In 1995, authors had already found a high incidence of audiological changes in HIV-positive patients27. Notwithstanding, they emphasize the difficulties in stating whether these findings would be due to the direct action of the virus on the hearing pathways or a consequence of the ototoxicity induced by the medication used by these patients.

In a recent study involving adult patients treated and not treated by ARV therapy, the audiological manifestations (hearing loss, tinnitus and dizziness) were more frequent than the vestibular changes in patients treated with ARV. There were thirty-nine treatment regimens utilized in the group of treated patients, and five of those treatment regimens were associated with otoneurological signs (Didanosine-Lamivudine-Lopinavir/r; Zidovudine-Lamivudine-Efavirenz; Zidovudine-Lamivudine-Nevirapine; Stavudine-Lamivu-dine-Lopinavir/r; Zidovudine-Didanosine-Nelfinavir), and there were no significant correlation between the ototoxicity and the ARV treatment15. Moreover, in 33 individuals using antiretroviral with peripheral T CD4+ cells below 200 cel./ml, we also did not correlate hearing loss to using AZT and ddI. Thus, the initial hearing involvement in adults may be associated with the direct action of the virus on the central auditory system9.

However, adult HIV-positive individuals between 18 and 58 years of age, exposed to ARV treatment, had changes suggestive of peripheral auditory pathway involvement and also had high frequency hearing thresholds compromised16 when compared to the untreated group.

HIV/AIDS patients may have changes in their conventional audiological assessment, high-frequency audiometry, otoacoustic emissions, otoacoustic emission suppression and in auditory evoked potentials, suggesting involvement in the periphery auditory pathway as well as in the central auditory pathway7,16.

High-frequency audiometry assesses hearing in the range above 8,000 Hz - between 9,000 and 20,000 Hz - and does not have standardized results, such as in a conventional audiometry - between 250 and 8,000 Hz. Nevertheless, people with HIV/AIDS are the first to be affected with some ear disorders, showing an important element used in early diagnosis28.

High-frequency audiometry is very useful to follow up patients exposed to intense noise: those who use ototoxic medication; as well as those exposed to degenerative etiological agents; nonetheless, some factors prevent this test to be part of the clinical routine, they are: we still lack a normality standard to test these frequencies, specificity in the equipment calibration patterns and the methodology employed, which may impact the results obtained29.

We stress the study carried out with 23 children (ranging between 5 months and 16 years of age) diagnosed with HIV/AIDS, receiving highly active ARV therapy. Tonal audiometry was carried out in 12 children with more than 4 years of age, and 33% had hearing loss, two were of conduction type. The brainstem responses were measured in all 23 children, suggesting a conductive hearing loss in six and sensorineural in two. Concerning the brainstem auditory responses, they had changes at different levels of the auditory pathways19, showing that children with HIV and using ARV therapy are prone to having auditory changes, just as well as adults are.

Thus, there are peripheral auditory pathway changes affecting people with HIV/AIDS associated with ototoxicity and to the high viral load or virus action. One may suppose that such fact is due to the morphological arrangement of the nervous fibers, since they have characteristics of the hair cells and/or of neurons, in responding in a specialized way to certain frequencies, which is called tonotopy. In tonotopy, the nervous fibers coming from the cochlear apex and forming the central region of the cochlear nerve are responsible for the transmission of low frequencies, while those fibers coming from the base and make up the periphery region of the nerve, are responsible for transmitting high frequencies, showing that, in current times it is not possible to be clear about the agent causing hearing loss in these people30.

Concerning opportunistic diseases associated with hearing loss, we have the prevalence of central nervous system infections by cytomegalovirus (CMV), which must be considered as a cause for hearing loss in HIV-infected patients18.

CMV is a broadly distributed infectious agent in the general population, belonging to the herpes virus family, and it is a frequent cause of infections in human beings. This virus has periods of activation and latency, and once the person is infected, the virus remains indefinitely in the host's body, and it can be reactivated at any time, especially in the presence of immunosuppression agents31.

CMV incidence in the United States population is 1.6 infections for every 100 persons per year - and these are individuals with low family income. There are about 27,000 new CMV infections among serum-negative pregnant women every year19. In Brazil, serum-prevalence studies in the adult population have shown approximately 90% of positivity in the city of São Paulo32, as well as in Santa Catarina state33.

Upon studying 50 cases of patients infected with HIV aiming at characterizing the occurrence of ear diseases, we used a questionnaire, ear exam, audiological assessment and reviewing hospital charts. Among the otological manifestations we had: ear fullness (34%), tinnitus (26%), hearing loss (29%), otalgia (23%) and otorrhea (5%). Otitis media was also a frequent finding in these patients, and the sensorineural hearing loss was more severe in HIV patients, but it was not associated with the routine medication used to treat HIV/AIDS. The authors concluded that auditory disease affects up to 33% of HIV-infected patients, and sensorineural hearing loss is more severe in this specific group20.

We know that otitis may cause temporary peripheral hearing loss, and it must be diagnosed as soon as possible in order to install proper medical treatment. According to the National Institute of Health of the USA, there are about 75% of adults with AIDS with some kind of hearing disorder arising from opportunistic infections, its treatment and ototoxic effect34.

There is a case report of a male patient infected with HIV who had hearing loss on the right side two months after secondary prophylaxis for cryptococcuc meningitis. The authors associate the unilateral hearing loss of adult patients with cryptococcus meningitis and the treatment of HIV-associated infections21.

HIV-infected children were assessed in order to measure their audiological skills and vestibular disorders, considering that they were under highly active antiretroviral treatment. We included 23 patients with mean age of 4.5 years; audiometry was carried out in 12 children with more than 4 years of age. Four children had sensorineural hearing loss and two of them had conduction-type hearing loss. Brainstem responses were measured in all the patients, suggesting conductive-type hearing loss in six children and sensorineural hearing loss in two. The ones diagnosed with conductive hearing loss had a past of acute or chronic otitis media. These results suggest that children with HIV-1 must be audiologically assessed as soon as possible in order to reduce its impact on their psychosocial development17. We have also noticed that HIV+ children develop bacterial meningitis, have a high mortality rate, and are more prone to recurrent diseases22.

One epidemiological study carried out in order to study the frequency and clinical presentation of otosyphilis results in developed countries confirmed that it still is a complication of syphilis in these countries. Thus, we can state that this disease is a known cause of sensorineural hearing loss and has a higher prevalence among HIV patients. The otological involvement by Treponema pallidum happens in the tertiary syphilis. Initial symptoms may include uni or bilateral sensorineural hearing loss, usually of rapid progression and, often times sudden. Tinnitus, ear pressure and labyrinthine symptoms may also be present. The audiometric curve usually shows a drop in the low frequencies, suggesting endolymphatic hydrops3.

Cerebromeningeal diseases may be associated with hearing loss. In a retrospective study carried out in Senegal, with the aim of establishing the prevalence of cerebromeningeal involvement in hospitalized patients and describe epidemiology, clinical signs and symptoms and disease etiology, there were 470 cases identified - 89 children and adults had HIV and numerous opportunistic disorders, such as meningeal syndrome, coma, seizure, focal neurological failure, cranial nerve dysfunction, cerebral malaria, purulent meningitis, cryptococcal meningitis, tuberculous meningitis, intracranial abscess, toxoplasmosis, cerebromeningeal hemorrhage. Of the 89 investigated, 22 survived and among these there were five with hearing loss. The study concluded that the labs must have greater technical capacity to diagnose the opportunistic infections presented by these patients, as well as involve the many experts to manage cerebromeningeal sequelae24.

There are also two studies which did not reach conclusions as to the causes of the hearing loss. In the first one, with nine HIV-positive men, between 25 and 42 years of age, there were five with hearing loss25. The second is a case study with a 36-year-old man with unilateral progressive hearing loss, high ipsilateral tinnitus, sudden hearing loss followed by ipsilateral paralysis. In an MRI they suspected of a vestibular schwannoma; however, when they ordered the anti-HIV they found the patient was serum-positive. The authors recommended a thorough exam to investigate the cause of the hearing loss26.

Knowing that, every day, HIV/AIDS kills 6,000 people and infects some 8,20035 more and infection by opportunistic agents is a constant concern of patients with HIV, we stress the need to pay special attention to the early diagnosis and prevention of hearing loss disorders.