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Vertigo
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
There are two main categories of vertigo: peripheral and central. Peripheral vertigo is a collection of vertigo types that are caused by problems in the inner ear, such as problems with the vestibular mechanisms that were mentioned above. The nerve that sends signals from your inner ear into your brain is called the vestibular nerve, and all kinds of peripheral vertigo warp the signals being sent through that nerve such that the signals end up being incorrect. Once the signals make it into your brain they don't make sense when compared to what your visual and proprioceptive systems are reporting, and this causes the sensation of spinning. Peripheral vertigo is usually temporary and may depend on the position that your body is in such as whether you are standing, lying down, or if your head is moving—if you have ever experienced temporary vertigo, it was probably caused by a peripheral change (Brandt et al., 2013). One potential cause of peripheral vertigo is that the otoconia crystals become misaligned in your semicircular canals and disrupt the movement of fluid. This results in a condition called benign paroxysmal positional vertigo, which usually shows up mysteriously but can sometimes be linked to anything from head trauma to viral infections, to the position that you sleep in at night, and many other factors (Yetiser, 2019). So yes, crystal misalignment can make you dizzy. That's just science.
The Special Sense Organs and Their Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
Hair cells, arranged in clusters called hair bundles, are specialized receptor cells of the vestibular sense organs. These hair cells convert a mechanical force into an electrical signal that is sent into the brain via the vestibular nerve. Statoconia, also called otoconia because of their location (oto- = ear), are calcium carbonate crystals in the inner ear that respond to gravity and cause the hair cells to stimulate the nerve fibers and eventually produce posture changes, keeping the person erect (stato- = standing).
Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
The sensorineural epithelium of the sacculus and utricle maculae is flat and located in a region of each called the maculae. The stereocilia of type I and type II hair cells of the utricle and sacculus are embedded in a gelatinous mass (otolith). The otolith contains calcium carbonate and calcite crystals (otoconia). These add weight to the otolith and allow sensitivity to gravity. The hair cells in the macula have several rows of stereocilia arranged in a specific orientation. Movement of the endolymph fluid in the sacculus is induced by linear acceleration or deceleration, head tilt and also influenced by gravity, even when the head is at rest.
Differential screen and treatment of vestibular dysfunction in an elderly patient: A case report
Published in Physiotherapy Theory and Practice, 2023
Carrie A. Barrett, Donald L Hoover
In contrast to LC, benign paroxysmal positional vertigo (BPPV) is another potential post-concussion sequela for individuals of any age. This condition is a vertiginous disorder wherein otoconia displacement within the semicircular canals creates severe dizziness related to head positioning BPPV is seen in 10.6% of individuals who sustain a head injury (Jozefowicz-Korczynska, Pajor, and Skora, 2018). BPPV is typically seen in one canal, with approximately 85–95% of BPPV found in the posterior semicircular canal (PSCC) (Bhattacharyya et al., 2017). In comparison, multiple canal (MC) involvement is seen in less than 4.6% of those with BPPV and occurs typically in the ipsilateral posterior and horizontal canals (Shim et al., 2014). Regardless of the site of otoconia displacement, use of canalith repositioning techniques (CRT) to clear BPPV can resolve symptoms 88.9% of the time, typically takes 1–2 visits to clear, and is well documented as a cost-effective treatment of BPPV following mTBI (Bhattacharyya et al., 2017).
Vertical “pseudospontaneous” nystagmus in a patient with posterior canal BPPV: case report
Published in Acta Oto-Laryngologica Case Reports, 2021
Bernardo Faria Ramos, Renato Cal, Pedro Luiz Mangabeira Albernaz, Francisco Zuma e Maia
In the same way, in our case, we could call it a vertical ‘pseudospontaneous’ nystagmus as it is due to a biomechanical etiology induced by the action of gravity. In this patient, the otoconia could be located in an atypical position in the posterior semicircular canal far from the ampulla in the transition of the ampullary and non-ampullary arm (Figure 1). This inclination relative to the horizontal plane allows the otoconia to slowly float in the direction of the ampulla provoking an ampullopetal inhibitory flow and resulting in a mild nystagmus with a vertical downbeating component. In the bow test, the otoliths will also move in the direction of the ampulla, provoking an ampullopetal inhibitory flow and resulting in a nystagmus with a vertical downbeating component (Figure 1). On the other hand, otoconia will fall away from the ampulla in the lean and Dix Hallpike tests, provoking an ampullofugal excitatory endolymphatic flow, resulting in a nystagmus with a vertical upbeating component (Figure 1). Indeed, vertical nystagmus in the bow and lean tests was previously described in patients with posterior canal BPPV [8].
VEMPs: pathophysiology, method and results (short review)
Published in Hearing, Balance and Communication, 2021
Leonardo Manzari, Ian S. Curthoys
How does otolithic activation by ACS and BCV take place? The key event for receptor activation is deflection of the hair bundle with respect to the receptor cell body in the neuroepithelial layer (NEL) of the utricular or saccular maculae. At low frequencies (like a head tilt), the inertia of the otoconia causes gravity to drag on the dense otoconia and so deflect the hair bundles of the otolithic receptors which are embedded in the otoconial membrane. However, the receptors at the striola have short, stiff cilia and tenuous attachment to the otoconial membrane and afferents from these receptors show poor response to low-frequency stimuli. These striolar receptors respond well to high-frequency ACS and BCV because, as we have argued, at high frequencies the NEL moves whereas, because of its inertia, the otoconial membrane remains relatively stationary (Figure 2) so once again the short stiff hair bundles of the striolar type-I receptors are deflected relative to the cell body and activated.