Clinical and Physiological Studies of Tremor Syndromes

Objectives

The purpose of this protocol is to study the phenotypic spectrum and the pathophysiology of tremor syndromes by performing small behavioral, electrophysiological and neuroimaging sub-studies. The protocol includes techniques with minimal risk (standard clinical evaluation, MRI, EEG, peripheral nerve stimulation, single and paired pulse TMS) and certain sub-studies may involve healthy volunteers. This protocol aims to study neurophysiological and behavioral outcomes in defined groups of patients with tremor syndromes, to inform future hypothesis-driven and confirmatory studies, which will be developed and submitted as separate protocols. For this purpose, we aim to conduct 1) pilot sub-studies, 2) individual patient investigations, 3) technical development studies.

Study population

We intend to enroll up to 300 patients with essential tremor and other isolated action tremor syndromes, as well as 150 healthy volunteers.

Design

This is a non-hypothesis driven study involving standardized phenotyping After patients and healthy volunteers complete a screening visit, patients will undergo a standardized phenotyping visit including clinical rating scales as well as electrophysiological tremorworkup. Patient and healthy controls may then be enrolled in sub-studies, and if a substudy leads to results of interest, a separate protocol will be submitted with a priori hypotheses, specific study design and power analysis adapted from the pilot or exploratory sub-studies performed in the present protocol.

Outcome measures

Outcome measures applied in this protocol involve methods for tremor phenotyping such as clinical rating scales and questionnaires, electrophysiological tremor studies, videotaped exam, as well as digitizing based tasks. During the sub-studies focused on the neurophysiological characterization of tremor syndromes, the following outcome measures will be applied: EMG: we will analyze tremor signals using spectral analyses, coherence analyses, and in combination with accelerometry, EEG, MEG, and TMS to explore tremor-networks. MRI: we will analyze measures such as the amplitude of the BOLD signal (fMRI); tractography between seed and target regions of interest (using DTI); morphometry of brain regions (using VBM); and different neurotransmitter levels in brain regions of interest (using MRS). EEG and MEG: we will quantify measures such as corticomuscular coherence, event- or task-related potentials, synchronization/desynchronization, and coherence between sensors or sources located close to the brain areas of interest. TMS: we will analyze measures such as MEP amplitude and central conduction time, as well as measures of cortical excitability and inhibition paradigms. Behavioral measures: we will quantify measures of voluntary movement involving tremor, reaction times to initiate movements, EMG patterns, movement kinematics (position, velocity, acceleration, curvature), eye movement. Actigraphy: We will quantify continuous recordings of motion sensors involving multiaxial accelerometers and gyroscopes. Furthermore, we may measure autonomic data during the course of experiments (such as blood pressure, skin co ductance, and respiratory rate) which would correlate to the outcome measures.

• INCLUSION CRITERIA FOR TREMOR PATIENTS:
• Patients diagnosed with a tremor syndrome, including, but not limited to

• Essential tremor (per definition of the Tremor Research Group)
• Parkinson disease (per UK Brain Bank criteria)
• Focal tremor such as isolated head tremor, voice tremor
• Task-specific tremor such as primary writing tremor
• Orthostatic tremor
• Patients with other tremor syndromes such as dystonic tremor, intention tremor, etc.
• Age 18 or older
• Able to give informed consent
• Agree to not drink caffeine or alcohol for 12 hours before phenotyping and selected sub-study visits because both agents can modify brain activity and may confound outcome measures.

Inclusion criteria

FOR HEALTHY VOLUNTEERS:

• Age 18 or older.
• Able to give informed consent.
• Agree to not consume caffeine or alcohol for 12 hours before selected sub-study visits because both agents may modify the activity of the brain during the study.

Exclusion criteria

FOR TREMOR PATIENTS:

• Problematic alcohol use, as defined by a score of 8 or higher on the WHO Alcohol Use Disorders Identification Test (AUDIT).
• History of a brain tumor, a stroke, traumatic brain injury, epilepsy or a history of seizures.
• History of psychotic disorder, Bipolar Disorder or a current depressive episode.
• History or clinical evidence of another neurologic disorder than a tremor syndrome as defined above, which may interfere with the ability to comply with protocol requirements or interpret the obtained results.

Exclusion criteria

FOR HEALTHY VOLUNTEERS:

• Have abnormal findings of clinical significance on the neurological examination that may affect the scientific integrity of the study
• Problematic alcohol use, as defined by a score of 8 or higher on the WHO Alcohol Use Disorders Identification Test (AUDIT)
• History of a brain tumor, a stroke, traumatic brain injury, epilepsy or a history of seizures.
• History of psychotic disorder, Bipolar Disorder or a current depressive episode.

ADDITIONAL EXCLUSION CRITERIA FOR MOVEMENT DISORDER PATIENTS AND HEALTHY VOLUNTEERS SPECIFICALLY FOR MRI:

We will follow the NMR Center guidelines for MR safety.

Some of the exclusions are:

• Have non-MRI compatible metal in the body, such as a cardiac pacemaker, brain stimulator, shrapnel, surgical metal, clips in the brain or on blood vessels, cochlear implants, artificial heart valves or ferromagnetic fragments in the eye or oral cavity as these make having an MRI unsafe.
• Unable to lie flat on the back for the expected length of the experiment.
• Have uncontrolled movements of the head.
• Have an abnormality on the brain imaging or neurologic examination not related to the diagnosis.
• Uncomfortable being in a small space for the expected length of the experiment.
• Non-removable body piercing or tattoo posing MRI risk
• Pregnancy.

ADDITIONAL EXCLUSION CRITERIA FOR TREMOR PATIENTS AND HEALTHY VOLUNTEERS FOR TMS AND MRI:

• Ferromagnetic metal in the cranial cavity or eye, e.g. aneurysm clip or ocular foreign body.
• Implanted electronic device including deep brain stimulation systems.