José Montero Vilela; Aleixandre Cortes i Fabregat; J. David Garrido Jaén; Ignacio Bermejo Bosch*; Rakel Poveda Puente; Ricard Barberà i Guillem; Mª Francisca Peydro de Moya; Beatriz Mañas Ballester; Paula Martínez Mollar
Instituto de Biomecánica (IBV)
Universitat Politècnica de València
Camino de Vera s/n. Edificio 9C
46022 Valencia, Spain
*(IBV Health Technology Group. Bioengineering, Biomaterials and Nanomedicine CIBER (CIBER-BBN)
Balance disorders, in their several manifestations (vertigo, dizziness, instability), are very frequent. Those who suffer from this disorder complain of highly incapacitating symptoms that make these alterations a real healthcare problem.
In this article, the Instituto de Biomecánica (IBV) presents a system that has been specifically designed for the functional assessment and rehabilitation of patients suffering from balance disorders, based on eValanz software.
Technological appropriateness, ease of use, reliability, robustness and maintenance not to mention cost have been aspects that IBV has taken into consideration during the development of the eValanz System application."
INTRODUCTION
Balance disorders, in their several manifestations (vertigo, dizziness, instability), are very frequent. It is estimated that around 2 per cent of visits to a Primary Care Physician are due to this disorder.
Subjects who suffer from this disorder complain of highly incapacitating symptoms, so much so that the patient’s quality of life is seriously affected.
For all these reasons, alterations of balance pose a very real healthcare problem.
In order to manage these patients correctly, it is necessary to reach as precise a diagnosis as possible.
It is estimated that in 40% of cases, the origin of the problem lies in peripheral vestibular alterations, 10% are due to a central injury, 15% to a psychiatric disorder, 25% to another type of problem such as a pre-syncope or other balance disorders, and, finally, in 10% of the cases, the exact diagnosis is unknown.
In order to try to reach as accurate a diagnosis as possible, the doctor must carry out a thorough clinical interview or anamnesis, a complete physical examination of the patient and he or she should complete their examination by performing a series of complementary explorations, prominent among which is Posturography, also known as Stabilography, Statokinesimetry, Stabilometry or Posturology.
INSTRUMENTED BALANCE ASSESSMENT POSTUROGRAPHY
Posturography analyzes an individual’s postural control and is able to quantify the functional state of a patient’s balance compared to the normal population. This technique makes it possible to assess the subject’s capacity to integrate the three systems that are responsible for maintaining posture (vestibular, visual and proprioceptive), and furthermore, to isolate and assess the relative contribution of each one of them by creating situations of sensory conflict by eliminating or reducing the contribution each one makes.
It does not provide an etiological diagnosis nor does it pinpoint the precise anatomical localization of an injury, rather it highlights the deficiency and it determines the compensation strategy for the patient. It makes it possible to assess the importance and the seriousness of the impact that balance disorders have on the subject’s everyday life. In addition, it can shed light on the type of treatment that should be implemented and it can evaluate its effectiveness.
Although the term Posturography encompasses all the techniques used to study and register human posture, it is now used to refer to those methods that employ dynamometric platforms to analyze an individual’s postural behavior during the performance of a Romberg Sensory Organization Test.
The aim of the Romberg Sensory Organization Test is to analyze the behavior of the three main components involved in maintaining balance (vestibular, visual and somatosensory), selectively altering the different sensory information that is received and subsequently evaluating the capacity of the patient to keep his or her balance.
To alter the sensory information, strategies are employed such as closing one’s eyes to eliminate visual afference and/or using unstable surfaces such as foam or making the platform itself move, in order to alter the somatosensory proprioceptive response.
Figure 1. Romberg test with eyes closed and foam (RGC).
It must be borne in mind that somatosensory distortion systems, foam and a moving dynamometric platform fundamentally alter the afferent response, i.e. the ability of the individual to correct a certain position. Nowadays, it is also possible to distort the afferent component, i.e. what the brain perceives, by using virtual reality techniques.
eValanz AS AN INSTRUMENTAL SYSTEM FOR EVALUATING BALANCE AND TREATING INSTABILITY
We know that visual information makes an important contribution to the maintenance of balance, to spatial orientation and to the perception of movement per se, and that changes in the visual environment can cause alterations in balance and falls in patients with a vestibular pathology.
Visual information must provide data about the three-dimensional structure of the environment; such factors as lighting, the complexity of the environment and how the subject adapts to that environment all play a part. Visual stimulation may be foveal and voluntary (slow tracking) or retinal and non-voluntary (the optokinetic system). Both systems run along different paths with the sole objective of stabilizing one’s vision.
Patients with vestibular disorders often complain of dizziness and visual vertigo in complex visual environments. In the rehabilitation of vestibular disorders, therapy based on virtual reality (VRBT) is an emerging technology that can be used to provide visual habituation exercises. Habituation exercises using visually provocative stimuli have been shown to be useful during vestibular rehabilitation.
Based on proven knowledge that feedback and exercise improve motor learning, the incorporation of virtual reality technology into rehabilitation programs provides an opportunity to help patients to get better. This is especially important in balance rehabilitation, a field in which the research work that has been carried out and the evidence that has been obtained are of great importance.
An important factor has to do with ensuring that the exercises are appreciably more "fun" for the patient, which in turn enhances the frequency and the duration of the rehabilitation sessions. Recently, videogames have been used in various areas related to health. One of the main reasons given has been increased motivation in patients when it comes to following the treatment.
Another aspect worth considering is that the patient can be left on his or her own to carry out the exercises. A predetermined exercise program can be followed without any need for supervision by clinical staff, provided that the patient is in good enough condition and there is no risk of falls.
The gradation of the difficulty of the rehabilitation exercises is equally important. The exercises must be designed so that it is possible to automatically adjust the parameters that determine how difficult they are (the range and speed of the movements, the sensitivity of the interaction devices).
The generation of controlled environments, which make it possible to recreate concrete situations in the field of balance assessment and rehabilitation (BA&R), has its best ally in the new technologies that are based on virtual reality. The application of these technologies, in addition to enhancing, intensifying or even shortening some of the rehabilitation processes, favors both the control of the intensity of the rehabilitation exercises and the beneficial effects they have on the patient. Equally or even more important is how it offers us the possibility to evaluate the functional capacities of the patient and his or her evolution during the rehabilitation process.
For these reasons, IBV has been working on the development of a system that, as a complement to its well-known BA&R methodology, makes it possible to apply virtual reality technologies in order to strengthen the visual system as part of the balance rehabilitation process.
Figure 2. The system that IBV has developed includes a rehabilitation module based on virtual reality that includes 3D videos that simulate environments and real situations.
We can classify requirements in two groups: those that have to do with how the technologies are appropriate to the intended goal (technological) and those that have to do with how possible it is to integrate them into clinical practice (methodological and economic).
These are the aspects that we have taken into consideration during the development of the eValanz System application:
Appropriateness of the technology
The force platform is the device used in eValanz System to record the position of the subject’s center of gravity (CoG). Ideally, this CoG position would remain stable while the subject is at rest in a standing position, although in reality it oscillates around this point of rest to a greater or lesser extent depending on the control the subject has over his or her balance position.
Figure 3. The force platform registers the position of the center of gravity (CoG) and is the device that interacts with the virtual environment for the rehabilitation exercises.
The position of the CoG can be modified voluntarily by the subject by moving his or her center of mass both in the anterior-posterior axis and in the median axis-lateral, given that they are able to use their CoG position as a joystick connected to the computer.
The eValanz system takes advantage of precisely this possibility to use the force platform as a device for interacting with the virtual environment during the rehabilitation exercises. By moving the center of gravity forward, the subject can "advance" in the virtual scenario, at a greater or lesser speed depending on how much he or she moves their CoG with respect to their rest position. Similarly, the subject can move backwards, turn to the right or to the left by moving their CoG backwards, to the right or to the left. In addition, these control options are not mutually exclusive, rather they can combine to produce complex displacements.
The rehabilitation module that is included in the application is based on the 3D simulation of environments and real situations, which helps the professional when it comes to prescribing the types of exercise that are best suited to the therapeutic needs of the patient, and to evaluating their effectiveness.
Figure 4. The information obtained from the eValanz software helps to guide the specialist as to the type of personalized exercise programme that best suits each patient and to evaluate their effectiveness.
Simplicity of use
Following this premise, eValanz System has been designed in line with standards of maximum usability and operational simplicity.
eValanz is an application that can be used easily in clinical practice. The hardware and software are auto-configurable and are perfectly integrated.
Users can install the eValanz System themselves; it includes the following elements:
♦ A license to use the eValanz software.
♦ A portable 600 x 370 x 40 mm force plate weighing approximately 7.5 kg.
♦ An all-in-one PC (a flat panel touch screen and a wireless mouse, keyboard and touchpad).
♦ Virtual Reality Glasses
♦ 9 cm foam.
Figure 5. The eValanz System balance assessment and rehabilitation system, once it has been set up.
Reliability, robustness and maintenance
The eValanz system requires simple maintenance and has satisfactory and effective technical support.
Cost
The eValanz System provides users with a high-performance tool at a very reasonable cost.
CONCLUSIONS
There are many pitfalls when it comes to incorporating new technologies into day-to-day clinical practice, and it is has been precisely its desire to overcome these barriers that has led IBV to work on commissioning the eValanz System application.
By means of this new application, IBV has endeavored to respond to the needs of professionals who specialize in BA&R. To do so, we have taken advantage of the opportunities that technology currently offers us, as well as the knowledge generated in this area that IBV has accumulated over so many years, not to mention the invaluable help of the users of our NedSVE/IBV balance evaluation application.
