Introduction
Vertigo is not an independent disease but a symptom that can occur against a background of various pathologies. According to Ma and Zeng (2019), vertigo is defined as “a sensation of environment spinning, often caused by a lesion in the vestibular pathway (also termed as true vertigo)” The source also underlines the difference between vertigo and dizziness, the latter being described as “a sensation of lightheadedness, presyncope or imbalance” (Ma & Zeng, 2019). Dizziness is sometimes referred to as psuedovertigo or can be used as a broader term that includes many interpretations. The primary system affected when diagnosing vertigo is the vestibular one.
Normal Anatomy of Major Body System Affected
The vestibular analyzer, which includes the vestibular apparatus, consists of a peripheral apparatus, nerve pathways of the vestibular analyzer; subcortical and cortical nuclear formations; associative links. They carry out the interaction of the vestibular apparatus and the nervous system (autonomic and somatic), in particular, with its sympathetic and parasympathetic divisions. The vestibular system is the essential part of the nervous system responsible for the balance. The peripheral part of the vestibular analyzer includes membranous formations located symmetrically. There are two pairs of sacs and a vestibule in each formation and three pairs of semicircular ducts enclosed in bone canals.
Based on the above, it can be concluded that a single closed endolymphatic system of the ear labyrinth consists of the cavity of the vestibule sacs and; the cavity of the semicircular ducts. A Pelo-lymph surrounds a single closed system. In the sacs of the vestibule and semicircular canals themselves, there are specialized receptors of the vestibular apparatus. These receptors respond to the mechanical displacement of the inertial masses of the vestibular apparatus. Moreover, such mechanical displacements can be of different strengths: both large enough and small. Also, the vestibular apparatus consists of three bony semicircular canals and an area of the vestibule.
Normal Physiology of Body System Affected
Rotational movements set the endolymph in motion in the semicircular canals located in the plane of movement. Depending on the direction of the current, the endolymph stimulates or inhibits the activity of the neurons of the hair receptors situated on the canal. Identical hair cells coat a matrix of calcium carbonate crystals (otoliths) in spherical and elliptical sacs. The deflection of the otoliths in space stimulates or inhibits the neuronal signal from the hair receptors. Visual perception and proprioceptive signals from peripheral nerves (via the spinal cord) also play an important role in balance (Zabolotnyi & Serhiivna, 2020). These signals enter the cerebral cortex from the lower centers, making it possible to perceive body movements in space.
Mechanism of Pathophysiology
Depending on which semicircular canal is affected, nystagmus has the following features. With the disease of the posterior semicircular canal, vertical nystagmus is upward with a rotator component towards the underlying (affected) ear. When the horizontal anterior canal is diseased, geotropic (directed to the surface of the earth), or apogeotropic (oppositely directed) horizontal nystagmus changes direction. With the affected anterior canal, vertical nystagmus is downward, sometimes with a weak rotator component.
Canalolithiasis suggests the presence of freely moving otoliths in the lumen of the canal. If they are attached to the cupula (much less common), cupulolithiasis takes place. Sometimes the concept of canal jam is encountered in the literature. It is believed that otoliths move freely in the canal but cannot leave it due to the block of the canal when they move from the broader part of the canal to the narrower one. For example, it is the case during the migration of otoliths from the ampulla into the smooth knee or the posterior or anterior semicircular canal into their common leg.
The causes of damage to the otolith membrane are still being specified. In some cases, benign paroxysmal positional vertigo is preceded by a head injury (Neuhauser, 2016). Postponed vestibular neuronitis or prolonged bed rest can also be a provoking factor (Neuhauser, 2016). Age-related degeneration of the proteinaceous and gel-like matrix of the otolith membrane may play a unique role. It has been shown (Neuhauser, 2016) that osteopenia and osteoporosis are more pronounced in patients with recurrent BPPV. It can be assumed that spontaneous detachment of otoliths from the membrane in BPPV is a local manifestation of impaired calcium metabolism in the body. This is confirmed by recent studies (Neuhauser, 2016), demonstrating the relationship of vitamin D deficiency with the development and frequent recurrence of BPPV.
With BPPV, the posterior, geotropic, and anterior semicircular canals can be affected, and their combined defeat is observed in some cases. Due to its anatomical location relative to gravity, the posterior canal is most often affected, accounting for an average of 85–90% of all BPPV cases. The geotropic semicircular canal causes BPPV in 5-10% of cases, posterior canal, and associated lesions in less than 5% of cases (Neuhauser, 2016). The diagnosis of BPPV is established based on anamnesis data, patient complaints, and examination results. As a rule, patients complain of an attack of systemic dizziness after specific head movements. Most often, an attack is provoked by turning from side to side, getting out of bed or lying in it, throwing the head back when looking up, or tilting the body forward. In general, any other sharp turns of the head can be a potential trigger for vertigo.
Prevention
To prevent vertigo, it is recommended to stay hydrated since dehydration leads to a decrease in the amount of blood, which makes the brain receive less oxygen. In addition, the balance maintenance system located in the inner ear uses a fluid in its work and focuses on its level (Neuhauser, 2016). The brain interprets the signals received from it and judges the balance of the body from them.
Also, such exercises as Epley and Brandt-Daroff help restore the inner ear’s balance control system by moving particles in the vestibular organs. These particles can settle in the inner ear and thus cause dizziness. These exercises involve the head and neck muscles and can be performed independently without the help of a doctor (Zwergal et al., 2019). The repetitive head movements practiced in these exercises help to disperse particles in the inner ear’s vestibular apparatus and relieve vertigo.
Treatment
The treatment of vertigo is always individual and is prescribed according to the established diagnosis and those symptoms observed in the patient. For instance, depending on symptoms, there are various types of vertigo, such as Benign paroxysmal positional vertigo (BPPV), Meniere’s disease, vestibular neuritis, and vestibular migraine (Zwergal et al., 2019). Therefore, therapy of vertigo varies greatly and is contingent on the type of disease.
Benign paroxysmal positional vertigo is the most common type of vertigo known for over a hundred years. However, this type of vertigo remains one of the most undiagnosed causes of the disease. For BPPV treatment, special rehabilitation maneuvers are used, which are to return otolith particles from the semicircular canal to the threshold of the labyrinth (Zwergal et al., 2019). There is a therapeutic maneuver for each semicircular canal, and the maneuvers’ efficiency is high – up to 95% or more.
The clinical picture of Meniere’s disease is characterized by the following four manifestations: attacks of systemic vertigo, progressive hearing loss, fluctuating noise in the ear, and a feeling of pressure in the ear. Treatment of Meniere’s disease consists of two directions: relief of an attack and prevention of exacerbations. Relief of an attack involves using vestibulolytic drugs, such as dimenhydrinate, benzodiazepine tranquilizers, and phenothiazines (Zwergal et al., 2019). Prevention of exacerbations requires adherence to a salt-free diet, the use of diuretics (such as acetazolamide or hydrochlorothiazide), and betahistine (betaserc).
Conclusion
Vertigo is a symptom that manifests itself as an illusion of movement. Dizziness is not a diagnosis; it is a symptom of certain diseases. It is a consequence of asymmetry in the vestibular system due to damage or dysfunction of the labyrinth, the vestibular nerve, or the central structures of the vestibular analyzer. One type of vertigo is rotational; other disorders manifested by vertigo are presyncope weakness, imbalance, and nonspecific or disease-related lightness in the head. It is customary to combine the causes of dizziness into groups of peripheral and central disorders. They have distinct clinical characteristics, however, their properties may be somewhat similar.
Peripheral causes of vertigo are responsible in the aggregate for the development of 80% of all cases (Zwergal et al., 2019). The most common of these are benign paroxysmal positional vertigo and vestibular neuronitis, and Meniere’s disease.
References
Zabolotnyi, D. I., & Mishchanchuk, N. S. (2020). Vestibular System: Anatomy, Physiology, and Clinical Evaluation. In T. Suzuki (Ed.), Somatosensory and Motor Research. IntechOpen.
Ma, J., & Zeng, R. (2019). In X.H. Wan & R. Zeng (Eds.), Handbook of Clinical Diagnostics, (pp. 87–88). Springer.
Neuhauser, H. (2016). The epidemiology of dizziness and vertigo. In J.M. Furman & T. Lempert (Eds.), Handbook of Clinical Neurology, (pp 67–82). Elsevier B.V.
Zwergal, A., Feil, K., Schniepp, R., & Strupp, M. (2019). Cerebellar dizziness and vertigo: Etiologies, diagnostic assessment, and treatment. Seminars in Neurology, 40(01), 87–96. Web.