Anterior Skull Base Approaches — MCQs
All of the following statements about spontaneous CSF leak are true, except:
Transection at mid-pons level with intact vagus results in:
Which of the following is an indication for Functional Endoscopic Sinus Surgery (FESS)?
All of the following arteries are branches of ECA that supply nasal septum except:
A nasal surgery was carried out with the incision shown in the image. What was the procedure likely carried out?
What is the most common malignancy found in the maxillary antrum?
A Young Male complained of intermittent pain, swelling and discharge at the base of spine. He also had episodes of fever and repeated abscesses that had burst spontaneously. By occupation, he is a jeep driver. Physical examination showed pilonidal sinus. Which flap-based procedure is used for pilonidal sinus surgery?
Which of the following is not a complication of maxillary sinus lavage and insufflation?
What is the treatment of choice for ethmoidal polyps?
Chordoma arises from:
Anterior Skull Base Approaches Indian Medical PG Practice Questions and MCQs
Question 1: All of the following statements about spontaneous CSF leak are true, except:
- A. Fluorescin Dye can be used intrathecally for diagnosis of site of leak
- B. MRI (Gadolinium enhanced) T1 images are best for diagnosis of site of leak
- C. Most common site of CSF leak is fovea ethmoidalis (Correct Answer)
- D. Beta 2 transferrin estimation is highly specific for diagnosis
Explanation: ***Most common site of CSF leak is fovea ethmoidalis*** - The **fovea ethmoidalis** is actually the **most common site for iatrogenic injury** during sinus surgery, but is **rarely the source of spontaneous CSF leaks.** - **Spontaneous CSF leaks** typically occur in the **cribriform plate** or the **sphenoid sinus**, usually due to congenital defects or increased intracranial pressure. *Fluorescin Dye can be used intrathecally for diagnosis of site of leak* - **Intrathecal fluorescein** can be used to visually locate the site of a CSF leak during endoscopy. - However, it carries a small risk of **neurotoxicity**, including seizures, and is therefore used cautiously and often diluted. *MRI (Gadolinium enhanced) T1 images are best for diagnosis of site of leak* - **High-resolution CT cisternography** with intrathecal contrast is generally considered the **gold standard** for precisely localizing CSF leaks, especially bony defects. - While MRI can show fluid collections and some dural defects, it is often **less definitive** for pinpointing the exact leak site compared to CT cisternography. *Beta 2 transferrin estimation is highly specific for diagnosis* - **Beta-2 transferrin** is a highly specific marker for CSF, as it is found almost exclusively in CSF, perilymph, and aqueous humor. - Its presence in nasal or ear discharge definitively confirms the fluid as CSF, making it a very reliable diagnostic test.
Question 2: Transection at mid-pons level with intact vagus results in:
- A. Apneusis
- B. Hyperventilation
- C. Irregular shallow breathing
- D. Deep and slow breathing (Correct Answer)
Explanation: ***Deep and slow breathing*** - A transection at the **mid-pons level** disconnects the **pneumotaxic center** from the medullary respiratory centers, while the **vagus nerves remain intact**. - Without the inhibitory input from the pneumotaxic center, inspirations become deep and prolonged due to the unopposed effect of the **apneustic center**, but the intact vagus still provides some inspiratory off-switch, preventing full apneusis. This leads to **deep and slow breathing**. *Apneusis* - **Apneusis**, characterized by prolonged inspiratory gasps, occurs when both the **pneumotaxic center and vagal afferents** (from lung stretch receptors) are non-functional or cut. - In this scenario, the vagus nerves are intact, providing an inspiratory off-switch that prevents the full development of apneusis. *Hyperventilation* - **Hyperventilation** typically results from metabolic acidosis, hypoxemia, or anxiety, leading to an increased rate and depth of breathing. - A mid-pons transection primarily affects the rhythm and duration of inspiration, not necessarily increasing the overall minute ventilation in a compensatory manner. *Irregular shallow breathing* - **Irregular shallow breathing** can be seen with damage to the **medullary respiratory centers** or severe respiratory muscle weakness. - The transection described primarily impacts the integration of pontine and medullary control, particularly the interaction between the apneustic and pneumotaxic centers, leading to deep and slow breaths, not shallow ones.
Question 3: Which of the following is an indication for Functional Endoscopic Sinus Surgery (FESS)?
- A. inverted papilloma
- B. Optic nerve decompression
- C. Orbital abscess
- D. Nasal polyposis (Correct Answer)
Explanation: ***Nasal polyposis*** - **Nasal polyposis refractory to medical management** is one of the most common and primary indications for **FESS**, as it allows for direct removal of polyps and restoration of sinus drainage and ventilation. - **FESS** aims to improve ventilation and mucociliary clearance within the paranasal sinuses, addressing the underlying chronic rhinosinusitis that leads to polyp formation. *Inverted papilloma* - **Inverted papilloma** is a benign but locally aggressive **epithelial tumor** that does require surgical excision, and FESS techniques are used for its removal. - However, it often requires **extended endoscopic approaches** (such as medial maxillectomy or modified endoscopic medial maxillectomy) rather than standard FESS to ensure complete removal and prevent recurrence due to its invasive growth pattern. - In the context of this question, **nasal polyposis** is the more straightforward and common indication for standard FESS. *Orbital abscess* - An **orbital abscess** is a surgical emergency requiring prompt drainage. While endoscopic sinus surgery may be used as part of the surgical approach to drain the abscess and address contributing sinusitis, the primary goal is abscess drainage rather than the sinus disease itself. - The indication here is the orbital complication, not chronic sinus disease per se. *Optic nerve decompression* - **Endoscopic optic nerve decompression** can be performed using FESS techniques for conditions like traumatic optic neuropathy or compressive lesions. - However, this is a specialized, advanced procedure for specific optic nerve pathology, not a routine indication for FESS in the management of chronic rhinosinusitis and its direct complications.
Question 4: All of the following arteries are branches of ECA that supply nasal septum except:
- A. Facial artery
- B. Superior labial artery
- C. Anterior ethmoidal artery (Correct Answer)
- D. Sphenopalatine artery
Explanation: ***Anterior ethmoidal artery*** - The **anterior ethmoidal artery** is a branch of the **ophthalmic artery**, which itself is a branch of the **internal carotid artery (ICA)**, not the external carotid artery (ECA). - It supplies the **upper anterior nasal septum** and lateral wall of the nasal cavity. *Facial artery* - The **facial artery** is a direct branch of the **external carotid artery (ECA)**. - It contributes to the blood supply of the nasal septum through its septal branches. *Superior labial artery* - The **superior labial artery** is a branch of the **facial artery**, meaning it indirectly originates from the **external carotid artery (ECA)**. - It sends a septal branch to supply the **anterior inferior part of the nasal septum**. *Sphenopalatine artery* - The **sphenopalatine artery** is a direct terminal branch of the **maxillary artery**, which is one of the terminal branches of the **external carotid artery (ECA)**. - It is the major blood supply to the **posterior nasal septum** and lateral wall, forming part of Kesselbach's plexus.
Question 5: A nasal surgery was carried out with the incision shown in the image. What was the procedure likely carried out?
- A. Submucosal resection (SMR)
- B. FESS (Functional Endoscopic Sinus Surgery)
- C. Open rhinoplasty (Correct Answer)
- D. Caldwell-Luc's procedure
Explanation: ***Open rhinoplasty*** - The image displays a **transcolumellar incision** (typically inverted V or W-shaped), which is the hallmark approach for **open rhinoplasty**. - This incision allows for direct visualization of the underlying nasal cartilages and bones, enabling precise reshaping of the nose. *Submucosal resection (SMR)* - SMR is a procedure to correct a **deviated nasal septum** by removing cartilage or bone from beneath the mucoperichondrial flaps. - It involves an **intranasal incision**, usually along the septal mucosa, not an external transcolumellar incision. *FESS (Functional Endoscopic Sinus Surgery)* - FESS is a minimally invasive procedure used to treat **chronic sinusitis** and other sinus conditions. - It is performed entirely **endoscopically through the nostrils**, with no external incisions on the nasal columella. *Caldwell-Luc's procedure* - This procedure accesses the **maxillary sinus** through an incision in the upper gum beneath the lip. - It is used for drainage of the maxillary sinus or removal of foreign bodies/tumors, and does not involve an external nasal incision.
Question 6: What is the most common malignancy found in the maxillary antrum?
- A. Mucoepidermoid Carcinoma
- B. Adenocarcinoma
- C. Squamous cell carcinoma (Correct Answer)
- D. Adenoid Cystic Carcinoma
Explanation: ***Squamous cell Ca*** - **Squamous cell carcinoma** (SCC) accounts for the vast majority (approximately 80%) of all malignancies arising in the **maxillary antrum** (or maxillary sinus). - Its high prevalence is often linked to chronic inflammation, environmental factors, and a higher density of **squamous epithelium** or metaplasia in the region. *Mucoepidermoid Carcinoma* - This is a common salivary gland malignancy but is **rare in the maxillary antrum**, where glandular tissue is less predominant. - While it can occur in sinonasal tracts, it is not the most frequent primary malignancy there. *Adenoid Cystic Carcinoma* - **Adenoid cystic carcinoma** is a common malignancy of the salivary glands and can occur in the sinonasal tract, but it is **much less frequent than SCC** in the maxillary antrum. - It often exhibits a **perineural invasion** pattern and a slow, but aggressive growth. *Adenocarcinoma* - While adenocarcinomas can arise from the **glandular epithelium** of the maxillary antrum, they are considerably **less common than squamous cell carcinoma**. - They are often associated with specific occupational exposures, such as **wood dust** or leather dust.
Question 7: A Young Male complained of intermittent pain, swelling and discharge at the base of spine. He also had episodes of fever and repeated abscesses that had burst spontaneously. By occupation, he is a jeep driver. Physical examination showed pilonidal sinus. Which flap-based procedure is used for pilonidal sinus surgery?
- A. Rhomboid flap (Correct Answer)
- B. Free flap
- C. Rotational flap
- D. Circular flap
Explanation: ***Rhomboid flap*** - The **rhomboid flap** (**Limberg flap**) is a common and effective surgical technique for pilonidal sinus, offering good wound closure and reduced recurrence rates. - It involves excising the sinus tract *en bloc* and closing the defect with a **rhomboid-shaped skin flap**, which distributes tension evenly. - This is a **transposition flap** that moves tissue laterally into the defect while maintaining blood supply. *Free flap* - **Free flaps** involve transplanting tissue with its own blood supply from one part of the body to another using microsurgery. - This method is overly complex and unnecessary for a typical pilonidal sinus repair, which usually only requires local tissue rearrangement. *Rotational flap* - A **rotational flap** is a type of local flap where tissue is rotated on a pivot point to cover a defect. - While rotational flaps (such as the **Karydakis flap**) can be used for pilonidal sinus surgery, the **rhomboid flap** is more commonly referenced as the standard flap-based technique due to its reliable outcomes and specific geometric design. - The rhomboid flap is technically a **transposition flap**, not a rotational flap, though both are local tissue rearrangement techniques. *Circular flap* - **Circular flaps** are generally not a standard design for closing excisional defects, especially in areas like the sacrococcygeal region where linear tension and dead space management are crucial. - Such a flap would likely create dog-ears and poor cosmetic outcomes, making it unsuitable for pilonidal sinus surgery.
Question 8: Which of the following is not a complication of maxillary sinus lavage and insufflation?
- A. Orbital injury
- B. Epistaxis
- C. Facial nerve injury (Correct Answer)
- D. Air embolism
Explanation: ***Facial nerve injury*** - The **facial nerve (CN VII)** passes through the parotid gland and temporal bone, far from the maxillary sinus. - There is no anatomical proximity or procedural mechanism during maxillary sinus lavage and insufflation that would put the facial nerve at risk of injury. *Air embolism* - **Insufflation of air** into the maxillary sinus, especially under pressure, can lead to air entering the bloodstream if a blood vessel is inadvertently punctured. - This can result in a serious and potentially fatal **air embolism**, particularly if the air reaches the cerebral circulation. *Orbital injury* - The **medial wall of the maxillary sinus** is in close proximity to the orbit, separated by thin bone. - During lavage, excessive force or incorrect angulation of instruments can perforate this thin bone, leading to **orbital complications** such as periorbital hematoma or injury to orbital contents. *Epistaxis* - During the procedure, the **mucosa of the nasal cavity** or the sinus itself can be traumatized by the instruments used for lavage. - This local trauma to the rich blood supply of these areas can easily cause **nasal bleeding (epistaxis)**.
Question 9: What is the treatment of choice for ethmoidal polyps?
- A. Functional Endoscopic sinus surgery with polypectomy (Correct Answer)
- B. Intranasal ethmoidectomy
- C. Transantral ethmoidectomy
- D. Extranasal ethmoidectomy
Explanation: ***Functional Endoscopic sinus surgery with polypectomy*** - This is the **gold standard treatment** for ethmoidal polyps, as it allows for **direct visualization** and complete removal of polyps while preserving healthy mucosa. - It also enables restoration of normal sinus ventilation and drainage, which helps prevent recurrence. *Intranasal ethmoidectomy* - This is an **older technique** that is performed blindly and carries a higher risk of complications, such as **orbital or intracranial injury**, compared to endoscopic approaches. - It often results in incomplete polyp removal, leading to a higher rate of recurrence. *Transantral ethmoidectomy* - This approach, also known as the **Caldwell-Luc procedure**, is primarily used for diseases of the **maxillary sinus** and is not the preferred method for isolated ethmoidal polyps. - It is a more invasive external approach with risks including facial swelling, pain, and damage to dental nerves. *Extranasal ethmoidectomy* - This is a more invasive **external approach** involving an incision on the face and is generally reserved for extensive or complicated cases, such as **tumors or severe trauma**, not for routine polyp removal. - It carries risks of visible scarring and longer recovery times, making it less favorable than endoscopic techniques.
Question 10: Chordoma arises from:
- A. Pharyngeal bursa
- B. Notochord (Correct Answer)
- C. Rathke’s pouch
- D. Luschka's bursa
Explanation: ***Notochord*** - Chordoma is a **rare, slow-growing malignant bone tumor** that originates from **persistent notochordal remnants**. - The notochord is a flexible rod-like structure that serves as the primary axial support during embryonic development, eventually becoming the **nucleus pulposus** of the intervertebral discs. *Pharyngeal bursa* - The pharyngeal bursa is a normal anatomical variant, a small recess in the **posterior wall of the nasopharynx**. - It is not associated with the development of chordomas. *Rathke's pouch* - Rathke's pouch is an **ectodermal invagination** from the roof of the primitive mouth (stomodeum) that gives rise to the **anterior pituitary gland**. - Tumors arising from remnants of Rathke's pouch are typically **craniopharyngiomas**, not chordomas. *Luschka's bursa* - This term is sometimes used to refer to a **pharyngeal bursa**, as mentioned in the first incorrect option. - It is not the origin of chordomas.
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