Distinguishing Parkinson's disease and essential tremor with transcranial sonography

Systematic review-based guideline "Parkinson's disease" of the German Society of Neurology: diagnostic use of transcranial sonography

BACKGROUND AND OBJECTIVE

Transcranial brain parenchyma sonography (TCS) has been recommended as a tool for the early and differential diagnosis of Parkinson's disease (PD) in German and European clinical guidelines. Still, the brain structures to be examined for the diagnostic questions and the requirements for being a qualified investigator were not specified in detail. These issues have now been addressed in the 2023 update of the clinical guideline on PD by the German Society of Neurology (DGN).

METHODS

The recommendations were based on a systematic literature review following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

RESULTS

Three diagnostic questions were defined: (1) What is the accuracy of TCS in the differential diagnosis of PD versus atypical and secondary Parkinsonian syndromes? (2) What is the accuracy of TCS in the differential diagnosis of PD versus essential tremor? (3) What is the accuracy of TCS in the diagnosis of PD in persons with typical early symptoms, compared with the diagnosis established by clinical follow-up? The brain structures to be assessed and the level of recommendation were formulated for these questions. The training requirements for being regarded as qualified TCS investigator were stipulated by the responsible medical societies (German Society of Ultrasound in Medicine, DEGUM; German Society for Clinical Neurophysiology and Functional Imaging, DGKN). Finally, the recommendations for these diagnostic questions reached strong consensus (each ≥ 97%) of the guideline committee. Here, the details of review and recommendations are presented.

CONCLUSION

The updated guideline clarifies the diagnostic uses and limitations of TCS in PD.

Brain structure comparison among Parkinson disease, essential tremor, and healthy controls using 7T MRI

Both Parkinson disease (PD) and Essential tremor (ET) are movement disorders causing tremors in elderly individuals. Although PD and ET are different disease, they often present with similar initial symptoms, making their differentiation challenging with magnetic resonance imaging (MRI) techniques. This study aimed to identify structural brain differences among PD, ET, and health controls (HCs) using 7-Tesla (T) MRI. We assessed the whole-brain parcellation in gray matter volume, thickness, subcortical volume, and small regions of basal ganglia in PD (n = 18), ET (n = 15), and HCs (n = 18), who were matched for age and sex. Brain structure analysis was performed automatic segmentation through Freesurfer software. Small regions of basal ganglia were manually segmented by ITK-SNAP. Additionally, we examined the associations between clinical indicators (symptom duration, unified Parkinson diseases rating scale (UPDRS), and clinical rating scale for tremor (CRST)) and brain structure. PD showed a significant reduction in gray matter volume in the postcentral region compared to ET. ET showed a significant reduction in cerebellum volume compared to HCs. There was a negative correlation between CRST scores (B and C) and gray matter thickness in right superior frontal in ET. This study demonstrated potential of 7T MRI in differentiating brain structure differences among PD, ET, and HCs. Specific findings, such as parietal lobe atrophy in PD compared to ET and cerebellum atrophy in ET compared to HCs, the importance of advanced imaging techniques in accurately diagnosing and distinguishing between movement disorders that present with similar initial symptoms.

Differentiating Parkinson’s Disease from Essential Tremor Using Transcranial Sonography: A Systematic Review and Meta-Analysis

Background:

Essential tremor (ET) and the tremor of Parkinson’s disease (PD) are the most common tremors encountered in clinical practice. Especially in early disease stages, discrimination between the tremors of ET and PD can be challenging.

Objective:

The aim of this study was to evaluate the diagnostic accuracy of transcranial sonography (TCS) of the substantia nigra echogenicity for differential diagnosis of PD versus ET.

Methods:

A systematic PubMed search identified 512 studies. Sensitivity and specificity of substantia nigra hyperechogenicity was estimated. Data synthesis was carried applying a random effects bivariate binomial model. To assess study quality and risk of bias, the QUADAS-2 tool was used.

Results:

Eighteen studies were suitable for analysis including 1,264 PD and 824 ET patients. The meta analysis showed a pooled sensitivity and specificity for TCS in the differential diagnosis of PD versus ET of 84.6% (95% CI, 79.4–88.6%) and 83.9% (95% CI, 78.4–88.2%), respectively. Furthermore, we found nearly similar results in sensitivity and specificity comparing TCS and DaTSCAN in a subgroup-analysis of three studies using both diagnostic tools including 107 patients with PD and 62 patients with ET. The QUADAS-2 toolbox revealed a high risk of bias regarding the methodological quality of patient selection.

Conclusion:

Substantia nigra hyperechogenicity yield high diagnostic accuracy for the discrimination of PD from ET. TCS is a low cost, widely available, non-invasive marker without radiation Therefore, a diagnostic algorithm based on presence or absence of substantia nigra hyperechogenicity is highly warranted.

Can Plasma α-Synuclein Help Us to Differentiate Parkinson's Disease from Essential Tremor?

Background

Studies have revealed controversial results regarding the diagnostic accuracy of plasma α-synuclein levels in patients with Parkinson's disease (PD). This study was aimed to analyze the diagnostic accuracy of plasma α-synuclein in PD versus healthy controls and patients with essential tremor (ET).

Methods

In this cross-sectional study, we included de novo (n = 19) and advanced PD patients [OFF (n = 33), and On (n = 35) states], patients with ET (n = 19), and controls (n = 35). The total plasma α-synuclein levels were determined using an ELISA sandwich method. We performed adjusted multivariate regression analysis to estimate the association of α-synuclein levels with group conditions [controls, ET, and de novo, OFF and ON-PD]. We studied the diagnostic accuracy of plasma α-synuclein using the area under the curve (AUC).

Results

The plasma α-synuclein levels were higher in controls compared to PD and ET (p < 0.0001), discriminating de novo PD from controls (AUC = 0.74, 95% CI 0.60-0.89), with a trend towards in advanced PD (OFF state) from ET (AUC = 0.69, 95% CI 0.53-0.84).

Conclusions

This is the first study examining and comparing plasma α-synuclein levels in ET vs. PD and controls. Preliminary findings suggest that plasma α-synuclein levels might help to discriminate de novo and advanced PD from controls and ET.

Multi-Dimensional, Short-Timescale Quantification of Parkinson's Disease and Essential Tremor Motor Dysfunction

Introduction: Parkinson's disease (PD) is a progressive movement disorder characterized by heterogenous motor dysfunction with fluctuations in severity. Objective, short-timescale characterization of this dysfunction is necessary as therapies become increasingly adaptive.

Objectives: This study aims to characterize a novel, naturalistic, and goal-directed tablet-based task and complementary analysis protocol designed to characterize the motor features of PD.

Methods: A total of 26 patients with PD and without deep brain stimulation (DBS), 20 control subjects, and eight patients with PD and with DBS completed the task. Eight metrics, each designed to capture an aspect of motor dysfunction in PD, were calculated from 1-second, non-overlapping epochs of the raw positional and pressure data captured during task completion. These metrics were used to generate a classifier using a support vector machine (SVM) model to produce a unifying, scalar “motor error score” (MES). The data generated from these patients with PD were compared to same-day standard clinical assessments. Additionally, these data were compared to analogous data generated from a separate group of 12 patients with essential tremor (ET) to assess the task's specificity for different movement disorders. Finally, an SVM model was generated for each of the eight patients with PD and with DBS to differentiate between their motor dysfunction in the “DBS On” and “DBS Off” stimulation states.

Results: The eight metrics calculated from the raw positional and force data captured during task completion were non-redundant. MES generated by the SVM analysis protocol showed a strong correlation with MDS-UPDRS-III scores assigned by movement disorder specialists. Analysis of the relative contributions of each of the eight metrics showed a significant difference between the motor dysfunction of PD and ET. Much of this difference was attributable to the homogenous, tremor-dominant phenotype of ET motor dysfunction. Finally, in individual patients with PD with DBS, task performance and subsequent SVM classification effectively differentiated between the “DBS On” and “DBS Off” stimulation states.

Conclusion: This tablet-based task and analysis protocol correlated strongly with expert clinical assessments of PD motor dysfunction. Additionally, the task showed specificity for PD when compared to ET, another common movement disorder. This specificity was driven by the relative heterogeneity of motor dysfunction of PD compared to ET. Finally, the task was able to distinguish between the “DBS On” and “DBS Off” states within single patients with PD. This task provides temporally-precise and specific information about motor dysfunction in at least two movement disorders that could feasibly correlate to neural activity.

Prodromal Markers of Parkinson's Disease in Patients With Essential Tremor

Background: Essential tremor (ET) is manifested as an isolated syndrome of bilateral upper limb action tremor. Parkinson's disease (PD) is the second most common neurodegenerative disease, with typical motor symptoms of bradykinesia, rigidity, and resting tremor. ET-PD describes the new-onset of PD in ET patients. Recently, numerous studies on epidemiology, genetics, pathology, clinical features, and neuroimaging studies are challenging the idea that ET is an isolated disease, suggesting that patients with ET have the tendency to develop PD. Methods: In this review article, we collected recent findings that reveal prodromal markers of PD in patients with ET. Results: Substantia nigra hyperechogenicity serves as a prodromal marker for predicting the development of PD in patients with ET and provides a reference for therapeutic strategies. Additional potential markers include other neuroimaging, clinical features, heart rate, and genetics, whereas others lack sufficient evidence. Conclusion: In consideration of the limited research of PD in patients with ET, we are still far from revealing the prodromal markers. However, from the existing follow-up studies on ET patients, Substantia nigra hyperechogenicity may enable further exploration of the relationship between ET and PD and the search for pathogenesis-based therapies.

New markers in Parkinson's disease

Parkinson's disease (PD) is a chronic, debilitating neurodegenerative disorder characterized clinically by a variety of progressive motor and nonmotor symptoms. Currently, there is a dearth of diagnostic tools available to predict, diagnose or mitigate disease risk or progression, leading to a challenging dilemma within the healthcare management system. The search for a reliable biomarker for PD that reflects underlying pathology is a high priority in PD research. Currently, there is no reliable single biomarker predictive of risk for motor and cognitive decline, and there have been few longitudinal studies of temporal progression. A combination of multiple biomarkers might facilitate earlier diagnosis and more accurate prognosis in PD. In this review, we focus on the recent developments of serial biomarkers for PD from a variety of clinical, biochemical, genetic and neuroimaging perspectives.

Transcranial brain sonography for Parkinsonian syndromes

Substantia nigra (SN) hyperechogenicity has been proved to be a characteristic finding for idiopathic Parkinson's disease (PD), occurring in more than 90% of the patients. This echofeature is owed to increased amounts of iron in the SN region and reflects a functional impairment of the nigrostriatal dopaminergic system. In a prospective blinded study in which a group of patients with early mild signs and symptoms of unclear Parkinsonism were followed until a definite clinical diagnosis of PD, the hyperechogenicity of the SN was demonstrated to be highly predictive of a final diagnosis of PD. For the diagnosis of PD in individuals with early motor symptoms, both the sensitivity and positive predictive value of SN hyperechogenicity were higher than 90% and both the specificity and negative predictive value were higher than 80%. For early differential diagnosis between PD and atypical Parkinsonian syndromes, the sensitivity and positive predictive value of SN hyperechogenicity were higher than 90%, and both the specificity and negative predictive value were higher than 80%. The diagnostic specificity is increased if combining the TCS findings of SN, lenticular nucleus and third ventricle. In asymptomatic adult subjects, SN hyperechogenicity, at least unilaterally, indicates a subclinical functional insufficiency of the nigrostriatal dopaminergic system. Recent papers revealed that SN hyperechogenicity might suggest preclinical PD. Reduced echogenicity of midbrain raphe indicates increased risk of depression in PD patients. Caudate nucleus hyperechogenicity has been associated with drug-induced psychosis, and frontal horn dilatation >20 mm with dementia. Transcranial brain sonography can be a valuable tool for managing patients with Parkinsonian signs and symptoms.

A transcranial sonography study of brainstem and its association with depression in idiopathic generalized epilepsy with tonic-clonic seizures

Brainstem raphe (BR) hypoechogenicity in transcranial sonography (TCS) has been depicted in patients with depression. But, up to date, the association of BR alterations in TCS with depression in patients with epilepsy has never been reported. This study was to investigate the possible role of BR examination via TCS in patients with idiopathic generalized epilepsy with tonic-clonic seizures (IGE-TCS) and depression. Forty-six patients with IGE-TCS and 45 healthy controls were recruited. Echogenicity of the caudate nuclei (CN), lentiform nuclei (LN), substantia nigra (SN), and BR and widths of the lateral ventricle (LV) frontal horns and the third ventricle (TV) were assessed via TCS. The determination of depression was based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), and depression severity measured by Chinese version Neurological Disorders Depression Inventory for Epilepsy (C-NDDI-E) and Beck Depression Inventory-II (BDI-II). The width of TV in patients with epilepsy was found significantly larger than that in healthy controls (p = 0.001), but there was no significant difference in TV width between patients with IGE-TCS with and without depression. There were no significant differences between patients with IGE-TCS and healthy controls in LV frontal horn width, as well as in SN, CN, LN, and BR echogenicity. Here, it seems that patients with IGE-TCS were detected with smaller SN echogenic area compared with controls though they had no statistical significance. Patients with IGE-TCS with hypoechogenic BR had significantly higher C-NDDI-E and BDI-II scores than those with normal BR signal, and most patients with IGE-TCS with depression exhibited hypoechogenic BR, but few patients with IGE-TCS without depression exhibited hypoechogenic BR. In conclusion, BR echogenic signal alterations in TCS can be a biomarker for depression in epilepsy, but it might not be associated with epilepsy itself. The alterations of SN echogenic area and TV width in TCS may reflect a potential role of SN and diencephalon structure in the pathogenesis of epilepsy, which needs to be further elucidated.

Substantia nigra hyperechogenicity in essential tremor and Parkinson's disease: a longitudinal study

BACKGROUND AND PURPOSE

Essential tremor (ET) and Parkinson's disease (PD) sometimes overlap in their clinical expression with ET preceding PD onset, often leading to misdiagnosis. Transcranial sonography (TCS) has been shown to be a valid and non-invasive diagnostic tool to identify early idiopathic PD and to differentiate it from ET. The purpose of this study was to investigate the relevance of substantia nigra hyperechogenicity in patients with ET.

METHODS

A total of 138 patients (79 with PD, 59 with ET) and 50 matched controls underwent TCS examination at baseline. All patients were followed in a 3-year longitudinal assessment.

RESULTS

A total of 10 subjects were excluded from the analysis due to the bilateral absence of a temporal acoustic window. During the follow-up period, 11 of the patients with ET developed new-onset parkinsonian features, without fulfilling criteria for PD diagnosis (ET+). Nine patients developed clinical features meeting diagnostic criteria for probable PD (ET-PD). Patients with ET- did not develop parkinsonian features. For each group, the maximum size of the substantia nigra hyperechogenicity was as follows: 5.62 ± 5.40 mm² in the control group, 19.02 ± 14.27 mm² in patients with PD, 9.15 ± 11.26 mm² in patients with ET-, 20.05 ± 13.78 mm² in patients with ET+ and 20.13 ± 13.51 mm² in patients with ET-PD. ET-PD maximum values were significantly different from controls. Maximum values in patients with ET+ were different from both controls and patients with ET-.

CONCLUSION

Substantia nigra hyperechogenicity in ET seems to represent a risk marker for developing early parkinsonian symptoms or signs in the 3 years following TCS assessment.

Hypoechogenicity of brainstem raphe correlates with depression in migraine patients

Background

Brainstem raphe (BR) hypoechogenicity in transcranial sonography (TCS) has been depicted in patients with major depression (MD) and in depressed patients with different neurodegenerative diseases. But, up to date, the association of BR alterations in TCS with depression in migraineurs has never been reported. This study was to investigate the possible role of BR examination via TCS in migraineurs with depression.

Methods

Forty two migraine without aura (MwoA) patients and 40 healthy controls were recruited. Echogenicity of lentiform nuclei (LN), caudate nuclei (CN), substantia nigra (SN) and brainstem raphe (BR) and width of the frontal horns of the lateral ventricles and the third ventricle were assessed with TCS. The diagnosis of depression was based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders IV (DSM –IV), and the severity of depression was measured by Hamilton Rating Scale for Depression (HAM-D) and Hospital Anxiety and Depression Scale depression subscale (HADS-D).

Results

There were no significant differences between migraineurs and controls in the width of frontal horn of the lateral ventricle (p = 0.955), width of third ventricle (p = 0.129) as well as in the echogenicity of SN (p = 0.942), CN (p = 0.053), LN (p = 0.052) and BR (p = 0.677). Here, it seems that more migraineurs were detected with increased echogenecity of CN and LN compared with controls (33.3% versus 15.0% for CN, 19.0% versus 5.0% for LN) though they had no statistical significance. Patients with hypoechogenic BR had significantly higher HAM-D and HADS-D scores than those with normal BR signal (p = 0.000 for both HAM-D and HADS-D), and most (83.33%) migraineurs with depression exhibited hypoechogenic raphe but none (0.00%) of the migraineurs without depression exhibited hypoechogenic raphe (p = 0.000).

Conlusions

TCS signal alteration of BR can be a biomarker for depression in migraine but it is not associated with migraine headache itself. LN and CN alterations in TCS may reflect a potential role of them in the pathogenesis of migraine, which needs to be further elucidated.

Combined Visualization of Nigrosome-1 and Neuromelanin in the Substantia Nigra Using 3T MRI for the Differential Diagnosis of Essential Tremor and de novo Parkinson's Disease

Differentiating early-stage Parkinson's disease (PD) from essential tremor (ET) remains challenging. In the current study, we aimed to evaluate whether visual analyses of neuromelanin-sensitive magnetic resonance imaging (NM-MRI) combined with nigrosome-1 (N1) imaging using quantitative susceptibility mapping (QSM) in the substantia nigra (SN) are of diagnostic value in the differentiation of de novo PD from untreated ET. Sixty-eight patients with de novo PD, 25 patients with untreated ET, and 34 control participants underwent NM-MRI and QSM. NM and N1 signals in the SN on MR images were visually evaluated using a 3-point ordinal scale. Receiver operating characteristic (ROC) analyses were performed to determine the diagnostic values of the visual ratings of NM and N1. The diagnostic values of the predicted probabilities were calculated via logistic regression analysis using the combination of NM and N1 visual ratings, as well as their quadratic items. The proportions of invisible NM and invisible N1 were significantly higher in the PD group than those in the ET and control groups (p < 0.001). The sensitivity/specificity for differentiating PD from ET was 0.882/0.800 for NM and 0.794/0.920 for N1, respectively. Combining the two biomarkers, the area under the curve (AUC) of the predicted probabilities was 0.935, and the sensitivity/specificity was 0.853/0.920 when the cutoff value was set to 0.704. Our findings demonstrate that visual analyses combing NM and N1 imaging in the SN may aid in differential diagnosis of PD and ET. Furthermore, our results suggest that patients with PD exhibit larger iron deposits in the SN than those with ET.

Echogenic alteration in the raphe nuclei measured by transcranial sonography in patients with Parkinson disease and depression

BACKGROUND

Recently, several studies using transcranial sonography (TCS) have demonstrated reduced echogenicity of the mesencephalic midline in unipolar depression and patients with comorbid depression and Parkinson disease (PD). However, there is no consensus on the conclusion that raphe nuclei (RN) hypoechogenicity is associated with depression in PD. The methods used in previous studies lack quantitative and objective indicators to some extent; therefore, the present study used the level of platelet 5-hydroxytryptamine (5-HT) as an objective indicator of depression. Additionally, the reason for the reduced echogenicity of the brainstem raphe is still unclear.

OBJECTIVES

The purpose of the present study was to assess the correlation between alterations in RN echogenicity and depressive symptoms in patients with PD using transcranial sonography (TCS). This information could provide a meaningful clinical reference for the antidiastole between depressive symptoms in PD and unipolar depression in patients with PD in whom depressive symptoms occur before motor symptoms.

METHODS

TCS was performed in patients with PD, patients with PD and depression, patients with depression and no PD, and healthy controls. Using the red nucleus as a reference, the RN was rated from grades 0 to 1 (grade 0: invisible, slightly echogenic, or interrupted RN; grade 1: hyperechogenicity in the RN observed as a continuous line).

RESULTS

The rate of abnormal RN (grade 0) was found to be 16.67% in patients with PD (5/30) and 14.29% in healthy controls (4/28). The presence of abnormal RN was significantly higher (χ = 15.983, P < .05) in patients with depression and PD (40%, 12/30) and in patients with depression only (58.33%, 14/24) than in those without depression and healthy controls. No correlation was found between RN changes and depression severity (P > .05). There were no statistical differences in the concentration of platelet serotonin among the 4 groups (P > .05).

CONCLUSIONS

TCS of the mesencephalic midline may be useful for detecting depression, which is an early symptom of PD. However, further neuropathological studies are needed to understand the principles underlying the use of platelet serotonin as a peripheral biomarker, as well as the connection between PD and depression.

Transcranial B-Mode Sonography in Movement Disorders

Applying a 2-4MHz probe at the temporal bone window transcranial B-mode sonography (TCS) enables the depiction of the brain parenchyma through the intact skull. Meanwhile it has been applied for the diagnosis and the differential diagnosis of movement disorders for decades. In the first part of this chapter, we summarize the technical requirements and describe the ultrasound method for optimal TCS examination. Imaging planes and the relevant structures are explained in detail. In the second part of the chapter, we focus on the role of substantia nigra hyperechogenicity for the diagnosis of Parkinson's disease (PD) and prodromal PD. In this part, we also mention the role of TCS in atypical and secondary Parkinsonian syndromes and other movement disorders. Summarizing all these information we explain how TCS can be helpful for the differential diagnosis of movement disorders. The current data show that TCS is an easily applicable and economic imaging method which can be used as an additional tool for the diagnosis of PD with a high sensitivity (>85%), specificity (>80%) and inter-rater reliability (>84%) as well as for the differential diagnosis of movement disorders. Lately, TCS has also been utilized in further areas such as the detection of individuals at risk for PD or the determination of electrode localization in patients with deep brain stimulation. An insufficient temporal bone window especially in the elderly and the necessity of an experienced investigator are limitations of this method.

Is transcranial sonography useful for diagnosing Parkinson's disease in clinical practice?

OBJECTIVE

Transcranial sonography (TCS) is an emerging ancillary examination for diagnosing Parkinson's disease (PD).

OBJECTIVE

To evaluate TCS features in patients with PD and its mimics, and establish their accuracy in predicting the final clinical diagnosis after follow-up.

METHODS

We retrospectively studied 85 patients with an initial clinical suspicion of PD, atypical parkinsonism or essential tremor, all of whom underwent TCS. Two specialists reviewed the follow-up clinical visit records and determined the final clinical diagnosis. The accuracy analysis of the TCS was determined using Bayesian statistical methods.

RESULTS

The finding of substantia nigra hyperechogenicity (> 20 mm2) showed high sensitivity (93.4%) and specificity (86.6%). The positive likelihood ratio showed 6.93-fold greater odds for diagnosing PD than an alternative condition when this finding was present.

CONCLUSIONS

This study revealed the practical usefulness of TCS in differentiating PD from its prevalent mimics when the clinical diagnosis was initially unclear.

Developments in the role of transcranial sonography for the differential diagnosis of parkinsonism

In the last two decades transcranial sonography (TCS) has developed as a valuable, supplementary tool in the diagnosis and differential diagnosis of movement disorders. In this review, we highlight recent evidence supporting TCS as a reliable method in the differential diagnosis of parkinsonism, combining substantia nigra (SN), basal ganglia and ventricular system findings. Moreover, several studies support SN hyperechogenicity as one of most important risk factors for Parkinson's disease (PD). The advantages of TCS include short investigation time, low cost and lack of radiation. Principal limitations are still the dependency on the bone window and operator experience. New automated algorithms may reduce the role of investigator skill in the assessment and interpretation, increasing TCS diagnostic reliability. Based on the convincing evidence available, the EFNS accredited the method of TCS a level A recommendation for supporting the diagnosis of PD and its differential diagnosis from secondary and atypical parkinsonism. An increasing number of training programmes is extending the use of this technique in clinical practice.

The predictive value of transcranial sonography in clinically diagnosed patients with early stage Parkinson's disease: comparison with DAT PET scans

Early and correct diagnosis of Parkinson's disease (PD) is critical for patient counseling and therapeutic management. The diagnostic accuracy of transcranial sonography of substantia nigra (SN-TCS) for early stage PD patients remains controversial. Dopamine transporter (DAT) imaging is sensitive to detect presynaptic dopamine neuronal dysfunction, and has been studied as a diagnostic tool for degenerative Parkinsonism. To investigate the predictive value of SN-TCS for the DAT PET scans in clinically diagnosed early stage PD patients, we performed the SN-TCS and DAT Positron Emission Computed Tomography (PET) imaging examinations on 53 patients. Using the DAT PET results as clinical gold standard, the sensitivity and specificity of TCS was 68.75% and 40% respectively. The positive predictive value (PPV) of an abnormal TCS for an abnormal PET scan was 91.67%. However, the negative predictive value (NPV) for a normal PET scan was only 11.76%. The false negative rate was 31.25%. In 35 patients, the result of the SN-TCD was in accordance with the result of the DAT PET scan (Kappa=0.042, P>0.05). The consistency between SN-TCS and PET scans was poor. We conclude that SN-TCS would not be used as a diagnostic tool for early stage PD patients. Negative result of TCS could not exclude the diagnosis of PD. Further tests like DAT-PET is needed for validation. On the other hand, positive SN-TCS will reduce the added diagnostic value of a presynaptic neuronimaging scan.

Transcranial sonography in Parkinson's disease

Transcranial sonography has become a useful tool in the differential diagnosis of parkinsonian syndromes. This is a non-invasive, low cost procedure. The main finding on transcranial sonography in patients with idiopathic Parkinson's disease is an increased echogenicity of the mesencephalic substantia nigra region. This hyperechogenicity is present in more than 90% of cases, and reflects a dysfunction in the dopaminergic nigrostriatal pathway. This study discussed how the hyperechogenicity of the substantia nigra may facilitate the differential diagnosis of parkinsonian syndromes.

How to measure substantia nigra hyperechogenicity in Parkinson disease: detailed guide with video

The detection of an enlarged echogenic size ("hyperechogenicity") of the substantia nigra on transcranial sonography is increasingly used for the early and differential diagnosis of Parkinson disease. However, the diagnostic value of substantia nigra sonography depends on the quality of its execution. This article with an accompanying video presents a step-by-step description and demonstration of ultrasound system settings, typical errors in assessment of the substantia nigra, planimetric measurement of substantia nigra echogenicity according to current guidelines, and its diagnostic implications in 2 exemplary patients with parkinsonism. Published cutoff values for grading substantia nigra hyperechogenicity with different ultrasound systems and novel technologies are reviewed.

EFNS/MDS-ES/ENS [corrected] recommendations for the diagnosis of Parkinson's disease

BACKGROUND

A Task Force was convened by the EFNS/MDS-ES Scientist Panel on Parkinson's disease (PD) and other movement disorders to systemically review relevant publications on the diagnosis of PD.

METHODS

Following the EFNS instruction for the preparation of neurological diagnostic guidelines, recommendation levels have been generated for diagnostic criteria and investigations.

RESULTS

For the clinical diagnosis, we recommend the use of the Queen Square Brain Bank criteria (Level B). Genetic testing for specific mutations is recommended on an individual basis (Level B), taking into account specific features (i.e. family history and age of onset). We recommend olfactory testing to differentiate PD from other parkinsonian disorders including recessive forms (Level A). Screening for pre-motor PD with olfactory testing requires additional tests due to limited specificity. Drug challenge tests are not recommended for the diagnosis in de novo parkinsonian patients. There is an insufficient evidence to support their role in the differential diagnosis between PD and other parkinsonian syndromes. We recommend an assessment of cognition and a screening for REM sleep behaviour disorder, psychotic manifestations and severe depression in the initial evaluation of suspected PD cases (Level A). Transcranial sonography is recommended for the differentiation of PD from atypical and secondary parkinsonian disorders (Level A), for the early diagnosis of PD and in the detection of subjects at risk for PD (Level A), although the technique is so far not universally used and requires some expertise. Because specificity of TCS for the development of PD is limited, TCS should be used in conjunction with other screening tests. Conventional magnetic resonance imaging and diffusion-weighted imaging at 1.5 T are recommended as neuroimaging tools that can support a diagnosis of multiple system atrophy (MSA) or progressive supranuclear palsy versus PD on the basis of regional atrophy and signal change as well as diffusivity patterns (Level A). DaTscan SPECT is registered in Europe and the United States for the differential diagnosis between degenerative parkinsonisms and essential tremor (Level A). More specifically, DaTscan is indicated in the presence of significant diagnostic uncertainty such as parkinsonism associated with neuroleptic exposure and atypical tremor manifestations such as isolated unilateral postural tremor. Studies of [(123) I]MIBG/SPECT cardiac uptake may be used to identify patients with PD versus controls and MSA patients (Level A). All other SPECT imaging studies do not fulfil registration standards and cannot be recommended for routine clinical use. At the moment, no conclusion can be drawn as to diagnostic efficacy of autonomic function tests, neurophysiological tests and positron emission tomography imaging in PD.

CONCLUSIONS

The diagnosis of PD is still largely based on the correct identification of its clinical features. Selected investigations (genetic, olfactory, and neuroimaging studies) have an ancillary role in confirming the diagnosis, and some of them could be possibly used in the near future to identify subjects in a pre-symptomatic phase of the disease.

Specificity and sensitivity of transcranial sonography of the substantia nigra in the diagnosis of Parkinson's disease: prospective cohort study in 196 patients

OBJECTIVE

Numerous ultrasound studies have suggested that a typical enlarged area of echogenicity in the substantia nigra (SN+) can help diagnose idiopathic Parkinson's disease (IPD). Almost all these studies were retrospective and involved patients with well-established diagnoses and long-disease duration. In this study the diagnostic accuracy of transcranial sonography (TCS) of the substantia nigra in the patient with an undiagnosed parkinsonian syndrome of recent onset has been evaluated.

DESIGN

Prospective cohort study for diagnostic accuracy.

SETTING

Neurology outpatient clinics of two teaching hospitals in the Netherlands.

PATIENTS

196 consecutive patients, who were referred to two neurology outpatient clinics for analysis of clinically unclear parkinsonism. Within 2 weeks of inclusion all patients also underwent a TCS and a (123)I-ioflupane Single Photon Emission CT (FP-CIT SPECT) scan of the brain (n=176).

OUTCOME MEASURES

After 2 years, patients were re-examined by two movement disorder specialist neurologists for a final clinical diagnosis, that served as a surrogate gold standard for our study.

RESULTS

Temporal acoustic windows were insufficient in 45 of 241 patients (18.67%). The final clinical diagnosis was IPD in 102 (52.0%) patients. Twenty-four (12.3%) patients were diagnosed with atypical parkinsonisms (APS) of which 8 (4.0%) multisystem atrophy (MSA), 6 (3.1%) progressive supranuclear palsy (PSP), 6 (3.1%) Lewy body dementia and 4 (2%) corticobasal degeneration. Twenty-one (10.7%) patients had a diagnosis of vascular parkinsonism, 20 (10.2%) essential tremor, 7 (3.6%) drug-induced parkinsonism and 22 (11.2%) patients had no parkinsonism but an alternative diagnosis. The sensitivity of a SN+ for the diagnosis IPD was 0.40 (CI 0.30 to 0.50) and the specificity 0.61 (CI 0.52 to 0.70). Hereby the positive predictive value (PPV) was 0.53 and the negative predictive value (NPV) 0.48. The sensitivity and specificity of FP-CIT SPECT scans for diagnosing IPD was 0.88 (CI 0.1 to 0.95) and 0.68 (CI 0.58 to 0.76) with a PPV of 0.75 and an NPV of 0.84.

CONCLUSIONS

The diagnostic accuracy of TCS in early stage Parkinson's disease is not sufficient for routine clinical use. CLINICALTRIALS.GOV IDENTIFIER: NCT0036819.

EMG signal morphology in essential tremor and Parkinson's disease

The aim of this work was to differentiate patients with essential tremor from patients with Parkinson's disease. The electromyographic signal from the biceps brachii muscle was measured during isometric tension from 17 patients with essential tremor, 35 patients with Parkinson's disease, and 40 healthy controls. The EMG signals were high pass filtered and divided to smaller segments from which histograms were calculated using 200 histogram bins. EMG signal histogram shape was analysed with a feature dimension reduction method, the principal component analysis, and the shape parameters were used to differentiate between different patient groups. The height of the histogram and the side difference between left and right hand were the best discriminators between essential tremor and Parkinson's disease groups. With this method, it was possible to discriminate 13/17 patients with essential tremor from 26/35 patients with Parkinson's disease and 14/17 patients with essential tremor from 29/40 healthy controls.

Specificity of transcranial sonography in parkinson spectrum disorders in comparison to degenerative cognitive syndromes

Background

Hyperechogenicity of the substantia nigra (SN+), detected by transcranial sonography (TCS), was reported as a characteristic finding in Parkinson's disease (PD), with high diagnostic accuracy values, when compared mainly to healthy controls or essential tremor (ET) group. However, some data is accumulating that the SN + could be detected in other neurodegenerative and even in non-neurodegenerative disorders too. Our aim was to estimate the diagnostic accuracy of TCS, mainly focusing on the specificity point, when applied to a range of the parkinsonian disorders, and comparing to the degenerative cognitive syndromes.

Methods

A prospective study was carried out at the Hospital of Lithuanian University of Health Sciences from January until September 2011. Initially, a TCS and clinical examination were performed on 258 patients and 76 controls. The General Electric Voluson 730 Expert ultrasound system was used. There were 12.8% of cases excluded with insufficient temporal bones, and 4.3% excluded with an unclear diagnosis. The studied sample consisted of the groups: PD (n = 71, 33.2%), ET (n = 58, 27.1%), PD and ET (n = 10, 4.7%), atypical parkinsonian syndromes (APS) (n = 3, 1.4%), hereditary neurodegenerative parkinsonism (HDP) (n = 3, 1.4%), secondary parkinsonism (SP) (n = 23, 10.8%), mild cognitive impairment (MCI) (n = 33, 15.4%), dementia (n = 13, 6.1%), and control (n = 71).

Results

There were 80.3% of PD patients at stages 1 & 2 according to Hoehn and Yahr. At the cut-off value of 0.20 cm² of the SN+, the sensitivity for PD was 94.3% and the specificity - 63.3% (ROC analysis, AUC 0.891), in comparison to the rest of the cohort. At the cut-off value of 0.26 cm², the sensitivity was 90% and the specificity 82.4%.

The estimations for the lowest specificity for PD, in comparison to the latter subgroups (at the cut-off values of 0.20 cm² and 0.26 cm², respectively) were: 0% and 33.3% to APS, 33.3% and 66.7% to HDP, 34.8% and 69.6% to SP, 55.2% and 82.8% to ET, 75% and 91.7% to dementia.

Conclusions

The high sensitivity of the test could be employed as a valuable screening tool. But TCS is more useful as a supplementary diagnostic method, due to the specificity values not being comprehensive.

Transcranial sonography (TCS) in Parkinson's disease (PD) and essential tremor (ET) in relation with putative premotor symptoms of PD

BACKGROUND

Hyperechogenicity of substantia nigra (SN+) is a common finding in transcranial ultrasound studies of parkinsonian patients. However, this feature is also found in 13-16% of ET patients. The possible links between ET and PD are of special interest, particularly with the familial aggregated data supporting this association. However, few studies have been conducted regarding the factors associated with the emergence of PD in the ET population. In this study, we investigated the possible association between SN+ and putative premotor symptoms of PD in patients with ET.

METHODS

A total of 47 patients with PD and 64 patients with ET were enrolled in the study. All patients underwent TCS and completed a structured interview for putative premotor symptoms of PD.

RESULTS

As expected, there were significant differences observed in the frequency and size of SN+, and the prevalence of the putative premotor symptoms of PD. More interestingly, in the ET group a significant association between SN+ and each premotor symptom was observed and a trend was also found that ET cases with more putative premotor symptoms of PD had a greater size of SN+. In contrast, in the PD group, SN+ was not influenced by the cumulative effect of premotor symptoms.

CONCLUSION

The results of this study suggest that SN+ in patients with ET is influenced by the putative premotor symptoms of PD.

Revisiting the relationship between essential tremor and Parkinson's disease

BACKGROUND

The relationship between essential tremor and Parkinson's disease has been a subject of reviews and debates for long time, but there is now growing evidence that the two common movement disorders are pathogenically related, at least in some patient populations.

METHODS

PubMed as well as authors' own files were searched for relevant keywords regarding overlap between the disorders in clinical features as well as on epidemiologic, genetic, imaging, and pathological studies.

RESULTS

New findings in each of these categories are critically reviewed and placed in the context of previously published data.

DISCUSSION

Although we believe that there is compelling evidence for the notion that some patients with "pure" ET evolve into PD, the biologic nature of the association is not well understood. Furthermore, it is not clear what factors predict which ET patients later develop PD and whether patients with PD are more likely to develop ET. Further epidemiologic, clinical, genetic, imaging, and pathological studies are needed to better understand this mixed, ET-PD phenotype.

Essential tremor and Parkinson's disease: lack of a link

BACKGROUND

Essential tremor (ET) is a very common disorder and proving that there is a relationship to another common movement disorder, Parkinson's disease (PD), has been debated for years.

METHODS

Review of the literature for links between ET and PD primarily focused on neuropathology as well as neurochemistry, epidemiology, genetics, olfactory function, and neuroimaging.

RESULTS

While there may be some evidence to suggest an increase in occurrence of PD in people who were previously diagnosed with ET, neuropathologic studies of ET with similarly assessed control subjects do not find an increase in Lewy bodies in the ET group. Studies of incidental Lewy body disease do not find an increase in ET or action tremor compared to controls. ET subjects as a group do not have neurochemical changes that are found in PD, do not respond to medications used to treat PD, are not hyposmic as is found in PD, and neuroimaging studies do not find changes of PD when groups are compared.

CONCLUSION

The overwhelming amount of evidence suggests that any link between ET and PD is coincidental and not biological. Prospective, longitudinal cohort studies with standardized clinical and biomarker assessments followed by neuropathologic confirmation are needed.

Substantia nigra hyperechogenicity is a risk marker of Parkinson's disease: no

During the past two decades, transcranial sonography (TCS) has developed to an increasingly used brain imaging method that visualizes characteristic patterns of basal ganglia alterations in distinct movement disorders. Since the discovery of a characteristic abnormal hyperechogenic appearance of substantia nigra (SN) on TCS in Parkinson's disease (PD), which is stable during the course of the disease and probably present already in preclinical disease stages, the results of several studies have promoted the idea that this TCS finding in healthy subjects might be a risk marker of PD. The present view summarizes current scientific evidence favouring the idea that the TCS finding of SN hyperechogenicity alone may not be a (strong) risk marker of PD. Especially, it is discussed how reliable this TCS finding is, whether this TCS finding can be regarded as a progression marker or a risk marker of PD, how strongly it may indicate a risk of PD, what else if not an increased risk of PD could be indicated, and which role TCS of SN may finally play in the detection of subjects at risk of PD.

Brainstem raphe lesion in patients with major depressive disorder and in patients with suicidal ideation recorded on transcranial sonography

Recent transcranial sonography (TCS) studies showed that disruption of echogenic midbrain line, corresponding to basal limbic system and raphe nuclei (RN) within, might represent functional marker for the development of depression. Major depressive disorder (MDD) is one of the most common psychiatric disorders associated with suicidal ideation. We initiated this study to assess the usefulness of TCS recording in a group of MDD patients and in MDD patients who also reported suicidal ideation, on the assumption that TCS might serve as a screening method for differentiating patients at risk of suicide. Altogether 71 subjects: 17 patients with MDD, 14 patients with MDD who also reported suicidal ideation and 40 healthy controls, were studied using TCS by two independent physicians. Reduced raphe echogenicity was found in 8 of 17 (47%) of the patients with MDD but only in 6 of 40 (15%) controls. In patients with suicidal ideations that finding was even more pronounced (12 of 14, 86%) with the highest frequency of completely not visible TCS RN finding (10 of 14, 72%). Data showed that altered echogenicity of the RN is frequent in patients with suicidal ideation. Normal RN echogenicity in MDD patients was associated with less severe depressive symptoms and rarely with the presence of suicidal ideations. As far as we know, these are the first ever obtained results which show that TCS might help differentiating MDD patients with suicidal risk or eventually predict good disease recovery based on the findings of RN hypo- or normoechogenicity.

Tremor

PURPOSE OF REVIEW

Tremor continuously attracts the attention of clinicians and basic researchers in search of pathophysiological, molecular and genetic mechanisms of the oscillatory activity.

RECENT FINDINGS

A widespread dynamic network of cortical and subcortical oscillators taking part in tremor generation intermittently has been postulated. Essential tremor is accompanied by functional deficits but may also occur along with subtle cerebellar changes. According to recent epidemiological studies there may be a link of essential tremor with Parkinson's disease. Many of the epidemiologic studies suffer from small cohorts, small effects or the lack of a definite test for essential tremor leaving the diagnosis a pure clinical one. A very recent large genome-wide association study has revealed that the LINGO1 gene is associated with an increased risk for essential tremor. Topiramate is becoming the best-established second line treatment for essential tremor. Targets for deep brain stimulation in the grey matter below the ventral intermediate nucleus of the thalamus seem to be most effective.

SUMMARY

New concepts of the central origin of tremors stimulate the search for new therapeutic targets for tremor suppression outside the basal ganglia and thalamus (e.g. cortex). The role of structural neurodegenerative changes in essential tremor remains an open question. Further studies on specific subgroups of patients are necessary.

Transcranial duplex in the differential diagnosis of parkinsonian syndromes: a systematic review

BACKGROUND

Transcranial duplex scanning (TCD) of the substantia nigra (SN) is increasingly used to diagnose Idiopathic Parkinson's Disease (IPD). Up until now 70 diagnostic studies have been published, not only on investigation of the SN, but also of the lenticular nucleus (LN) and the Raphe nuclei (RN).

METHOD

We systematically reviewed all diagnostic TCD studies in parkinsonian patients up to June 2008.

RESULTS

We found 35 eligible studies. Of the 1534 IPD patients investigated in the 35 studies 200 (13%) had an inconclusive SN-TCD. An increased echo-intensity of the SN was seen in 1167 (87%) of the 1334 IPD patients, 276 (12%) of the 2340 healthy controls and in 41 (30%) of the 138 patients with an atypical parkinsonian syndrome (APS). On the contrary, a pathological LNTCD was found more often in APS patients (79%) than in IPD patients (23%) and healthy controls (6%). A decreased echo-intensity of the RN was found more often in depressed (46%) than in non-depressed IPD patients (16%).

CONCLUSIONS

SN-TCD accurately differentiates between patients with IPD and healthy controls, but not between patients with IPD and APS. LN-TCD is only moderate accurate to delineate IPD from APS, but combinations of SN- and LN-TCD may be more promising. RN-TCD has only marginal diagnostic accuracy in diagnosing depression in IPD and non-IPD patients. Before TCD can be implicated, more research is needed to standardize the TCD technique, to investigate the TCD in non-research settings and to determine the additional value of TCD compared with currently used clinical techniques like SPECT imaging.