The Effect of Pinhole Glasses on Vestibular Electrical Stimulation

Balance is the ability to control and maintain the body's center of gravity within the support area. It can be described as a person's ability to stand without falling, even in the most extraordinary situations, and to feel 'good' in his position in space. from the vestibular system, the visual system, and sensory inputs from tactile-propioceptive sources form the organization of our sense of balance. On the other hand, with the participation of the body muscles, motor coordination occurs and in this way, dynamic balance control is provided as well as the completion of afferent inputs. Balance is an active system that works spontaneously and maintaining the posture is one of its biggest goals. Posture in humans is under a complex and intense regulation by the neuromuscular system. Thanks to this regulation, a rapid postural adaptation takes place against changes in the center of gravity during rest and activity. Postural responses that provide this harmony occur with the integration of vestibular, proprioceptive and visual data in the central nervous system. Any disorder in sensory organization and/or motor coordination provided for balance results in 'balance disorder (imbalance)'. One of the important causes of imbalance is right or left sided unilateral vestibular hypofunction. Vestibular hypofunction may be caused by pathologies originating from the vestibular organ located in the petrous part of the temporal bone and/or the vestibular nerve, which carries sensory information from the vestibular organ to the central nervous system. In these pathologies, which can generally be symptomatic from the time of onset, symptoms are often; vertigo, drowsiness, nausea (sometimes with vomiting), postural dysfunction and imbalance. Unilateral vestibular hypofunction; From Ménière's disease, infections with viral agents such as vestibular neuritis or labyrinthitis, vascular etiologies, toxic reactions due to drugs, weakened function of the inner ear due to aging, head trauma that disrupts inner ear structures, brain tumors (acoustic neuroma, etc.) however, it may be caused by surgical interventions or idiopathic processes that do not cause significant structural changes. In patients with acute vestibular loss, severe dizziness, blurred vision, and nausea and vomiting may accompany. Some of the aforementioned causes (such as vestibular neuritis, vestibular labyrinthitis) usually heal after the acute phase without becoming chronic. Chronic vestibular hypofunction describes the loss of unilateral peripheral vestibular function lasting more than 3 months. In these patients, there is a deterioration in image clarity due to balance disorder and rapid head movements, especially on unstable floors or in conditions where visual information is insufficient, which occurs or increases with movement. Vestibular disorders are usually well treated with medical, surgical, or rehabilitative methods. Compensatory mechanisms play an extremely important role in its recovery. The first mechanism in recovery is internuclear inhibition, causing bilateral reduction in vestibular responses, this inhibition should be prevented. The most successful results are obtained with sensory replacement therapy. The main goals of rehabilitation in vestibular hypofunction are; Reducing the failure of the gravitational muscles on the affected side, reducing oscillopsia due to nystagmus, activating the sensory substitution phenomenon, reducing internuclear inhibition, re-activating coordination, reducing spatial disorientation. Exercises applied in vertigo rehabilitation programs; gaze stabilization exercises (adaptation + replacement exercises), postural stability exercises, habituation exercises, relaxation, flexibility, strengthening and proprioception exercises, conditioning exercises. Appropriate exercise is selected depending on the type of vestibular loss, symptoms, and functional capacity. Vestibular Electrical Stimulation Vestibular Electrical Stimulation (VES) with Transcutaneous Electrical Nerve Stimulation (TENS) is the first step in the rehabilitative treatment of acute vertigo.Direct stimulation of vestibular receptors is highly invasive and not suitable in this case, so electrical stimulation of the paravertebral muscles known as vestibular electrical stimulation (VES) is used. Electrical stimulation is a noninvasive method used for the treatment and rehabilitation of unilateral vestibular pathologies in which muscles and nerves are stimulated with surface electrodes. Nerve and muscle stimulation is provided by means of superficial electrodes. Stimulation of peripheral motor nerves and muscles at the same time with TENS can be done by applying electric current to the skin. These are compatible with motor spots. At the same time, the sensory nerves in the skin are also stimulated. This type of stimulation depolarizes the motor nerves either centrifugally or centripedally. Thus, the motor and sensory effects of TENS are seen together. For this reason, it is also used for pain relief. Electrical stimulation with TENS is called Galvanic Electrical Stimulation (GVS), since both are low-frequency currents, although not using galvanic current. GVS is one of the few methods to artificially stimulate the vestibular system. It is mostly applied on the mastoid body, the reason for choosing the mastoid body is because of its proximity to the vestibule in the inner ear. Other artificial methods are caloric and magnetic vestibular stimulation. Since GVS is a more practical and noninvasive method, it is one of the most commonly used types of VES. GVS is a new and highly effective neurorehabilitation method used in many movement disorders. VES is an important method for replacing the sensory afferents lost in the sudden onset of unilateral vestibular hypofunction and for the correct processing of information in the balance center. Regarding the mechanism of action of VES, it is suggested that it generally affects the auditory system at various levels. There is an electrophonic activation of the basilar membrane. There are direct changes in hairy cell receptor potentials. Together, there is a modulation in the transmitter oscillation. It causes changes in the spontaneous activity of the auditory nerve. Modifies cardiovascular autonomic responses. Increases visual spatial abilities. Cognitive function and vestibulospinal reflexes also improve. Auditory illusions present with VES are also affected. It has been shown to suppress tinnitus in some patients. Decreased tinnitus is associated with decreased spontaneous activity in the auditory nerve. All this occurs as a result of the change in cochlear hemostasis. As a result of VES, inner ear reflexes are activated. The use of pinhole glasses, which have an effect on visual field stability by increasing the patient's depth of vision and fixation ability, may increase the effectiveness during VES. However, no study with a similar design was found in the literature review on this subject. Study aimed it was hypothesized that the use of pinhole glasses providing visual focusing, which will be applied in addition to VES, will increase the effectiveness of VES and be effective on vestibular symptoms.