Cross-sectional Anatomy: Brain and Head — MCQs
What is the investigation of choice for diagnosing subarachnoid hemorrhage (SAH)?
What is not a feature of raised ICP
Which type of shift in intracranial content is common in children with progressive hydrocephalus –
Which CT view is best for visualizing paranasal polyps?
A 49-year-old woman has had a severe headache for 2 days. On physical examination, she is afebrile and normotensive. Funduscopic examination shows papilledema on the right. One day later, she has the right pupillary dilation and impaired ocular movement. She then becomes obtunded. Which of the following lesions best explains these findings?
A middle-aged person is rushed to the emergency department with a history of loss of motor power in the left upper and lower limb since the last 30 minutes. The imaging modality of choice to plan appropriate treatment would be
A radiopaque density may be noticed in poisoning by which of the following agents?
The following X-ray is used to evaluate \qquad sinus?
Characteristic of venous blood flow of lower limb in duplex Doppler is?
Shenton's Line is present in which joint?
Cross-sectional Anatomy: Brain and Head Indian Medical PG Practice Questions and MCQs
Question 1: What is the investigation of choice for diagnosing subarachnoid hemorrhage (SAH)?
- A. Radionuclide scan
- B. X-ray skull
- C. MRI
- D. CT scan (Correct Answer)
Explanation: ***CT scan*** - A **non-contrast CT scan of the head** is the immediate investigation of choice for diagnosing SAH due to its high sensitivity for detecting fresh blood. - It can quickly identify the presence of **blood in the subarachnoid space**, especially within the first 6-12 hours after symptom onset. *Radionuclide scan* - This imaging technique uses **radioactive tracers** to evaluate organ function or blood flow. - It is **not used for acute diagnosis** of SAH, as it does not directly visualize blood in the CNS. *X-ray skull* - An **X-ray of the skull** primarily visualizes bone structures and can detect fractures or other bony abnormalities. - It is **ineffective at detecting blood** in the subarachnoid space and is not used for SAH diagnosis. *MRI* - While MRI can detect SAH, especially in subacute or chronic phases, it is **less sensitive than CT for acute SAH** due to longer acquisition times and motion artifacts. - It is often considered if CT is negative and clinical suspicion remains high, but **not as the initial investigation of choice** in an acute setting.
Question 2: What is not a feature of raised ICP
- A. Vomiting
- B. Tachycardia (Correct Answer)
- C. Blurring of vision
- D. Hypertension
Explanation: ***Tachycardia*** - **Bradycardia**, not tachycardia, is a classic component of the **Cushing's triad**, which is a physiological response to increased ICP. - The elevated ICP triggers a reflex arc that causes a decrease in heart rate as the body attempts to maintain cerebral perfusion. *Vomiting* - **Vomiting**, especially projectile and without nausea, is a common symptom of increased ICP due to activation of the **chemoreceptor trigger zone** in the medulla. - The pressure directly stimulates this area, leading to emesis. *Blurring of vision* - **Blurring of vision** is a frequent symptom of raised ICP, often associated with **papilledema** (swelling of the optic disc). - The elevated pressure is transmitted to the optic nerve sheath, impeding venous return and causing nerve swelling. *Hypertension* - **Hypertension** is part of the **Cushing's triad** in response to increased ICP, where the body raises systemic blood pressure to overcome resistance and maintain cerebral blood flow [2]. - This is a compensatory mechanism to ensure adequate perfusion to the brain [1].
Question 3: Which type of shift in intracranial content is common in children with progressive hydrocephalus –
- A. Central transtentorial herniation (Correct Answer)
- B. Transforaminal herniation
- C. Upward cerebellar herniation
- D. Unilateral transtentorial herniation
Explanation: ***Central transtentorial herniation*** - In progressive hydrocephalus, the increase in overall intracranial pressure causes a **downward displacement of the diencephalon and midbrain** through the tentorial incisura [1]. - This type of herniation is often due to **diffuse supratentorial pressure increase**, which is characteristic of unresolved hydrocephalus. *Transforaminal herniation* - Also known as **tonsillar herniation**, this involves the displacement of the cerebellar tonsils through the **foramen magnum** [2]. - It is typically caused by **posterior fossa masses** or severe supratentorial pressure leading to global brain edema, but less specifically linked to the common progression of hydrocephalus. *Upward cerebellar herniation* - This occurs when a **mass in the posterior fossa** or increased pressure within the posterior fossa causes the cerebellum to herniate **upward** through the tentorial opening. - It is not a common herniation pattern for generalized hydrocephalus, which usually produces a **diffuse downward pressure**. *Unilateral transtentorial herniation* - Also called **uncal herniation**, this type involves the medial temporal lobe (uncus) being forced over the petrous ridge and through the tentorial incisura [1]. - It is primarily caused by **unilateral supratentorial mass lesions** (e.g., tumors, hematomas), rather than the diffuse pressure seen in hydrocephalus. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 698-700. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1257-1258.
Question 4: Which CT view is best for visualizing paranasal polyps?
- A. Coronal view (Correct Answer)
- B. Axial view
- C. Sagittal view
- D. 3D view
Explanation: ***Coronal*** - The **coronal view** provides the best visualization of the **ostia of the paranasal sinuses**, which are crucial for assessing the extent and obstruction caused by polyps. - This orientation effectively demonstrates whether polyps are **protruding into the nasal cavity** or obstructing the drainage pathways. *Axial view* - The axial view is useful for evaluating **posterior structures** and **bony erosion** but is less optimal for assessing the vertical extent of polyps or ostial obstruction. - It can show the **anteroposterior dimensions** of polyps but does not offer the same clarity for sinus outflow tracts as the coronal view. *Sagittal view* - The sagittal view is good for showing the **craniocaudal extent** of lesions and differentiating between the nasal cavity and sphenoid sinus, but it is not ideal for comprehensive paranasal sinus polyp evaluation. - It can help in localizing some polyps but does not provide a clear overview of **sinus ostia** or lateral extension. *3D view* - A 3D reconstruction can be helpful for a general overview and surgical planning but does not offer the fine detail and specific orientation needed for primary polyp detection and ostial assessment as effectively as direct 2D views. - It is a derived image rather than a primary acquisition plane and might obscure smaller polyps or subtle anatomical relationships.
Question 5: A 49-year-old woman has had a severe headache for 2 days. On physical examination, she is afebrile and normotensive. Funduscopic examination shows papilledema on the right. One day later, she has the right pupillary dilation and impaired ocular movement. She then becomes obtunded. Which of the following lesions best explains these findings?
- A. Hydrocephalus ex vacuo
- B. Frontal lobe abscess
- C. Glioblastoma with edema (Correct Answer)
- D. Chronic subdural hematoma
Explanation: ***Glioblastoma with edema*** - The rapid progression from headache and **papilledema** to **pupillary dilation**, **impaired ocular movement**, and obtundation suggests an acute increase in **intracranial pressure** due to a rapidly expanding mass with significant associated **vasogenic edema**. - **Glioblastoma multiforme** is a highly aggressive primary brain tumor that typically presents with rapidly progressive neurological deficits and elevated ICP due to its fast growth and propensity for extensive peritumoral edema. *Hydrocephalus ex vacuo* - This condition involves enlarged ventricles due to **brain atrophy**, not due to increased CSF pressure. - It would not cause symptoms of increased ICP, such as **papilledema** or acute neurological deterioration. *Frontal lobe abscess* - While a **frontal lobe abscess** can cause increased ICP and focal neurological deficits, the rapid progression of symptoms, especially the acute onset of pupillary dilation and obtundation, is more characteristic of a highly aggressive and rapidly expanding mass like a glioblastoma. - The absence of **fever** initially also makes an abscess less likely. *Chronic subdural hematoma* - A **chronic subdural hematoma** typically presents with a more insidious onset of symptoms over weeks to months, and while it can cause increased ICP, the acute onset and rapid deterioration in a 49-year-old with these specific findings make a glioblastoma more probable. - Pupillary dilation usually indicates severe uncal herniation, which can occur, but the presentation is less acute.
Question 6: A middle-aged person is rushed to the emergency department with a history of loss of motor power in the left upper and lower limb since the last 30 minutes. The imaging modality of choice to plan appropriate treatment would be
- A. CT scan of the head (Correct Answer)
- B. MRI of the brain
- C. Carotid doppler study
- D. EEG
Explanation: ***CT scan of the head*** - A **non-contrast CT scan of the head** is the immediate imaging modality of choice in acute stroke symptoms to quickly rule out a **hemorrhagic stroke**. - This rapid assessment guides treatment decisions; if hemorrhage is absent, **thrombolytic therapy (tPA)** can be considered within the critical time window. *MRI of the brain* - While **MRI** offers superior detail for detecting ischemic stroke, it is **unsuitable for initial emergency assessment** due to longer acquisition times and limited availability. - The delay in obtaining an MRI could critically hinder the initiation of time-sensitive therapies like **thrombolysis**. *Carotid doppler study* - A **carotid Doppler study** is useful for identifying **carotid artery stenosis**, which can be a cause of ischemic stroke but is not an acute diagnostic tool for stroke itself. - It does not provide information about the presence of hemorrhage or acute ischemic changes within the brain parenchyma. *EEG* - An **EEG (electroencephalogram)** measures electrical activity in the brain and is primarily used to diagnose conditions like **seizures** or evaluate altered mental status. - It provides no structural information and is not indicated for the initial evaluation of acute motor deficits indicative of a stroke.
Question 7: A radiopaque density may be noticed in poisoning by which of the following agents?
- A. Chloroquine
- B. Phenazopyridine
- C. Ethylene glycol
- D. Chloral hydrate (Correct Answer)
Explanation: ***Chloral hydrate*** - Due to its halogenated structure, **chloral hydrate** can be radio-opaque on X-rays, making it one of the "CHIPES" substances. - This property allows for radiological detection of its presence in the **gastrointestinal tract** following ingestion, particularly in large overdoses. *Chloroquine* - **Chloroquine** is not significantly radio-opaque and is generally not detectable on plain radiographs following overdose. - Clinical diagnosis of chloroquine poisoning relies on symptoms such as **hypotension**, **cardiac arrhythmias**, and **hypokalemia**, not radiological findings. *Phenazopyridine* - **Phenazopyridine** is a urinary analgesic that does not possess properties that render it radiographically detectable. - Its metabolism and excretion do not produce **radio-opaque metabolites** or complexes. *Ethylene glycol* - **Ethylene glycol** itself is not radio-opaque on plain X-rays, and its presence is typically diagnosed through laboratory tests like anion gap metabolic acidosis. - While it can lead to the formation of **calcium oxalate crystals** in the kidneys, these are typically microscopic and not visible as general radiopacities in the GI tract.
Question 8: The following X-ray is used to evaluate \qquad sinus?
- A. Frontal
- B. Maxillary (Correct Answer)
- C. Ethmoidal
- D. Sphenoidal
Explanation: ***Maxillary*** - The image provided is a **Waters' view** (occipitomental view) X-ray of the paranasal sinuses, which is primarily used to visualize the **maxillary sinuses**. - In a Waters' view, the **petrous ridges** (dense bone at the base of the skull) are projected below the maxillary sinuses, allowing for a clear view of these sinuses. *Frontal* - While the **frontal sinuses** are visible in a Waters' view, they are generally better visualized in a **Caldwell view** (occipitofrontal view) or lateral view. - In this projection, their visualization can be obscured by other bony structures, and they are not the primary focus. *Ethmoidal* - The **ethmoidal sinuses** are typically comprised of multiple small air cells located between the orbits and are best seen on a **Caldwell view** or specialized oblique views. - In a Waters' view, their evaluation is limited due to superimposition of other facial bones. *Sphenoidal* - The **sphenoidal sinuses** are located deep within the skull, inferior to the sella turcica, and are quite difficult to visualize on standard plain radiographs like the Waters' view. - They are best assessed using a **lateral view of the skull** or advanced imaging like **CT scans**.
Question 9: Characteristic of venous blood flow of lower limb in duplex Doppler is?
- A. Biphasic (Correct Answer)
- B. Non phasic
- C. Monophasic
- D. Triphasic
Explanation: ***Biphasic*** - Normal venous blood flow in the **major lower limb veins** (femoral, popliteal) on duplex Doppler is characteristically **biphasic**, showing variations with respiration. - This biphasic pattern reflects the influence of the **thoracoabdominal pump**, where inspiration decreases intrathoracic pressure and increases intra-abdominal pressure, thus impeding venous return, and expiration reverses this action. - The two phases correspond to **acceleration during expiration** and **deceleration during inspiration**. *Non phasic* - **Non-phasic** (continuous) flow usually indicates a **proximal obstruction** such as deep vein thrombosis (DVT). - This pattern means the respiratory variations are absent due to the blockage preventing normal pressure changes from affecting venous return. - Loss of phasicity is an important sign of venous pathology. *Monophasic* - **Monophasic** flow shows only one phase (forward flow) without clear respiratory variation. - While monophasic flow can be **normal in smaller peripheral veins** (e.g., calf veins), in major lower limb veins it may suggest **partial obstruction** or poor respiratory effort. - It lacks the distinct respiratory modulation seen with biphasic flow. *Triphasic* - **Triphasic** flow is characteristic of **arterial waveforms** in peripheral arteries, showing rapid antegrade flow, brief reversal during early diastole, and slower forward flow during late diastole. - This is not a normal finding for venous blood flow and represents arterial rather than venous physiology.
Question 10: Shenton's Line is present in which joint?
- A. Knee
- B. Shoulder
- C. Elbow
- D. Hip (Correct Answer)
Explanation: **Explanation:** **Shenton’s Line** is a fundamental radiological landmark used to assess the integrity of the **Hip joint** on an Anteroposterior (AP) X-ray. It is an imaginary curved line formed by the continuous arc of the **inferior border of the superior pubic ramus** and the **medial border of the femoral neck**. 1. **Why Hip is Correct:** In a normal, healthy hip, this arc is smooth and unbroken. A disruption or "step-off" in Shenton’s Line is a critical diagnostic sign indicating pathology, most commonly a **femoral neck fracture**, **developmental dysplasia of the hip (DDH)**, or a **slipped capital femoral epiphysis (SCFE)**. 2. **Why Other Options are Incorrect:** * **Knee:** Radiological assessment of the knee focuses on lines like the *Blumensaat’s line* (intercondylar notch) or the *Insall-Salvati ratio* (patellar height). * **Shoulder:** Key lines include the *Moloney’s line* (scapular arc), used to detect dislocations. * **Elbow:** The primary landmarks here are the *Anterior Humeral Line* and the *Radiocapitellar Line*, used to diagnose supracondylar fractures and radial head dislocations. **High-Yield Clinical Pearls for NEET-PG:** * **DDH:** Shenton’s line is broken (superiorly displaced femur) and is often used alongside *Hilgenreiner* and *Perkin* lines. * **Positioning:** A broken Shenton’s line can occasionally be a false positive if the hip is significantly externally rotated; however, in the context of trauma, it is highly suggestive of a fracture. * **Ward’s Triangle:** Another high-yield hip landmark referring to an area of low bone density in the femoral neck, susceptible to osteoporosis.
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