Mitochondrial Sensorineural Hearing Loss: A Retrospective Study and a Description of Cochlear Implantation in a MELAS Patient

Abstract

Hearing impairment is common in patients with mitochondrial disorders, affecting over half of all cases at some time in the course of the disease. In some patients, deafness is only part of a multisystem disorder. By contrast, there are also a number of “pure” mitochondrial deafness disorders, the most common probably being maternally inherited. We retrospectively analyzed the last 60 genetically confirmed mitochondrial disorders diagnosed in our Department: 28 had bilateral sensorineural hearing loss, whereas 32 didn't present ear's abnormalities, without difference about sex and age of onset between each single group of diseases. We reported also a case of MELAS patient with sensorineural hearing loss, in which cochlear implantation greatly contributed to the patient's quality of life. Our study suggests that sensorineural hearing loss is an important feature in mitochondrial disorders and indicated that cochlear implantation can be recommended for patients with MELAS syndrome and others mitochondrial disorders.

MELAS syndrome: Clinical manifestations, pathogenesis, and treatment options

“…Sensorineural hearing loss has been successfully treated with cochlear implants [56]. Seizures respond to traditional anticonvulsant therapy and standard analgesics can be used for migraine headaches.…”

Temporal bone histopathology in MELAS syndrome

“…If hearing worsens to nonaidable level, cochlear implantation can be considered. Despite the ubiquitous insult to the central nervous system in MELAS syndrome, cochlear implantation can be effective …”

“…Their administration can result in increased nitrous oxide availability and may lessen the stroke-like episodes typical of MELAS implantation can be effective. [13][14][15][16] Based on the observed findings of good preservation of auditory neurons effective stimulation with a cochlear implant could be expected. This finding may have implications for patients with hearing loss associated with other mitochondrial disease.…”

Advances in Genetic Diagnosis and Treatment of Hearing Loss — A Thirst for Revolution

“…Mitochondrial DNA (mtDNA) mutations account for at least 5% of cases of postlingual, nonsyndromic hearing impairment [21]. MtDNA mutations are classified as either large-scale rearrangements (partial deletions or duplications) that are usually sporadic or point mutations, which are usually maternally inherited, and concern genes responsible for protein synthesis (rRNAs or tRNAs), or genes encoding subunits of the electron transport chain (ETC) [22,23]. Tang et al reported that mitochondrial mutations by themselves are not sufficient to produce a deafness phenotype.…”

“…The use of streptomycin, and to a lesser extent other aminoglycoside antibiotics, can cause hearing loss in genetically susceptible individuals. These drugs are known to exert their antibacterial effects at the level of the decoding site of the small ribosomal subunit, causing miscoding or premature termination of protein synthesis [28][29][30]. The hearing loss is primarily high frequency and may be unilateral.…”