Diseases of the Ear — MCQs

Diseases of the Ear Indian Medical PG Practice Questions and MCQs

Question 121: The secondary tympanic membrane is present over which structure?

A. Round window (Correct Answer)
B. Oval window
C. Lateral wall of middle ear
D. Scala media

Explanation: **Explanation:** The **secondary tympanic membrane** is a thin, three-layered membrane that closes the **round window (fenestra cochleae)**. It separates the middle ear cavity from the scala tympani of the cochlea. **Why it is the correct answer:** In the physiology of hearing, when the stapes footplate pushes into the oval window, it creates a pressure wave in the perilymph. Since fluids are incompressible and the cochlea is encased in bone, the secondary tympanic membrane must bulge outward into the middle ear to accommodate this pressure. This "reciprocal movement" allows the fluid wave to travel through the cochlea and stimulate the Organ of Corti. **Analysis of Incorrect Options:** * **B. Oval window:** This is closed by the **footplate of the stapes** and the annular ligament. It is the entry point for sound vibrations into the inner ear. * **C. Lateral wall of middle ear:** This is primarily formed by the **tympanic membrane** (primary) and the bony meatus. * **D. Scala media:** This is the middle compartment of the cochlea containing endolymph; it is bounded by Reissner’s membrane and the basilar membrane, not the secondary tympanic membrane. **High-Yield Clinical Pearls for NEET-PG:** * **Layers:** Like the primary tympanic membrane, the secondary membrane has three layers: outer (mucous), middle (fibrous), and inner (endothelial). * **Round Window Reflex:** During surgery, if the stapes is moved, one can see the reflex movement of the round window membrane, confirming ossicular continuity. * **Clinical Correlation:** In cases of **Otosclerosis**, the oval window is fixed, but the round window can also rarely be involved (obliterative otosclerosis).

Question 122: What is true about Acute Necrotizing Otitis Media (ANOM)?

A. The most common organism is Pseudomonas Aeruginosa.
B. The most common organism is β-Hemolytic streptococci. (Correct Answer)
C. It occurs in patients with low immunity.
D. It causes marginal perforation.

Explanation: **Explanation:** **Acute Necrotizing Otitis Media (ANOM)** is a virulent form of acute otitis media characterized by rapid destruction of the tympanic membrane and middle ear structures. 1. **Why Option B is Correct:** The classic causative organism for ANOM is **$\beta$-Hemolytic streptococci**. While other organisms like *Staphylococcus aureus* or *Streptococcus pneumoniae* can be involved, $\beta$-Hemolytic streptococci are historically and clinically recognized as the most common and aggressive pathogens in this specific necrotizing variant. 2. **Why Other Options are Incorrect:** * **Option A:** *Pseudomonas aeruginosa* is the primary pathogen in **Malignant Otitis Externa** (seen in elderly diabetics) and Chronic Suppurative Otitis Media (CSOM), but not typically in ANOM. * **Option C:** While it can occur in debilitated patients, ANOM is classically associated with **children suffering from exanthematous fevers** (e.g., Measles, Scarlet fever, or Influenza). It is the severity of the specific infection rather than generalized "low immunity" that defines its presentation. * **Option D:** ANOM typically results in a **large central perforation** (often described as a "total" or "subtotal" perforation) due to the sloughing of the tympanic membrane. Marginal perforations are more characteristic of Attico-antral (unsafe) CSOM. **High-Yield Clinical Pearls for NEET-PG:** * **Pathology:** Rapid necrosis leads to the formation of a large central perforation and can result in permanent hearing loss due to ossicular destruction (especially the incus). * **Healing:** The perforation rarely heals spontaneously; it often heals by secondary intention, leading to a thin, atrophic membrane or permanent defect. * **Key Association:** Always link ANOM with **Measles** in exam questions.

Question 123: Hyperacusis is caused by damage to which muscle?

A. Stapedius (Correct Answer)
B. Tensor Palati
C. Tensor Tympani
D. All of the above

Explanation: **Explanation:** **1. Why Stapedius is the Correct Answer:** The **Stapedius muscle** is the smallest skeletal muscle in the body, nerve-supplied by the **Stapedial branch of the Facial Nerve (CN VII)**. Its primary physiological role is the **Acoustic Reflex**. When exposed to loud sounds (>70-90 dB), the stapedius contracts, pulling the stapes bone away from the oval window. This increases the stiffness of the ossicular chain, thereby dampening the vibrations reaching the cochlea and protecting the inner ear. If the stapedius muscle or the facial nerve is paralyzed (e.g., in **Bell’s Palsy**), this protective dampening mechanism is lost. Consequently, normal environmental sounds are perceived as uncomfortably loud or painful, a clinical phenomenon known as **Hyperacusis**. **2. Why Other Options are Incorrect:** * **Tensor Tympani:** Supplied by the **Mandibular nerve (V3)**, this muscle attaches to the malleus. While it also increases ossicular stiffness, its role in the human acoustic reflex is significantly less dominant than the stapedius. Damage to it does not typically result in clinical hyperacusis. * **Tensor Palati:** This muscle is involved in opening the **Eustachian tube** during swallowing and yawning. It has no direct role in dampening sound vibrations at the ossicular level. **3. Clinical Pearls for NEET-PG:** * **Nerve Supply:** Stapedius (CN VII); Tensor Tympani (CN V3). * **Topodiagnostic Value:** The presence of hyperacusis in a patient with facial palsy indicates that the lesion is **proximal to the nerve to stapedius** (in the vertical segment of the facial canal). * **Recruitment vs. Hyperacusis:** Do not confuse these. **Recruitment** is seen in cochlear hearing loss (e.g., Meniere’s), where there is an abnormal growth in loudness perception despite a high hearing threshold. Hyperacusis is a mechanical failure of the dampening system.

Question 124: Painless discharge from the ear and multiple tympanic membrane perforations are characteristic of which condition?

A. Tuberculous otitis media (Correct Answer)
B. Fungal otitis media
C. Serous otitis media
D. Viral otitis media

Explanation: **Explanation:** **Tuberculous Otitis Media (TOM)** is the correct answer because it presents with a classic clinical triad: **painless ear discharge**, **multiple tympanic membrane (TM) perforations**, and profound hearing loss disproportionate to the symptoms. The infection usually reaches the middle ear via the Eustachian tube (secondary to pulmonary TB) or hematogenous spread. The multiple perforations occur due to the coalescence of multiple small tubercles on the TM; these eventually merge into a single large central perforation. **Analysis of Incorrect Options:** * **Fungal Otitis Media (Otomycosis):** Characteristically presents with intense itching, pain, and a "wet newspaper" or "cotton wool" appearance (Aspergillus/Candida). It does not typically cause multiple TM perforations. * **Serous Otitis Media (Otitis Media with Effusion):** Characterized by a retracted, dull TM with air-fluid levels or bubbles. The TM remains **intact**, and there is no discharge. * **Viral Otitis Media:** Often presents as Myringitis Bullosa, characterized by severe pain and hemorrhagic blebs on the TM. It does not cause chronic painless discharge or multiple perforations. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic sign:** Multiple "sieve-like" perforations (though these often coalesce into one large perforation later). * **Discharge:** Characteristically thin, odorless, and watery (flocculent). * **Facial Nerve Paralysis:** A known complication of TOM due to bone necrosis. * **Diagnosis:** Confirmed by identifying *Mycobacterium tuberculosis* in the discharge (AFB staining) or via middle ear mucosa biopsy showing granulomas.

Question 125: What type of tympanic membrane perforation is considered unsafe?

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

Explanation: In Chronic Suppurative Otitis Media (CSOM), perforations are clinically classified into **Safe (Tubotympanic)** and **Unsafe (Atticoantral)** types based on the risk of serious complications. ### Why Marginal Perforation is "Unsafe" A **marginal perforation** is one that reaches the fibrous annulus (the periphery of the tympanic membrane). It is considered "unsafe" because the absence of a mucosal rim at the margin allows the keratinizing squamous epithelium from the external auditory canal to migrate into the middle ear cleft. This process leads to the formation of **cholesteatoma**, an osteolytic sac that can erode vital structures (ossicles, facial nerve, labyrinth, or tegmen), leading to intracranial and extracranial complications. ### Explanation of Incorrect Options * **A & C. Central and Paracentral Perforations:** These are "Safe" types. A central perforation is surrounded by a rim of the tympanic membrane (pars tensa) on all sides. Since the annulus is intact, there is no pathway for skin migration, and the risk of cholesteatoma is minimal. * **D. Multiple Central Perforations:** While rare, these are typically associated with **Tuberculous Otitis Media**. Although they indicate a specific pathology, they are still "central" and do not carry the inherent risk of squamous migration seen in marginal or attic perforations. ### High-Yield Clinical Pearls for NEET-PG * **Unsafe CSOM Locations:** Marginal perforations (posterosuperior) and **Attic perforations** (pars flaccida). * **Hallmark of Unsafe CSOM:** Scanty, foul-smelling discharge (due to bone erosion) and the presence of cholesteatoma/granulation tissue. * **Management:** Safe CSOM is managed medically or via Myringoplasty; Unsafe CSOM always requires surgical intervention (**Mastoidectomy**) to remove the disease.

Question 126: A false positive fistula test is associated with which of the following conditions?

A. Perilymph fistula
B. Malignant sclerosis
C. Congenital syphilis (Correct Answer)
D. Cholesteatoma

Explanation: **Explanation:** The **Fistula Test** is used to identify an abnormal communication between the inner and middle ear. A positive result occurs when pressure changes in the external auditory canal (via a Siegle’s speculum) induce nystagmus and vertigo. **Why Congenital Syphilis is Correct:** In **Congenital Syphilis**, a **False Positive Fistula Test (Hennebert’s Sign)** occurs. This means the test is positive despite the absence of a physical bony fistula in the horizontal semicircular canal. It happens due to: 1. **Hypermobile stapes footplate:** Fibrous adhesions between the footplate and the membranous labyrinth. 2. **Endolymphatic Hydrops:** Increased pressure makes the labyrinth more sensitive to pressure changes. **Analysis of Incorrect Options:** * **Perilymph Fistula:** This causes a **True Positive** test. There is an actual leak of perilymph at the oval or round window. * **Cholesteatoma:** This is the most common cause of a **True Positive** test, usually due to erosion of the bony lateral semicircular canal. * **Malignant Sclerosis (Otosclerosis):** While advanced otosclerosis can rarely be associated with Hennebert’s sign if there is concomitant hydrops, it is not the classic or primary association compared to syphilis. **High-Yield Clinical Pearls for NEET-PG:** * **Hennebert’s Sign:** Positive fistula test without a fistula (seen in Congenital Syphilis and Meniere’s Disease). * **Tullio’s Phenomenon:** Vertigo/nystagmus induced by loud sounds (seen in Syphilis, Meniere’s, and Superior Semicircular Canal Dehiscence). * **False Negative Fistula Test:** Occurs when the fistula is present but the test is negative because the labyrinth is dead (e.g., dead labyrinth in chronic canal erosion) or the fistula is plugged by cholesteatoma/granulation tissue.

Question 127: Facial nerve palsy is seen in which of the following conditions?

A. Seborrhoeic otitis externa
B. Otomycosis
C. Malignant otitis externa (Correct Answer)
D. Eczematous otitis externa

Explanation: **Explanation:** **Malignant Otitis Externa (MOE)**, also known as Necrotizing Otitis Externa, is a severe, life-threatening infection of the external auditory canal and skull base, typically caused by *Pseudomonas aeruginosa*. It primarily affects elderly diabetic or immunocompromised individuals. The hallmark of MOE is its spread beyond the soft tissues into the bony structures (osteomyelitis of the skull base). The infection typically spreads through the **Fissures of Santorini** and the tympanomastoid suture. As the infection reaches the stylomastoid foramen, the **Facial Nerve (CN VII)** is the most commonly involved cranial nerve, leading to lower motor neuron facial palsy. Involvement of the facial nerve is a key clinical indicator of disease severity and progression. **Why the other options are incorrect:** * **Seborrhoeic, Otomycosis, and Eczematous Otitis Externa:** These are superficial inflammatory or fungal infections (Otomycosis is usually caused by *Aspergillus niger* or *Candida*). They are confined to the skin of the external ear canal and do not cause bone destruction or neurovascular invasion; therefore, they do not result in cranial nerve palsies. **High-Yield Clinical Pearls for NEET-PG:** * **Pathogen:** *Pseudomonas aeruginosa* (>95% cases). * **Clinical Sign:** Exquisite pain and presence of **granulation tissue** at the junction of the cartilaginous and bony canal. * **Diagnosis:** **Technetium-99m scan** is best for initial diagnosis (detects osteoblastic activity); **Gallium-67 scan** is best for monitoring treatment response (detects active infection). * **Treatment:** Long-term intravenous antipseudomonal antibiotics (e.g., Ciprofloxacin, Ceftazidime) and strict glycemic control.

Question 128: The "Brown Sign" is characteristic of which of the following conditions?

A. Glomus tumour (Correct Answer)
B. Acoustic neuroma
C. Adenoid cystic carcinoma of the parotid gland
D. Warthin tumour

Explanation: **Explanation:** The **Brown Sign** (also known as the Rising Sun sign) is a classic clinical finding in **Glomus tumours** (Paragangliomas), specifically Glomus Tympanicum. It refers to a reddish-blue, pulsatile mass seen behind an intact tympanic membrane. The "sign" is elicited by applying positive pressure with a Siegle’s speculum: the pressure causes the tumour to blanch (turn pale) and its pulsations to cease temporarily. **Why the other options are incorrect:** * **Acoustic Neuroma (Vestibular Schwannoma):** This is a tumour of the 8th cranial nerve. It typically presents with retrocochlear deafness and equilibrium issues, but no vascular mass is visible behind the eardrum. * **Adenoid Cystic Carcinoma:** This is a malignant salivary gland tumour known for perineural invasion and pain. While it can involve the ear canal via the parotid, it does not exhibit the Brown sign. * **Warthin Tumour:** A benign parotid tumour (adenolymphoma) usually found in the tail of the parotid. It is associated with smoking and does not present with middle ear signs. **Clinical Pearls for NEET-PG:** * **Aquino’s Sign:** Blanching of the glomus tumour upon compression of the ipsilateral common carotid artery. * **Phelps’ Sign:** Loss of the bony plate between the jugular bulb and the middle ear (seen on CT). * **Treatment of Choice:** Surgical excision (e.g., via a transcanal or hypotympanotomy approach). Pre-operative embolization is often used to reduce vascularity. * **Histology:** Characterized by **Zellballen patterns** (clusters of chief cells surrounded by sustentacular cells).

Question 129: Malignant otitis externa is most commonly caused by?

A. Pseudomonas aeruginosa (Correct Answer)
B. Staphylococcus aureus
C. Streptococcus pneumoniae
D. Staphylococcus epidermidis

Explanation: **Explanation:** **Malignant Otitis Externa (Necrotizing Otitis Externa)** is a severe, potentially life-threatening infection of the external auditory canal that spreads to the skull base (osteomyelitis). 1. **Why Pseudomonas aeruginosa is correct:** * **Pseudomonas aeruginosa** is the causative organism in over **95% of cases**. It is an opportunistic, gram-negative aerobe that thrives in moist environments. * It produces virulence factors like exotoxins and enzymes (elastase, collagenase) that allow it to invade soft tissue, blood vessels (causing vasculitis and thrombosis), and eventually bone. * The disease typically affects **elderly diabetic patients** or the immunocompromised, where the microangiopathy and high pH of the earwax provide an ideal environment for Pseudomonas to proliferate. 2. **Why the other options are incorrect:** * **Staphylococcus aureus:** While a common cause of localized otitis externa (furunculosis), it is rarely the primary driver of the invasive necrotizing form. * **Streptococcus pneumoniae:** This is a classic cause of Acute Otitis Media (middle ear infection), not external ear infections. * **Staphylococcus epidermidis:** Usually considered normal skin flora; while it can cause biofilm-related infections on implants, it does not possess the invasive machinery required for malignant otitis externa. **High-Yield Clinical Pearls for NEET-PG:** * **Cardinal Sign:** Presence of **granulation tissue** at the bony-cartilaginous junction of the external auditory canal. * **Key Symptom:** Deep-seated, excruciating ear pain (otalgia) that is worse at night. * **Cranial Nerve Involvement:** The **Facial nerve (VII)** is the most commonly affected nerve as the infection spreads to the stylomastoid foramen. * **Diagnosis:** **CT scan** is best for assessing bone destruction; **Technetium-99m** scan is used for initial diagnosis (detects osteoblastic activity); **Gallium-67** scan is used to monitor treatment response (shows resolution of infection). * **Treatment:** Long-term systemic anti-pseudomonal antibiotics (e.g., Ciprofloxacin).

Question 130: What is keratosis obturans?

A. Foreign body in the external auditory canal
B. Desquamated epithelial cells and cholesterol (Correct Answer)
C. Cholesterol crystals surrounded by calcium
D. Earwax in the external auditory canal

Explanation: **Explanation:** **Keratosis Obturans (KO)** is a clinical condition characterized by the accumulation of large plugs of **desquamated keratin (epithelial cells)** in the deep external auditory canal (EAC). The correct answer is **B** because these plugs consist of concentric layers of shed squamous epithelium, often mixed with **cholesterol** and debris, which fail to migrate out of the canal due to a failure in the ear's self-cleaning mechanism. **Analysis of Options:** * **Option A:** While KO acts like a "functional" foreign body, it is an endogenous accumulation of skin cells, not an exogenous object. * **Option C:** This describes a calcified mass. While KO can erode bone, it is not primarily a calcified or calcium-surrounded lesion. * **Option D:** Earwax (cerumen) is a physiological secretion of the sebaceous and ceruminous glands. KO is pathologically distinct, consisting of hard, pearly-white keratin sheets rather than soft wax. **Clinical Pearls for NEET-PG:** * **Classic Presentation:** Typically seen in younger patients (5–20 years). It presents with severe otalgia (ear pain), conductive hearing loss, and is often associated with **bronchiectasis** or sinusitis. * **Pathology:** It causes **circumferential widening** of the bony EAC due to pressure necrosis. * **Differential Diagnosis:** Must be distinguished from **EAC Cholesteatoma**, which typically occurs in older patients, is unilateral, and shows focal bone erosion/sequestrum rather than generalized widening. * **Management:** Repeated syringing or microscopic clearance; surgical widening of the canal may be required in recurrent cases.

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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