What a Neurosurgeon Should Know about the Endolymphatic Sac: Part 1–Anatomy and Physiology

Abstract

Objective To describe the microsurgical anatomy and the physiology of the endolymphatic sac (ES) that a neurosurgeon should know.

Methods Review of previous studies from 1927 to 2021, from basic and translational research using human and animal ES tissue or cells, as well as previous reviews about the subject. The present article is divided into three parts. In this first part, we review the microsurgical anatomy and physiology of the ES.

Results The ES is a structure situated in the inner ear, together with the cochlea, the vestibular system, and other structures. Differently from its adjacent structures, the ES does not have a specialized epithelium; instead, it has mitochondria-rich cells and ribosomal-rich cells, which are responsible for ionic transportation and secretory activity. Apart from these functions, the ES is also responsible for homeostasis regulation of the inner ear, endolymphatic fluid volume control, immune response, elimination of inner ear cellular debris and floating otoconia, regulation of membranous labyrinth pressure, acid/basic transport, and secretion of substances. Its anatomy is not very variable, since in most studies no more than 20mm separates the location of the ES in the samples, in any direction.

Conclusion The human ES has vital functions in the inner ear, and its anatomy is rarely variable. Knowing that, and the importance of this area for neurosurgery, the present study elucidates the exact location of the ES and the lost functions that a lesion in this structure must cause.

Resumo

Objetivo Descrever a anatomia microcirúrgica e a fisiologia do saco endolinfático (SE) que um neurocirurgião deve saber.

Métodos Revisão de estudos prévios de 1927 até 2021, de pesquisa básica até translacional usando tecidos ou células do SE humanas e animais, além de revisões sobre o assunto. O presente artigo é dividido em três partes. Nesta primeira, nós revisamos a anatomia microcirúrgica e a fisiologia do SE.

Resultados O SE é uma estrutura situada no ouvido interno, junto da cóclea, do sistema vestibular e outras estruturas. Diferentemente das estruturas adjacentes, o SE não tem um epitélio especializado; ao invés disso, possui células ricas em mitocôndrias e outras ricas em ribossomos, que são responsáveis por transporte iônico e atividade secretória. Além dessas funções, o SE é responsável por regulação homeostática do ouvido interno, controle do fluido endolinfático, resposta imune, eliminação de detritos e otólitos livres, regulação da pressão da membrana labiríntica, transporte ácido/básico e secreção de substâncias. Sua anatomia não é muito variável, já que na maior parte dos estudos a máxima diferença de localização entre as amostras do SE foi dada em 20 mm, em todas as direções.

Conclusão O SE humano tem uma função vital no ouvido interno e sua anatomia não é muito variável. Sabendo disso, e da importância dessa região para a neurocirurgia, o presente estudo elucida a localização exata do SE e as funções perdidas em uma eventual lesão dessa estrutura.

Keywords

endolymphatic sac - anatomy - physiology - neurosurgery

Palavras-chave

saco endolinfático - anatomia - fisiologia - neurocirurgia

Publikationsverlauf

Eingereicht: 16. November 2021

Angenommen: 01. August 2022

Artikel online veröffentlicht:
09. Oktober 2023

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