Ákos Jobbágy

Analysis of finger-tapping movement.

The piano-playing-like finger-tapping movement has been analyzed with a precision image-based motion analyzer (PRIMAS). 32 healthy subjects (148 recordings) and 10 Parkinsonian patients (25 recordings) were tested. The tracking of fingers during the whole movement increased the level of information obtained from the finger-tapping test compared to visual observation or to measurement with simple contact sensors. Different feature extraction methods have been developed to evaluate the movement and thus the actual performance of the tested person. The reliability of a novel parameter, the finger-tapping test score (FTTS), that takes into account both the speed and the regularity (periodicity) of finger-tapping, was assessed in six control subjects, with four subjects tested at least 14 times. FTTS helps in staging of Parkinsonian patients. A simple and cheap device (passive marker-based analyser of movement, PAM) has been developed that is affordable for routine clinical use.

Early detection of Parkinson's disease through automatic movement evaluation

Therapy for a patient with a neurological disease is more effective the earlier it is started. This also means a better quality of life for the patient and more effective health care for the country. Movement disorders may indicate several neurological diseases (including Parkinsons disease (PD)) before other diagnostic methods may reveal them. In this article a measurement technique is described that can be used to diagnose PD including the movement patterns to be analyzed, the necessary measurement set-up based on the PRIMAS precision motion analyzer, and the evaluation algorithms. The aim of the described work is to develop a screening test that could also be applied to patients already diagnosed as Parkinsonians to objectively measure the progress of the disease and/or the efficiency of the therapy.

Analysis of movement patterns aids the early detection of Parkinson's disease

The movement patterns are characteristic for a person. The changes in his/her movement patterns indicate changes in his/her state. Several diseases result in well distinguishable deviation from normal movement patterns. The deviation starts with subtle changes; our aim is to detect these changes and thus aid the early diagnosis of neurological diseases. We have been using a passive marker based motion analyzer (PRIMAS) to record the movement patterns defined by neurologists. Healthy subjects and Parkinsonian patients participated is the tests. We suggest a measurement set-up and evaluation algorithms that fit to the movement patterns to be analyzed.

Precision 3-D motion analysis system for real-time applications

Abstract The paper identifies and discusses the main modules of the PRIMAS real-time TV/computer-based movement recording and analysis system. Emphasis is on the functional concatenation of CCD sensors, dedicated DSP marker detection hardware, an embedded system CPU with alternatives in RISC processing, and interfacing to the host PC. The applications of the PRIMAS precision motion analysis system in the tracking of passive markers usually require subpixel resolution which can be achieved if the marker image covers several pixels. The marker midpoint is estimated on the basis of the digitized contour coordinates. The quantization error of the digitization of the marker images on the basic pixel grid is a limiting factor in both the resolution and the accuracy of marker centre coordinate estimation. The obtainable resolution has been investigated by simulation, on condition that the marker image is an ideal circle projected on the discrete pixel grid. With the same assumption the theoretical limit of accuracy has been determined as a function of the imaged marker diameter expressed in pixel size. The simulation results show that the accuracy of the most widely used geometric centroid estimation falls short of the theoretical limit and may be outperformed by other algorithms.

PAM: passive marker-based analyzer to test patients with neural diseases

Neurologists observed specific changes in the movement coordination of their patients - compared to healthy control subjects - a long time ago. In the early, preclinical phase the subtle changes cannot be detected by visual inspection. Similarly, variations in the performance of a patient resulting from minor changes in the stage of the disease remain undetected for the human observer. Evaluation of well-defined movement patterns aids the diagnosis even early diagnosis and assessment of the actual state of patients with neural diseases. Passive marker-based motion analysis is especially suitable for testing human movements. The markers are lightweight (1...10 grams), and no wires are needed between the markers and the analyzer. The markers and the analysis cause absolutely no discomfort to the persons. The performance of commercially available motion analyzers by far exceeds the requirements needed to record and evaluate the movement patterns of patients with neural diseases. As a consequence, these devices are too expensive for this purpose. A simple device has been developed that is affordable for routine clinical use. In harmony with the practice of neurologists, parameters have been defined that characterize both the speed and the regularity of movements. These parameters help in staging patients.

Effectiveness of unilateral pallidotomy for meige syndrome confirmed by motion analysis.

Background: We report the case of a 64-year-old woman with bilateral manifestation of Meige syndrome (MS) successfully treated with left-side unilateral ventroposterolateral pallidotomy. Methods: Symptoms were evaluated according to the Burke-Fahn-Marsden dystonia rating scale. Head tremor, blepharospasm and orofacial dyskinesia were measured with an infrared, video-based, computerized, real-time passive marker-based analyzer of motions (RTPAM). Results: The Burke-Fahn-Marsden score showed a 90.2% reduction (from 25.5 to 2.5) at 6 months, and an 88.2% long-lasting benefit (to 3.0) at the 3-year follow-up with good bilateral control of the blepharospasm and orofacial movements. The RTPAM showed a substantial regression of acceleration for all markers, and abolishment of the 4.8-Hz head tremor. The correlation between symmetrical markers, and between markers within the right and left sides, was significantly decreased. Conclusions: Pallidotomy with staged procedure is recommended for the treatment of MS in patients on whom deep brain stimulation could not be performed. In case of good bilateral benefits from the unilateral procedure, contralateral surgery is not needed. The RTPAM is a useful tool for the mapping of facial involuntary movements.

Early experiences with a novel (robot hand) technique in the course of microneurosurgery

BACKGROUND The physiologic tremor may cause difficulties in microsurgery, in spite of using armrest. The new (robot hand) technique consists of the I-III finger support, which holds the instruments on Bethlehem (ANDAN BT, Budapest, Hungary) bridge above the operation area, which reduces the tremor at the end of the instruments. METHODS Exact measurement of tremor reduction was performed. Last year, 23 microsurgical cases were operated on by the robot hand technique. RESULTS The tremors of the operating hand and the number of complications have decreased effectively. CONCLUSION By this technique, the microsurgical work has become more precise.

Quantitative evaluation of long-term locomotor activity of rats

The locomotor activity of small animals gives information on their actual psychophysiological state. Changes in it might be used to characterize effects of different impacts on the animals (electric and magnetic field, side effects of medication, etc.). The conventional animal activity meters could not provide the resolution and precision necessary for position measurement during the behavioral studies. Passive marker-based motion analysis offers the solution. For the research work, the PRIMAS analyzer was available. The experiments confirmed that position-time functions of rats held in transparent tube-like cages can be recorded for long periods (several days) with excellent resolution (0.1-mm), precision (1-mm), and accuracy (2-mm).

Blood Pressure Measurement at Home

Blood pressure varies during the day and also has beat-to-beat variations. Presently available meters determine momentary pressure values which are often misleading. Further drawback of the most frequently used oscillometric method is that it determines arterial mean pressure; the systolic and diastolic values are only derived from it. Though it would be necessary, it is impossible to use personalised constants for the calculation. Thus there are substantial deviations from reference values measured by trained medical operator manually. Measuring blood pressure at home is advantageous because the well-known white coat effect does not influence the result and measurements can be done always at the same phase of daily activity. Presently available automatic devices do not provide reliable results.

Identification of the cuff transfer function increases indirect blood pressure measurement accuracy

At present, oscillometric blood pressure meters are among the most commonly used medical devices in the world. While substantial effort has been invested in developing more reliable evaluation algorithms, the actual hardware setup-an inflatable cuff and a pressure transducer connected to it-remained basically unchanged since the mid 19th century. Our research work has concentrated on developing an experimental test set-up to determine the transfer function of cuffs. The relationship between the volume pulses in the brachial artery and the pressure changes induced in the bladder was studied for cuffs of different size and placement. Significant differences have been found between small-, standard- and large-size cuffs. The placement of the bladder (tight, loose, upside down, over a shirtsleeve) remarkably affects the estimated systolic and diastolic pressures. Based on the reported research work it is possible to identify an improperly applied cuff that would result in a misleading BP measurement. Distortion caused by miscuffing is rather patient specific.