Encyclopedia of Health and Medicine

ototoxicity 43
perforation, deformities, movement, and signs of
increased pressure in the middle ear such as
bulging or fluid that suggests otitis media (middle
ear infection). Otoscopy is the primary diagnostic
procedure for many conditions affecting the outer
ear, and the first step of the diagnostic path for
conditions affecting the middle ear. Otoscopy cannot
determine hearing ability or HEARING LOSS.
See also AUDIOLOGIC ASSESSMENT; MYRINGITIS; RUP-
TURED EARDRUM.
ototoxicity A medication SIDE EFFECT that results
in damage to the functions and structures of the
EAR and hearing. The damage can be temporary, in
which case symptoms recede and hearing returns
when the person stops taking the medication, or
permanent. Numerous medications can be ototoxic
at therapeutic doses, making it prudent to
weigh this potential consequence against the
anticipated benefits of the medication. Often medication
options are available that can achieve the
desired therapeutic effect without the risk for ototoxicity.
Symptoms of ototoxicity include
• TINNITUS (sensation of ringing or rushing sound)
• indications of HEARING LOSS, such as difficulty
understanding conversation or being unable to
hear the telephone ring
• balance disturbances and dizziness
• VERTIGO (sensation of spinning)
Report any of these symptoms to the doctor
immediately, though do not stop taking any medications
until discussing the circumstances with
him or her. Most ototoxic medications appear to
act on the delicate HAIR cells in the COCHLEA, stunning
or destroying their ability to translate sound
waves into NERVE signals. Ototoxicity is most devastating
when it affects high-frequency hearing,
the range of normal conversation.
Numerous industrial chemicals are also ototoxic.
They include butyl nitrite, carbon disulfide,
hexane, manganese, lead, mercury, styrene, and
toluene. Hearing loss resulting from exposure to
these chemicals is often permanent.
See also AUDIOLOGIC ASSESSMENT; NOISE EXPOSURE
AND HEARING; OCCUPATIONAL HEALTH AND SAFETY; TOXIC
OPTIC NEUROPATHY.