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Hipertensão e perda auditiva
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A hipertensão arterial aumenta o risco de diversas patologias devido ao dano que provoca nos
órgãos e vasos sanguíneos, nomeadamente acidente vascular cerebral, insuficiência renal
crónica, doença isquémica cardíaca, doença arterial periférica, retinopatia e, mais recentemente,
colocou-se a hipótese desta patologia causar também lesões no ouvido interno, refletindo-se em
perda auditiva neurossensorial.
A perda auditiva neurossensorial consiste na perda irreversível de acuidade auditiva com
origem na lesão da componente coclear do ouvido interno. Pode diminuir consideravelmente a
qualidade de vida dos doentes, levando a diversas complicações como o isolamento social,
depressão e problemas cognitivos. A etiologia desta patologia está associada a processos
degenerativos, tais como o envelhecimento, mutações genéticas, exposição a fármacos
ototóxicos e exposição ao ruído. No entanto, nos últimos anos têm surgido diversos estudos que
sugerem a existência de uma relação entre hipertensão arterial e perda auditiva neurossensorial.
Esses estudossugerem que a stria vascularis da cóclea, a estrutura responsável pela manutenção
da homeostase coclear e da barreira hemato-labiríntica, é o local do ouvido humano mais
afetado pela hipertensão, causando um forte impacto no processo de transdução auditiva. Dentre
os mecanismos descritos para as lesões cocleares causadas pela hipertensão arterial salientam se o aumento dos níveis do péptido natriurético atrial na corrente sanguínea, que conduz à
diminuição da expressão dos canais ENaC na stria vascularis, aumentando a concentração de
sódio na endolinfa; a lesão direta dos capilares da stria vascularis, resultando no aumento da
permeabilidade capilar e passagem de substâncias nocivas para o espaço extracelular das suas
células; aumento da atividade da bomba de sódio/potássio nas células marginais que resulta no
aumento de potássio na endolinfa; redução do fluxo sanguíneo coclear levando a uma
diminuição do aporte de oxigénio e nutrientes para as células ciliares. Ainda que possam ter
contribuições relativas diferentes, estes mecanismos conduzem à morte das células ciliares e/ou
perda da homeostase iónica coclear, traduzindo-se no comprometimento da transdução
sensorial e consequente perda auditiva.
Para melhor compreender a relação entre a hipertensão arterial e a perda auditiva será
importante existir um maior conhecimento dos mecanismos responsáveis pela lesão coclear,
eliminando fatores de confundimento como é o caso da idade avançada, e ainda, investigar a
hipótese de existirem fármacos antihipertensores que poderão ter um papel de proteção coclear.
Arterial hypertension increases the risk of several pathologies due to the damage it causes to organs and blood vessels, namely stroke, chronic renal failure, ischemic heart disease, peripheral arterial disease, retinopathy and, more recently, it was hypothesized that this pathology also causes lesions in the inner ear, resulting in sensorineural hearing loss. Sensorineural hearing loss consists of irreversible loss of auditory acuity originating from damage to the cochlear component of the inner ear. It can considerably reduce the quality of life of patients, leading to various complications such as social isolation, depression and cognitive problems. The etiology of this pathology is associated with degenerative processes, such as aging, genetic mutations, exposure to ototoxic drugs and exposure to noise. However, in recent years, several studies have appeared that suggest the existence of a relationship between arterial hypertension and sensorineural hearing loss. These studies suggest that the cochlear stria vascularis, the structure responsible for maintaining cochlear homeostasis and the blood-labyrinthine barrier, is the site of the human ear most affected by hypertension, causing a strong impact on the auditory transduction process. Among the mechanisms described for cochlear lesions caused by arterial hypertension, it’s highlighted the increase in the levels of atrial natriuretic peptide in the bloodstream, which leads to a decrease in the expression of ENaC channels in the stria vascularis, increasing the concentration of sodium in the endolymph; direct injury to the capillaries of the stria vascularis, resulting in increased capillary permeability and passage of harmful substances into the extracellular space of the stria vascularis cells; increased sodium/potassium pump activity in marginal cells resulting in increased potassium in the endolymph; reduction in cochlear blood flow leading to a decrease in the supply of oxygen and nutrients to the ciliary cells. Although they may have different relative contributions, these mechanisms lead to the death of hair cells and/or loss of cochlear ionic homeostasis, translating into impairment of sensory transduction and consequent hearing loss. To better understand the relation between arterial hypertension and hearing, it’ll be important to have a greater knowledge of the mechanisms responsible for cochlear damage, eliminating confounding factors such as advanced age, and to investigate the hypothesis that there are antihypertensive drugs that may play a role in cochlear protection.
Arterial hypertension increases the risk of several pathologies due to the damage it causes to organs and blood vessels, namely stroke, chronic renal failure, ischemic heart disease, peripheral arterial disease, retinopathy and, more recently, it was hypothesized that this pathology also causes lesions in the inner ear, resulting in sensorineural hearing loss. Sensorineural hearing loss consists of irreversible loss of auditory acuity originating from damage to the cochlear component of the inner ear. It can considerably reduce the quality of life of patients, leading to various complications such as social isolation, depression and cognitive problems. The etiology of this pathology is associated with degenerative processes, such as aging, genetic mutations, exposure to ototoxic drugs and exposure to noise. However, in recent years, several studies have appeared that suggest the existence of a relationship between arterial hypertension and sensorineural hearing loss. These studies suggest that the cochlear stria vascularis, the structure responsible for maintaining cochlear homeostasis and the blood-labyrinthine barrier, is the site of the human ear most affected by hypertension, causing a strong impact on the auditory transduction process. Among the mechanisms described for cochlear lesions caused by arterial hypertension, it’s highlighted the increase in the levels of atrial natriuretic peptide in the bloodstream, which leads to a decrease in the expression of ENaC channels in the stria vascularis, increasing the concentration of sodium in the endolymph; direct injury to the capillaries of the stria vascularis, resulting in increased capillary permeability and passage of harmful substances into the extracellular space of the stria vascularis cells; increased sodium/potassium pump activity in marginal cells resulting in increased potassium in the endolymph; reduction in cochlear blood flow leading to a decrease in the supply of oxygen and nutrients to the ciliary cells. Although they may have different relative contributions, these mechanisms lead to the death of hair cells and/or loss of cochlear ionic homeostasis, translating into impairment of sensory transduction and consequent hearing loss. To better understand the relation between arterial hypertension and hearing, it’ll be important to have a greater knowledge of the mechanisms responsible for cochlear damage, eliminating confounding factors such as advanced age, and to investigate the hypothesis that there are antihypertensive drugs that may play a role in cochlear protection.
Descrição
Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2023, Universidade de Lisboa, Faculdade de Farmácia.
Palavras-chave
Hipertensão arterial Perda auditiva Cóclea Células ciliares Stria vascularis Mestrado Integrado - 2023