Diseases of the Ear — MCQs

Diseases of the Ear Indian Medical PG Practice Questions and MCQs

Question 341: Light house sign is seen in which stage of acute suppurative otitis media?

A. Stage of suppuration (Correct Answer)
B. Stage of hyperaemia
C. Stage of resolution
D. Stage of perforation

Explanation: ***Stage of suppuration*** - The **lighthouse sign** is observed when pus accumulates in the middle ear and perforates the tympanic membrane, resulting in pulsations of pus through the perforation which gives the appearance of a "lighthouse." - This stage is characterized by the formation and accumulation of **purulent exudate** and increased pressure within the middle ear. *Stage of hyperaemia* - This is the initial stage, characterized by **inflammation** and vascular congestion of the tympanic membrane, making it appear red. - There is no pus formation or perforation at this stage, so the lighthouse sign would not be present. *Stage of resolution* - This stage occurs after successful treatment or spontaneous healing, where the **inflammation subsides** and the tympanic membrane returns to normal appearance. - Perforation, if present, would be healing, and pus drainage, if any, would be minimal or absent. *Stage of perforation* - While perforation occurs during the stage of suppuration, the "lighthouse sign" specifically refers to the **pulsating discharge of pus** through the perforation. - The term "stage of perforation" is not typically used as a distinct stage in the progression of acute otitis media in the same way as hyperaemia or suppuration.

Question 342: In a patient with chronic suppurative otitis media, which structure is most commonly involved in labyrinthine fistula?

A. Superior semicircular canal
B. Posterior semicircular canal
C. Utricle
D. Lateral semicircular canal (Correct Answer)

Explanation: ***Lateral semicircular canal*** - The **lateral semicircular canal** is the most commonly involved structure in labyrinthine fistula due to its anatomical prominence in the **epitympanum** and its thinner bony wall compared to other labyrinths, making it susceptible to erosion from cholesteatoma. - **Cholesteatoma**, a common complication of chronic suppurative otitis media, erodes bone due to its enzymatic activity, frequently affecting this canal as it lies in the direct path of disease extension. *Superior semicircular canal* - While possible, involvement of the **superior semicircular canal** is much less common than the lateral canal due to its deeper and more protected anatomical position. - Erosion leading to fistula in this canal would typically indicate very extensive and aggressive disease. *Posterior semicircular canal* - The **posterior semicircular canal** is also less frequently affected in labyrinthine fistula compared to the lateral canal. - Its deep anatomical location and often thicker surrounding bone provide more protection against erosion. *Utricle* - The **utricle** is part of the vestibule and is surrounded by a substantial bony labyrinth, making direct fistulization from otitis media or cholesteatoma relatively rare. - Fistulae usually occur in the semicircular canals where the bony walls are thinner and more exposed to disease processes.

Question 343: All of the following statements about sodium fluoride in otosclerosis are true, except:

A. Does not act by inhibiting proteolytic enzymes in cochlea.
B. Is indicated in patients with otosclerosis.
C. Is contraindicated in patients with chronic nephritis.
D. Acts by inhibiting osteoblastic activity (Correct Answer)

Explanation: ***Acts by inhibiting osteoblastic activity*** - Sodium fluoride in otosclerosis primarily acts by **inhibiting osteoclastic activity**, NOT osteoblastic activity - It promotes the formation of harder, more mineralized bone and stabilizes the bony labyrinth - By reducing osteoclastic bone resorption, it helps slow the progression of otosclerotic lesions *Is indicated in patients with otosclerosis* - Sodium fluoride is **indicated in active otosclerosis** to stabilize otosclerotic lesions and slow hearing loss progression - It is particularly useful in patients with documented active disease (elevated serum alkaline phosphatase) - This statement is TRUE *Is contraindicated in patients with chronic nephritis* - Sodium fluoride is **renally excreted**, making it contraindicated in patients with **chronic nephritis** - Impaired kidney function can lead to fluoride accumulation and toxicity - This statement is TRUE *Does not act by inhibiting proteolytic enzymes in cochlea* - Sodium fluoride has been shown to **inhibit proteolytic enzymes, particularly collagenase**, in the cochlea - This enzymatic inhibition helps stabilize bone and prevent further damage - Since it DOES inhibit these enzymes, the statement "does not act by inhibiting" is FALSE, but the double-negative phrasing makes this confusing - However, Option B is more clearly the false statement

Question 344: Which of the following statements about Bone Anchored Hearing Aids (BAHA) is true?

A. It transmits sound through air conduction, making it ideal for sensorineural hearing loss.
B. It is useful in patients with canal atresia and microtia. (Correct Answer)
C. It is used after surgery for acoustic neuroma in neurofibromatosis type 2.
D. It is beneficial for patients with bilateral severe sensorineural hearing loss.

Explanation: ***It is useful in patients with canal atresia and microtia.*** - BAHA operates by **bone conduction**, bypassing the external auditory canal and middle ear structures. - This makes it an ideal solution for conductive hearing loss caused by malformations like **canal atresia** and **microtia**, where air conduction is impaired. - BAHA is particularly effective when the cochlea is functional but sound cannot reach it via normal air conduction pathways. *It transmits sound through air conduction, making it ideal for sensorineural hearing loss.* - This statement is incorrect on both counts. - BAHA uses **bone conduction**, not air conduction. - BAHA is primarily indicated for **conductive or mixed hearing loss**, not sensorineural hearing loss, as it requires a functional cochlea. *It is used after surgery for acoustic neuroma in neurofibromatosis type 2.* - After acoustic neuroma surgery, especially in Neurofibromatosis type 2, the primary concern is often **unilateral sensorineural hearing loss** or **single-sided deafness**. - While BAHA can be used for single-sided deafness, the first-line option for single-sided deafness is **Cochlear Implants (CIs)** or contralateral routing of signal (CROS) hearing aids. *It is beneficial for patients with bilateral severe sensorineural hearing loss.* - For **bilateral severe sensorineural hearing loss**, the primary intervention is typically **cochlear implantation**, not BAHA. - BAHA is less effective for severe sensorineural loss because it still relies on a functional cochlea to convert bone-conducted vibrations into neural signals.

Question 345: An old diabetic male presented with rapidly spreading infection of the external auditory canal with involvement of the bone and presence of granulation tissue. The drug of choice for this condition is:

A. Ciprofloxacin (Correct Answer)
B. Second generation cephalosporin
C. Penicillin
D. Aminoglycosides

Explanation: ***Ciprofloxacin*** - This clinical presentation describes **necrotizing otitis externa (NOE)**, a severe infection predominantly caused by **Pseudomonas aeruginosa**. - **Ciprofloxacin** is the drug of choice due to its excellent anti-pseudomonal activity and good tissue penetration, necessary to treat the extensive infection involving bone. *Penicillin* - **Penicillin** has limited activity against **Pseudomonas aeruginosa**, which is the primary pathogen in necrotizing otitis externa, making it ineffective. - Its spectrum of activity is primarily against gram-positive bacteria and some gram-negative cocci, not the specific atypical gram-negative rods causing this infection. *Second generation cephalosporin* - **Second-generation cephalosporins** generally lack sufficient anti-pseudomonal coverage to effectively treat necrotizing otitis externa. - While they offer broader gram-negative coverage than first-generation agents, they are typically not robust enough for severe Pseudomonas infections, especially those involving bone. *Aminoglycosides* - **Aminoglycosides** are potent against Pseudomonas aeruginosa but are generally administered parenterally and are associated with significant **ototoxicity** and **nephrotoxicity**. - While effective, their side effect profile and the availability of equally effective and safer oral options like ciprofloxacin make them less favorable as a first-line monotherapy for NOE.

Question 346: What is the effective area of the tympanic membrane that is optimal for sound transmission?

A. 55 mm²
B. 30 mm²
C. 40 mm²
D. 45 mm² (Correct Answer)

Explanation: ***45 mm²*** - This value represents the **effective vibrating area** of the tympanic membrane crucial for sound transmission. - While the total surface area of the **tympanic membrane is approximately 90 mm²**, only about half of this area is involved in the vibratory process that transmits sound to the ossicles. *55 mm²* - This value is **too high** for the effective vibratory area of the tympanic membrane. - It would imply a larger functional area than what is typically accepted for efficient sound conduction. *30 mm²* - This value is **too low** for the effective vibratory area. - A smaller effective area would lead to **reduced efficiency** in the transmission of sound energy to the middle ear ossicles. *40 mm²* - While close, this value is **not the most accurate** representation of the effective functional area. - The precise area for optimal sound conduction is typically given as 45 mm².

Question 347: A patient presents with fullness in the ear and hearing loss. Tympanometry shows a type B curve. What does this indicate?

A. Normal middle ear function
B. Eustachian tube dysfunction
C. Middle ear effusion (Correct Answer)
D. Otosclerosis

Explanation: ***Middle ear effusion*** - A **Type B tympanogram** indicates a stiff, non-compliant middle ear system, typically due to fluid (effusion) filling the middle ear space. - This fluid prevents the eardrum from moving freely, leading to the **flat curve** on the tympanogram and resulting in hearing loss and a sense of fullness. *Normal middle ear function* - **Normal middle ear function** would be indicated by a **Type A tympanogram**, which shows a characteristic peak pressure near 0 daPa and normal compliance. - This type of curve signifies an air-filled middle ear with a mobile tympanic membrane. *Eustachian tube dysfunction* - **Eustachian tube dysfunction** can lead to negative middle ear pressure, often shown as a **Type C tympanogram** (a peak shifted to negative pressure). - While it can precede effusion, a Type B curve specifically suggests the presence of fluid, not just pressure imbalance. *Otosclerosis* - **Otosclerosis** often results in increased stiffness of the ossicular chain, leading to a **Type As (shallow A) tympanogram**. - This curve shows normal middle ear pressure but reduced compliance with a shallow peak because of the fixation of the stapes.

Practice by Chapter

Otitis Externa

Practice Questions

Acute Otitis Media

Practice Questions

Chronic Otitis Media

Practice Questions

Complications of Otitis Media

Practice Questions

Otosclerosis

Practice Questions

Presbycusis

Practice Questions

Sudden Sensorineural Hearing Loss

Practice Questions

Noise-Induced Hearing Loss

Practice Questions

Ménière's Disease

Practice Questions

Benign Paroxysmal Positional Vertigo

Practice Questions

Vestibular Neuritis

Practice Questions

Tumors of the Ear and Temporal Bone

Practice Questions

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