Lateral Skull Base Approaches — MCQs
In acoustic neuroma, cranial nerve to be involved earliest is
All of the following are indications for Gamma Knife Radiosurgery EXCEPT
All pass through jugular foramen except
Treatment of choice for CSOM with vertigo and facial nerve palsy is:
CSF Otorrhea is due to trauma of:
A case of CSOM presenting with vertigo can have any of the following except -
FISCH classification is used for-
What does a bluish-purple discoloration behind the mastoid indicate?
A lady comes to OPD after fall from scooty. Her vitals are stable. She is having continuous, clear watery discharge from nose after 2 days. This is most likely a feature of?
Lucid Interval is seen in?
Lateral Skull Base Approaches Indian Medical PG Practice Questions and MCQs
Question 1: In acoustic neuroma, cranial nerve to be involved earliest is
- A. Cranial nerve VIII (Correct Answer)
- B. Cranial nerve VII
- C. Cranial nerve IX
- D. Cranial nerve V
Explanation: ***Cranial nerve VIII*** - Acoustic neuromas (vestibular schwannomas) arise from the **Schwann cells** of the vestibular branch of the **eighth cranial nerve (vestibulocochlear nerve)** [1]. - Due to their origin, symptoms related to CN VIII, such as **unilateral hearing loss**, **tinnitus**, and **vertigo**, are typically the earliest to appear [1]. *Cranial nerve VII* - The **facial nerve (CN VII)** is anatomically close to the eighth nerve within the **internal auditory canal**, but its involvement usually occurs later as the tumor grows and compresses it [1]. - Early involvement of CN VII would primarily manifest as **facial weakness or paralysis** or taste disturbances [1]. *Cranial nerve IX* - The **glossopharyngeal nerve (CN IX)** is located more medially in the **cerebellopontine angle** and is typically affected only by larger tumors. - Symptoms would primarily include **dysphagia (difficulty swallowing)** or loss of taste on the posterior tongue. *Cranial nerve V* - The **trigeminal nerve (CN V)** is also situated in the cerebellopontine angle, further from the initial growth site of an acoustic neuroma. - Involvement of CN V would lead to **facial numbness**, pain, or weakness in the muscles of mastication, which are late manifestations.
Question 2: All of the following are indications for Gamma Knife Radiosurgery EXCEPT
- A. Acoustic neuroma
- B. Arteriovenous malformation
- C. Trigeminal neuralgia
- D. Brain tumours or lesions 4 cm or larger in diameter (Correct Answer)
Explanation: ***Brain tumours or lesions 4 cm or larger in diameter*** - **Gamma Knife radiosurgery** is typically used for **small to medium-sized lesions** (generally less than 3-4 cm in diameter). - Larger lesions carry a **higher risk of cerebral edema** and radiation necrosis when treated with radiosurgery, making conventional surgery or fractionated radiotherapy more appropriate. *Acoustic neuroma* - **Gamma Knife radiosurgery** is a well-established treatment option for **acoustic neuromas** (vestibular schwannomas). - It aims to control tumor growth and preserve hearing and facial nerve function with a high success rate. *Arteriovenous malformation* - **Arteriovenous malformations (AVMs)** are commonly treated with **Gamma Knife radiosurgery** to induce thrombosis and obliteration of the abnormal vascular nidus. - This treatment helps in preventing future hemorrhage and reducing seizure risk. *Trigeminal neuralgia* - **Gamma Knife radiosurgery** is an effective treatment for **refractory trigeminal neuralgia**. - It delivers a highly focused dose of radiation to the trigeminal nerve root, creating a lesion that disrupts the pain signals.
Question 3: All pass through jugular foramen except
- A. Mandibular nerve (Correct Answer)
- B. Vagus nerve
- C. Internal jugular vein
- D. Glossopharyngeal nerve
Explanation: ***Mandibular nerve*** - The **mandibular nerve** (CN V3) exits the skull through the **foramen ovale**, not the jugular foramen. - It is a branch of the **trigeminal nerve** and is responsible for motor innervation to muscles of mastication and sensory innervation to the lower face and mouth. *Glossopharyngeal nerve* - The **glossopharyngeal nerve** (CN IX) is one of the three cranial nerves that exit through the **jugular foramen**. - It provides motor, sensory, and parasympathetic innervation including taste from posterior third of tongue and motor to stylopharyngeus muscle. *Vagus nerve* - The **vagus nerve** (CN X) is one of the major cranial nerves that exits the skull through the **jugular foramen**. - It provides extensive motor, sensory, and parasympathetic innervation to the head, neck, thorax, and abdomen. *Internal jugular vein* - The **internal jugular vein** is formed at the jugular foramen by the continuation of the **sigmoid sinus**, and it exits the skull through this foramen. - It is one of the primary venous drainage pathways for the brain.
Question 4: Treatment of choice for CSOM with vertigo and facial nerve palsy is:
- A. Myringoplasty
- B. Antibiotics and labyrinthine sedative
- C. Immediate mastoid exploration (Correct Answer)
- D. Labyrinthectomy
Explanation: ***Immediate mastoid exploration*** - Vertigo and facial nerve palsy in the context of CSOM (Chronic Suppurative Otitis Media) indicate **intracranial complications** or significant **bone erosion** by the cholesteatoma, necessitating urgent surgical intervention. - **Mastoid exploration** allows for removal of the cholesteatoma, drainage of infection, and decompression of the facial nerve, preventing irreversible damage and life-threatening complications. *Myringoplasty* - This procedure involves **repairing the tympanic membrane** (eardrum) and is primarily performed for simple perforations without labyrinthine involvement or facial nerve complications. - It would not address the underlying pathology of **cholesteatoma erosion** or the serious symptoms of vertigo and facial nerve palsy. *Antibiotics and labyrinthine sedative* - While antibiotics may be part of the management for active infection, they alone cannot resolve an extensive **cholesteatoma** causing bone destruction and nerve compression. - **Labyrinthine sedatives** might temporarily relieve vertigo but do not treat the causative disease process, which requires surgical intervention. *Labyrinthectomy* - This procedure involves **destroying the labyrinth** to alleviate intractable vertigo, typically reserved for severe, unilateral Meniere's disease or non-functioning labyrinths. - It is a **destructive procedure** that would result in complete hearing loss and would not address the underlying **cholesteatoma** or the facial nerve palsy.
Question 5: CSF Otorrhea is due to trauma of:
- A. Tympanic membrane
- B. Cribriform plate
- C. Parietal bone
- D. Petrous temporal bone (Correct Answer)
Explanation: ***Petrous temporal bone*** - **CSF otorrhea** (leakage of cerebrospinal fluid from the ear) most commonly results from a fracture of the **petrous portion of the temporal bone**. - This bone forms part of the skull base and houses structures of the inner and middle ear, a fracture here can create a direct communication between the **subarachnoid space** and the external ear canal. *Tympanic membrane* - A rupture of the **tympanic membrane** alone would lead to **otorrhea** (ear discharge), but it would primarily involve blood or middle ear fluid, not CSF. - While a ruptured tympanic membrane is necessary for CSF to exit the ear canal, the source of the CSF leak itself is proximal to the middle ear. *Cribriform plate* - A fracture of the **cribriform plate** typically results in **CSF rhinorrhea** (CSF leakage from the nose), as it is located structurally above the nasal cavity. - It is not directly involved in CSF leakage from the ear. *Parietal bone* - Fractures of the **parietal bone** are typically associated with epidural or subdural hematomas or brain injury, depending on the extent of the trauma. - They are not a usual cause of CSF leakage from the ear since this bone does not contain CSF pathways that directly communicate with the ear.
Question 6: A case of CSOM presenting with vertigo can have any of the following except -
- A. Dural sinus thrombosis (Correct Answer)
- B. Cerebellar abscess
- C. Fistula with semicircular canal
- D. Any of the above
Explanation: ***Dural sinus thrombosis (Correct - Does NOT typically cause vertigo)*** - Dural sinus thrombosis is an intracranial complication of CSOM that presents with **headache**, **papilledema**, **seizures**, and **focal neurological deficits** - **Vertigo is NOT a characteristic feature** of dural sinus thrombosis - While it's a serious complication of CSOM, it does not directly affect the vestibular system, making it the exception in this list *Cerebellar abscess (Incorrect - DOES cause vertigo)* - Cerebellar abscess is a serious intracranial complication of CSOM that **commonly causes vertigo** - Due to proximity to the **vestibular nuclei** and brainstem pathways, cerebellar pathology disrupts balance and coordination - Presents with prominent **vertigo**, **ataxia**, **nystagmus**, and other cerebellar signs *Fistula with semicircular canal (Incorrect - DOES cause vertigo)* - **Labyrinthine fistula** is a direct cause of vertigo in CSOM - Erosion from chronic infection creates an abnormal communication between the middle ear and inner ear (commonly affects the **lateral semicircular canal**) - Produces **pressure-induced vertigo** (positive fistula test) as pressure changes directly stimulate the vestibular system - Classic presentation: vertigo triggered by loud sounds (Tullio phenomenon) or pressure changes *Any of the above (Incorrect)* - This option is incorrect because NOT all listed complications cause vertigo - While cerebellar abscess and labyrinthine fistula are well-established causes of vertigo in CSOM, dural sinus thrombosis does not typically present with vertigo - Therefore, "any of the above" is not accurate
Question 7: FISCH classification is used for-
- A. Juvenile nasopharyngeal angiofibroma
- B. Nasopharyngeal carcinoma
- C. Vestibular schwannoma
- D. Glomus tumor (Correct Answer)
Explanation: ***Glomus tumor*** - The **FISCH classification** is a surgical staging system used to classify **glomus tumors** based on their extent and involvement of surrounding structures. - This classification helps guide surgical management and predict procedural outcomes for these highly vascular tumors. *Juvenile nasopharyngeal angiofibroma* - **Radkowski's classification**, or **Andrews' classification**, are commonly used for staging **juvenile nasopharyngeal angiofibroma**, not FISCH. - These classifications categorize tumors based on their extension into the nasal cavity, paranasal sinuses, orbit, or intracranial space. *Nasopharyngeal ca* - The staging of **nasopharyngeal carcinoma** is typically based on the **AJCC (American Joint Committee on Cancer) TNM classification system**. - This system assesses the **tumor (T)** size and local extension, **node (N)** involvement, and **metastasis (M)**. *Vestibular schwannoma* - **Vestibular schwannomas** are usually staged using systems that describe their size and extension into the **cerebellopontine angle** and brainstem, such as the **Koos grade**. - The FISCH classification is specifically for **glomus tumors** of the temporal bone and is not applicable to vestibular schwannomas.
Question 8: What does a bluish-purple discoloration behind the mastoid indicate?
- A. Battle sign (Correct Answer)
- B. Bezold abscess
- C. Both A and B
- D. None of the options
Explanation: ***Battle sign*** - A **bluish-purple discoloration behind the mastoid** (postauricular ecchymosis) is a classic sign of a **basilar skull fracture**, particularly involving the middle cranial fossa. - This bruising is caused by the extravasation of blood from the fracture site into the soft tissues over the mastoid process. *Bezold abscess* - A Bezold abscess is a rare complication of **mastoiditis**, where infection erodes through the mastoid tip and spreads to the soft tissues of the neck. - It presents as a **painful swelling in the neck** and is typically not associated with a bluish-purple discoloration *behind* the mastoid unless there is significant necrotic tissue or a secondary hematoma, which is not the primary feature. *Both A and B* - These conditions represent distinct pathologies, one related to **trauma (Battle sign)** and the other to **infection (Bezold abscess)**. - While both involve the mastoid region, their underlying causes and typical presentations are different. *None of the options* - The image directly displays the characteristic bruising of a Battle sign, making this option incorrect. - The appearance is highly indicative of a specific medical condition.
Question 9: A lady comes to OPD after fall from scooty. Her vitals are stable. She is having continuous, clear watery discharge from nose after 2 days. This is most likely a feature of?
- A. CSF rhinorrhoea (Correct Answer)
- B. Acute respiratory infection
- C. Rhinitis
- D. Middle cranial fossa fracture
Explanation: ***CSF rhinorrhoea*** - **Clear watery discharge** appearing **two days after head trauma** (fall from scooty) is highly suggestive of **cerebrospinal fluid (CSF) rhinorrhoea**. - This occurs due to a breach in the **skull base**, allowing CSF to leak from the subarachnoid space into the nasal cavity. *Acute respiratory infection* - An acute respiratory infection typically presents with symptoms like **fever, cough**, and **nasal discharge** that is often thicker and discolored, not clear and watery. - The onset of discharge two days after trauma without other signs of infection also makes this less likely. *Rhinitis* - Rhinitis involves inflammation of the nasal mucosa, leading to watery discharge, sneezing, and congestion. - However, the traumatic etiology and the specific timing of the discharge make **CSF leak** a more pertinent diagnosis than simple rhinitis. *Middle cranial fossa fracture* - While a **middle cranial fossa fracture** can cause CSF leakage, the discharge from the nose (rhinorrhoea) typically originates from an **anterior cranial fossa fracture**. - A middle cranial fossa fracture is more commonly associated with **otorrhoea** (CSF leakage from the ear) if the temporal bone is involved.
Question 10: Lucid Interval is seen in?
- A. All of these
- B. Subarachnoid hemorrhage
- C. Extradural hemorrhage (Correct Answer)
- D. Subdural hemorrhage
Explanation: ***Extradural hemorrhage*** - A **lucid interval** is a hallmark feature of an **extradural (epidural) hemorrhage**, where a patient briefly regains consciousness after initial head trauma before deteriorating [3]. - This transient improvement occurs due to a temporary cessation of bleeding or accommodation by the brain before the hematoma expands significantly, compressing the brain. *All of these* - While other forms of intracranial hemorrhage can cause fluctuating consciousness, the classic and most distinct **lucid interval** is traditionally associated with extradural hemorrhage [3]. - It is not a consistent or characteristic feature across all types of intracranial bleeds. *Subarachnoid hemorrhage* - Patients with **subarachnoid hemorrhage** typically present with a sudden, severe headache (**worst headache of life**) and often rapidly develop neurological deficits or loss of consciousness without a clear lucid interval [2]. - The bleeding is usually arterial and rapid, leading to immediate symptom onset. *Subdural hemorrhage* - **Subdural hemorrhages** often present with a more gradual onset of symptoms (hours to days or even weeks), especially in chronic cases, due to venous bleeding [1]. - While fluctuations in consciousness can occur, a distinct **lucid interval** followed by rapid deterioration is less common than in extradural bleeds [3].
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