Physiology of Hearing and Tuning Fork Tests MCQs

The middle ear converts sound of greater amplitude but lesser force, to that oflesser amplitude but greater force. This function of the middle ear is called impedance matching mechanism or the transformer action. This is to counterbalance the loss of sound energy in the inner ear fluids. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Pg. no - 17, 18.

This is a case of Sudden SNHL. Treatment(Proposed) : Bed rest Steroid therapy. Inhalation of carbogen(5% CO 2 + 95% O 2 ) Vasodilator drugs Hyperbaric oxygen therapy Caroverine is not used in the treatment of sudden SNHL. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 42.

Hearing loss is a presenting symptom in otosclerosis , usually starts in early twenties, often bilateral conductive type. In conductive type of hearing loss, Rinne's test shows negative result for frequencies (BC>AC) and Weber's test is lateralized to affected (worse) ear. Tuning fork test will show negative Rinne (BC>AC) first for 256 and then 512 Hz and after complete stapes fixation, for 1026 Hz. Weber will be lateralized to ear with greater conductive hearing loss. Absolute bone conduction may be normal.

SUDDEN SNHL Definition- It is defined as sudden hearing loss of minimum 30dB It should be visible in at least 3 continuous frequencies in PTA It should have happened within 3 days. It’s unilateral. And has Unknown etiology. Hypothesis- Inflammatory cochleitis. Viral cochleitis. Autoimmune disease. Vascular cause. Treatment – DOC-oral steroids. Other treatments- Transtympanic injection of dexamethasone (using MICROWICK). Hyperbaric oxygen therapy. Betahistine (It is a labyrinthine vasodilator). Antiviral drugs. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 42.

Noise Induced Hearing Loss causes damage to hair cells, starting in the basal turn of cochlea. Outer hair cells are affected before the inner hair cells. Outer hair cells are vulnerable to sounds and drugs while the inner hair cells are more resistant. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page - 41.

Drugs such as cisplatin, mitomycin-C, 5-fluorouracil, pacititaxel, docetaxel and hydroxyurea have been used in concomitant chemoradiation. They act as radiosensitisers and potentiate the effect of radiation by their additive or synergistic effect. Reference: Diseases of Ear, Nose, AND Throat by PL Dhingra, Pg no. 426

Schwabach and ABC(Absolute Bone Conduction) test both are used to test the bone conduction(functioning of cochlea). To give proper meaning to Rinne and Weber test findings, they should be followed by either of these. In ABC, external auditory canal is occluded while in Schwabach's test, EAC is not occluded. Reference: Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8 th Edition, Page -

It is a situation of false negative Rinne. Rinne is negative in right ear but Weber is heard in left ear(better ear). This contradiction is the best hint for false negative Rinne which is seen in unilateral severe SNHL. Reference : Diseases of Ear, Nose and Throat & Head and Neck Surgery by P L Dhingra, 8th Edition, Chapter name: Assessment of Hearing, Page number: 26