Motor and Non-motor Features: Differences between Patients with Isolated Essential Tremor and Patients with Both Essential Tremor and Parkinson's Disease

Phenotypic Features of Isolated Essential Tremor, Essential Tremor Plus, and Essential Tremor-Parkinson's Disease in a Movement Disorders Clinic

Background:

Patients with essential tremor were initially considered to have isolated tremor, but additional motor and non-motor features have been increasingly recognized. The term “essential tremor plus” was adopted by the Task Force on Tremor of the International Parkinson and Movement Disorder Society to describe essential tremor patients with additional neurologic signs.

Objectives:

To characterize essential tremor patients and their phenotypes in a movement disorders clinic population in the context of the new tremor classification.

Methods:

Demographic, clinical, historical, treatment, and diagnostic data were retrospectively collected on 300 patients diagnosed by movement disorder experts with essential tremor. Patients were classified as having essential tremor, essential tremor plus, or essential tremor-Parkinson’s disease combination, and features between these groups were compared.

Results:

Of the 300 patients, 20.7% were classified as isolated essential tremor, 53.3% as essential tremor plus, and 26.0% as essential tremor-Parkinson’s disease. There was no significant difference in the duration of tremor symptoms. Essential tremor plus patients were more likely to have dystonia, tandem gait abnormalities, head tremor and greater tremor severity. Essential tremor-Parkinson’s disease patients were more likely to have RBD symptoms. There was no significant difference in cognitive impairment between essential tremor plus and essential tremor-Parkinson’s disease patients.

Conclusions:

Additional motor and non-motor features, including parkinsonism, are common in patients with essential tremor. Further studies are needed to clarify essential tremor phenotypes and to provide insights into possible subtypes.

Highlights:

300 patients with essential tremor from a movement disorders clinic were re-classified based on the Movement Disorder Society Consensus Statement on the Classification of Tremors. Additional motor and non-motor features, including parkinsonism, were common, and only 20.7% of patients remained classified as isolated essential tremor.

Sleep Disorders in Patients with Essential Tremor

PURPOSE OF THE REVIEW

Patients diagnosed with essential tremor (ET) report frequent sleep complaints. This review focuses on the main findings of studies addressing sleep features in patients diagnosed with ET, updating previously reported information. Bad quality of sleep and excessive daytime somnolence are very frequent in patients with ET, although the effects of the drugs used for the therapy of ET could contribute to these complaints. REM sleep behavior disorder, restless legs, insomnia, and nocturia are frequent complaints as well. There is a lack of studies addressing polysomnographic features of ET.

Clinical Characteristics and Electrophysiological Biomarkers of Parkinson's Disease Developed From Essential Tremor

Background and Objective: Parkinson's disease developed from essential tremor (ET-PD) is a distinct clinical syndrome that is different from essential tremor (ET) and Parkinson's disease (PD). There is currently a lack of research on ET-PD. Tremor characteristics (amplitude and frequency) are primary quantitative indexes for diagnosing and monitoring of tremors. In this study, we aimed to explore specific clinical and electrophysiological biomarkers for the identification of ET-PD. Methods: The study included patients with ET-PD (n = 22), ET (n = 42), and tremor-dominant PD (t-PD, n = 47). We collected demographic data, clinical characteristics (including motor and non-motor symptoms), and tremor analysis. The frequency, amplitude, contracting patterns of resting tremor and postural tremor were collected. The analysis of ET-PD and ET/t-PD was compared. The receiver operating characteristic (ROC) curve was used to analyze the electrophysiological features in distinguishing ET-PD from ET or t-PD. Results: Compared with ET, hyposmia, bradykinesia, rigidity, postural abnormality, and resting tremor were more common in the ET-PD group (P = 0.01, 0.003, 0.001, 0.001, 0.019, respectively). The postural tremor frequencies of the head, upper limbs, and lower limbs were significantly lower in the ET-PD than in the ET (P = 0.007, 0.003, 0.035, respectively), which were the most appropriate variables for distinguishing ET-PD from ET (AUC: 0.775, 0.727, and 0.701, respectively). Compared with t-PD, bradykinesia, rigidity, postural abnormality (both P < 0.001), and resting tremor (P = 0.024) were less common in the ET-PD. The postural tremor amplitudes of the head and upper limbs were significantly higher in the ET-PD than in the t-PD (P = 0.022, 0.001, respectively), which were the most appropriate variables for distinguishing ET-PD from t-PD (AUC: 0.793 and 0.716). Conclusions: Hyposmia and electrophysiological biomarkers (postural tremor frequencies and amplitudes) help early recognition of ET-PD.

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.

Auditory and Olfactory Deficits in Essential Tremor - Review of the Current Evidence

Background:

Essential tremor (ET) is the most common adult movement disorder, characterized by several motor and increasingly well recognized non-motor symptoms. Sensory deficits, such as hearing impairment and olfactory dysfunction, are amongst them. This review analyzes the available evidence of these sensory deficits and their possible mechanistic basis in patients with ET.

Method:

A PubMed literature search on the topic was performed in the May 2019 database.

Results:

Nineteen articles on hearing impairment and olfactory dysfunction in ET patients were identified. The prevalence of hearing impairment is higher in ET patients than healthy controls or Parkinson disease. Cochlear pathologies are suggested as the underlying cause, but there is still a lack of information about retrocochlear pathologies and central auditory processing. Reports on olfactory dysfunction have conflicting results. The presence of mild olfactory dysfunction in ET was suggested. Conflicting results may be due to the lack of consideration of the disease’s heterogeneity, but according to recent data, most studies do not find prominent evidence of olfactory loss in ET.

Conclusion:

Although there is increasing interest in studies on non-motor symptoms in ET, there are few studies on sensory deficits, which are of particularly high prevalence. More studies are needed on to investigate the basis of non-motor symptoms, including sensory deficits.

Tremorography in fragile X-associated tremor/ataxia syndrome, Parkinson's disease and essential tremor

Background

Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disease affecting carriers of a 55-200 CGG repeat in the fragile X mental retardation 1 gene, may receive an initial diagnosis of Parkinson's disease (PD) or essential tremor (ET) due to overlapping motor symptoms. Therefore, tremor and bradykinesia were compared in these disorders using quantitative tremorography.

Methods

The inertial sensor based Kinesia ™ system was used to quantify upper extremity tremor and bradykinesia in participants with FXTAS (n = 25), PD (n = 23), ET (n = 18) and controls (n = 20) and regression analysis was performed to determine whether tremorography measures distinguished between the groups. The FXTAS Rating scale (FXTAS-RS) was administered to determine whether sub-score items on the clinician rated scale correlated with tremorography variables.

Results

FXTAS participants had reduced finger tap speed compared to those with ET, and ET had increased kinetic tremor compared to PD. Higher kinetic tremor distinguished FXTAS from PD (p = .02), and lower finger tap speed distinguished FXTAS from ET (p = .004). FXTAS-RS tremor and bradykinesia items correlated with tremorography measures (p = .005 to <0.0001).

Conclusions

This is the first quantitative study to compare tremor and bradykinesia in FXTAS, PD and ET. Kinetic tremor and bradykinesia measures using a quantitative inertial sensor system distinguished FXTAS from PD and ET, respectively. Such technologies may be useful for detecting precise tremor and bradykinesia abnormalities and distinguishing the tremor and bradykinesia profiles in each of these disorders.

Comparison of the Olfactory Bulb Volume and the Olfactory Tract Length Between Patients Diagnosed with Essential Tremor and Healthy Controls: Findings in Favor of Neurodegeneration

Purpose Essential tremor (ET) is the most common movement disorder. In recent years, an increasing number of studies have shown that this disease also has a variety of non-motor findings and may be of a neurodegenerative nature. This study aimed to evaluate the olfactory bulb volume (OBV) and the olfactory tract length (OTL) and to demonstrate possible neurodegeneration in ET patients using magnetic resonance imaging (MRI). Methods The study included 30 ET patients (mean age=29.53±11.82 years) and 30 healthy controls (mean age=30.00±11.68 years). In the cranial MRI examination of both groups, the right, left and total OBV values ​​were measured in mm³ and the right and left OTL values ​​were calculated manually in mm. Results There was no significant difference between the patient and control groups in the measured OBV values, but the OTL value of the patient group was statistically significantly lower than the control group. Conclusion Our study showed that the olfactory system might be involved in ET cases. We think that olfactory dysfunction, one of the non-motor symptoms in ET, can be clearly elucidated through both anatomical and functional studies, to be conducted with larger patient groups.

Etiologic links between environmental and lifestyle factors and Essential tremor

Essential tremor (ET) is one of the most common adult movement disorders, characterized by clinical tremor and other nonmotor symptoms. It is a progressive disease that shares features with other neurodegenerative diseases. ET is a complex disease with both genetic and environmental underpinnings. While genetic forms of ET are well recognized, the role of environmental and lifestyle factors in ET has been debated. Studies suggest that exposure to neurotoxic compounds such as β-carboline alkaloids and ethanol are potential risk factors for ET, while antioxidant intake may be protective. In addition, smoking acts as a protective factor in ET, parallel to its effects in other neurological diseases. New evidence points to pesticide and lead exposure as potential risk factors. There is growing evidence to suggest that environmental and lifestyle factors play a role in ET but additional research is needed in order to completely understand their cause and effect association. There is also a need for larger case-control and prospective cohort studies across different populations to further evaluate the etiological importance of these factors in ET.

Probable REM-Sleep Behavior Disorder and Dysautonomic Symptoms in Essential Tremor

Background

Non-motor symptoms can be present in essential tremor (ET). We intend to assess the frequency of rapid eye movement (REM) sleep behavior disorder (RBD) and dysautonomic symptoms in ET patients and evaluate the differences between patients with ET and RBD (ET-RBD and ET without RBD [ET-nonRBD]).

Methods

All ET patients were contacted by telephone. Autonomic symptoms were assessed using the Scales for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT) questionnaire, and RBD symptoms with the RBD screening questionnaire (RBDSQ) using ≥5 as a cut-off for probable RBD (pRBD).

Results

From 92 ET patients contacted, 53 (55% female) were included. The mean age at assessment was 73.6±19 years, and the average disease duration was 19.9±17.3 years. Fourteen patients (26.4%) had pRBD and 52 (98.1%) reported at least one autonomic symptom, the most prevalent being urinary symptoms (96%). The ET-RBD group had higher SCOPA-total and thermoregulatory scores than ET-nonRBD patients (13.9±9.6 vs. 7.7±5.1, p=0.017 and 2.5±2.0 vs. 0.9±1.6, p=0.001). There were no other differences between groups.

Discussion

Our results suggest that pRBD is common in ET, and its presence is associated with dysautonomic symptoms. As these symptoms are known to be prodromal symptoms of Parkinson's disease (PD), we question if this patient subgroup has a higher risk of developing a synucleinopathy.

Analysis of pramipexole dose-response relationships in Parkinson's disease

BACKGROUND

Pramipexole (PPX), a non-ergot dopamine receptor agonist, is a first-line treatment for Parkinson's disease (PD). A critical dose level above which a better benefit-to-harm ratio exists has not been examined.

METHODS

Chinese PD patients (n=464) were retrospectively analyzed by PPX maintenance dose, PD stage, combined levodopa dose, and baseline tremor contribution. The sum score of Baseline Activities of Daily Living (part II) and Motor Examination (III) of the Unified Parkinson's Disease Rating Scale (UPDRS II+III) was used as a covariate for final score adjustment.

RESULTS

Sustained-release (SR) and immediate-release (IR) PPX showed similar efficacy based on score changes at 18 weeks, with comparable tolerability. Approximately two-third of patients received PPX at ≥1.5 mg/d, and one fourth of patients had ≥20% tremor contribution to UPDRS II+III. After treatment, patients receiving PPX ≥1.5 mg/d showed better improvement in UPDRS II+III scores (P=0.0025), with similar trends with the IR and SR formulations. Patients with ≥20% tremor contribution showed better improvement in UPDRS II+III scores (P=0.0017). No differences were seen based on PD stage or combined levodopa dose. The overall proportions of adverse events (AEs) were similar. More patients discontinued because of intolerable side effects, and more investigator-defined drug-related AEs were recorded in the <1.5 mg/d subgroup.

CONCLUSION

UPDRS II+III improvement was better with PPX ≥1.5 than with <1.5 mg/d in Chinese PD patients after 18 weeks of treatment, with similar trends seen with IR and SR formulations. The frequency of AEs in PPX ≥1.5 and <1.5 mg/d subgroups was similar.

Fragile X-associated tremor/ataxia syndrome: phenotypic comparisons with other movement disorders

OBJECTIVE

The purpose of this paper is to review the typical cognitive and motor impairments seen in fragile X-associated tremor/ataxia syndrome (FXTAS), essential tremor (ET), Parkinson disease (PD), spinocerebellar ataxias (SCAs), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP) in order to enhance diagnosis of FXTAS patients.

METHODS

We compared the cognitive and motor phenotypes of FXTAS with each of these other movement disorders. Relevant neuropathological and neuroimaging findings are also reviewed. Finally, we describe the differences in age of onset, disease severity, progression rates, and average lifespan in FXTAS compared to ET, PD, SCAs, MSA, and PSP. We conclude with a flow chart algorithm to guide the clinician in the differential diagnosis of FXTAS.

RESULTS

By comparing the cognitive and motor phenotypes of FXTAS with the phenotypes of ET, PD, SCAs, MSA, and PSP we have clarified potential symptom overlap while elucidating factors that make these disorders unique from one another. In summary, the clinician should consider a FXTAS diagnosis and testing for the Fragile X mental retardation 1 (FMR1) gene premutation if a patient over the age of 50 (1) presents with cerebellar ataxia and/or intention tremor with mild parkinsonism, (2) has the middle cerebellar peduncle (MCP) sign, global cerebellar and cerebral atrophy, and/or subcortical white matter lesions on MRI, or (3) has a family history of fragile X related disorders, intellectual disability, autism, premature ovarian failure and has neurological signs consistent with FXTAS. Peripheral neuropathy, executive function deficits, anxiety, or depression are supportive of the diagnosis.

CONCLUSIONS

Distinct profiles in the cognitive and motor domains between these movement disorders may guide practitioners in the differential diagnosis process and ultimately lead to better medical management of FXTAS patients.

Essential tremor-Parkinson's disease: A double whammy

BACKGROUND

Surprisingly little has been written about the combined clinical entity, essential tremor-Parkinson's disease (ET-PD), which is the result of a double disease hit. We carefully quantified tremor burden using a wide range of measures (tremor severity, tremor-related disability, tremor-related quality of life) and furthermore, studied additional motor and non-motor features in ET-PD.

METHODS

In this prospective, clinical-epidemiological study, we performed a standardized, structured clinical evaluation of 27 ET-PD patients, comparing them to age-matched samples of 35 PD and 109 ET patients.

RESULTS

The number of hours/day shaking was lowest in PD (median=3.0), intermediate in ET (median=10.0) and highest in ET-PD (median=14.0) (p<0.001). All measures of mobility and balance (Berg Balance test, Activities-specific Balance Confidence Scale, Timed Up and Go test) worsened across groups in a stepwise manner from ET to PD to ET-PD (p<0.05). Mini-mental state test scores worsened (p=0.002) and daytime sleepiness increased (p=0.002) across groups from ET to PD to ET-PD.

CONCLUSIONS

The ET-PD patient seems to be more than just a PD patient with a little more kinetic tremor. Aside from a significantly greater tremor burden, ET-PD patients exhibited more cognitive and sleep problems and more mobility and balance problems than patients with isolated PD.