DIMETER Tremor measurement device



Neurosensory disorders are characterised by tremors of the upper extremities of those who suffer this disease. The present instrument for measuring and diagnosing the type of tremors, allows doctors and health care professionals to evaluate in an objective manner the type and degree of the pathological tremor under observation.

DIMETER is composed by a tremor acquisition system controlled by the patient's finger, a computer that obtains and processes the samples and a pattern series or tasks to be made by the patient. These patterns are different trajectories or movements on which it is possible to apply virtual forces aimed to obtain richer information above the patient's movement capacity. After the trial realization, which have been chosen by a qualified medical team from a huge pattern set, the system gives detailed information about the tremor features in three dimensions, like for example trajectories, fundamental frequencies, amplitudes, level of tremor depending on the pattern.

DIMETER employs an electromechanical device able to generate virtual forces over the patient's finger in combination with a pattern set. These patterns are defined by spatial trajectories that the patient should follow during the tremor assessment. The different kinds of patterns are:
•       Statics: holding the finger in the same position during all the test.
•       Kinetics: following a defined trajectory on the computer screen or in the real space.
•       Reactive: touching a spatial point as soon as possible.
•       Dynamics: any of the previous ones including artificial forces like gravity, friction, repulsive forces referenced to the final point, or depending on the error during the trajectory pursuit.

The movement is sampled, processed and displayed as graphics on a computer, being the information presented in a format easily understood by the evaluator. The level of detail is selectable by medical staff. The movement features are 3D decomposed in spatial, temporal and frequency domain. Hence it is possible to observe differences in the movement depending on the subject's voluntary movement direction. Good precision and useful information is obtained. The diagnostics and the monitoring of symptomatology tremor diseases can be done very efficiently. Furthermore, DIMETER enables the clinical history to be kept thus allowing an evaluation of the temporal evolution of the tremor and of the patient’s disorder.

One singular features on DIMETER are the diagnostic set pattern which measures the effect of applying different forces (friction, load, etc) on the tremor. In this manner it is possible to obtain more detail of the pathologic characteristic.

Neurophysiologists and neuro-surgeons have been involved in the development of the DIMETER system, aimed to the necessity to obtain objective features over amplitude, frequency and tremor morphology in the Parkinson, Charcot Marie-Tooth or Essential Tremor among others. A battery of different tests, to be followed by the patient, has been developed. They are aimed to identify tremor features in different conditions.

The Systems Engineering and Automatic Control Division UPM-DISAM of Universidad Politécnica de Madrid collaborates with medical specialists in neurology and other specialists to develop the equipment that helps in the diagnostics, evaluation, treatment and follow-up of patients with neurosensory disorders. In developing these systems we apply the technical expertise in gathering and filtering the signals, robotics, development of interfaces men-machines, virtual reality and enhanced reality, adapted to the specific needs of the medical professional or of medical research. UPM-DISAM can thus:
•       Adapt the existing technology to the specific needs of the client
•       Develop new tailor-made systems
•       Provide advisory services in the development of R&D projects in the fields of Robotics and Tele-robotics applied to medicine, amongst others
•       Provide the necessary training in the use of these technologies.

The use of DIMETER system allows:


•       A simple, friendly   and robust way to tremor data recording
•       Objective evaluation of the patient's tremor using movement pattern equivalent to that used in clinical practice.
•       Evaluate the effect of different treatment (surgical or pharmacologic) of the pathology that generate the tremor. This permits the use of easy criteria for adjustment or dose selection.
•       Objective follow-up of the patient's disease along the time.

The use of this kind of technology is linked with the improvement of quality of life. It uses to allow objective measurements and precise information of the tremor features, which offer an easy and better disease diagnostic. With the observation of tremor evolution in the chase of the disease, and principally after medication, it allows the adjustment of the correct dose, making lower the secondary effects and extending the valid period of this treatment.

In some disease like Parkinson, Charcot-Marie-Tooth or Essential Tremor, surgical treatment can be based on electrical stimulation and they can offer a notorious improvement in the patient's quality of life. In these cases the DIMETER system permits the localization of the implant point and the stimulator adjustment.