Vestibüler Sistem Fizyolojisi ve Vestibüler Sistem Fonksiyonel Testleri
Özet
Vestibüler sistem, denge ve propriyosepsiyon işlevlerini yöneten, periferik ve merkezi olmak üzere iki ana bölümden oluşan karmaşık bir yapıdır. İç kulakta yer alan periferik sistem, sodyum açısından zengin perilenf ile potasyum içeren endolenf sıvılarını barındıran kemik ve membranöz labirentlerden meydana gelir. Bu sistemde doğrusal ivmelenmeyi algılayan utrikul ve sakkul makulaları ile açısal hareketleri saptayan semisirküler kanallardaki krista ampullaris olmak üzere iki temel algılayıcı organel bulunur. Mekanoreseptör saç hücrelerinin kinosilyuma doğru hareketi depolarizasyona, tersi ise hiperpolarizasyona yol açarak sinirsel iletimi sağlar. Uyarılar, vestibülokoklear sinir vasıtasıyla pontomedüller bileşkeden beyin sapındaki dört ana vestibüler nükleusa ve serebelluma iletilir. Merkezi sistem, kafa hareketleri sırasında görme keskinliğini koruyan Vestibülooküler Refleks (VOR) ve duruşu düzenleyen Vestibulospinal Refleks (VSR) gibi kritik mekanizmaları kontrol eder. Klinik değerlendirmelerde Videonistagmografi (VNG), Video Head Impulse Test (v-HIT), Vestibular Evoked Myogenic Potentials (VEMP), Elektrokokleografi (ECOG), Rotasyon Sandalyesi ve Bilgisayarlı Dinamik Posturografi (CDP) gibi fonksiyonel testler kullanılarak periferik ve merkezi patolojiler ayırt edilir.
The vestibular system is a complex structure divided into peripheral and central components that govern balance and proprioception. Located within the inner ear, the peripheral system consists of the bony and membranous labyrinths containing sodium-rich perilymph and potassium-rich endolymph, respectively. This system utilizes two main sensory organs: the maculae of the utricle and saccule for detecting linear acceleration, and the crista ampullaris within the semicircular canals for detecting angular movements. Mechanoreceptor hair cells trigger neural transmission through depolarization when moving toward the kinocilium, and hyperpolarization when moving away. Signals are transmitted via the vestibulocochlear nerve to the four primary vestibular nuclei in the brainstem and the cerebellum. The central vestibular system regulates critical mechanisms, including the Vestibulocular Reflex (VOR) to maintain visual acuity during head movements, and the Vestibulospinal Reflex (VSR) to coordinate spinal muscles for postural control. For clinical evaluation, functional tests such as Videonystagmography (VNG), Video Head Impulse Test (v-HIT), Vestibular Evoked Myogenic Potentials (VEMP), Electrocochleography (ECOG), Rotary Chair, and Computerized Dynamic Posturography (CDP) are utilized to differentiate peripheral and central pathologies.
Referanslar
Marianne Dieterich , Thomas Brandt, The bilateral central vestibular system: its pathways, functions, and disorders, Ann N Y Acad Sci, 2015 Apr;1343:10-26. https://doi.org/10.1111/nyas.12585
Martin Hitier , Stephane Besnard , Paul F Smith, Vestibular pathways involved in cognition, Front Integr Neurosci, 2014 Jul 23;8:59. https://doi.org/10.3389/fnint.2014.00059
Christopher K Zalewski ,Aging of the Human Vestibular System, Semin Hear, 2015 Aug;36(3):175-96. https://doi.org/10.1055/s-0035-1555120
Casale J, Browne T, Murray I, Gupta G. Physiology, Vestibular System. 2021 May 9. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 30422573.
Önerci T. M.( 2016) , Kulak Burun Boğaz Baş ve Boyun Cerrahisi, Nörootoloji, Cilt 2, Ankara: Matsa Basımevi
Cummings CW (2007), F.P.e.a. Cummings Otolaringoloji Baş ve Boyun Cerrahisi., ed. K.C. Baskı., Ankara: Güneş Kitapevi.
R R Ciuman, Stria vascularis and vestibular dark cells: characterisation of main structures responsible for inner-ear homeostasis, and their pathophysiological relations,J Laryngol Otol,2009 Feb;123(2):151-62. https://doi.org/10.1017/S0022215108002624
Akyıldız N.(1998), Kulak Hastalıkları Ve Mikrocerrahisi I. 1. Baskı, Ankara, Bilimsel Tıp Yayınevi.
Ardıç F.N.(2005), Vertigo. 1. Baskı, İzmir: İzmir Güven Kitapevi
R R Ciuman, Auditory and vestibular hair cell stereocilia: relationship between functionality and inner ear disease J Laryngol Otol, 2011 Oct;125(10):991-1003. https://doi.org/10.1017/S0022215111001459
Sarah Khan , Richard Chang, Anatomy of the vestibular system: a review, NeuroRehabilitation,2013;32(3):437-43. https://doi.org/10.3233/NRE-130866
H Kingma , R van de Berg, Anatomy, physiology, and physics of the peripheral vestibular system, Handb Clin Neurol, 2016;137:1-16. https://doi.org/10.1016/B978-0-444-63437-5.00001-7
Sarah Khana and Richard Changb, Anatomy of the vestibular system, a review, NeuroRehabilitation 32 (2013) 437–43 https://doi.org/10.3233/NRE-130866
Lee, S. C., et al. (2011) Vestibular System Anatomy. Retrieved from: Emedicine.medscape.com/article/883956- overview aw2aab6c10. Accessed August 30, 2012
Seilesh Babu, Christopher A. Schutt, Dennis I. Bojrab (2019), Diagnosis and Treatment of Vestibular Disorders, Switzerland, Springer
Belgin Tutar, Vertigolu Hastaya Yaklaşımda Vestibuler Laboratuvarda Yapılan Testler, January 2020, Vertigoya Olgular Eşliğinde Multidisipliner Bakış, İstanbul Tıp Kitabevi
Lee.K.J.(2012), Essential Otolaryngology Baş ve Boyun Cerrahisi. (Önerci M., Korkmaz H. Çev. Ed.). Güneş Tıp Kitapevi, 9. Basım
Mangabeira Albernaz PL, Zuma E Maia FC. The video head impulse test. Acta Otolaryngol. 2014 Dec;134(12):1245-50. https://doi.org/10.3109/00016489.2014.942439
Dastan Temirbekov, Current Practice in Vertigo and Dizziness, Vertigo ve Denge Sorunlarına Güncel Yaklaşım, Curr Pract ORL 2018, 14(1): 10-20
Numan Kokten, Servet Karaca,. Armağan İncesulu et.al., A new and objective test to evaluate functions of the semicircular canals: A review of video head impulse test, Kulak Burun Bogaz Ihtis Derg 2017;27(5):241-250, https://doi.org/10.5606/kbbihtisas.2017.08505
Godha S, Upadhyay Mundra A, Mundra RK et. al. VEMP: An Objective Test for Diagnosing the Cases of BPPV. Indian J Otolaryngol Head Neck Surg. 2020 Jun;72(2):251-6. https://doi.org/10.1007/s12070-020-01802-3
Venhovens J, Meulstee J, Verhagen WIM. Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders. Clin Neurophysiol. 2016 Jan;127(1):40-9. https://doi.org/10.1016/j.clinph.2014.12.021
Choi, J.-Y. Vestibular-evoked myogenic potentials: principle and clinical findings. Annals of Clinical Neurophysiology. The Korean Society of Clinical Neurophysiology (KAMJE),2020, October 30. https://doi.org/10.14253/acn.2020.22.2.67
Dalbert A, Pfiffner F, Hoesli M et. al. Assessment of Cochlear Function during Cochlear Implantation by Extra- and Intracochlear Electrocochleography. Front Neurosci. 2018 Jan 26;12:18. https://doi.org/10.3389/fnins.2018.00018
Zalewski C.K., McCaslin D.L., Carlson M.L. (2019) Rotary Chair Testing. In: Babu S., Schutt C., Bojrab D. (eds) Diagnosis and Treatment of Vestibular Disorders. Springer, Cham. https://doi.org/10.1007/978-3-319-97858-1_6
Oda DTM, Gananca CF. Computerized dynamic posturography in the assessment of body balance in individuals with vestibular dysfunction. Audiol Commun Res. 2015;20:89–95
Peggy R. Trueblood, Monica Rivera, Christian Lopez et.al. Age-based normative data for a computerized dynamic posturography system that uses a virtual visual surround environment, Acta Oto-Laryngologica, 2018;138:7, 597-602, https://doi.org/10.1080/00016489.2018.1429653
