Neurotology — MCQs

Neurotology Indian Medical PG Practice Questions and MCQs

Question 161: What is the commonest operation performed in chronic suppurative otitis media (CSOM)?

A. Modified radical mastoidectomy (Correct Answer)
B. Radical mastoidectomy
C. Simple mastoidectomy
D. Tympanoplasty

Explanation: **Explanation:** The correct answer is **Modified Radical Mastoidectomy (MRM)**. In the context of Chronic Suppurative Otitis Media (CSOM), specifically the **attico-antral (unsafe) type**, the primary goal is to eradicate disease (cholesteatoma) and create a "safe" ear. MRM is the most frequently performed surgery because it effectively removes the disease from the attic and mastoid antrum while **preserving the middle ear remnants** (like the pars tensa and ossicular chain) to maintain or reconstruct hearing. **Analysis of Options:** * **Modified Radical Mastoidectomy (MRM):** It is the gold standard for cholesteatoma. It converts the mastoid, antrum, and external auditory canal into a single common cavity while preserving hearing function. * **Radical Mastoidectomy:** This is rarely performed today. It involves the total removal of all middle ear structures (tympanic membrane, ossicles except stapes, and mucosa). It is reserved for extensive disease, malignancy, or primary cholesteatoma of the petrous apex where hearing preservation is impossible. * **Simple (Schwartze) Mastoidectomy:** This is used for **Acute Mastoiditis** (a complication of ASOM). It removes mastoid air cells without disturbing the middle ear or the posterior canal wall. * **Tympanoplasty:** This is the surgery of choice for **Tubotympanic (safe) CSOM** to reconstruct the hearing mechanism, but it does not address the mastoid bone disease seen in unsafe CSOM. **High-Yield Clinical Pearls for NEET-PG:** * **Bondy’s Procedure:** A type of MRM used specifically for attic cholesteatoma where the middle ear and pars tensa are completely normal. * **Goal of Surgery:** In CSOM, the priority is: 1. Safety (disease clearance), 2. A dry ear, 3. Hearing preservation. * **Wall-Down vs. Wall-Up:** MRM is a "canal wall-down" procedure, which provides better exposure and lower recurrence rates compared to "canal wall-up" techniques.

Question 162: What is the most common site of schwannomas of the 8th cranial nerve?

A. Petrous bone
B. Intracanalicular (Correct Answer)
C. Cisternal
D. Cerebellopontine angle

Explanation: **Explanation:** The 8th cranial nerve (Vestibulocochlear nerve) consists of a vestibular and a cochlear component. Schwannomas most commonly arise from the **vestibular division**, specifically from the **inferior vestibular nerve**. **Why Intracanalicular is the correct answer:** The most common site of origin for these tumors is the **Obersteiner-Redlich zone**. This is the transition point where the nerve's myelin sheath changes from central (oligodendrocytes) to peripheral (Schwann cells). In the 8th nerve, this transition zone is located within the **Internal Auditory Canal (IAC)**. Therefore, the vast majority of vestibular schwannomas begin as **intracanalicular** tumors before expanding into the cerebellopontine angle (CPA). **Analysis of Incorrect Options:** * **Petrous bone:** While the IAC is located within the petrous part of the temporal bone, "petrous bone" is too broad a term and does not specify the anatomical origin of the nerve sheath tumor. * **Cisternal:** This refers to the segment of the nerve within the subarachnoid space. While tumors grow into this space, they rarely originate here. * **Cerebellopontine angle (CPA):** Although vestibular schwannoma is the **most common tumor of the CPA** (accounting for ~80%), it typically *originates* in the canal and *extends* into the CPA. **High-Yield Clinical Pearls for NEET-PG:** * **Most common symptom:** Progressive unilateral sensorineural hearing loss (SNHL). * **Earliest symptom:** Tinnitus. * **Gold Standard Investigation:** Contrast-enhanced MRI (shows "ice-cream cone" appearance when extending into the CPA). * **Bilateral Schwannomas:** Pathognomonic for **Neurofibromatosis Type 2 (NF2)**. * **Hitlerberger’s Sign:** Hypesthesia of the posterior external auditory canal wall due to pressure on the facial nerve (sensory fibers).

Question 163: During ear examination, cough occurs due to stimulation of which nerve?

A. Vagus (Correct Answer)
B. Trigeminal
C. Hypoglossal
D. Trochlear

Explanation: **Explanation:** The correct answer is **Vagus (Option A)**. This phenomenon is known as **Arnold’s Reflex** (or the Ear-Cough Reflex). **1. Why Vagus is Correct:** The external auditory canal (EAC) receives sensory innervation from multiple nerves. The **Arnold’s nerve**, which is the auricular branch of the **Vagus nerve (CN X)**, supplies the posterior and inferior walls of the EAC. When this area is stimulated—such as during ear syringing, cleaning with a cotton bud, or clinical examination with an otoscope—it triggers a reflex arc. The sensory impulse travels via the Vagus nerve to the medulla, stimulating the cough center, resulting in an involuntary cough. **2. Why Other Options are Incorrect:** * **Trigeminal (CN V):** The Auriculotemporal branch of the Mandibular nerve (V3) supplies the anterior and superior walls of the EAC. Stimulation here may cause pain but not a cough reflex. * **Hypoglossal (CN XII):** This is a purely motor nerve responsible for tongue movements; it has no sensory distribution in the ear. * **Trochlear (CN IV):** This is a motor nerve that supplies the superior oblique muscle of the eye; it is unrelated to ear sensation. **Clinical Pearls for NEET-PG:** * **Hittselberger’s Sign:** Reduced sensation in the area supplied by the facial nerve in the EAC, seen in Acoustic Neuroma. * **Innervation Summary:** Remember the "V3, VII, IX, X" rule for the ear. The EAC is supplied by V3 (Auriculotemporal), X (Arnold’s), and VII (Facial). The middle ear is primarily supplied by IX (Jacobson’s nerve). * **Vagal Stimulation:** Apart from coughing, intense stimulation of Arnold’s nerve can occasionally cause bradycardia or fainting (vasovagal syncope).

Question 164: Lateral sinus thrombosis is associated with all of the following except?

A. Greisinger sign
B. Gradenigo sign (Correct Answer)
C. Crowe-Beck test
D. Tobey Ayer test

Explanation: **Explanation:** **Lateral Sinus Thrombosis (LST)**, also known as Sigmoid Sinus Thrombosis, is a serious intracranial complication of chronic suppurative otitis media. The correct answer is **Gradenigo sign** because it is the clinical hallmark of **Petrositis** (inflammation of the petrous apex), not lateral sinus thrombosis. **Why Gradenigo sign is the correct answer:** Gradenigo syndrome consists of a clinical triad: 1. **Otorrhea** (Ear discharge) 2. **Retro-orbital pain** (due to trigeminal nerve/CN V involvement at Meckel’s cave) 3. **Diplopia** (due to abducens nerve/CN VI palsy in Dorello’s canal) **Why the other options are associated with LST:** * **Greisinger sign:** This is edema over the mastoid process caused by thrombosis of the mastoid emissary vein. It is a classic clinical sign of LST. * **Tobey-Ayer test:** Performed during a lumbar puncture. In LST, manual compression of the internal jugular vein (IJV) on the **affected** side fails to show a rise in CSF pressure, whereas compression on the healthy side causes a rapid rise. * **Crowe-Beck test:** This involves compressing the IJV on the **healthy** side. In a patient with LST on the opposite side, this leads to engorgement of retinal veins and supraorbital veins due to obstructed venous outflow. **High-Yield Clinical Pearls for NEET-PG:** * **Picket-fence fever:** The characteristic hectic fever pattern seen in LST due to periodic release of bacteria into the bloodstream. * **Delta Sign (Empty Triangle Sign):** Seen on contrast-enhanced CT, representing a thrombus in the sinus surrounded by enhanced dural walls. * **Treatment:** Management involves IV antibiotics, cortical mastoidectomy, and incision of the sinus (Pickrell’s procedure) if needed. Anticoagulants are controversial but used if the thrombus propagates.

Question 165: In otosclerosis, tinnitus is most commonly due to which of the following?

A. Cochlear involvement (Correct Answer)
B. Increased vascularity in the lesion
C. Conductive hearing loss
D. All of the above

Explanation: ### Explanation **Correct Answer: A. Cochlear involvement** In otosclerosis, tinnitus is a common symptom, often described as a low-pitched, roaring, or hissing sound. While the primary pathology of otosclerosis is the fixation of the stapes footplate (leading to conductive hearing loss), the development of **tinnitus is most strongly associated with cochlear involvement (Sensory Neural component)**. The underlying mechanism involves the release of toxic enzymes (like lysosomal hydrolases) from the active otosclerotic focus into the perilymph. These enzymes cause biochemical changes and damage to the hair cells or the stria vascularis, leading to secondary cochlear degeneration. This sensorineural irritation is the primary driver of persistent tinnitus in these patients. **Why other options are incorrect:** * **B. Increased vascularity:** While an active focus (Schwartze sign) shows increased vascularity, this typically causes *pulsatile* tinnitus, which is much less common than the continuous tinnitus caused by cochlear irritation. * **C. Conductive hearing loss:** CHL makes a patient more aware of internal body sounds (autophony) because the "masking effect" of ambient environmental noise is lost. However, it is not the primary physiological cause of the tinnitus itself in otosclerosis. --- ### High-Yield Clinical Pearls for NEET-PG: * **Schwartze Sign (Flamingo Flush):** Indicates active otosclerosis (Otospongiosis) with increased vascularity over the promontory. * **Carhart’s Notch:** A characteristic dip in the bone conduction threshold at **2000 Hz**. * **Gelle’s Test:** Negative in otosclerosis (indicates a fixed ossicular chain). * **Treatment of Choice:** Stapedotomy (using a Teflon piston). * **Medical Management:** Sodium Fluoride (used to mature an active focus and prevent cochlear progression).

Question 166: What is the initial mechanism of action of intra-tympanic gentamicin delivered via a microwick catheter in the treatment of Meniere's disease?

A. Damage to outer hair cells
B. Binds to hair cell Na*-K+ ATPase channel
C. Acts on melanoreceptors of outer hair cells (Correct Answer)
D. Binds to Mg++ channel

Explanation: ### Explanation **Correct Answer: C. Acts on melanoreceptors of outer hair cells** **Mechanism of Action:** Intratympanic gentamicin is a "chemical labyrinthectomy" used for intractable Meniere’s disease. Gentamicin is selectively **vestibulotoxic**. The initial step in its action involves the drug binding to **melanoreceptors** (melanin-containing cells) located in the **stria vascularis** and the **dark cells** of the vestibular labyrinth. These cells are responsible for endolymph production. By targeting these receptors, gentamicin reduces endolymph secretion, thereby relieving endolymphatic hydrops before significant destruction of the sensory neuroepithelium occurs. **Analysis of Incorrect Options:** * **Option A:** While gentamicin eventually causes damage to the vestibular hair cells (Type I > Type II), this is a secondary destructive effect rather than the *initial* physiological mechanism of action in the context of endolymph regulation. * **Option B:** Gentamicin does not primarily act by binding to the Na⁺-K⁺ ATPase channel; rather, it interferes with protein synthesis and mitochondrial function once inside the cell. * **Option D:** Aminoglycosides are known to block **mechanosensitive ion channels** (non-specific cation channels) at the tips of stereocilia, but they do not specifically target Mg⁺⁺ channels as their primary therapeutic mechanism in Meniere's. **NEET-PG High-Yield Pearls:** * **Selective Toxicity:** Gentamicin is more vestibulotoxic than cochleotoxic (unlike Amikacin/Neomycin which are more cochleotoxic). * **Target Cells:** The primary vestibular targets are the **Type I hair cells** of the crista ampullaris. * **Titration:** The "low-dose" or "titration" protocol aims to control vertigo while preserving hearing by exploiting the drug's affinity for the secretory dark cells first. * **Microwick/Microcatheter:** These delivery systems allow for continuous, sustained release of the drug into the round window niche.

Question 167: Glomus jugulare commonly arises from which anatomical region of the middle ear?

A. Hypotympanum (Correct Answer)
B. Mesotympanum
C. Epitympanum
D. Prussak's space

Explanation: **Explanation:** **Glomus Jugulare** (also known as Paraganglioma Jugulare) is a highly vascular, slow-growing tumor arising from the **glomus bodies** (chemoreceptors) located along the adventitia of the dome of the jugular bulb. 1. **Why Hypotympanum is Correct:** The jugular bulb is located immediately beneath the floor of the middle ear. Glomus jugulare tumors typically arise from the jugular bulb and erode through the floor of the middle ear to enter the **hypotympanum**. From here, the tumor often presents as a "red flush" behind the intact tympanic membrane. 2. **Why other options are Incorrect:** * **Mesotympanum:** This is the primary site for **Glomus Tympanicum**, which arises from the glomus bodies on the promontory along the Jacobson’s nerve (tympanic branch of CN IX). * **Epitympanum & Prussak’s Space:** These are superior compartments of the middle ear. While a large glomus tumor may eventually involve these areas, they are not the site of origin. Prussak’s space is more commonly associated with the origin of primary acquired cholesteatoma. **High-Yield Clinical Pearls for NEET-PG:** * **Pulsatile Tinnitus:** The most common presenting symptom (synchronous with the pulse). * **Brown’s Sign:** Blanching of the vascular mass on positive pressure with a Siegel’s speculum (Pathognomonic). * **Aquino’s Sign:** Pulsation of the tumor decreases with carotid artery compression. * **Phelps’ Sign:** Loss of the bony septum between the jugular bulb and the carotid canal (seen on CT). * **Salt and Pepper Appearance:** Characteristic MRI finding (Salt = hemorrhage/slow flow; Pepper = flow voids of high-velocity vessels). * **Classification:** Fisch Classification is used to grade the extent of Glomus tumors.

Question 168: Schwannoma of the 8th cranial nerve is typically found at which site?

A. Intrapetrous
B. Intracanalicular
C. Cisternal (Correct Answer)
D. Parotid

Explanation: **Explanation:** **Vestibular Schwannoma** (Acoustic Neuroma) is a benign tumor arising from the Schwann cells of the vestibular portion of the 8th cranial nerve. 1. **Why Cisternal is correct:** The 8th cranial nerve consists of a glial segment (proximal) and a Schwann cell segment (distal). The junction between these two, known as the **Obersteiner-Redlich zone**, is the site of origin for these tumors. This zone is located within the **cerebellopontine angle (CPA) cistern**. Therefore, the vast majority of vestibular schwannomas are found in the **cisternal** portion of the nerve. As they grow, they may expand into the internal auditory canal (IAC). 2. **Why other options are incorrect:** * **Intrapetrous:** While the nerve travels through the petrous part of the temporal bone, the tumor originates at the nerve sheath junction in the subarachnoid space, not within the bone itself. * **Intracanalicular:** Although small tumors can be confined to the internal auditory canal (IAC), this is usually an extension of the tumor rather than the primary site of origin for the majority of cases. * **Parotid:** This site is associated with tumors of the **7th cranial nerve (Facial nerve)**, such as pleomorphic adenoma or facial nerve schwannomas, but not the 8th nerve. **Clinical Pearls for NEET-PG:** * **Most common symptom:** Progressive unilateral sensorineural hearing loss (SNHL) and tinnitus. * **Gold Standard Investigation:** Gadolinium-enhanced MRI of the Internal Auditory Canal (IAC). * **Bilateral Schwannomas:** Pathognomonic for **Neurofibromatosis Type 2 (NF2)**. * **Audiometry:** Characterized by "Rollover phenomenon" (poor speech discrimination out of proportion to pure tone loss).

Question 169: All the following are causes of vertigo by vestibular origin, except?

A. Meniere's disease
B. Benign Paroxysmal Positional Vertigo (BPPV)
C. Vertebrobasilar insufficiency (Correct Answer)
D. Vestibular neuronitis

Explanation: ### Explanation The classification of vertigo is broadly divided into **Peripheral (Vestibular)** and **Central (Neurological)** origins. Understanding this distinction is crucial for NEET-PG. **Why Vertebrobasilar Insufficiency (VBI) is the correct answer:** Vertebrobasilar insufficiency is a **Central cause** of vertigo. It occurs due to transient ischemia to the brainstem or cerebellum, which are part of the central nervous system. Unlike peripheral causes, vertigo in VBI is often associated with "D's": Diplopia, Dysarthria, Dysphagia, and Drop attacks. Since the question asks for the exception to vestibular (peripheral) origin, VBI is the right choice. **Analysis of Incorrect Options (Peripheral Causes):** * **Meniere’s Disease:** A peripheral disorder caused by endolymphatic hydrops. It is characterized by the triad of episodic vertigo, sensorineural hearing loss, and tinnitus. * **BPPV:** The most common cause of peripheral vertigo. It is caused by canalolithiasis (usually in the posterior semicircular canal) and is triggered by specific head movements. * **Vestibular Neuronitis:** An acute peripheral vestibulopathy, likely viral in origin, causing severe vertigo without hearing loss. **High-Yield Clinical Pearls for NEET-PG:** * **Nystagmus Rule:** Peripheral nystagmus is usually horizontal-rotatory and inhibited by visual fixation. Central nystagmus can be purely vertical or pendular and is *not* inhibited by fixation. * **HINTS Exam:** Used to differentiate central from peripheral vertigo in acute vestibular syndrome (Head Impulse, Nystagmus, Test of Skew). * **Labyrinthitis vs. Neuronitis:** Labyrinthitis involves hearing loss; Vestibular Neuronitis spares hearing.

Question 170: All of the following are seen in Bell's palsy except?

A. Ipsilateral facial palsy
B. Ipsilateral loss of taste sensation
C. Hyperacusis
D. Ipsilateral ptosis (Correct Answer)

Explanation: **Explanation:** Bell’s palsy is an idiopathic, lower motor neuron (LMN) paralysis of the facial nerve (CN VII). To identify the correct answer, one must understand the functional anatomy of the facial nerve as it exits the stylomastoid foramen and its branches within the facial canal. **Why Ipsilateral Ptosis is the Correct Answer:** Ptosis (drooping of the upper eyelid) is caused by paralysis of the **Levator Palpebrae Superioris** (supplied by CN III) or the **Superior Tarsal muscle** (sympathetic supply). In Bell’s palsy, the facial nerve is affected, leading to paralysis of the **Orbicularis Oculi** muscle. This results in an inability to close the eye (lagophthalmos), not ptosis. In fact, the eye often appears wider due to the loss of sphincter action of the lids. **Analysis of Incorrect Options:** * **Ipsilateral facial palsy:** This is the hallmark of Bell’s palsy. Being an LMN lesion, it involves both the upper and lower quadrants of the face on the same side. * **Ipsilateral loss of taste:** The **Chorda Tympani** nerve (a branch of CN VII) carries taste from the anterior 2/3 of the tongue. If the lesion is proximal to the origin of this branch, taste is lost. * **Hyperacusis:** This occurs due to paralysis of the **Stapedius muscle** (supplied by the nerve to stapedius, a branch of CN VII). Without the stapedial reflex, loud sounds are not dampened, leading to painful sensitivity to sound. **High-Yield Clinical Pearls for NEET-PG:** 1. **Bell’s Phenomenon:** On attempting to close the eye, the eyeball rolls upwards and outwards (a normal protective reflex that becomes visible in Bell’s palsy). 2. **Schirmer’s Test:** Used to check the involvement of the Greater Superficial Petrosal Nerve (lacrimation). 3. **Treatment:** Oral corticosteroids (Prednisolone) are the mainstay of treatment; they should ideally be started within 72 hours. 4. **House-Brackmann Scale:** Used to grade the severity of facial nerve paralysis (Grade I is normal, Grade VI is total paralysis).

Practice by Chapter

Vestibular System Anatomy and Physiology

Practice Questions

Vestibular Testing

Practice Questions

Benign Paroxysmal Positional Vertigo

Practice Questions

Ménière's Disease

Practice Questions

Vestibular Neuritis

Practice Questions

Labyrinthitis

Practice Questions

Acoustic Neuroma

Practice Questions

Other Cerebellopontine Angle Tumors

Practice Questions

Facial Nerve Disorders

Practice Questions

Skull Base Surgery

Practice Questions

Cochlear Implantation

Practice Questions

Vestibular Schwannoma Management

Practice Questions

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