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This is a glossary of medical terms related to communication disorders which are psychological or medical conditions that could have the potential to affect the ways in which individuals can hear, listen, understand, speak and respond to others.
The sense of balance or equilibrioception is the perception of balance and spatial orientation. It helps prevent humans and nonhuman animals from falling over when standing or moving. Equilibrioception is the result of a number of sensory systems working together; the eyes, the inner ears, and the body's sense of where it is in space (proprioception) ideally need to be intact.
A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Balance is the result of several body systems working together: the visual system (eyes), vestibular system (ears) and proprioception. Degeneration or loss of function in any of these systems can lead to balance deficits.
The vestibulo-ocular reflex (VOR) is a reflex acting to stabilize gaze during head movement, with eye movement due to activation of the vestibular system. The reflex acts to stabilize images on the retinas of the eye during head movement. Gaze is held steadily on a location by producing eye movements in the direction opposite that of head movement. For example, when the head moves to the right, the eyes move to the left, meaning the image a person sees stays the same even though the head has turned. Since slight head movement is present all the time, VOR is necessary for stabilizing vision: people with an impaired reflex find it difficult to read using print, because the eyes do not stabilise during small head tremors, and also because damage to reflex can cause nystagmus.
The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals.
Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness.
Spatial disorientation is the inability to determine position or relative motion, commonly occurring during periods of challenging visibility, since vision is the dominant sense for orientation. The auditory system, vestibular system, and proprioceptive system collectively work to coordinate movement with balance, and can also create illusory nonvisual sensations, resulting in spatial disorientation in the absence of strong visual cues.
Labyrinthitis is inflammation of the labyrinth, a maze of fluid-filled channels in the inner ear. Vestibular neuritis is inflammation of the vestibular nerve. Both conditions involve inflammation of the inner ear. Labyrinths that house the vestibular system sense changes in the head's position or the head's motion. Inflammation of these inner ear parts results in a sensation of the world spinning and also possible hearing loss or ringing in the ears. It can occur as a single attack, a series of attacks, or a persistent condition that diminishes over three to six weeks. It may be associated with nausea, vomiting, and eye nystagmus.
Benign paroxysmal positional vertigo (BPPV) is a disorder arising from a problem in the inner ear. Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. This can occur with turning in bed or changing position. Each episode of vertigo typically lasts less than one minute. Nausea is commonly associated. BPPV is one of the most common causes of vertigo.
Electronystagmography (ENG) is a diagnostic test to record involuntary movements of the eye caused by a condition known as nystagmus. It can also be used to diagnose the cause of vertigo, dizziness or balance dysfunction by testing the vestibular system. Electronystagmography is used to assess voluntary and involuntary eye movements. It evaluates the cochlear nerve and the oculomotor nerve. The ENG can be used to determine the origin of various eye and ear disorders.
Vertigo is a condition in which a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspiration, or difficulties walking. It is typically worse when the head is moved. Vertigo is the most common type of dizziness.
In medicine, the caloric reflex test is a test of the vestibulo-ocular reflex that involves irrigating cold or warm water or air into the external auditory canal. This method was developed by Robert Bárány, who won a Nobel prize in 1914 for this discovery.
The otolithic membrane is a fibrous structure located in the vestibular system of the inner ear. It plays a critical role in the brain's interpretation of equilibrium. The membrane serves to determine if the body or the head is tilted, in addition to the linear acceleration of the body. The linear acceleration could be in the horizontal direction as in a moving car or vertical acceleration such as that felt when an elevator moves up or down.
The Dix–Hallpike or Nylén–Bárány test is a diagnostic maneuver from the group of rotation tests used to identify benign paroxysmal positional vertigo (BPPV).
Illusions of self-motion occur when one perceives bodily motion despite no movement taking place. One can experience illusory movements of the whole body or of individual body parts, such as arms or legs.
Videonystagmography (VNG) is a technology for testing inner ear and central motor functions, a process known as vestibular assessment. It involves the use of infrared goggles to trace eye movements during visual stimulation and positional changes. VNG can determine whether dizziness is caused by inner ear disease, particularly benign paroxysmal positional vertigo (BPPV), as opposed to some other cause such as low blood pressure or anxiety.
The righting reflex, also known as the labyrinthine righting reflex, is a reflex that corrects the orientation of the body when it is taken out of its normal upright position. It is initiated by the vestibular system, which detects that the body is not erect and causes the head to move back into position as the rest of the body follows. The perception of head movement involves the body sensing linear acceleration or the force of gravity through the otoliths, and angular acceleration through the semicircular canals. The reflex uses a combination of visual system inputs, vestibular inputs, and somatosensory inputs to make postural adjustments when the body becomes displaced from its normal vertical position. These inputs are used to create what is called an efference copy. This means that the brain makes comparisons in the cerebellum between expected posture and perceived posture, and corrects for the difference. The reflex takes 6 or 7 weeks to perfect, but can be affected by various types of balance disorders.
The rod and frame test is a psychophysical method of testing perception. It relies on the use of a rod and frame apparatus which uses a rotating rod set inside an individually rotatable drum, allowing an experimenter to vary the participant's frame of reference and thus test for their perception of vertical.
The ocular tilt reaction (OTR) comprises skew deviation, head tilt and ocular torsion involving structures of the inner ear responsible for maintenance of balance of the body i.e. the semi-circular canals (SCC), utricle and saccule.
Vestibular rehabilitation (VR), also known as vestibular rehabilitation therapy (VRT), is a specialized form of physical therapy used to treat vestibular disorders or symptoms, characterized by dizziness, vertigo, and trouble with balance, posture, and vision. These primary symptoms can result in secondary symptoms such as nausea, fatigue, and lack of concentration. All symptoms of vestibular dysfunction can significantly decrease quality of life, introducing mental-emotional issues such as anxiety and depression, and greatly impair an individual, causing them to become more sedentary. Decreased mobility results in weaker muscles, less flexible joints, and worsened stamina, as well as decreased social and occupational activity. Vestibular rehabilitation therapy can be used in conjunction with cognitive behavioral therapy in order to reduce anxiety and depression resulting from an individual's change in lifestyle. However, there is often confusion about whether vestibular rehabilitation falls under physical therapy (PT) or occupational therapy (OT).
References
- ↑ "Subjective Visual Vertical (SVV) and the Dizzy Patient". 31 October 2017.
- ↑ "Balance And Vestibular Program | Tests and Procedures | Boston Children's Hospital". www.childrenshospital.org. Retrieved 2018-07-11.