Otology — MCQs

Otology Indian Medical PG Practice Questions and MCQs

Question 201: The Crowe-Beck test is positive in which of the following conditions?

A. Stage of localization of brain abscess
B. Stage of termination of brain abscess
C. Lateral sinus thrombophlebitis (Correct Answer)
D. Otitic hydrocephalus

Explanation: **Explanation:** **Crowe-Beck Test** is a clinical bedside test used to assess the patency of the internal jugular vein (IJV) and the lateral (sigmoid) sinus. It is based on the physiological principle of intracranial pressure and venous drainage. **Why the correct answer is right:** In **Lateral Sinus Thrombophlebitis (LSTP)**, the affected sinus is obstructed by a thrombus. Under normal conditions, compressing one IJV causes a mild rise in intracranial venous pressure, which is easily compensated by the opposite side. In the Crowe-Beck test, the examiner compresses the IJV on the **healthy side**. Because the opposite (diseased) side is already obstructed by a clot, the venous return from the brain is severely hampered. This leads to a sudden engorgement of retinal veins and supraorbital veins, which is considered a **positive test**. **Analysis of Incorrect Options:** * **A & B (Brain Abscess):** While brain abscesses are complications of otitis media, they do not primarily obstruct the major venous outflow tracts. Diagnosis relies on imaging (CT/MRI) and focal neurological deficits rather than venous pressure tests. * **D (Otitic Hydrocephalus):** This condition involves increased intracranial pressure following lateral sinus thrombosis, but the Crowe-Beck test specifically identifies the *obstruction* of the sinus itself rather than the resulting hypertensive state. **High-Yield Clinical Pearls for NEET-PG:** * **Griesinger’s Sign:** Edema over the mastoid process due to thrombosis of the mastoid emissary vein (also seen in LSTP). * **Tobey-Ayer Test:** A similar principle to Crowe-Beck but performed during a lumbar puncture; compressing the healthy IJV causes a rapid rise in CSF pressure, whereas compressing the diseased side shows no rise. * **Delta Sign:** Seen on contrast-enhanced CT, representing a thrombus in the sigmoid sinus. * **Treatment of Choice for LSTP:** Intravenous antibiotics and Modified Radical Mastoidectomy with decompression of the sinus.

Question 202: Which of the following statements are true about idiopathic sudden sensorineural hearing loss?

A. Vertigo is always present.
B. Carbogen (5% CO2 + 95% O2) is beneficial.
C. Hearing loss occurs within 24 hours. (Correct Answer)
D. Hearing loss occurs within 72 hours.

Explanation: **Explanation:** **Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL)** is defined as a sensorineural hearing loss of at least **30 dB** over at least **three contiguous frequencies** occurring within a period of **72 hours or less**. 1. **Why Option C is correct:** While the standard clinical definition allows up to 72 hours, the classic presentation of "sudden" hearing loss often occurs instantaneously or over a very short window, typically cited in many textbooks and competitive exams as occurring within **24 hours**. In the context of this specific question, 24 hours represents the most acute and characteristic timeframe for the "sudden" onset. 2. **Why the other options are incorrect:** * **Option A:** Vertigo is present in only about 30-40% of cases. Its presence is actually a **poor prognostic factor** for hearing recovery, but it is by no means "always" present. * **Option B:** Carbogen therapy (5% $CO_2$ and 95% $O_2$) was historically used to induce vasodilation and increase cochlear oxygenation. However, modern clinical practice guidelines (AAO-HNS) no longer recommend it due to a lack of proven efficacy compared to steroids. * **Option D:** While 72 hours is the upper limit of the formal definition, in a single-choice format where 24 hours is an option, the latter is often preferred to emphasize the "apoplectic" nature of the event. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Viral infection (e.g., Herpes Simplex) or vascular compromise. * **Treatment of Choice:** Systemic **Corticosteroids** (e.g., Prednisolone 1mg/kg/day). Intratympanic steroid injections are used as salvage therapy. * **Prognosis:** 65% of patients recover spontaneously. Poor prognostic factors include: profound hearing loss, presence of vertigo, and advanced age. * **Investigation:** **MRI Brain/IAC** is mandatory to rule out Vestibular Schwannoma (Acoustic Neuroma), which presents as sudden loss in 10% of cases.

Question 203: Stapedial reflex is absent in:

A. VIth nerve lesion
B. Xth nerve lesion
C. VIIIth nerve lesion (Correct Answer)
D. Vth nerve lesion

Explanation: ### Explanation The **stapedial reflex** (acoustic reflex) is an involuntary muscle contraction of the stapedius muscle in response to high-intensity sound stimuli. To understand why it is absent in certain lesions, one must know the components of the **reflex arc**: 1. **Afferent Limb:** **VIIIth Cranial Nerve** (Vestibulocochlear nerve) – carries the sound impulse from the cochlea to the brainstem. 2. **Center:** Ventral Cochlear Nucleus and Superior Olivary Complex (Pons). 3. **Efferent Limb:** **VIIth Cranial Nerve** (Facial nerve) – carries the motor command to the stapedius muscle. **Why VIIIth Nerve Lesion is Correct:** Since the VIIIth nerve forms the **afferent limb** of the reflex arc, any lesion here (e.g., Vestibular Schwannoma) prevents the sound stimulus from reaching the brainstem. Consequently, the reflex cannot be triggered, leading to its absence. **Analysis of Incorrect Options:** * **A. VIth Nerve (Abducens):** Involved in lateral eye movement; it has no role in the auditory pathway. * **B. Xth Nerve (Vagus):** Involved in parasympathetic control and laryngeal functions; not part of this arc. * **D. Vth Nerve (Trigeminal):** While the Vth nerve supplies the *tensor tympani* muscle (which also contracts to loud sounds in some animals), the clinical "stapedial reflex" measured via impedance audiometry specifically tests the VIIth nerve-stapedius pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Facial Nerve Lesion:** The reflex is absent if the lesion is proximal to the nerve to stapedius. This is used topographically to localize VIIth nerve palsy. * **Hyperacusis:** Loss of the stapedial reflex (as seen in Bell’s Palsy) leads to hyperacusis (normal sounds appearing painfully loud). * **Reflex Decay:** If the reflex is present but fades quickly, it is a hallmark of **retrocochlear pathology** (e.g., Acoustic Neuroma). * **Otosclerosis:** The reflex is typically absent because the stapes footplate is fixed and cannot move, despite the nerve pathways being intact.

Question 204: Rinne's test is negative in which of the following conditions?

A. Presbycusis
B. Chronic suppurative otitis media (CSOM) (Correct Answer)
C. Labyrinthitis
D. Meniere's disease

Explanation: ### Explanation **Concept of Rinne’s Test** Rinne’s test compares Air Conduction (AC) and Bone Conduction (BC). * **Rinne Positive (Normal/Sensorineural):** AC > BC. This is seen in healthy ears or in Sensorineural Hearing Loss (SNHL). * **Rinne Negative (Conductive):** BC > AC. This occurs when there is a pathology in the external or middle ear that impedes sound conduction. **Why Option B is Correct** **Chronic Suppurative Otitis Media (CSOM)** involves a perforated tympanic membrane and/or ossicular chain damage. This creates a **Conductive Hearing Loss (CHL)**. In CHL, the air conduction pathway is blocked, but the cochlea (tested via bone conduction) remains functional. Therefore, BC becomes louder than AC, resulting in a **Negative Rinne’s test**. **Why Other Options are Incorrect** * **A. Presbycusis:** This is age-related **SNHL**. In SNHL, both AC and BC are reduced, but the relative relationship (AC > BC) is maintained. Thus, Rinne is positive. * **C. Labyrinthitis:** This is an inflammatory condition of the inner ear causing **SNHL**. Rinne remains positive. * **D. Meniere’s Disease:** This involves endolymphatic hydrops affecting the inner ear, leading to **SNHL**. Rinne remains positive. **High-Yield Clinical Pearls for NEET-PG** 1. **The 256 Hz Rule:** A negative Rinne test usually indicates a conductive air-bone gap of at least **15–20 dB**. 2. **False Negative Rinne:** Occurs in severe **unilateral SNHL**. The patient appears to hear the tuning fork better via BC on the affected side because the sound travels through the skull to the *opposite* healthy ear. 3. **Tuning Fork of Choice:** The **512 Hz** fork is preferred for Rinne’s test as it provides the best balance between bone-conduction vibration and decay time.

Question 205: What is the function of the stria vascularis?

A. To produce perilymph
B. To absorb perilymph
C. To maintain the electric milieu of endolymph (Correct Answer)
D. To maintain the electric milieu of perilymph

Explanation: ### Explanation The **stria vascularis** is a highly vascularized layer of stratified epithelium located on the lateral wall of the cochlear duct (scala media). It is often referred to as the "battery of the cochlea." **Why Option C is Correct:** The primary function of the stria vascularis is to maintain the unique ionic composition and the **endocochlear potential (EP)** of the endolymph. It actively pumps Potassium ($K^+$) ions into the scala media, creating a high concentration of $K^+$ and a positive electrical potential of approximately **+80 mV**. This steep electrochemical gradient is essential for the transduction of sound, as it allows $K^+$ to flow into the hair cells during stimulation. **Analysis of Incorrect Options:** * **Options A & B:** Perilymph is primarily formed as an ultrafiltrate of blood plasma or from cerebrospinal fluid (via the cochlear aqueduct). It is absorbed into the venous plexus of the modiolus. The stria vascularis is specifically associated with **endolymph**, not perilymph. * **Option D:** The electrical milieu of perilymph is relatively neutral (0 mV) and resembles extracellular fluid (high $Na^+$, low $K^+$). The stria vascularis does not regulate this space; the perilymphatic space is maintained by the blood-perilymph barrier. **High-Yield Clinical Pearls for NEET-PG:** * **Composition of Endolymph:** High $K^+$ (150 mEq/L) and low $Na^+$ (2 mEq/L). It is the only extracellular fluid in the body that resembles intracellular fluid. * **Waardenburg Syndrome:** Often involves stria vascularis defects, leading to sensorineural hearing loss due to the absence of melanocytes (which are essential for stria function). * **Ototoxicity:** Loop diuretics (e.g., Furosemide) act on the stria vascularis by inhibiting the $Na^+-K^+-2Cl^-$ cotransporter, leading to a temporary or permanent loss of endocochlear potential.

Question 206: Teunissen's classification is used for congenital anomalies of which anatomical structure?

A. Middle ear (Correct Answer)
B. Larynx
C. Trachea
D. Pharynx

Explanation: **Explanation:** **Teunissen and Cremers Classification** is the standard system used to categorize **congenital middle ear malformations** in patients with an intact tympanic membrane and no external ear canal atresia. The classification is divided into four main classes based on the surgical findings and the specific ossicular chain pathology: * **Class 1:** Isolated stapes ankylosis (congenital stapes fixation). * **Class 2:** Stapes ankylosis combined with other ossicular chain malformations (e.g., incudostapedial joint discontinuity). * **Class 3:** Ossicular chain malformations with a mobile stapes footplate. * **Class 4:** Congenital aplasia or severe dysplasia of the oval or round window. **Why other options are incorrect:** * **Larynx:** Congenital anomalies of the larynx (e.g., Laryngomalacia, Laryngeal webs) are typically classified using systems like the **Benjamin-Inglis classification** (for webs). * **Trachea:** Tracheal anomalies (e.g., Tracheomalacia, Stenosis) use classifications based on the length and site of the segment involved, such as the **Lobeck classification**. * **Pharynx:** Pharyngeal anomalies (e.g., Branchial cleft cysts) are classified based on their embryological origin (1st, 2nd, or 3rd branchial arches). **High-Yield Clinical Pearls for NEET-PG:** 1. **Jahrsdoerfer Scale:** Used to assess candidacy for surgery in patients with **Congenital Aural Atresia** (External Ear). A score of $\geq$ 6 is generally required for surgery. 2. **Most common ossicular anomaly:** The most common isolated ossicular deformity is the **fixation of the stapes footplate**. 3. **Clinical Presentation:** These patients typically present with non-progressive, congenital conductive hearing loss and a normal-looking tympanic membrane.

Question 207: What is the most common site of perilymph fistula?

A. Round window
B. Oval window (Correct Answer)
C. Otic capsule
D. Attic

Explanation: **Explanation:** A **perilymph fistula (PLF)** is an abnormal communication between the fluid-filled perilymphatic space of the inner ear and the air-filled middle ear cavity. This leakage of perilymph results in sudden or fluctuating sensorineural hearing loss and vertigo. **Why the Oval Window is correct:** The **oval window** is the most common site for a perilymph fistula. Anatomically, it is more vulnerable to barotrauma (sudden pressure changes) or physical trauma because the stapes footplate sits within it, held only by the annular ligament. Rupture typically occurs at this ligamentous interface. Common triggers include heavy lifting, straining (Valsalva maneuver), or sudden atmospheric pressure changes (diving/flying). **Analysis of Incorrect Options:** * **Round Window:** While the second most common site, the round window membrane is generally more resilient than the annular ligament of the oval window. * **Otic Capsule:** This is the dense bone surrounding the inner ear. While fractures of the otic capsule (e.g., temporal bone fractures) can cause perilymph leaks, they are less common than spontaneous or barotrauma-induced leaks at the windows. * **Attic:** The attic (epitympanum) is a part of the middle ear containing the head of the malleus and body of the incus. It is not a site of perilymph containment; therefore, a fistula cannot originate here. **Clinical Pearls for NEET-PG:** * **Hennebert’s Sign:** Vertigo/nystagmus induced by applying pressure to the external auditory canal (positive in PLF and Meniere’s). * **Tullio Phenomenon:** Vertigo induced by loud sounds (seen in PLF and Superior Semicircular Canal Dehiscence). * **Management:** Initial treatment is strict bed rest with head elevation. If symptoms persist, surgical exploration and patching of the windows are indicated.

Question 208: In the majority of cases with otosclerosis, what is the typical appearance of the tympanic membrane?

A. Normal (Correct Answer)
B. Flamingo pink
C. Blue
D. Yellow

Explanation: In otosclerosis, the primary pathology is the replacement of normal dense lamellar bone with irregular, vascular spongy bone in the otic capsule, most commonly at the **fissula ante fenestram**. This leads to stapes fixation and conductive hearing loss. **Explanation of Options:** * **A. Normal (Correct):** In the vast majority of patients (approx. 90%), the tympanic membrane appears completely normal on otoscopy. This is because otosclerosis is a disease of the bony labyrinth and ossicles, not the middle ear mucosa or the drum itself. * **B. Flamingo pink:** This refers to **Schwartz’s sign** (or Fleischer's sign). It represents the hypervascularity of the promontory seen through a transparent drum during the active phase of the disease (otospongiosis). While pathognomonic for otosclerosis, it is only seen in about **10% of cases**, making "Normal" the more typical finding. * **C. Blue:** A blue tympanic membrane is characteristic of **Hemotympanum** (blood in the middle ear) or a **High Jugular Bulb/Glomus tumor**. * **D. Yellow:** A yellowish or amber-colored drum is typically seen in **Otitis Media with Effusion (Serous Otitis Media)** due to the presence of sterile fluid. **High-Yield Clinical Pearls for NEET-PG:** 1. **Gelle’s Test:** Negative (indicates stapes fixation). 2. **Carhart’s Notch:** A characteristic dip in the bone conduction threshold at **2000 Hz**. 3. **Bezold’s Triad:** Includes (a) Raised bone conduction threshold, (b) Negative Rinne, and (c) Prolonged Schwabach test. 4. **Treatment of Choice:** Stapedotomy (using a Teflon piston). 5. **Paracusis Willisi:** A clinical feature where the patient hears better in noisy surroundings.

Question 209: Which structure of the inner ear produces endolymph?

A. A filtrate of blood serum
B. Secreted by the stria vascularis (Correct Answer)
C. Secreted by the basilar membrane
D. Secreted by hair cells

Explanation: **Explanation:** The correct answer is **B. Secreted by the stria vascularis.** **1. Why the correct answer is right:** Endolymph is the unique fluid found within the membranous labyrinth (scala media). It is actively secreted by the **stria vascularis**, a highly vascularized layer of stratified epithelium located on the lateral wall of the cochlear duct. The stria vascularis acts as a "battery," maintaining the high potassium ($K^+$) concentration and the positive endocochlear potential (+80 mV) necessary for hair cell depolarization. **2. Why the incorrect options are wrong:** * **A. A filtrate of blood serum:** This describes **Perilymph**, which is chemically similar to extracellular fluid or CSF (high $Na^+$, low $K^+$). Perilymph is formed partly as an ultrafiltrate of blood and partly from CSF via the cochlear aqueduct. * **C. Secreted by the basilar membrane:** The basilar membrane is a structural fibrous layer that supports the Organ of Corti; it has no secretory function. * **D. Secreted by hair cells:** Hair cells are sensory receptors that *utilize* the ionic gradient of endolymph to generate nerve impulses; they do not produce the fluid itself. **3. NEET-PG High-Yield Pearls:** * **Composition:** Endolymph is the only extracellular fluid in the body that resembles intracellular fluid (High $K^+$, Low $Na^+$). * **Absorption:** Endolymph is drained via the endolymphatic duct and absorbed by the **endolymphatic sac**. * **Clinical Correlation:** **Meniere’s Disease** (Endolymphatic Hydrops) is caused by either the overproduction or under-absorption of endolymph, leading to the classic triad of vertigo, tinnitus, and sensorineural hearing loss. * **Helicotrema:** The point where the scala vestibuli and scala tympani communicate, allowing perilymph to flow between them.

Question 210: What type of eardrum perforation is considered unsafe?

A. Central
B. Marginal (Correct Answer)
C. Paracentral
D. Multiple central

Explanation: ### Explanation In Otology, tympanic membrane perforations are classified into **Safe (Tubotympanic)** and **Unsafe (Atticoantral)** types based on their risk of developing life-threatening complications. **Why Marginal is the Correct Answer:** A **Marginal perforation** is one that reaches the **annulus fibrosus** (the fibrous rim of the eardrum). It is considered "unsafe" because the absence of a mucosal or fibrous rim at the periphery allows the keratinizing squamous epithelium of the external auditory canal to migrate into the middle ear. This migration leads to the formation of **cholesteatoma**, an osteolytic sac that can erode vital structures (ossicles, facial nerve, labyrinth, or tegmen plate), leading to intracranial and extracranial complications. **Analysis of Incorrect Options:** * **A. Central:** A perforation is "central" if there is a rim of tympanic membrane (annulus) preserved all around it. These are typically associated with **Safe CSOM** (Tubotympanic type) and carry a low risk of cholesteatoma. * **C. Paracentral:** This is a subtype of central perforation located away from the umbo. Like other central perforations, it is considered safe. * **D. Multiple central:** Often seen in **Tuberculous Otitis Media**. While clinically significant, they are still "central" in nature and do not inherently carry the "unsafe" epithelial migration risk associated with marginal or attic perforations. **High-Yield Clinical Pearls for NEET-PG:** 1. **Unsafe CSOM** is characterized by either a **Marginal** perforation or an **Attic** perforation. 2. **Safe CSOM** (Tubotympanic) usually presents with profuse, mucoid, non-foul-smelling discharge. 3. **Unsafe CSOM** (Atticoantral) presents with scanty, purulent, **foul-smelling** (due to bone erosion) discharge and may show granulations or aural polyps. 4. **Management:** Safe CSOM is often managed medically or via Myringoplasty; Unsafe CSOM almost always requires surgical intervention (**Mastoidectomy**) to remove the cholesteatoma.

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Tympanic Membrane Perforation

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Cholesteatoma

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Tympanoplasty Techniques

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Ossicular Chain Reconstruction

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Mastoidectomy

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Stapedectomy

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Implantable Hearing Devices

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Congenital Aural Atresia

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Otologic Trauma

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Glomus Tumors

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Facial Nerve Decompression

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Rehabilitative Audiology

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Otology — MCQs

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