Balance disorders, often overlooked and misunderstood, can have a profound impact on an individual's daily life, making even simple tasks a formidable challenge. From feeling dizzy and lightheaded to experiencing unexplained falls, balance disorders encompass a range of symptoms that can be both frustrating and debilitating. In this article we will explore different causes for balance dysfunction and patient populations that do suffer from it, let us discuss the true nature of balance disorders.
1. Dizziness and Disequilibrium
Dizziness is a common complaint in people with balance disorders. For the past years, dizziness has been used as a term that includes vertigo, leading to some confusion even within research. The Committee for Classification of Vestibular Disorders of the Bárány Society was inaugurated with the goal of developing an implementable classification of vestibular disorders. Although the typical American usage identifies dizziness as an umbrella term that includes vertigo as a subset, the Bárány Society decided to make terms non-hierarchical, suggesting that dizziness and vertigo should be defined separately. In their first consensus document you can find the following definitions for vertigo and dizziness (Bisdorff et al., 2009):
1. Vertigo is the sensation of self-motion when no self-motion is occurring or the sensation of distorted self-motion during an otherwise normal head movement.
2. Dizziness is the sensation of disturbed or impaired spatial orientation without a false or distorted sense of motion.
Although dizziness and disequilibrium are often associated with vestibular impairments, they can also be present in other contexts. They can be classified in different types, such as presyncope and lightheadedness. In cardiovascular dysfunctions, dizziness classified as presyncope can be observed in arrhythmias, myocardial infarction, carotid artery stenosis, and orthostatic hypotension. As for lightheadedness, described as a type of disequilibrium, is often found in Psychiatric context, particularly in anxiety and panic disorders. In addition, some medications have been linked to increased dizziness and disequilibrium, including cardiac medication, central nervous system medication and urologic medication (Post & Dickerson, 2010).
2. Falling in the Elderly
Aging is associated with a decline in balance control system function, which results in impaired mobility, social isolation, phycological alterations and in an increased risk of fall. Different factors can influence the decline in postural control, such as biomechanical constraints, impaired movement strategies and sensory strategies, changes in orientation is space and declined cognitive processing, as it is shown in the figure below, created by Horak in 2006 (Horak, 2006). This figure shows us the increase in fall risk with ageing, however, as Horak states, it is not due to ageing of the balance system, but to an increase in likelihood of developing impairments in specific subsystems underlying balance control. We already know that older people with balance disorders often suffer from multi-sensory loss, muscle weakness and cognitive impairments, being susceptible to a higher risk of falling. (Ali Gujar, 2019).
Therefore, it is vital to understand the interaction between sensory systems and the central nervous system in terms of integration and organization of different afferent inputs, encompassing compensatory mechanisms (sensory inputs reweighting), and environmental factors surrounding a specific person with balance dysfunction so we can predict context- specific instability and prevent falls.
3. Neurological Disorders
Neurological disorders are one of the major causes of mortality and disability worldwide (GBD 2016 Neurology Collaborators, 2019) and are frequently associated with varying degrees of sensory, motor, and central function problems. Expectably, balance control impairment is often present in patients suffering from these disorders, highly impacting daily life. Within neurological disorders it is possible to observe serious alterations in matters of peripheral and central nervous system, such as somatosensory impairments, that include changes in proprioception resulting from slowed transmission of somatosensory impulses or changes in mechanoreceptors, as well as difficulties within integration and organization of all afferent inputs, changes in reflexes, muscle strength, neuromuscular function and muscle tone, among others constraints that have a serious impact on postural control. Some examples of neurological disorders that frequently lead to balance dysfunction are multiple sclerosis, parkinson's disease, stroke, polineurophaties and concussions. You can read more about it here.
4. Orthopedic Injuries
Balance dysfunction is frequently associated with orthopedic injuries. Firstly, because most of the times we will be facing biomechanical constraints, such as decreased range of motion and muscle strength, accompanied by pain, which will negatively affect neuromuscular activity, meaning that movement strategies (reactive, anticipatory, and voluntary) required for balance maintenance will probably be less effective. Whitin this context, we can also expect the sensory input to be decreased. We know that joint injuries can result in loss of afferent input through damage in mechanoreceptors, this is frequent in ACL injuries and ankle injuries (Chmielewski et al., 2002). For instance, several studies have identified impaired postural control in patients with lower back pain, that can be explained by deficit in proprioception in the lumbar spine and changes in neuromuscular activity (Bouche et al., 2006). Other orthopedic injuries that most often lead to balance dysfunction are total knee replacement, total hip replacement, fractures, muscle injuries and spine injuries.
5. Pharmacological Ototoxicity
Ototoxicity is defined as damage to the inner ear, targeting cochlear and vestibular structures as well as sensory function, due to exposure to certain pharmaceuticals, chemicals, and/or ionizing radiation. In fact, there are many potentially ototoxic substances. As for pharmaceutical induced ototoxicity, there are 200 to 600 medications that can cause damage to hearing and balance, resulting in symptoms such as vertigo, dizziness and imbalance (Watts, 2019).
An example of pharmacological induced ototoxicity are aminoglycoside antibiotics, broad-spectrum medications used to treat bacterial infections, including neonatal sepsis, mycobacterial infections, and meningitis, are known to induce anatomical and functional damage to the vestibular system (Steyger, 2021). By way of example, the vestibulotoxicity of gentamicin, an aminoglycoside antibiotic, does not cause spontaneous vertigo, patients that are bed bound may show minimal signs of vestibular dysfunction. Symptoms such as motion-induced dizziness, oscillopsia and gait ataxia are visible when patients start to mobilize. Therefore, it is recommended to monitor vestibular function as soon as possible, for example through vestibular-ocular reflex assessment with the visual acuity test (Turnidge & Waterston, 2012).
6. Vestibular Disorders
Vestibular Disorders is considered a generic term for balance disturbance caused by injuries and/or functional alterations in the Vestibular System. They can be classified as Peripheral Vestibulopathies, Central Vestibulopathies and Mixed Vestibulopathies.
In Peripheral Vestibulopathies the peripheral vestibular system is compromised, symptoms like vertigo, oscillopsia, postural instability, dizziness, nausea, and disequilibrium are frequently present. Central Vestibulopathies include an extensive list of possible diagnosis with a high variety of symptoms. Some possible causes of damage in the Central Vestibular System include the following: posterior inferior cerebellar artery stoke, damage in the brain stem, parietal cortex, thalamus and cerebellum, neurodegenerative disorders, concussions, neoplasia, among others. All this different natures and symptoms justify the need for a multidisciplinary approach to help patients suffering from balance dysfunction (Seabra et al., 2023).
Commonly Diagnosed Vestibular Disorders |
|---|
Benign Paroxysmal Positional Vertigo |
Vestibular Migraine |
Ménière's Disease |
Vestibular Neuritis |
Labyrinthitis |
Vestibular Damage due to Head Injury |
Do you have questions about this topic? Or want to know more about balance system?
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Ana Souto
Meet Ana, a physiotherapist with a master's degree in human physiology, currently specializing in neurobiology. Her professional journey has led her to gain extensive expertise in both neurology and sports physiotherapy.
Ana currently serves as the clinical specialist at PhysioSensing, a cutting-edge Balance Assessment and training device. Leveraging her strong foundation in scientific research and evidence-based practices, Ana creates customized assessment and training plans. Her approach is firmly rooted in the latest scientific findings, ensuring that PhysioSensing users receive the most effective and up-to-date care.
In addition to her role in designing tailored programs, Ana plays a pivotal role in guiding new clients through the learning process of using PhysioSensing. She also provides advanced training and support to existing customers seeking to further deepen their clinical practice knowledge and stay on top of the latest scientific advancements.
References
Ali Gujar, T. (2019). Effect of aging in cortical activity during sensory integration to balance posture. Otto-von-Guericke-Universität Magdeburg.
Bisdorff, A., Von Brevern, M., Lempert, T., & Newman-Toker, D. E. (2009). Classification of vestibular symptoms: Towards an international classification of vestibular disorders. Journal of Vestibular Research, 19(1–2), 1–13. https://doi.org/10.3233/VES-2009-0343
Bouche, K., Stevens, V., Cambier, D., Caemaert, J., & Danneels, L. (2006). Comparison of postural control in unilateral stance between healthy controls and lumbar discectomy patients with and without pain. European Spine Journal, 15(4), 423–432. https://doi.org/10.1007/s00586-005-1013-4
Chmielewski, T. L., Wilk, K. E., & Snyder-Mackler, L. (2002). Changes in weight-bearing following injury or surgical reconstruction of the ACL: Relationship to quadriceps strength and function. Gait & Posture, 16(1), 87–95. https://doi.org/10.1016/s0966-6362(01)00202-8
Horak, F. B. (2006). Postural orientation and equilibrium: What do we need to know about neural control of balance to prevent falls? Age and Ageing, 35(suppl_2), ii7–ii11. https://doi.org/10.1093/ageing/afl077
Post, R. E., & Dickerson, L. M. (2010). Dizziness: A diagnostic approach. American Family Physician, 82(4), 361–368, 369.
Seabra, R., Monteiro, C., Trigueiros, N., Costa, S., Subtil, J., & Lemos, J. (2023). Otoneurologia (1a). Círculo Médico.
Steyger, P. S. (2021). Mechanisms of Ototoxicity and Otoprotection. Otolaryngologic Clinics of North America, 54(6), 1101–1115. https://doi.org/10.1016/j.otc.2021.08.007
Turnidge, J. D., & Waterston, J. A. (2012). Gentamicin and ototoxicity: Why this drug is still in use. Medical Journal of Australia, 196(11), 665–666. https://doi.org/10.5694/mja12.10733
Watts, K. (2019). Ototoxicity: Visualized in Concept Maps. Seminars in Hearing, 40(02), 177–187. https://doi.org/10.1055/s-0039-1684046