-omics in PD promises to improve the personalized care of patients.

Lewy body disease as a potential negative outcome modifier of glioblastoma treatment: a case report

BACKGROUND

Elderly patients with glioblastoma are particularly susceptible to the adverse effects of ionizing radiation to the brain. This population also has an increasing prevalence of dementia in the successive seventh, eighth and nineth decade of life, and dementia with Lewy bodies is characterized by pathologic α-synucleins, proteins that take part in neuronal DNA damage repair.

CASE PRESENTATION

We report a 77-year-old man, with a history of coronary artery disease and mild cognitive impairment, who experienced subacute behavioral changes over 3 months with wording-finding difficulty, memory loss, confusion, perseveration, and irritable mood. Neuroimaging studies disclosed a 2.5 × 2.4 × 2.7 cm cystic enhancing mass with central necrosis in the left temporal lobe of the brain. Gross total resection of the tumor revealed IDH-1 wild-type glioblastoma. After treatment with radiation and temozolomide chemotherapy, his cognitive status deteriorated rapidly, and he died from unexpected sudden death 2 months after radiation. Autopsy of his brain revealed (i) tumor cells with atypical nuclei and small lymphocytes, (ii) neuronal cytoplasmic inclusions and Lewy bodies that were positive for α-synuclein in the midbrain, pons, amygdala, putamen and globus pallidus, and (iii) no amyloid plaques and only rare neurofibrillary tangles near the hippocampi.

CONCLUSIONS

This patient most likely had pre-clinical limbic subtype of dementia with Lewy bodies prior to his diagnosis of glioblastoma. The radiation and temozolomide that was used to treat his tumor may have accelerated neuronal damage due to induction of DNA breakage when his brain was already compromised by pathologic α-synucleins. α-Synucleinopathy could be a negative outcome modifier in glioblastoma patients.

Prognostic biomarkers in prodromal α-synucleinopathies: DAT binding and REM sleep without atonia

BACKGROUND

Isolated rapid eye movement (REM) sleep behaviour disorder (iRBD) is a prodromal state of clinical α-synucleinopathies such as Parkinson's disease and Lewy body dementia. The lead-time until conversion is unknown. The most reliable marker of progression is reduced striatal dopamine transporter (DAT) binding, but low availability of imaging facilities limits general use. Our prospective observational study aimed to relate metrics of REM sleep without atonia (RWA)-a hallmark of RBD-to DAT-binding ratios in a large, homogeneous sample of patients with RBD to explore the utility of RWA as a marker of progression in prodromal α-synucleinopathies.

METHODS

DAT single-photon emission CT (SPECT) and video polysomnography (vPSG) were performed in 221 consecutive patients with clinically suspected RBD.

RESULTS

vPSG confirmed RBD in 176 patients (162 iRBD, 14 phenoconverted, 45 non-synucleinopathies). Specific DAT-binding ratios differed significantly between groups, but showed considerable overlap. Most RWA metrics correlated significantly with DAT-SPECT ratios (eg, Montreal tonic vs most-affected-region: r=-0.525; p<0.001). In patients taking serotonergic/noradrenergic antidepressants or dopaminergic substances or with recent alcohol abuse, correlations were weaker, suggesting a confounding influence, unlike other possible confounders such as beta-blocker use or comorbid sleep apnoea.

CONCLUSIONS

In this large single-centre prospective observational study, we found evidence that DAT-binding ratios in patients with iRBD can be used to describe a continuum in the neurodegenerative process. Overlap with non-synucleinopathies and clinical α-synucleinopathies, however, precludes the use of DAT-binding ratios as a precise diagnostic marker. The parallel course of RWA metrics and DAT-binding ratios suggests in addition to existing data that RWA, part of the routine diagnostic workup in these patients, may represent a marker of progression. Based on our findings, we suggest ranges of RWA values to estimate whether patients are in an early, medium or advanced state within the prodromal phase of α-synucleinopathies, providing them with important information about time until possible conversion.

Manifestations of Intellectual Disability, Dystonia, and Parkinson's Disease in an Adult Patient with ARX Gene Mutation c.558_560dup p.(Pro187dup)

We describe a 38-year-old male patient with intellectual disability and progressive motor symptoms who lacked an etiological diagnosis for many years. Finally, clinical exome sequencing showed a likely pathogenic variant of the ARX gene suggesting Partington syndrome. His main symptoms were mild intellectual disability, severe kinetic apraxia, resting and action tremor, dysarthria, tonic pupils, constant dystonia of one upper limb, and focal dystonia in different parts of the body, axial rigidity, spasticity, epilepsy, and poor sleep. Another likely pathogenic gene variant was observed in the PKP2 gene and is in accordance with the observed early cardiomyopathy. Single-photon emission computed tomography imaging of dopamine transporters showed a reduced signal in the basal ganglia consistent with Parkinson's disease. Therapies with a variable number of drugs, including antiparkinsonian medications, have yielded poor responses. Our case report extends the picture of the adult phenotype of Partington syndrome.

Deep Brain Stimulation in the Treatment of Parkinson’s Disease

Parkinson’s disease (PD) is a common progressive neurodegenerative movement disorder. The cardinal feature of Parkinson's is neuronal degeneration causing a dopamine deficit in the brain which leads to a host of clinical features in the patient. However, consensus over specific clinical criteria for diagnosis remains to be established. Parkinson’s does not have a cure yet, but a variety of diagnostic and treatment protocols have been developed over the years with a primary focus on pharmacological therapy. Anti-parkinsonian drugs such as levodopa lose their efficacy over time and are needed in higher doses as the disease inevitably progresses. An alternative to pharmacological therapy is deep brain stimulation (DBS). Deep brain stimulation involves transcranial placement of unilateral or bilateral leads (wires) most commonly in the sub-thalamic nucleus or the globus pallidus interna of the brain by stereotactic surgery. Given the multiple hypotheses explaining the different effects of DBS with sometimes conflicting mechanisms, it is difficult to pinpoint the exact way in which DBS operates. Nevertheless, it has proven to be significantly effective. DBS, although being a cost-effective treatment measure for Parkinson's patients, is not without limitations. A careful selection of patients is required preoperatively that determines the response and tolerance to the therapy in patients. This review aims to summarize the current literature on DBS in Parkinson's with a focus on the hypothesized mechanisms, selection criteria, advantages and its limitations.

Image-guided/improved diseases management: From immune-strategies and beyond

Timely and accurate assessment and diagnosis are extremely important and beneficial for all diseases, especially for some of the major human disease, such as cancers, cardiovascular diseases, infectious diseases, and neurodegenerative diseases. Limited by the variable disease microenvironment, early imperceptible symptoms, complex immune system interactions, and delayed clinical phenotypes, disease diagnosis and treatment are difficult in most cases. Molecular imaging (MI) techniques can track therapeutic drugs and disease sites in vivo and in vitro in a non-invasive, real-time and visible strategies. Comprehensive visual imaging and quantitative analysis based on different levels can help to clarify the disease process, pathogenesis, drug pharmacokinetics, and further evaluate the therapeutic effects. This review summarizes the application of different MI techniques in the diagnosis and treatment of these major human diseases. It is hoped to shed a light on the development of related technologies and fields.

Neuroprotection and Disease Modification by Astrocytes and Microglia in Parkinson Disease

Oxidative stress and neuroinflammation are common bases for disease onset and progression in many neurodegenerative diseases. In Parkinson disease, which is characterized by the degeneration of dopaminergic neurons resulting in dopamine depletion, the pathogenesis differs between hereditary and solitary disease forms and is often unclear. In addition to the pathogenicity of alpha-synuclein as a pathological disease marker, the involvement of dopamine itself and its interactions with glial cells (astrocyte or microglia) have attracted attention. Pacemaking activity, which is a hallmark of dopaminergic neurons, is essential for the homeostatic maintenance of adequate dopamine concentrations in the synaptic cleft, but it imposes a burden on mitochondrial oxidative glucose metabolism, leading to reactive oxygen species production. Astrocytes provide endogenous neuroprotection to the brain by producing and releasing antioxidants in response to oxidative stress. Additionally, the protective function of astrocytes can be modified by microglia. Some types of microglia themselves are thought to exacerbate Parkinson disease by releasing pro-inflammatory factors (M1 microglia). Although these inflammatory microglia may further trigger the inflammatory conversion of astrocytes, microglia may induce astrocytic neuroprotective effects (A2 astrocytes) simultaneously. Interestingly, both astrocytes and microglia express dopamine receptors, which are upregulated in the presence of neuroinflammation. The anti-inflammatory effects of dopamine receptor stimulation are also attracting attention because the functions of astrocytes and microglia are greatly affected by both dopamine depletion and therapeutic dopamine replacement in Parkinson disease. In this review article, we will focus on the antioxidative and anti-inflammatory effects of astrocytes and their synergism with microglia and dopamine.

Dopamine Transporter Imaging, Current Status of a Potential Biomarker: A Comprehensive Review

A major goal of current clinical research in Parkinson's disease (PD) is the validation and standardization of biomarkers enabling early diagnosis, predicting outcomes, understanding PD pathophysiology, and demonstrating target engagement in clinical trials. Molecular imaging with specific dopamine-related tracers offers a practical indirect imaging biomarker of PD, serving as a powerful tool to assess the status of presynaptic nigrostriatal terminals. In this review we provide an update on the dopamine transporter (DAT) imaging in PD and translate recent findings to potentially valuable clinical practice applications. The role of DAT imaging as diagnostic, preclinical and predictive biomarker is discussed, especially in view of recent evidence questioning the incontrovertible correlation between striatal DAT binding and nigral cell or axon counts.

Predicting Neuropsychiatric Symptoms of Parkinson's Disease with Measures of Striatal Dopaminergic Deficiency

BACKGROUND

The role of nigrostriatal dopaminergic neurons degeneration is well established in the pathophysiology of Parkinson's disease. However, it is unclear if and how the degeneration of the dopamine pathways affects the manifestation of the neuropsychiatric symptoms (NPS) of Parkinson's Disease (PD). Dopamine transporter (DAT) imaging, a technique to measure the reduction in dopamine transporters is increasingly used as a tool in the diagnosis of PD.

METHODS

In this study, we examine if the baseline dopamine transporter density in the striatum measured by the Striatal Binding Ratio (SBR) is associated with the longitudinal onset and/or progression of NPS in PD as measured by part 1 of Movement Disorder Society - Unified Parkinson's Disease Rating Scale, over four years. Data of patients with PD and an abnormal screening present on 123I-ioflupane single-proton emission computed tomography were obtained from Parkinson's Progression Markers Initiative (PPMI) database. Latent Growth Modeling (LGM), a statistical technique that can model the change over time while considering the variability in the rate of change at the individual level, was used to examine the progression of NPS over time.

RESULTS

The results indicate the SBR did not correlate with the baseline NPS but did correlate with the rate of change of NPS (p<0.001) over the next four years, even after eliminating age-related variance, which can be a significant confounding factor.

CONCLUSION

In conclusion, this study showed gradual worsening in NPS in patients with Parkinson's disease, which inversely correlates with the density of the dopamine transporters as measured by SBR at baseline.

123I-Ioflupane SPECT and 18F-FDG PET Combined Use in the Characterization of Movement and Cognitive Associated Disorders in Neurodegenerative Diseases

BACKGROUND

Both movement (MD) and cognitive (CD) disorders can occur associated in some neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD).

OBJECTIVE

We further investigated the usefulness of 123I-Ioflupane SPECT and 18F-FDG PET combined use in patients with these disorders in the early stage.

METHODS

We retrospectively enrolled twenty-five consecutive patients with MD and CD clinical symptoms of recent appearance. All patients had undergone neurologic examination, neuropsychological tests, and magnetic resonance imaging. 123I-Ioflupane SPECT was performed in all cases, followed by 18F-FDG PET two weeks later. In the two procedures, both qualitative (QL) and quantitative (QN) image analyses were determined.

RESULTS

In patients with both 123I-Ioflupane SPECT and 18F-FDG PET pathologic data, associated dopaminergic and cognitive impairments were confirmed in 56% of cases. Pathologic SPECT with normal PET in 16% of cases could diagnose MD and exclude an associated CD, despite clinical symptoms. On the contrary, normal SPECT with pathologic PET in 28% of cases could exclude basal ganglia damage while confirming CD. QN 123I-Ioflupane SPECT analysis showed better performance than QL since QN correctly characterized two cases of MD with normal QL. Moreover, correct classification of normal metabolism was made only by QN analysis of 18F-FDG PET in four cases, despite suspect areas of hypometabolism at QL.

CONCLUSION

The combined use of these imaging procedures proved a reliable diagnostic tool to accurately identify and characterize MD and CD in early stage. QN analysis was effective in supporting QL evaluation, and its routine use is suggested, especially with inconclusive QL.

Impact of DaTscan Imaging on Clinical Decision Making in Clinically Uncertain Parkinson's Disease

Background:

The diagnosis of Parkinson’s disease (PD) is primarily clinical, but in cases of diagnostic uncertainty, evaluation of nigrostriatal dopaminergic degeneration (NSDD) by imaging of the dopamine transporter using DaTscan with single-photon emission computed tomography (SPECT) brain imaging may be helpful.

Objective/Methods:

In the current paper, we describe clinical scenarios for which DaTscan imaging was used in a prospective case series of 201 consecutive patients in whom a movement disorder specialist ordered DaTscan imaging to clarify NSDD. We describe the impact of DaTscan results on changing or confirming pre-DaTscan clinical diagnosis and on post-DaTscan treatment changes.

Results/Conclusion:

DaTscan imaging can be useful in several clinical scenarios to determine if NSDD is present. These include in patients with early subtle symptoms, suboptimal response to levodopa, prominent action tremor, drug-induced parkinsonism, and in patients with lower extremity or other less common parkinsonism clinical presentations. We also found DaTscan imaging to be useful to determine underlying NSDD in patients with PD diagnosis for 3-5 years but without apparent clinical progression or development of motor fluctuations. Overall, in 201 consecutive patients with clinically questionable NSDD, DaTscan was abnormal in 58.7% of patients, normal in 37.8%, and inconclusive in 3.5%. DaTscan imaging changed clinical diagnosis in 39.8% of patients and led to medication therapy changes in 70.1% of patients.

[18F]PR04.MZ PET/CT Imaging for Evaluation of Nigrostriatal Neuron Integrity in Patients With Parkinson Disease

INTRODUCTION

Degeneration of dopaminergic, nigrostriatal neurons is the hallmark of Parkinson disease (PD), and PET quantification of dopamine transporters is a widely accepted method for differential diagnosis between idiopathic PD and essential tremor. [18F]PR04.MZ is a new PET tracer with excellent imaging properties allowing for precise quantification of striatal and extrastriatal dopamine transporter. Here we describe our initial experience with [18F]PR04.MZ PET/CT in a larger cohort of healthy controls and PD patients as a proof-of-concept study for this tracer.

METHODS

Eighteen healthy subjects, 19 early PD patients (Hoehn-Yahr I-II), and 13 moderate-advanced PD patients (Hoehn-Yahr III-IV) underwent static PET/CT scans 60 to 90 minutes after injection of 5.16 ± 1.03 mCi (191 ± 38 MBq) [18F]PR04.MZ. Specific binding ratios (SBRs) were calculated for caudate nucleus, anterior putamen, posterior putamen, substantia nigra (SNpc), compared between different groups and correlated with clinical ratings.

RESULTS

[18F]PR04.MZ showed very high and specific uptake in the putamen, caudate, and substantia nigra pars compacta and very low nonspecific binding in other brain regions, and SBR values for the control group were 22.3 ± 4.1, 19.1 ± 3.5, and 5.4 ± 1.2, respectively. A reduction of SBR values was observed in all regions and in both initial and moderate PD, ranging from 35% to 89% (P < 0.001). The observed pattern of reduction was posterior putamen > anterior putamen > substantia nigra pars compacta > caudate, with contralateral posterior putamen being the most affected region. Rostrocaudal depletion gradient was evident in all PD patients and progression correlated with motor manifestations.

CONCLUSIONS

[18F]PR04.MZ PET/CT is a highly sensitive imaging modality for the detection of dopaminergic deficit in nigrostriatal pathways in PD.

A Real-World Study of Cerebral 99mTc-TRODAT-1 Single-Photon Emission Computed Tomography (SPECT) Imaging of the Dopamine Transporter in Patients with Parkinson Disease from a Tertiary Hospital in Brazil

Background

Studies on the routine clinical use of dopamine transporter (DAT) imaging have largely been conducted in Europe and the United States. In this real-world study, we investigated the use of cerebral 99mTc-TRODAT-1 SPECT imaging of DAT in patients with Parkinson disease (PD) at a tertiary hospital in Brazil.

Material/Methods

We included 119 patients with suspected PD or clinically unclear parkinsonism who underwent brain scintigraphy with 99mTc-TRODAT-1 during a 3-year period. Additionally, a brief interview was conducted with the physician who requested the scan to determine the usefulness of the method in clinical decision-making.

Results

Regarding the scan requests, most were intended to evaluate or confirm dopaminergic denervation (69%), distinguish PD from essential tremor (10%), or distinguish degenerative parkinsonism from drug-induced parkinsonism (6%). Data analysis showed that scintigraphy with 99mTc-TRODAT-1 was useful in 85% of cases, changing the management of 75% of the patients who underwent a scan. The majority of physicians who requested the scan were neurologists, and 54% were self-reported movement disorder specialists. An inappropriate use of DAT imaging was seen in 5% of cases.

Conclusions

This study demonstrated that brain scintigraphy with the DAT ligand 99mTc-TRODAT-1 may influence diagnostic or therapeutic interventions, meaning that Brazilian physicians who requested the exam have taken in vivo DAT results into account at the time of clinical decision-making.

Usefulness of PET With [18F]LBT-999 for the Evaluation of Presynaptic Dopaminergic Neuronal Loss in a Clinical Environment

Purpose: The density of the neuronal dopamine transporter (DAT) is directly correlated with the presynaptic dopaminergic system injury. In a first study, we evaluated the brain distribution and kinetics of [¹⁸F]LBT-999, a DAT PET radioligand, in a group of eight healthy subjects. Taking into account the results obtained in healthy volunteers, we wanted to evaluate whether the loss of presynaptic striatal dopaminergic fibers could be estimated, under routine clinical conditions, using [¹⁸F]LBT-999 and a short PET acquisition.

Materials and methods: Six patients with Parkinson's disease (PD) were compared with eight controls. Eighty-nine minutes of dynamic PET following an intravenous injection of [¹⁸F]LBT-999 were acquired. Using regions of interest for striatal nuclei, substantia nigra (SN), cerebellum, and occipital cortex, defined over each T1 3D MRI, time–activity curves (TACs) were obtained. From TACs, binding potential (BP_ND) using the simplified reference tissue model and distribution volume ratios (DVRs) using Logan graphical analysis were calculated. Ratios obtained for a 10-min image, acquired between 30 and 40 min post-injection, were also calculated. Cerebellum activity was used as non-specific reference region.

Results: In PD patients and as expected, striatal uptake was lower than in controls which is confirmed by BP_ND, DVR, and ratios calculated for both striatal nuclei and SN, significantly inferior in PD patients compared with controls (p < 0.001).

Conclusions: PET with [¹⁸F]LBT-999 could be an alternative to assess dopaminergic presynaptic injury in a clinical environment using a single 10 min acquisition.

Diagnosis and Treatment of Parkinson Disease: A Review

IMPORTANCE

Parkinson disease is the most common form of parkinsonism, a group of neurological disorders with Parkinson disease-like movement problems such as rigidity, slowness, and tremor. More than 6 million individuals worldwide have Parkinson disease.

OBSERVATIONS

Diagnosis of Parkinson disease is based on history and examination. History can include prodromal features (eg, rapid eye movement sleep behavior disorder, hyposmia, constipation), characteristic movement difficulty (eg, tremor, stiffness, slowness), and psychological or cognitive problems (eg, cognitive decline, depression, anxiety). Examination typically demonstrates bradykinesia with tremor, rigidity, or both. Dopamine transporter single-photon emission computed tomography can improve the accuracy of diagnosis when the presence of parkinsonism is uncertain. Parkinson disease has multiple disease variants with different prognoses. Individuals with a diffuse malignant subtype (9%-16% of individuals with Parkinson disease) have prominent early motor and nonmotor symptoms, poor response to medication, and faster disease progression. Individuals with mild motor-predominant Parkinson disease (49%-53% of individuals with Parkinson disease) have mild symptoms, a good response to dopaminergic medications (eg, carbidopa-levodopa, dopamine agonists), and slower disease progression. Other individuals have an intermediate subtype. For all patients with Parkinson disease, treatment is symptomatic, focused on improvement in motor (eg, tremor, rigidity, bradykinesia) and nonmotor (eg, constipation, cognition, mood, sleep) signs and symptoms. No disease-modifying pharmacologic treatments are available. Dopamine-based therapies typically help initial motor symptoms. Nonmotor symptoms require nondopaminergic approaches (eg, selective serotonin reuptake inhibitors for psychiatric symptoms, cholinesterase inhibitors for cognition). Rehabilitative therapy and exercise complement pharmacologic treatments. Individuals experiencing complications, such as worsening symptoms and functional impairment when a medication dose wears off ("off periods"), medication-resistant tremor, and dyskinesias, benefit from advanced treatments such as therapy with levodopa-carbidopa enteral suspension or deep brain stimulation. Palliative care is part of Parkinson disease management.

CONCLUSIONS AND RELEVANCE

Parkinson disease is a heterogeneous disease with rapidly and slowly progressive forms. Treatment involves pharmacologic approaches (typically with levodopa preparations prescribed with or without other medications) and nonpharmacologic approaches (such as exercise and physical, occupational, and speech therapies). Approaches such as deep brain stimulation and treatment with levodopa-carbidopa enteral suspension can help individuals with medication-resistant tremor, worsening symptoms when the medication wears off, and dyskinesias.

Parkinson's Disease

The diagnosis of Parkinson disease (PD) is based on the presence of bradykinesia and either resting tremor or rigidity and there should be no features from the history or examination to suggest an alternative cause of parkinsonism. In addition to the motor manifestations of PD, there is a long list of nonmotor symptoms, several of which occur before motor signs and are considered "prodromal" PD. These are classified as neuropsychiatric, autonomic, sleep, and sensory. There are many medical options for the treatment of PD but levodopa remains the mainstay. Deep brain stimulation and other advanced therapies are also available.