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While tremor is often the most visible symptom of Parkinson’s disease, bradykinesia can be the most impairing to the patient. The term "bradykinesia" literally means "slowed movements"; however, in the literature, the "bradykinesia" is often used synonymously with the terms "akinesia" and "hypokinesia." Technically, "bradykinesia" only refers to slowness of movement; however, lack of spontaneous movement (akinesia) and smaller than desired movements (hypokinesia) are often grouped together as "bradykinesia." This misuse in terminology can result in widespread variability in clinical ratings.

The standard clinical method for evaluating bradykinesia is qualitative assessment by a clinician and score assignment (0 – 4) based on the Unified Parkinson’s Disease Rating Scale (UPDRS). This score is assigned while the subject completes repetitive tasks of finger-tapping, hand opening-closing, and pronation-supination. Evaluators are instructed to account for a wide array of factors such as speed, amplitude, fatiguing, hesitations, arrests in movement, and how these variables change during the task. This is challenging to even the most experienced movement disorder specialist. A given patient could be scored a 2 on the UPDRS finger-tapping task due to slow and large amplitude movements or fast and small amplitude movements. It is difficult to gauge weights that specific clinicians place on different bradykinesia manifestations.

The inconsistency among raters may have implications beyond symptom severity assessments. Recent data have shown that speed and amplitude respond differentially to dopaminergic medication ^[1]. Furthermore, it is unknown if the underlying neural mechanisms that cause the various bradykinesia manifestations are the same. A quantitative understanding of different bradykinesia features could ultimately lead to the development of more targeted treatments for specific patients with Parkinson’s disease.

Parkinson’s disease is a neurodegenerative disease of the central nervous system and is primarily characterized by cardinal motor symptoms such as tremor, bradykinesia (slowness of movement), and rigidity. Lower extremity symptoms such as gait and balance disturbances (initiating movement, freezing of movement, improper movement form), especially in advanced patients, can be very debilitating, leading to decreased mobility and independence, decreased quality of life, and an increased falling/hip fracture risk ^[1]. A positive PD diagnosis occurs when a minimum of two cardinal symptoms present themselves. However, less attention is given to gait and balance abnormality as it typically develops in the advanced stages of PD.

Standard clinical assessment of gait and balance based on a 0 (no severity) – 4 (high severity) scale is performed using a subset of the Unified Parkinson’s Disease Rating Scale (UPDRS) motor section. Tasks typically consist of foot stomping while seated, gait assessment while walking, arising from chair with arms crossed over the chest, and balance assessment while being pulled backwards. As gait is particularly sensitive to ON-OFF therapy state changes in PD and incorporates upper extremity function such as arm swing as well as rigidity and bradykinesia in lower extremities, gait analysis may be a reliable method of assessing overall motor function over time in PD ^[2].

When diagnosed with PD, the first line of treatment typically consists of L-Dopa medication to alleviate motor symptoms. However over time, drug effectiveness decreases, requiring the patient to increase dosage. Frequent and stronger side effects such as dyskinesias (uncontrolled arm movement) and unpredictable “on”/”off” episodes are cause for more invasive therapeutic intervention. Deep brain stimulation (DBS) has been widely recognized as an appropriate treatment option when medication no longer adequately alleviates motor symptom severity. Several therapy targets have been established for PD. Subthalamic nucleus (STN) and Globus Pallidus Interna (GPi) stimulation are recognized treatments for sustained improvement in tremor, rigidity, and bradykinesia ^{[3, 4]}. However the effects on gait disturbance are less understood. During DBS lead placement and post-evaluation, neurologists adjust several settings: electrode contact configuration and stimulation parameters (frequency, pulse width, and amplitude). Studies show that while high-frequency/high voltage stimulation improves cardinal symptoms, patients exhibit increased frequency of freezing episodes. However, stimulation at lower frequencies has demonstrated improved gait ^[5].

New PD gait therapies are being researched and developed and existing interventions further established. Another DBS target, the pedunculopontine nucleus (PPN), located near the brain stem plays an important role in locomotion function in animal models, specifically initiation and modulation of gait ^[6-8]. Patients with advanced stages of PD only exhibit mild improvement of freezing with standard medication such as L-Dopa ^{[9, 10]}. Preliminary studies of PPN surgeries off-medication marked a significant improvement of the UPDRS motor exam section III, specifically gait and postural qualities. In addition, the combination of STN and PPN DBS resulted in a further significant improvement. Despite promising results, PPN surgical intervention is currently in its infancy as little is known about the nucleus’ function in humans and how well animal model testing translates to human clinical trials ^[7].

CleveMed has collaborated with Dr. Joe Jankovic at the Baylor University Parkinson’s Disease Center and Movement Disorders Clinic using CleveMed’s Kinesia device for essential tremor symptom evaluations. Kinesia is currently used for Parkinson’s disease symptom evaluations but this study may help broaden the potential applications the device can be used for.

The current methods of evaluating essential tremor symptom severity are the Essential Tremor (ET) clinical rating scales. These are similar to the Unified Parkinson’s Disease Rating Scale in which a visual assessment by a clinician produces a numeric score that correlates to symptom severity. Recently, the Tremor Research Group developed The Essential Tremor Rating Assessment Scale, or TETRAS, for the assessment of action tremor in ET. The TETRAS scale utilizes a half point interval, 0 to 4 scale to rate symptom severity.

In this study, our collaborators at Baylor University compared the output of Kinesia to the scores assigned to patients using the TETRAS for upper extremity postural and kinetic tremor. More information on the methods used are available on this poster, which was presented at the Movement Disorder Society Annual Meeting in June 2009, Paris France: Read here. The study concluded that there was a significant correlation between the TETRAS score and the output of the Kinesia system and that the system may provide a useful adjunct to the current subjective rating scales.

To demonstrate the benefits of Kinesia, a compact patient worn device for assessing Parkinson’s disease (PD) motor symptom severity, and the tremor scoring feature recently released, CleveMed has launched the new interactive website UPDRS.CleveMed.com.

CleveMed Online UPDRS Challenge (to highlight benefits of objective monitoring of motor symptoms with Kinesia)

The CleveMed UPDRS Scoring Challenge is an online educational tool intended for movement disorder clinicians and researchers, patients, caregivers or anyone interested in Parkinson’s disease motor symptom evaluations. The interactive site allows a visitor to view and rate a series of videos displaying Parkinson’s disease patients performing tasks for evaluating tremor. After each short video is complete, the user enters the score they feel is appropriate ranging from 0 to 4, 0 being the absence of symptoms and 4 being the most severe, and the next video starts. Once the twelve videos are scored, the user scores are compared to scores from two movement disorder specialists for the same videos. This demonstrates the variability in scores that can occur between different clinicians for the same patient, which is an issue with the subjective UPDRS. Scores are also compared to the automated scoring provided by Kinesia which demonstrates the benefits of having a device that can provide consistent, repeatable results.

Everyone is encouraged to try the site out and see how you would perform again actual clinicians when rating tremor symptom severity. If you find it interesting, please pass it along to others who may feel the same. Any comments, suggestions or questions on the site are welcome at any time.