Quantification of neuromotor symptoms with device-based measures provides a useful supplement to clinical evaluation. Research using the CATSYS has established its utility as a computerized measurement system to quantify neuromotor function. The primary objective of this study is to provide technical guidance on the use of the CATSYS in Parkinson's disease (PD). Forty-four patients with idiopathic PD and 28 healthy controls were prospectively recruited and evaluated with CATSYS, a portable, Windows-based system consisting of a data logger and four different sensors (tremor pen, touch recording plate, reaction time handle, and force plate for balance recording) for quantification of neuromotor functions. CATSYS discriminated between PD and controls on measurements of rest/postural tremor, pronation/supination, finger tapping, simple reaction time, and postural sway intensity and velocity. CATSYS measurements using the proposed test battery were associated with relevant clinician-rated Unified Parkinson's disease rating scale (UPDRS) items assessing tremor and bradykinesia. More work is warranted to establish CATSYS as a diagnostic/monitoring instrument in movement disorders using the proposed technical approaches.
Quantification of neuromotor symptoms such as tremor, bradykinesia, and imbalance using objective, device-based measures provides a useful supplement to clinical evaluation. Research using the Coordination Ability Test System (CATSYS, Danish Product Development Ltd., Denmark) has established its utility as a sensitive computerized measurement system to quantify normal and abnormal (clinical and subclinical) neuromotor function. Normative data has been obtained on 150 healthy men and women across five age groups, all of whom were shown to be free of neurologic deficits at the time of testing [
We evaluated 44 patients with idiopathic Parkinson’s disease (PD) recruited from the Movement Disorders Clinic at the University of Miami Miller School of Medicine. A diagnosis of PD was made according to the UK PD Society Brain Bank criteria [
Clinical Demographic Data for Sample.
PD | Control | |
Age | 62.7 (9.5) | 51.1 (16.9) |
Gender: % M/F | 71/29 | 54/46 |
Ethnicity: % Nonhispanic/Hispanic | 51/49 | 57/43 |
Age of Onset | 52.8 (11.3) | |
Disease Duration | 9.0 (5.4) | |
Hoehn & Yahr Stage | 2.3 (0.7) | |
UPDRS-III Motor Score | 21.7 (9.8) |
The Coordination Ability Test System (CATSYS 2000; Danish Product Development, Ltd., Snekkersten, Denmark,
The Coordination Ability Test System (CATSYS) including a data logger and four different sensors: a tremor pen, a touch recording plate, a reaction time handle, and a force plate for balance (static posturography) recording.
The Tremor Pen stylus (12 cm
The circular Touch Recording Plate (10 cm in diameter) is a round drum which connects to the datalogger and records each contact with the plate via a sensitive microphone. Using the CATSYS software, the (a) Mean frequency (Hz) of touches (MFT) and the (b) SD of the mean frequency (MFT-SD) are calculated for each task. The MFT is calculated as the total number of hits divided by the recording time and is measured in Hz. The MFT-SD is the deviation of hits from the average frequency calculated metronome hits. A person who is able to maintain the same hit speed will have a small deviation from the average frequency as opposed to a person with a variation in the hit speed. The Touch Recording Plate can be used to measure bradykinesia with a pronation/supination and finger tapping task, as will be described below.
The Reaction Time Handle (17 cm long and 2.4 cm in diameter) connects to the datalogger which records the press/release of a black button. A mechanical click response is also provided as feedback for a successful response to the subject with each click. Audible signals are emitted from the speaker on the datalogger at random intervals during a fixed time period. Responses, which are simple clicks with the thumb, are recorded in respect to the time lapse between an audible signal and handle click. Reaction times less than 0.10 seconds are considered invalid and are discounted by the software. Reaction times larger than a user-specified “maximum reaction time” are also excluded. The maximum permitted reaction time is a predefined waiting period. After each stimulus, the system waits this amount of time for the reaction time handle to be clicked. If no click occurs, the next period at which a stimulus is randomly emitted begins. Using the CATSYS software, the (a) Mean reaction time (RT; measured in seconds) and the (b) SD of the reaction time (RT-SD) are calculated for the task. This device can be used to measure simple reaction time, as will be described below.
The force plate is a rectangular static posturography plate (40 cm in length and 29 cm in width) that connects to the datalogger and records changes in vertical force. The plate records weight measured in kilograms. Forces along the vertical plane are recorded in three points to determine the position of the center of force on the plate. The movement of the force center in the XY-plane defined by the surface of the force plate is recorded in time and analyzed to provide key variables. Transversal Sway (TS) and Sagittal Sway (SS) are measured in mm and are defined as the mean of the
With the hand in a relaxed position, the tremor pen was inserted between the index and middle finger bordered by the thumb on the opposite side. Participants were instructed to count backwards as a distracter task. Resting tremor was measured for 8.2 seconds in each hand, successively.
The tremor pen was inserted between the index and middle finger while lying on the thumb. Participants were asked to hold the pen horizontally, at eye level, approximately 10 cm from the nose with their elbow joint at a right angle and free from the body. Participants were instructed to count backwards as a distracter task. Postural tremor was measured for 8.2 seconds in each hand, successively.
The touch recording plate was placed on a flat surface next to the patient. Participants were asked to tap, with their hand in an alternating pronation/supination pattern, on the plate, as fast as possible with the recording plate on a table in front of them. Performance on the maximum frequency pronation/supination task was measured for 10 seconds for both the dominant and non-dominant hand.
The touch recording plate was placed on a flat surface next to the patient. While seated with the recording plate on a table in front of them, participants were asked to position their thumb and middle finger to straddle the touch recording plate with the wrist resting on the table. Participants were asked to tap on the plate with their index finger as quickly as possible, while raising the index finger as far off the plate as possible between each tap. Performance on the maximum frequency finger tapping task was measured for 10 seconds for the dominant and non-dominant hand.
The reaction time handle was placed in the patient’s hand, with the thumb situated over the black “click” area. Participants were instructed to respond to a series of randomly sequenced audible tones, as fast as possible, by clicking the black area on the handle. Performance on simple reaction time was measured in response to nine randomly spaced tones during a 40-second time period for both the dominant and non-dominant hand.
The Force Plate was placed on a flat, hard surface, and the participants were asked to stand on the plate for a period of 80.5 seconds with their eyes open. Recording began after a 10- second run-in period. There was also a five-second run-out period, so that the recording time for PI was 65.5 seconds. This task was only completed in the outpatient setting.
Spearman correlation coefficients were used to examine the relationship between UPDRS-III motor scores and CATSYS measurements. Mann-Whitney
CATSYS values were collected for upper extremity tremor (resting and postural), bradykinesia (pronation/supination and finger tapping), and reaction time. Postural sway data was collected for a subset of PD participants (
Both right and left CATSYS resting TI scores were significantly correlated with the right and left values for UPDRS item 20 (Right
Both right and left CATSYS postural TI scores were significantly correlated with the right and left values for UPDRS item 21 (Right
The mean value for CATSYS pronation/supination ([R
The PD group demonstrated greater resting TI (
CATSYS Values for PD and Control Participants.
PD | Control | |||||
---|---|---|---|---|---|---|
CATSYS Rest | 44 | 1.34 | 3.02 | 28 | 0.10 | 0.07 |
CATSYS Rest F50 | 44 | 6.63 | 2.33 | 28 | 6.84 | 3.08 |
CATSYS Rest SF50 | 44 | 2.22 | 1.34 | 28 | 2.61 | 1.16 |
CATSYS Rest | 44 | 0.92 | 0.06 | 28 | 0.88 | 0.07 |
CATSYS Postural | 44 | 1.75 | 3.20 | 18 | 0.21 | 0.30 |
CATSYS Postural F50 | 44 | 6.20 | 1.98 | 18 | 4.96 | 2.40 |
CATSYS Postural SF50 | 44 | 2.33 | 1.56 | 18 | 2.93 | 1.48 |
CATSYS Postural HI | 44 | 0.91 | 0.06 | 18 | 0.89 | 0.06 |
CATSYS Pronation/Supination (events/s) | 40 | 2.45 | 0.81 | 18 | 3.43 | 0.60 |
CATSYS SD of Pronation/Supination (events/s) | 40 | 1.29 | 0.34 | 18 | 1.65 | 0.23 |
CATSYS Finger Tapping (events/s) | 38 | 3.83 | 1.01 | 18 | 4.63 | 0.82 |
CATSYS SD Finger Tapping (events/s) | 38 | 1.57 | 0.26 | 18 | 1.68 | 0.17 |
CATSYS Reaction Time | 42 | 0.41 | 0.21 | 22 | 0.29 | 0.06 |
CATSYS SD of Reaction Time | 42 | 0.11 | 0.08 | 22 | 0.07 | 0.05 |
CATSYS Mean Sway (mm) | 7 | 7.83 | 5.24 | 10 | 4.90 | 1.16 |
CATSYS Transversal Sway (mm) | 7 | 3.29 | 2.55 | 10 | 2.84 | 1.15 |
CATSYS Sagittal Sway (mm) | 7 | 6.53 | 4.09 | 10 | 3.40 | 0.87 |
CATSYS Sway Area ( | 7 | 1375.57 | 2816.46 | 10 | 188.60 | 91.62 |
CATSYS Sway Intensity | 7 | 9.15 | 8.57 | 10 | 3.40 | 0.70 |
CATSYS Sway Velocity (mm/s) | 7 | 12.89 | 7.43 | 10 | 7.24 | 1.67 |
This study provides technical guidance on the use of the CATSYS and proposes a battery of tests to help investigators obtain uniform/standardized data. The CATSYS system demonstrated clinically relevant measurement feasibility of selected parkinsonian symptoms relative to the UPDRS. These preliminary data suggest that the CATSYS system is able to discriminate between PD patients and healthy individuals without evidence of disordered movements. The purpose of the current study was not to evaluate the diagnostic utility of the CATSYS system, but to describe how it can be used to provide objective measurements of parkinsonian symptoms. CATSYS offers an opportunity to quantify objectively several parkinsonian motor symptoms and supplement clinician observation. Unlike traditional clinical rating scales that utilize categorical ratings, the CATSYS quantifies motor performance on a continuum, allowing for greater precision in recording subtle change in PD motor symptomatology.
Other methods are available which permit the objective assessment of motor symptomatology. There are at least eight systems that have been published with data demonstrating the ability to quantify PD motor symptoms [
Using a noninvasive, simple, and sensitive electronic recording method of symptom registration, we were able to objectively quantify parkinsonian neuromotor symptoms and provide reference values that differentiate patients from control subjects. More work is warranted to establish CATSYS as a diagnostic or monitoring instrument in movement disorders using the proposed technical approaches
This work was conducted during Dr. B. K. Scanlon's graduate training at the University of Miami, under the direction of Drs. B. E. Levin and S. Papapetropoulos. Dr. Scanlon is now a member of the VA Advanced Fellowship Program in Mental Illness Research and Treatment at the VA Palo Alto Health Care System. Dr. Scanlon is currently supported by the Office of Academic Affiliations, Advanced Fellowship Program in Mental Illness Research and Treatment, Department of Veteran Affairs, the Medical Research Service of the Veterans Affairs Palo Alto Health Care System, and the Department of Veterans Affairs Sierra-Pacific Mental Illness Research, Education, and Clinical Center (MIRECC). Dr. Papapetropoulos is currently employed by Biogen Idec Inc. (Cambridge, MA).