Audiometric Tests and Special Tests of Hearing MCQs

The history and investigations done suggest the diagnosis as OTOSCLEROSIS. TREATMENT : Rx of choice is surgery called Stapedotomy>Stapedectomy. Other treatment for Otosclerosis Hearing aid- is given for patients unwilling for surgery. Sodium fluoride (NaF) oral therapy. It i is treatment of choice for Schwartz sign (+) patient. (Early stage of disease) Cochlear otosclerosis. NaF leads to stabilization of disease. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 105, 106.

Abnormal perception of loudness is seen in Meniere's disease. It is called Recruitment phenomenon. It is tested using ABLB testing(alternate binaural loudness balancing test). Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 30.

Ototoxic drugs involve high frequency more commonly than the low frequencies. Hence high frequency audiometry is useful in its diagnosis. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 39.

Vth nerve. This is the earliest nerve to be involved. There is reduced corneal sensitivity, numbness or paraesthesia of face. Involvement of this nerve indicates that the tumour is roughly 2.5 cm in diameter and occupies the cerebellopontine angle. VIIth nerve. Sensory fibres are affected early. There is hypoaesthesia of posterior meatal wall (Hitzelberger's sign), loss of taste (as tested by electrogustometry) and reduced lacrimation on Schirmer test. Motor fibres are more resistant and are affected late. Delayed blink reflex may be an early manifestation. IXth and Xth nerves. There is dysphagia and hoarseness due to palatal, pharyngeal and laryngeal paralysis. Other cranial nerves. XIth and XIIth, IIIrd, IVth and VIth are affected when tumour is very large. Reference: Diseases of Ear, Nose & Head and Neck surgery by P L Dhingra, 9 th edition, Pg.no.132

The audiogram in Noise Induced Hearing Loss shows a typical notch at 4 kHz, both for air and bone conduction. It is usually symmetrical on both sides. At this stage, patient complains of high-pitched tinnitus and difficulty in hearing in noisy surroundings but no difficulty in day-to-day hearing. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 41.

OTOTOXICITY (DRUG INDUCED HEARING LOSS) Aminoglycoside-e.g.- Amikacin, Streptomycin, Gentamicin->Irreversible damage to outer hair cell of cochlea Loop diuretics-e.g.- Furosemide, ethacrynic acid. (Act at stria vascularis cochlea of cochlea) Antimalarials- e.g.- Chloroquine, Quinine. NSAIDs-e.g.- Aspirin, Ibuprofen, Indomethacin. Anticancer-e.g.- Cisplatin, Carboplatin. Deferoxamine. Vancomycin. Erythomycin. Reversible Ototoxicity- seen in Aspirin, diuretic, antimalarials. Ototoxicity shows High frequency SNHL in early stages, therefore high frequency Audiometry (9000 to18000Hz) is a special test used to diagnose Ototoxicity. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 39, 40.

Conductive hearing loss of 54 dB implies that hearing loss is due to ossicular chain disruption with an intact TM. Type Ad tympanogram is seen in such cases. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 29.

The hearing test results are plotted on a graph with the y-axis representing hearing threshold and the x-axis representing frequency. The right ear is generally plotted with a O and the left ear with a X. Reference: Diseases of Ear, Nose, AND Throat by PL Dhingra