Tympanometry and Acoustic Reflexes — MCQs
In otosclerosis, the tympanogram is:
Regarding the stapedial reflex, which of the following is true?
Which of the following statements about conductive deafness is true?
Tone decay test is done for:
A pure tone audiogram showing a bone conduction dip (Carhart notch) at 2000 Hz is characteristic of-
Identify the investigation being carried out in the image.
Carhart's notch in audiometry is seen in -
C-shaped curve on tympanometry is seen in?
Average hearing at 500, 1000, 2000 Hz is 45 dB in the left ear. What is the percentage hearing loss in the left ear, when 25 dB loss is considered normal?
The following test is useful for diagnosis of all except:
Tympanometry and Acoustic Reflexes Indian Medical PG Practice Questions and MCQs
Question 1: In otosclerosis, the tympanogram is:
- A. Low compliance (Correct Answer)
- B. High compliance
- C. Normal compliance
- D. None of the options
Explanation: ***Low compliance*** - In **otosclerosis**, the **stapes footplate** becomes fixed in the **oval window**, hindering sound transmission. - This fixation leads to reduced movement of the **tympanic membrane** and ossicular chain, resulting in a **low-compliance tympanogram** (Type As). *High compliance* - **High compliance** (Type Ad tympanogram) indicates a very mobile or **flaccid tympanic membrane**, often seen in conditions like **ossicular discontinuity**. - This is opposite to the stiffening effect seen in otosclerosis. *Normal compliance* - A **normal tympanogram** (Type A) signifies healthy middle ear function with appropriate pressure and mobility. - This would not be observed in otosclerosis, where there is a clear pathology affecting the **ossicular chain** and sound conduction. *None of the options* - This is incorrect because **otosclerosis** presents with a characteristic **low-compliance tympanogram**. - The disease specifically impairs the **mobility of the middle ear system**, which directly impacts tympanometric findings.
Question 2: Regarding the stapedial reflex, which of the following is true?
- A. It helps to enhance the sound conduction in middle ear
- B. It is a protective reflex against loud sound (Correct Answer)
- C. It helps in masking the sound waves
- D. It is unilateral reflex
Explanation: ***It is a protective reflex against loud sound*** - The stapedial reflex, also known as the **acoustic reflex**, primarily functions to contract the **stapedius muscle** in response to loud sounds. - This contraction stiffens the ossicular chain, reducing the transmission of sound energy to the inner ear, thereby protecting it from **acoustic trauma**. *It helps to enhance the sound conduction in middle ear* - The stapedial reflex's primary action is to **dampen** sound transmission, not enhance it. - By stiffening the ossicular chain, it **attenuates** low-frequency sounds, which is opposite to enhancing conduction. *It helps in masking the sound waves* - Masking refers to the phenomenon where one sound makes another sound inaudible or harder to hear, typically due to similar frequencies. - The stapedial reflex **reduces overall sound intensity** reaching the inner ear and does not specifically mask certain frequencies over others. *It is unilateral reflex* - The stapedial reflex is a **bilateral reflex**, meaning that a loud sound presented to one ear typically elicits a contraction of the stapedius muscle in **both ears**. - This bilateral response is mediated through auditory pathways involving the brainstem.
Question 3: Which of the following statements about conductive deafness is true?
- A. Weber's test shows no lateralization in conductive deafness.
- B. There is no decay in threshold tone in conductive deafness.
- C. Rinne's test is negative in conductive deafness. (Correct Answer)
- D. Air conduction is always completely absent in conductive deafness during Rinne's test
Explanation: ***Rinne's test is negative in conductive deafness.*** - A **negative Rinne's test** indicates that **bone conduction is heard longer or equally as long as air conduction** in the affected ear. - This occurs because the sound transmission through the middle ear is impaired due to the conductive hearing loss. *Weber's test shows no lateralization in conductive deafness.* - In unilateral conductive deafness, the **Weber's test will lateralize to the affected ear**, not show no lateralization. - This is because the sound is perceived as louder in the ear with the conductive loss due to the masking effect of ambient noise being reduced. *There is no decay in threshold tone in conductive deafness.* - **Threshold tone decay** is typically associated with **retrocochlear lesions** (sensorineural hearing loss), not conductive deafness. - Conductive hearing loss is a mechanical problem that does not affect the persistence of auditory nerve firing. *Air conduction is always completely absent in conductive deafness during Rinne's test.* - While air conduction is poorer than bone conduction (making Rinne's negative), it is **not always completely absent**. - In a profound conductive loss, air conduction might be near absent, but in milder cases, it is simply significantly reduced compared to bone conduction.
Question 4: Tone decay test is done for:
- A. Neural deafness (Correct Answer)
- B. Cochlear deafness
- C. Otosclerosis
- D. Middle ear problem
Explanation: ***Neural deafness*** - The **tone decay test** measures the ability to sustain the perception of a continuous tone; significant decay indicates **retrocochlear pathology**, which is characteristic of neural deafness. - This test helps differentiate between cochlear and retrocochlear lesions by assessing the auditory nerve's ability to maintain a neural response. *Cochlear deafness* - While patients with **cochlear deafness** may experience some tone decay, it is typically less pronounced than in neural deafness. - **Cochlear pathologies** primarily affect the hair cells, leading to issues with sound perception and clarity rather than rapid decay of tone perception. *Otosclerosis* - **Otosclerosis** is a condition of the **middle ear** that causes **conductive hearing loss** due to the abnormal growth of bone. - It does not primarily affect the neural pathways or the inner ear's ability to sustain tones, so the tone decay test is not the primary diagnostic tool. *Middle ear problem* - **Middle ear problems** generally result in **conductive hearing loss** as they impede the transmission of sound to the inner ear. - The tone decay test is designed to evaluate issues within the inner ear and auditory nerve, not conductive pathologies.
Question 5: A pure tone audiogram showing a bone conduction dip (Carhart notch) at 2000 Hz is characteristic of-
- A. Otosclerosis (Correct Answer)
- B. Presbyacusis
- C. Ototoxicity
- D. Noise induced hearing loss
Explanation: ***Otosclerosis*** - A **Carhart notch** is a characteristic feature on a pure tone audiogram in otosclerosis, specifically a **bone conduction dip at 2000 Hz**. - This notch is believed to be an **artifact of cochlear mechanics** caused by the fixation of the stapes in the oval window. *Presbyacusis* - Characterized by a **bilateral, symmetrical, high-frequency sensorineural hearing loss** that gradually worsens with age. - It does not present with a specific bone conduction dip like the Carhart notch. *Ototoxicity* - Hearing loss induced by ototoxic drugs (e.g., aminoglycosides, loop diuretics) typically causes **bilateral, progressive, high-frequency sensorineural hearing loss**. - A Carhart notch is not a typical finding in ototoxicity. *Noise induced hearing loss* - Often presents with a **sensorineural hearing loss notch at 4000 Hz** (or sometimes 3000 Hz or 6000 Hz) on the audiogram. - This pattern is distinct from the 2000 Hz bone conduction dip seen in a Carhart notch.
Question 6: Identify the investigation being carried out in the image.
- A. Fluoroscopy
- B. X-ray after alkali ingestion
- C. X-ray after acid ingestion
- D. Barium Swallow (Correct Answer)
Explanation: ***Barium Swallow*** - The image shows a contrast material, characteristic of **barium**, flowing through the esophagus, captured as a sequence of X-ray images, which is the definition of a barium swallow study. - This **dynamic imaging** allows for evaluation of swallowing function and esophageal motility. *Fluoroscopy* - While a barium swallow uses **fluoroscopy** to visualize the movement of barium, fluoroscopy itself is the technique, not the specific investigation being performed. The image depicts the result of a specific type of fluoroscopic examination. - Fluoroscopy is a general term for real-time X-ray imaging, whereas "Barium Swallow" specifies the type of study being done on the upper GI tract. *X-ray after alkali ingestion* - This scenario would typically involve viewing the effects of **corrosive injury** to the esophagus, which would appear as mucosal damage, narrowing, or perforation. The image does not show these features; instead, it shows smooth passage of contrast. - There is no visible evidence of an acute or chronic injury pattern consistent with **alkali ingestion**, which often leads to severe burns or strictures. *X-ray after acid ingestion* - Similar to alkali ingestion, acid ingestion also causes **corrosive injury**, typically affecting the stomach more severely than the esophagus. The image does not demonstrate these pathological changes. - The smooth, unobstructed flow of contrast in multiple frames is indicative of normal esophageal function rather than the sequelae of corrosive ingestion.
Question 7: Carhart's notch in audiometry is seen in -
- A. Ossicular discontinuity
- B. Otosclerosis (Correct Answer)
- C. Otomycosis
- D. Haemotympanum
Explanation: ***Otosclerosis*** - **Carhart's notch** is a characteristic dip in the **bone conduction threshold** at 2000 Hz, typically observed in patients with **otosclerosis**. - This phenomenon is believed to be due to an artifact caused by the **stapes fixation** interfering with the normal inertial and compressional bone conduction mechanisms. *Ossicular discontinuity* - While ossicular discontinuity causes a **conductive hearing loss**, it typically does not present with a specific notch at 2000 Hz in bone conduction. - The audiogram would show a significant **air-bone gap** but without the characteristic bone conduction dip. *Otomycosis* - **Otomycosis** is a fungal infection of the external auditory canal and can cause **conductive hearing loss** if there is significant debris or swelling. - It does not, however, lead to a Carhart's notch on the audiogram. *Haemotympanum* - **Haemotympanum**, or blood behind the tympanic membrane, causes a **conductive hearing loss** by dampening the movement of the tympanic membrane and ossicles. - This condition results in a **flat or low-frequency conductive hearing loss** without the specific audiometric feature of Carhart's notch.
Question 8: C-shaped curve on tympanometry is seen in?
- A. Serous otitis media
- B. Otosclerosis
- C. Eustachian tube obstruction (Correct Answer)
- D. TM perforation
Explanation: ***Eustachian tube obstruction*** - A **C-shaped curve** (Type C tympanogram) indicates **negative middle ear pressure**, which results from a poorly functioning **Eustachian tube**. - This type of curve shows maximal compliance at a **negative pressure**, signifying that the middle ear is under suction. *Serous otitis media* - **Serous otitis media** (otitis media with effusion) typically presents with a **Type B tympanogram**, indicating **reduced or absent tympanic membrane mobility** due to fluid in the middle ear. - This is a flat curve with no distinct peak, reflecting the presence of **effusion**. *Otosclerosis* - **Otosclerosis** causes **stiffening of the ossicular chain**, particularly the stapes, leading to a **Type As tympanogram**. - This curve shows **normal middle ear pressure** but **reduced compliance** (shallower peak) compared to a normal Type A. *TM perforation* - A **tympanic membrane perforation** results in an **open middle ear space**, leading to an **extremely high compliance** and **no discernible peak** on the tympanogram (Type B with a large ear canal volume). - This is because the pressure applied by the tympanometer escapes through the perforation, failing to pressurize the system.
Question 9: Average hearing at 500, 1000, 2000 Hz is 45 dB in the left ear. What is the percentage hearing loss in the left ear, when 25 dB loss is considered normal?
- A. 0.45
- B. 0.2
- C. 0.3 (Correct Answer)
- D. 0.4
Explanation: ### **0.3** * To calculate the percentage of hearing loss, subtract the **normal hearing threshold** (25 dB) from the **average hearing loss** (45 dB): 45 dB - 25 dB = 20 dB. * This **20 dB excess loss** is then divided by the total range for calculating percentage, which is typically 60 dB. Thus, 20 dB / 60 dB = **0.33** or 30%, which is closest to 0.3. ### *0.45* * This value incorrectly uses the absolute average hearing loss (45 dB) without adjusting for the **normal hearing threshold** (25 dB). * The calculation of percentage hearing loss requires considering the amount of hearing loss *above* the normal threshold, not the total average hearing. ### *0.2* * This response potentially arises from an incorrect assumption about the **normal hearing threshold** or the total range used in the calculation. * It does not correctly account for the 25 dB considered normal hearing, or it applies an incorrect denominator for the percentage calculation. ### *0.4* * This result might stem from a miscalculation of the **excess hearing loss** or an incorrect **denominator** for normalizing the percentage. * It does not accurately reflect the difference between the observed hearing loss and the normal threshold, nor the standard range for calculating percentage hearing impairment.
Question 10: The following test is useful for diagnosis of all except:
- A. Ossicular discontinuity
- B. Otosclerosis
- C. Serous otitis media
- D. Postmeningitis deafness (Correct Answer)
Explanation: ***Postmeningitis deafness*** - The image illustrates a **tympanometer**, which primarily assesses the function of the **middle ear** and **eardrum mobility** within the context of air pressure changes. - **Postmeningitis deafness** typically results from **sensorineural hearing loss** due to damage to the **cochlea** or **auditory nerve**, which is a condition of the inner ear and cannot be directly diagnosed by tympanometry. *Ossicular discontinuity* - This condition involves a break or separation in the **ossicular chain**, leading to excessive mobility of the tympanic membrane. - Tympanometry in **ossicular discontinuity** typically shows a **Type Ad tympanogram**, characterized by abnormally high compliance due to the lack of resistance from the damaged ossicles. *Otosclerosis* - **Otosclerosis** involves abnormal bone growth around the **stapes** footplate, leading to its fixation and reduced mobility. - Tympanometry in otosclerosis typically yields a **Type As tympanogram**, indicating abnormally low compliance or a shallow peak. *Serous otitis media* - Also known as **otitis media with effusion**, this condition involves the accumulation of fluid in the middle ear without signs of acute infection. - Tympanometry in **serous otitis media** typically presents with a **Type B tympanogram**, characterized by a flat curve due to reduced or absent eardrum mobility caused by the fluid.
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