THE INFLUENCE OF DRUGS IN THE VESTIBULOCOCHLEAR SYSTEM IN CHILDHOOD. A special focus on the mechanism of injury

Dr. Paulo Liberalesso. Department of Neurology, Hospital Pequeno Príncipe, Curitiba, Brazil.
Coordinator of Digital EEG Laboratory, Hospital da Cruz Vermelha, Curitiba, Brazil..

Ototoxicoses are iatrogenic diseases caused by drug administration, compromising the auditory function and / or the vestibular system. The ototoxicoses are characterized by neurossensorial hearing loss of more than 25 dB in one or more frequencies in the range of 250 to 8000 Hz, with or without symptoms of dizziness and imbalance. There are numerous drugs with ototoxic capacity and diverse are the mechanisms of injury of the auditory and vestibular system.

The causes of hearing loss in childhood can be divided into two main groups: genetic and nongenetic. The major genetic causes of hearing loss are Treacher-Collins syndrome, Crouzon, Alpert, Usher, Klippel-Feil syndrome, Alport, Hurler, Pendred, Hunter, Edwards, Waardenburg, Down syndrome and osteogenesis imperfecta.

The main nongenetic causes of hearing loss in children can be divided into: (a) prenatal (maternal infection by the rubella virus, CMV, syphilis, herpes and toxoplasmosis, radiation during pregnancy, maternal therapy with ototoxic drugs); ( b) perinatal (prematurity, jaundice, anoxia, birth trauma, use of ototoxic drugs) and (c) post-natal (ear infections, bacterial meningitis, viral encephalitis, measles, mumps, diabetes, ototoxic drugs, acoustical trauma, otosclerosis, tumor of the auditory nerve).

In intensive care units for newborns, the diseases most frequently observed are prematurity, severe jaundice, meconium aspiration, severe hyaline membrane disease, neonatal convulsions, neonatal asphyxia, complications related to birth trauma, neonatal sepsis, necrotizing enterocolitis and surgical diseases. Moreover, the drugs most commonly used in intensive care units for newborns are surfactant, dopamine, dobutamine, ampicillin, gentamicin, amikacin, cefepime, cefazolin, vancomycin, furosemide, amphotericin. Except for the first three medications (surfactant, dopamine and dobutamine) all others can be ototoxic.

In pediatric intensive care units (for children after the first month of life), the most frequently diseases are pneumonia, asthma, diarrhea, severe allergic reactions and complications of surgical diseases. In these units, medications most commonly used are dipyrone, paracetamol, drugs for vomiting, fenoterol, crystalline penicillin, ampicillin, gentamicin, amikacin, chloramphenicol, cephalosporins (third and fourth generation) and vancomycin. Of all these medications, ampicillin, gentamicin, amikacin, chloramphenicol, cephalosporins and vancomycin can be ototoxic.