Non-Motor Features of Cervical Dystonia (CD)

Study Overview
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Brief Summary
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This study will examine the prevalence of four previously identified non-motor markers in a population of cervical dystonia patients, unaffected family members, and healthy volunteers in an attempt to identify a distinct combination of non-motor symptoms that may be indicative of disease development.

Detailed Description
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The primary aim of this study is to identify the prevalence of four previously identified non-motor markers - (1) spatial discrimination threshold, (2) temporal discrimination threshold, (3) vibration-induced illusion of movement, and (4) kinesthesia - in a population of cervical dystonia patients, unaffected family members, and healthy volunteers (control group). Consenting participants will receive a neurological examination performed by a movement disorders neurologist, followed by an assessment of the four non-motor symptoms. The investigators hypothesize that a distinct combination of non-motor symptoms will be more prevalent in the CD group, and therefore this set of symptoms may be indicative of disease development. This combination will be identified through analysis of the concurrence of the non-motor features across the three groups of participants. This study will fill an important unmet need, as to the investigators' knowledge there are no published studies assessing the comorbid presentation of these four non-motor symptoms in a single cervical dystonia population. The exploration of a distinct combination of concurrent non-motor symptoms as a marker for the development of cervical dystonia will improve the ability of movement disorders neurologists to diagnose the condition. The results of this study will facilitate the investigators' longstanding aim of improving rates of cervical dystonia diagnosis. Cervical dystonia is currently diagnosed based upon the exclusion of other movement disorders; therefore, characterization of non-motor features in cervical dystonia patients will help to refine the diagnostic criteria for this condition. This investigation will also improve understanding of the factors associated with CD. Future studies can examine the source of these associated factors in order to help understand the cause of CD, since the etiology is currently unknown.

Official Title
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Non-Motor Features of Cervical Dystonia

Conditions
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Cervical Dystonia, Movement Disorders, Focal Dystonia, Signs and Symptoms, Nervous System Diseases, Neurologic Manifestations, Neuromuscular Manifestations, Spasmodic Torticollis

Intervention / Treatment
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* Diagnostic Test: Neurological Examination
* Diagnostic Test: Assessment of Non-Motor Features


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Have a diagnosis of cervical dystonia, OR a first order relation of a Vanderbilt patient diagnosed with cervical dystonia, OR a healthy volunteer who is neurologically normal Capable of participating in all study procedures Willing and able to provide written or verbal informed consent. Exclusion Criteria: Subjects for whom participation in the study may cause medical harm Subjects who are not considered competent to make their own medical decisions Subjects who display sensory deficits during a short screening examination prior to study enrollment

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CD Patients<br>Subjects must have a prior diagnosis of cervical dystonia and be capable of participating in all study procedures. Subjects will undergo assessment of non-motor features. | Diagnostic Test: Assessment of Non-Motor Features<br>* All subjects will be assessed for four non-motor symptoms, including (1) spatial discrimination threshold, (2) temporal discrimination threshold, (3) vibration-induced illusion of movement, and (4) kinesthesia.<br>|
| Family Members<br>Subjects must be a first order relation of a Vanderbilt patient diagnosed with cervical dystonia. The subject must pass a short neurological examination to ensure the subject does not have cervical dystonia or any sensory deficits. Subjects will undergo assessment of non-motor features. | Diagnostic Test: Neurological Examination<br>* The family members and healthy volunteers will undergo elements of the neurological examination during which the movement disorders neurologist will look specifically for the presence of cervical dystonia and other sensory abnormalities. If the subject is found to have cervical dystonia or any other sensory abnormalities, the subject will be excluded from the study.<br>Diagnostic Test: Assessment of Non-Motor Features<br>* All subjects will be assessed for four non-motor symptoms, including (1) spatial discrimination threshold, (2) temporal discrimination threshold, (3) vibration-induced illusion of movement, and (4) kinesthesia.<br>|
| Healthy volunteers<br>Subjects must be healthy volunteers who are neurologically normal. The subject must pass a short neurological examination to ensure the subject does not have cervical dystonia or any sensory deficits. Subjects will undergo assessment of non-motor features. | Diagnostic Test: Neurological Examination<br>* The family members and healthy volunteers will undergo elements of the neurological examination during which the movement disorders neurologist will look specifically for the presence of cervical dystonia and other sensory abnormalities. If the subject is found to have cervical dystonia or any other sensory abnormalities, the subject will be excluded from the study.<br>Diagnostic Test: Assessment of Non-Motor Features<br>* All subjects will be assessed for four non-motor symptoms, including (1) spatial discrimination threshold, (2) temporal discrimination threshold, (3) vibration-induced illusion of movement, and (4) kinesthesia.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of spatial discrimination threshold in cervical dystonia patients, unaffected family members, and healthy volunteers | For participants in all groups, the investigators will examine the prevalence of spatial discrimination threshold. Prevalence of spatial discrimination threshold will be determined with a task using Johnson-Van-Boven-Phillips (JVP) domes. The spatial discrimination threshold will be recorded as the mean of both hands at the 75% level of accuracy. The research coordinator will report prevalence of spatial discrimination threshold as a descriptive statistic. | Up to 6 months after consent is obtained | 
| Prevalence of temporal discrimination threshold in cervical dystonia patients, unaffected family members, and healthy volunteers | For participants in all groups, the investigators will examine the prevalence of temporal discrimination threshold. Prevalence of temporal discrimination threshold will be determined with a visual-visual discrimination task.The research coordinator will report prevalence of temporal discrimination threshold as a descriptive statistic. | Up to 6 months after consent is obtained | 
| Prevalence of vibration-induced illusion of movement in cervical dystonia patients, unaffected family members, and healthy volunteers | For participants in all groups, the investigators will examine the prevalence of vibration-induced illusion of movement. Prevalence of vibration-induced illusion of movement will be determined by recording the change in displacement of the tracking arm during a vibration-induced illusion of movement task. The research coordinator will report prevalence of vibration-induced illusion of movement as a descriptive statistic. | Up to 6 months after consent is obtained | 
| Prevalence of impaired kinesthesia in cervical dystonia | For participants in all groups, the investigators will examine the prevalence of impaired kinesthesia. Kinesthesia will be determined by a neurologist during the neurological examination. The research coordinator will report prevalence of impaired kinesthesia as a descriptive statistic. | Up to 6 months after consent is obtained | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Probability of concurrence of multiple non-motor features | The concurrence of multiple non-motor symptoms will be assessed using a multinomial logistic regression model to determine if a distinct combination of non-motor symptoms is more prevalent in the cervical dystonia patient group than in the unaffected family members or healthy volunteer groups. | Up to 6 months after consent is obtained |