LE 5 - Neuro

Question 1

Which of the following intracranial tumors characteristically involve the gray-white matter junction?

A. Cerebellopontine angle schwannoma
B. Metastasis
C. Pilocytic astrocytoma of the cerebellum
D. Trigeminal schwannoma

Answer 1

B. Metastasis
Rationale: Metastatic tumors commonly lodge in the gray-white matter junction due to the abrupt change in vascular caliber, which causes embolized tumor cells to become trapped.

Question 2

Which of the following is true regarding sporadic Creutzfeldt-Jakob disease?

A. May occur following vaccination
B. Multiple ring-enhancing lesions in the frontal lobes
C. Optic neuritis is common
D. Rapidly progressive dementia, ataxia, myoclonus, and death

Answer 2

D. Rapidly progressive dementia, ataxia, myoclonus, and death
Rationale: Sporadic Creutzfeldt-Jakob disease (sCJD) is a prion disease characterized by rapidly progressive neurodegeneration, presenting with dementia, ataxia, and myoclonus, ultimately leading to death.

Question 3

What is the imaging modality of choice for diagnosing Diffuse Axonal Injury (DAI)?

A. MRI
B. CT angiography
C. Electroencephalogram (EEG)
D. Contrast-enhanced CT scan

Answer 3

A. MRI
Rationale: MRI, particularly Diffusion-Weighted Imaging (DWI) and Susceptibility-Weighted Imaging (SWI), is the most sensitive modality for detecting DAI, which often presents with small hemorrhages and shearing injuries in the deep white matter.

Question 4

Which of the following is true regarding mucormycosis?

A. Low mortality rate
B. Often involves the parietal lobes
C. Presents clinically as meningitis
D. Usually spreads by direct extension from the sinuses

Answer 4

D. Usually spreads by direct extension from the sinuses
Rationale: Mucormycosis is an aggressive fungal infection that often originates in the sinuses and spreads directly to the brain, leading to infarcts, hemorrhage, and meningoencephalitis.

Question 5

Acute intracranial hemorrhage appears ___ on a non-contrast CT scan.

A. Hypodense
B. Isodense to gray matter
C. Hyperdense
D. Isodense to white matter

Answer 5

C. Hyperdense
Rationale: Fresh (acute) hemorrhage appears hyperdense (bright) on a non-contrast CT scan due to the high protein content of clotted blood.

A. CT Scan
• HYPERDENSE: Indicates acute intracranial hemorrhage (acute bleed).
• HYPODENSE: Indicates acute infarction.
• Advantage: Highly sensitive to acute blood.

B. MRI
• Best for detecting hyperacute infarcts using Diffusion Weighted Imaging (DWI).
• Advantage: Can assess blood vessels without contrast using MR-Angiography (MRA).

Question 6

Reactivation of the JC virus in AIDS results in:

A. AIDS dementia complex
B. Communicating hydrocephalus
C. Multicystic encephalomalacia
D. Progressive multifocal leukoencephalopathy (PML)

Answer 6

D. Progressive multifocal leukoencephalopathy (PML)
Rationale: JC virus reactivation in immunocompromised individuals leads to PML, a demyelinating disease of the CNS characterized by multifocal white matter lesions without mass effect or enhancement.

Question 7

Which of the following is an example of an intra-axial mass?

A. Arachnoid cyst
B. Glioma
C. Meningioma
D. Subarachnoid hemorrhage

Answer 7

B. Glioma
Rationale: Intra-axial masses originate within the brain parenchyma itself, and gliomas are primary brain tumors arising from glial cells.

Question 8

Encephalomalacia may be seen approximately ___ post-infarction.

A. Less than 24 hours
B. 7 to 14 days
C. 30 to 90 days
D. 2 to 5 days

Answer 8

C. 30 to 90 days
Rationale: Encephalomalacia (brain softening) occurs as a late sequela of infarction, typically within 30-90 days, due to liquefactive necrosis and brain tissue loss.

Question 9

Which of the following intracranial tumors arise from the cell nests at the margins of the lateral ventricles?

A. Craniopharyngioma
B. Ependymoma
C. Pituitary adenoma
D. Schwannoma

Answer 9

B. Ependymoma
Rationale: Ependymomas arise from ependymal cells, which line the ventricles, and commonly occur near the lateral ventricle or fourth ventricle.

Question 10

Which imaging modality is the best study to perform when there is clinical suspicion of meningitis?
A. CT scan without contrast
B. PET-CT scan with contrast
C. MRI without contrast
D. MRI with contrast

Answer 10

D. MRI with contrast
Rationale: MRI with contrast is the most sensitive imaging modality for detecting meningitis, showing meningeal enhancement and complications such as abscess or ventriculitis.

Question 11

Ventricular dilatation secondary to intraventricular extension of hemorrhage and subarachnoid hemorrhage is classified as which type of hydrocephalus?
A. Non-communicating
B. Communicating
C. Obstructive
D. Normal-pressure

Answer 11

B. Communicating
Rationale: Communicating hydrocephalus occurs when CSF absorption is impaired due to obstruction at the arachnoid granulations, often secondary to hemorrhage or meningitis.

Question 12

Which anatomical landmark is used to identify the occipital lobe?
A. Calcarine fissure
B. Rolandic fissure
C. Sylvian fissure
D. Interhemispheric fissure

Answer 12

A. Calcarine fissure
Rationale: The calcarine fissure is a crucial landmark for locating the occipital lobe, which primarily contains the primary visual cortex.

Question 13

Which MRI pulse sequences are the most sensitive for detecting early ischemic stroke changes as soon as 30 minutes post-ictus?
A. Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC)
B. Gradient Recall Echo (GRE) and Fluid Attenuated Inversion Recovery (FLAIR)
C. T1-weighted and T2-weighted sequences
D. T2-weighted and Fluid Attenuated Inversion Recovery (FLAIR)

Answer 13

A. Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC)
Rationale: DWI detects cytotoxic edema within minutes of ischemia, while ADC maps confirm restricted diffusion, making them the most sensitive sequences for acute stroke.

Question 14

Which of the following statements is true regarding CNS aspergillosis?
A. Involves the CNS in only 10% of cases
B. Has a low mortality rate
C. Spreads hematogenously or by direct extension
D. Usually forms granulomas

Answer 14

C. Spreads hematogenously or by direct extension
Rationale: Aspergillosis can enter the CNS via hematogenous dissemination from the lungs or by direct invasion from the sinuses, often causing abscesses and infarcts.

Question 15

Which intracranial tumor characteristically parasitizes the vasculature of adjacent brain tissue, as seen on angiography?
A. Craniopharyngioma
B. Oligodendroglioma
C. Pituitary macroadenoma
D. Meningioma

Answer 15

D. Meningioma
Rationale: Meningiomas derive their blood supply from the dura mater but often recruit adjacent brain vasculature, leading to characteristic angiographic findings.

Question 16

Which vessel is most commonly injured in an epidural hematoma?
A. Middle meningeal vein
B. Middle cerebral artery
C. Superficial dural veins
D. Middle meningeal artery

Answer 16

D. Middle meningeal artery
Rationale: The middle meningeal artery is frequently lacerated in skull fractures, leading to an epidural hematoma with a classic biconvex (lentiform) shape on CT.

Question 17

Inferior cerebellar displacement and fullness of the foramen magnum are indicative of which type of herniation?
A. Uncal herniation
B. Transtentorial herniation
C. Subfalcine herniation
D. Tonsillar herniation

Answer 17

D. Tonsillar herniation
Rationale: Tonsillar herniation occurs when the cerebellar tonsils are pushed downward through the foramen magnum, potentially compressing the brainstem and leading to respiratory arrest.

Question 18

Which of the following intracranial tumors predominantly exhibits a cystic appearance in pathological and radiographic imaging?
A. Glioblastoma multiforme
B. Low-grade astrocytoma
C. Ependymoma
D. Metastasis

Answer 18

B. Low-grade astrocytoma
Rationale: Low-grade astrocytomas, especially pilocytic astrocytomas, frequently present with cystic components, often with an enhancing mural nodule.

Question 19

Which imaging modality is the best study for evaluating suspected intracranial hemorrhage?
A. CT scan without contrast
B. CT scan with contrast
C. MRI without contrast
D. MRI with contrast

Answer 19

A. CT scan without contrast
Rationale: A non-contrast CT scan is the gold standard for detecting acute hemorrhage due to its ability to quickly identify hyperdense (bright) blood.

Question 20

What is the most common opportunistic CNS infection in AIDS?
A. Aspergillosis
B. Cytomegalovirus
C. Toxoplasmosis
D. Tuberculoma

Answer 20

C. Toxoplasmosis
Rationale: Cerebral toxoplasmosis is the most frequent opportunistic CNS infection in AIDS patients, typically presenting with ring-enhancing lesions on imaging.

Question 21

What is the primary role of a preliminary non-contrast CT scan in cases of acute stroke?
A. To assess prognosis
B. To diagnose hyperacute infarcts
C. To evaluate for intracranial herniation
D. To exclude hemorrhage

Answer 21

D. To exclude hemorrhage
Rationale: The primary reason for an initial non-contrast CT in stroke is to rule out hemorrhagic stroke, which requires different management from ischemic stroke.

Question 22

Which of the following is true regarding toxoplasmosis?
A. Acute encephalitis ensues when the parasite dies
B. Frequently affects the lungs and liver
C. May show marginal nodules
D. Causes brain atrophy, dilated ventricles, and calcifications

Answer 22

D. Causes brain atrophy, dilated ventricles, and calcifications
Rationale: Congenital toxoplasmosis can result in brain atrophy, ventriculomegaly, and characteristic periventricular calcifications seen on imaging.

Question 23

Displacement of the cingulate gyrus under the margin of the interhemispheric fissure is called:
A. Central herniation
B. Subfalcine herniation
C. Tentorial herniation
D. Uncal herniation

Answer 23

B. Subfalcine herniation
Rationale: Subfalcine herniation occurs when the cingulate gyrus is displaced under the falx cerebri, often due to mass effect from a unilateral lesion.

Question 24

Despite involvement of a significant volume of the brain, true multicentric tumors are rare in which of the following intracranial tumors?
A. Craniopharyngioma
B. Glioblastoma multiforme
C. Meningioma
D. Metastasis

Answer 24

B. Glioblastoma multiforme
Rationale: Glioblastoma multiforme (GBM) is highly invasive and can spread across the corpus callosum, but true multicentric tumors (separate tumors with independent origins) are rare.

Question 25

What is the most common site of aneurysm in the circle of Willis? A. Anterior communicating artery B. Middle cerebral artery bifurcation C. Tip of the basilar artery D. Anterior cerebral artery

Answer 25

A. Anterior communicating artery Rationale: The anterior communicating artery is the most common site of intracranial aneurysms due to hemodynamic stress at the bifurcation.

Question 26

Which of the following intracranial tumors produces erosion of the floor of the sella turcica? A. Craniopharyngioma B. Pilocytic astrocytoma C. Pituitary adenoma D. Acoustic schwannoma

Answer 26

C. Pituitary adenoma Rationale: Pituitary adenomas, particularly large macroadenomas, can cause sella turcica expansion and erosion due to their slow-growing nature.

Question 27

A patient presenting with amenorrhea and galactorrhea will most likely demonstrate which tumor on contrast MRI of the brain? A. Pituitary microadenoma B. Ependymoma C. Low-grade astrocytoma D. Oligodendroglioma

Answer 27

A. Pituitary microadenoma Rationale: Prolactin-secreting pituitary microadenomas cause hyperprolactinemia, leading to amenorrhea and galactorrhea.

Question 28

One of the basic principles in the interpretation of central nervous system imaging is: A. CSF spaces, particularly the basal cisterns, create a mass-like effect on the brain parenchyma B. Loss of sulci should be presumed to be due to a mass lesion C. A mass lesion is presumed whenever there is a shift in midline structures D. The sulci and gyri pattern of the cerebrum depends on the patient's age

Answer 28

C. A mass lesion is presumed whenever there is a shift in midline structures Rationale: Any deviation of midline structures suggests the presence of a mass effect, necessitating further investigation.

Question 29

Which of the following is an endemic fungal infection? A. Aspergillosis B. Coccidioidomycosis C. Cryptococcosis D. Mucormycosis

Answer 29

B. Coccidioidomycosis Rationale: Coccidioidomycosis is an endemic fungal infection found in the southwestern United States and parts of Central and South America.

Question 30

A large enhancing mass lesion obliterating the cerebellopontine angle and displacing the fourth ventricle is most likely due to: A. Acoustic schwannoma B. Astrocytoma of the brainstem C. Fibrillary astrocytoma D. Metastasis to the cerebellum

Answer 30

A. Acoustic schwannoma Rationale: Acoustic schwannomas (vestibular schwannomas) typically arise in the cerebellopontine angle and can compress the fourth ventricle.

Question 31

Thick, irregular contrast enhancement at the edges of a lesion in the cerebral hemisphere on contrast-enhanced MRI suggests: A. Central necrosis B. Multiloculation C. Vasogenic edema D. Presence of a capsule

Answer 31

A. Central necrosis Rationale: Thick, irregular contrast enhancement at the edges of a lesion on contrast-enhanced MRI suggests central necrosis, which is commonly seen in late cerebritis, high-grade gliomas (e.g., glioblastoma multiforme), and abscesses. This occurs due to tissue breakdown and reduced vascularity in the center of the lesion, leading to necrosis, while the periphery remains viable and enhances with contrast.

Question 32

What is the imaging modality of choice for gunshot wounds? A. Non-contrast cranial CT scan B. MRI with brain attack protocol C. CT angiography of the neck and intracranial vessels D. Skull X-ray

Answer 32

A. Non-contrast cranial CT scan Rationale: Non-contrast CT is the fastest and most effective imaging modality for assessing bullet trajectory, fractures, and hemorrhage.

Question 33

Acute territorial infarct appears ____ on a non-contrast CT scan. A. Hyperdense B. Isodense to white matter C. Isodense to gray matter D. Hypodense

Answer 33

D. Hypodense Rationale: Acute infarcts appear hypodense (dark) on non-contrast CT due to cytotoxic edema and loss of normal tissue attenuation.

Question 34

Which imaging modality is the best study to perform for a patient presenting with a sudden, severe headache? A. CT scan without contrast B. CT scan with contrast C. MRI without contrast D. MRI with contrast

Answer 34

A. CT scan without contrast Rationale: A non-contrast CT is the gold standard for evaluating sudden severe headaches, especially for detecting subarachnoid hemorrhage.

Question 35

Which of the following is true regarding CNS cryptococcosis? A. Most frequently reported CNS fungal infection B. Has a high 75% mortality rate C. Commonly presents with multiple abscesses D. Usually spreads by direct extension from the sinuses

Answer 35

A. Most frequently reported CNS fungal infection Rationale: Cryptococcus is the most common CNS fungal infection, particularly in immunocompromised patients, such as those with AIDS. It often presents as chronic meningitis.

Question 36

The most common pyogenic etiologic agent in cerebritis is: A. Actinomyces B. Listeria C. Pneumococcus D. Staphylococcus

Answer 36

D. Staphylococcus Rationale: Staphylococcus aureus is the most common cause of pyogenic cerebritis, often following trauma, surgery, or hematogenous spread from a distant infection.

Question 37

What is the next best imaging modality to evaluate for subarachnoid hemorrhage in a young, non-hypertensive adult with a sudden onset of severe headache? A. Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) map in a non-contrast MRI B. Conventional angiography of the great neck vessels C. CT angiography D. Transcranial ultrasound

Answer 37

C. CT angiography Rationale: CT angiography is the next step if a non-contrast CT is negative, as it can detect aneurysms and vascular abnormalities that may have caused the hemorrhage.

Question 38

Effacement of the ambient cistern and contralateral hydrocephalus are seen in: A. Central herniation B. Subfalcine herniation C. Tentorial herniation D. Uncal herniation

Answer 38

D. Uncal herniation Rationale: Uncal herniation results in compression of the ambient cistern, midbrain displacement, and may cause obstructive hydrocephalus due to compression of the cerebral aqueduct.

Question 39

Which of the following intracranial tumors characteristically spreads through the corpus callosum? A. Astrocytoma of the brainstem B. Glioblastoma multiforme C. Meningioma D. Oligodendroglioma

Answer 39

B. Glioblastoma multiforme Rationale: Glioblastoma multiforme (GBM) is known for its aggressive nature and characteristic butterfly spread through the corpus callosum.

Question 40

Which imaging modality is the best study to perform for a patient presenting with memory loss? A. CT scan without contrast B. CT scan with contrast C. MRI without contrast D. MRI with contrast

Answer 40

C. MRI without contrast **Explanation:** - **Memory loss** is often associated with **neurodegenerative disorders** (e.g., Alzheimer's disease, vascular dementia) or **chronic structural brain changes**. - **MRI without contrast** is the **best study** for assessing **brain atrophy, white matter changes, and vascular pathology**. - **Contrast is not necessary** unless there is suspicion of an underlying tumor, infection, or inflammation. **Why not the other options?** - **A. CT scan without contrast** → Can detect gross atrophy but is **not detailed enough** for early neurodegenerative changes. - **B. CT scan with contrast** → Used mainly for detecting tumors or infections, **not ideal for dementia evaluation**. - **D. MRI with contrast** → Reserved for suspected malignancy, inflammation, or vascular pathology with contrast enhancement.

Question 41

What is the reason for recommending weekly imaging in cases of cerebritis? A. To assess complications B. To check for epileptogenic focus C. To determine etiology D. For diagnosis

Answer 41

A. To assess complications Rationale: Weekly imaging helps monitor the progression of cerebritis, check for abscess formation, and detect complications such as ventriculitis or infarction.

Question 42

Which of the following intracranial tumors arise from remnants of Rathke’s pouch? A. Craniopharyngioma B. Ependymoma C. Pilocytic astrocytoma D. Schwannoma

Answer 42

A. Craniopharyngioma Rationale: Craniopharyngiomas are congenital tumors that arise from Rathke’s pouch remnants and are commonly found in the suprasellar region.

Question 43

Which of the following is true regarding cysticercosis? A. Cysts are usually solitary, unilocular, and large B. Caused by larvae of the dog tapeworm C. Clinically presents with seizures D. Usually affects the base of the brain and brainstem

Answer 43

C. Clinically presents with seizures Rationale: Neurocysticercosis, caused by the larvae of Taenia solium, commonly presents with seizures due to the inflammatory response around dying cysts.

Question 44

Early signs of ischemic stroke on a CT scan include: A. Significant cytotoxic edema B. Fairly defined hypodensity involving a vascular territory C. Hyperdense MCA sign D. Vasogenic edema

Answer 44

C. Hyperdense MCA sign Rationale: The hyperdense MCA sign represents an early indication of ischemic stroke, seen as increased attenuation in the occluded middle cerebral artery.

Question 45

A metastatic tumor to the ovary that usually originates in the gastrointestinal tract is called: A. Brenner tumor B. Mucinous cystadenoma C. Papillary tumor D. Krukenberg tumor

Answer 45

D. Krukenberg tumor Rationale: A Krukenberg tumor is a metastatic ovarian tumor, most commonly originating from gastric adenocarcinoma and characterized by mucin-secreting signet ring cells.

Question 46

Which of the following is an example of an extra-axial mass? A. Astrocytoma of the cerebellum B. Glioma C. Ependymoma D. Meningioma

Answer 46

D. Meningioma Rationale: Meningiomas arise from the meninges and are classified as extra-axial tumors because they are located outside the brain parenchyma.

Question 47

Hypertensive hemorrhages most commonly occur in which of the following sites? A. Putamen, cerebellum, thalamus, and pons B. Gray-white matter interface, corpus callosum, and cerebellum C. Tectum, tegmentum, hypothalamus, and pineal gland D. Sella, basal cistern, thalamus, and hypothalamus

Answer 47

A. Putamen, cerebellum, thalamus, and pons Rationale: Hypertensive hemorrhages typically affect deep brain structures such as the putamen, cerebellum, thalamus, and pons due to the rupture of small perforating arteries.

Question 48

Which of the following is true regarding acute disseminated encephalomyelitis (ADEM)? A. Occurs after a viral infection B. Both temporal lobes show low density on CT C. Cerebral angiitis causes contralateral hemiparesis D. Increased contrast enhancement of the facial nerve

Answer 48

A. Occurs after a viral infection Rationale: ADEM is an autoimmune demyelinating disease that typically follows a viral infection or vaccination. It presents with multifocal white matter lesions on MRI.

Question 49

The most common intracranial tumor in AIDS patients is: A. Anaplastic astrocytoma B. Glioblastoma multiforme C. Lymphoma D. Tuberculoma

Answer 49

C. Lymphoma Rationale: Primary CNS lymphoma, often associated with EBV infection, is the most common intracranial tumor in AIDS patients. It typically appears as a ring-enhancing lesion on imaging.

Question 50

The most common source of pyogenic cerebritis by direct extension is: A. Congenital heart disease B. Endocarditis C. Pneumonia D. Sinusitis

Answer 50

D. Sinusitis Rationale: Pyogenic cerebritis can occur from direct extension of infections such as sinusitis, otomastoiditis, or dental infections, particularly affecting the frontal and temporal lobes.

Question 51

On an axial CT scan, the quadrigeminal plate cistern appears as a: A. Jewish star B. Pentagon C. Sellar mass D. Smile

Answer 51

D. Smile Rationale: The quadrigeminal plate cistern has a characteristic "smile" appearance on axial CT, and any asymmetry or effacement suggests a mass or pathology in the posterior fossa.

Question 52

Which of the following is true regarding CNS tuberculomas in adults? A. Common in developed countries B. Occurs by direct extension from sinusitis C. Affects individuals at extremes of age D. Mostly located in the cerebellar or infratentorial region

Answer 52

C. Affects individuals at extremes of age Rationale: CNS tuberculomas commonly affect the very young and elderly in endemic regions due to weaker immune responses, often spreading hematogenously from pulmonary TB.

Question 53

Which of the following is NOT part of the circle of Willis? A. Anterior cerebral arteries B. Posterior cerebral arteries C. Internal carotid arteries D. Middle cerebral arteries

Answer 53

D. Middle cerebral arteries Rationale: The middle cerebral arteries are major branches of the internal carotid arteries but are not part of the circle of Willis. The circle consists of the anterior cerebral, anterior communicating, internal carotid, posterior cerebral, and posterior communicating arteries.

Question 54

The most common manifestation of HIV infection in the brain is: A. Calcifications B. Demyelination sparing the centrum semiovale C. Diffuse atrophy D. Multiple rim-enhancing abscesses

Answer 54

C. Diffuse atrophy Rationale: HIV encephalopathy leads to progressive diffuse cerebral atrophy, seen on imaging as ventricular enlargement and cortical thinning, with gliosis and neuronal loss.

Question 55

What is the primary arterial supply of infarcted areas in the brain? A. Internal carotid arteries B. Vertebrobasilar system C. Anterior circulation D. Posterior communicating arteries

Answer 55

C. Vertebrobasilar system Rationale: The CT images show infarction in the posterior circulation territory, particularly affecting the posterior cerebral artery (PCA) territory, which is supplied by the vertebrobasilar system. The infarcts involve the occipital lobes and possibly the thalamus, areas commonly affected by posterior circulation strokes. The vertebrobasilar system consists of the vertebral arteries, basilar artery, and their branches, which supply the brainstem, cerebellum, occipital lobes, and parts of the thalamus.

Question 56

Identify the type of hemorrhage depicted in this non-contrast axial CT scan of a vehicular accident patient. A. Intraparenchymal hematoma B. Subarachnoid hemorrhage C. Subdural hematoma D. Epidural hematoma

Answer 56

C. Subdural hematoma Rationale: The CT scan shows a crescent-shaped, hyperdense collection along the cerebral convexity, which is characteristic of a subdural hematoma. Subdural hematomas result from tearing of the bridging veins, often due to trauma such as a vehicular accident. They typically spread across the convexity of the brain but do not cross the midline due to the presence of the falx cerebri. Intraparenchymal hematoma would appear as a focal hyperdense area within the brain tissue. Subarachnoid hemorrhage presents as hyperdensity within the sulci and cisterns. Epidural hematoma appears as a biconvex (lentiform) hyperdense collection, usually associated with middle meningeal artery rupture.

Question 57

1. A 30-year-old vehicular accident patient in the ER underwent a plain cranial CT scan, which showed a large biconvex extra-axial hyperdense fluid collection along the right parieto-temporal convexities with fracture of the overlying parietal and temporal bones. What is the diagnosis? A. Contre-coup hematoma B. Epidural hemorrhage C. Subarachnoid hemorrhage D. Subdural hematoma

Answer 57

B. Epidural hemorrhage Rationale: A biconvex (lentiform) hyperdense collection on CT with an associated skull fracture is characteristic of an epidural hematoma, typically caused by middle meningeal artery rupture.

Question 58

2. A 50-year-old female was brought from another hospital due to abrupt left-sided weakness. Relatives reported that the preliminary CT scan was negative for bleeding. What is the next best step to evaluate for stroke? A. Conventional angiogram B. Repeat plain cranial CT scan C. Cranial MRI with MR angiography D. Contrast-enhanced CT scan with angiography

Answer 58

C. Cranial MRI with MR angiography Rationale: If an initial CT scan is negative for bleeding, MRI with MRA is the next best step to evaluate for ischemic stroke and assess vascular occlusions.

Question 59

3. A 55-year-old woman was rushed to the ER due to sudden loss of consciousness. Preliminary CT showed acute hemorrhage. Given her history of uncontrolled hypertension, what is the most common location of the hematoma? A. Cerebellum B. Pons C. Putamen D. Thalamus

Answer 59

C. Putamen Rationale: Hypertensive hemorrhages most commonly occur in the putamen, followed by the thalamus, pons, and cerebellum due to rupture of small perforating arteries.

Question 60

4. A STAT CT scan of an elderly patient with rapid deterioration of right-sided weakness demonstrated a relatively normal brain parenchyma. No gross hemorrhagic foci were detected. With a high clinical suspicion of acute infarct, what is the best imaging modality for further evaluation? A. CT angiography with reconstruction B. CT scan with contrast C. MRI with emphasis on Diffusion-Weighted Imaging (DWI) D. MRI with emphasis on Gradient Recall Echo (GRE)

Answer 60

C. MRI with emphasis on Diffusion-Weighted Imaging (DWI) Rationale: DWI is the most sensitive imaging modality for acute ischemic stroke, detecting infarcts within minutes.

Question 61

5. What is the expected finding for the patient in the previous question? A. Aneurysm in the Circle of Willis B. Enhancing mass in the left cerebral hemisphere C. "Light bulb" bright area of restricted diffusion on the left parietal lobe D. Susceptibility effect / "blooming" artifact on the right cerebral hemisphere

Answer 61

C. "Light bulb" bright area of restricted diffusion on the left parietal lobe Rationale: Acute ischemic strokes show restricted diffusion as hyperintense (bright) areas on DWI due to cytotoxic edema.

Question 62

6. A 60-year-old male diagnosed with cerebrovascular disease underwent a CT scan showing fairly defined hypodense areas in the left parieto-occipital region with gyriform enhancement. What is the estimated age of the infarct based on this imaging feature? A. Acute B. Chronic C. Hyperacute D. Subacute

Answer 62

D. Subacute Rationale: Gyriform enhancement appears in the subacute phase of infarction (1-3 weeks), indicating blood-brain barrier disruption and reperfusion.

Question 63

7. A 40-year-old hypertensive male presented to the ER with severe headache and right-sided body weakness. A non-contrast CT scan showed intraparenchymal hemorrhage in the left basal ganglia with a contralateral shift of midline structures and displacement of the cingulate gyrus. What type of herniation does this patient have? A. Ascending transtentorial herniation B. Descending transtentorial herniation C. Subfalcine herniation D. Uncal herniation

Answer 63

C. Subfalcine herniation Rationale: Displacement of the cingulate gyrus across the midline under the falx cerebri indicates subfalcine herniation, the most common type of brain herniation.

Question 64

8. Acute intracranial hemorrhage appears as ____ on a non-contrast CT scan. A. Hyperdense B. Hypodense C. Isodense to white matter D. Isodense to gray matter

Answer 64

A. Hyperdense Rationale: Acute intracranial hemorrhage appears hyperdense (bright) on non-contrast CT due to high attenuation of fresh blood.

Question 65

9. Acute territorial infarction appears as ____ on a non-contrast CT scan. A. Hyperdense B. Hypodense C. Isodense to white matter D. Isodense to gray matter

Answer 65

B. Hypodense Rationale: Acute infarction appears hypodense (dark) on non-contrast CT due to cytotoxic edema and loss of gray-white differentiation.

Question 66

10. CT angiography is best performed in which of the following scenarios? A. Dementia evaluation B. Evaluation after acute trauma C. Seizure assessment D. Young adult non-hypertensive patients with suspected vascular pathology

Answer 66

D. Young adult non-hypertensive patients with suspected vascular pathology Rationale: CT angiography is best used in young patients with suspected vascular pathologies such as arteriovenous malformations, dissections, or aneurysms.

Question 67

11. Vasogenic edema is most commonly seen in: A. Hypoxic ischemia B. Metastasis C. Stroke D. Viral cerebritis

Answer 67

B. Metastasis Rationale: Vasogenic edema is commonly associated with metastatic tumors, which disrupt the blood-brain barrier, leading to extracellular fluid accumulation.

Question 68

12. Cytotoxic edema is most commonly seen in: A. Cerebral infarction B. Gliomas C. Microabscesses D. Metastasis

Answer 68

A. Cerebral infarction Rationale: Cytotoxic edema occurs in ischemic stroke due to failure of ATP-dependent ion pumps, resulting in intracellular water accumulation.

Question 69

13. A subdural hematoma manifests as: A. A homogeneous crescentic hyperdense extra-axial fluid collection on CT B. Hydrocephalus and intraventricular bleed C. A hyperdense biconvex extra-axial mass on non-enhanced CT in the acute phase D. A mass that may cross dural attachments but not suture lines

Answer 69

A. A homogeneous crescentic hyperdense extra-axial fluid collection on CT Rationale: Subdural hematomas appear as crescent-shaped hyperdense collections along the convexities, often due to tearing of bridging veins.

Question 70

14. Chronic infarction typically appears as: A. Diffusion restriction with correlating ADC map B. Gyral enhancement and hemorrhagic transformation C. "Light bulb" sign on the DWI sequence D. Volume loss with gliosis along affected margins

Answer 70

D. Volume loss with gliosis along affected margins Rationale: Chronic infarcts lead to parenchymal loss, gliosis, and ventricular enlargement due to tissue necrosis and resorption.

Question 71

15. Injury to the middle meningeal artery most commonly results in: A. Cerebral contusion B. Diffuse axonal injury C. Epidural hematoma D. Subdural hemorrhage

Answer 71

C. Epidural hematoma Rationale: Epidural hematomas result from middle meningeal artery rupture, often due to temporal bone fractures, forming a biconvex hyperdense collection.

Question 72

16. Which of the following vessels is NOT a part of the Circle of Willis? A. Anterior cerebral artery B. Middle cerebral artery C. Posterior cerebral artery D. Internal carotid artery

Answer 72

B. Middle cerebral artery Rationale: The middle cerebral artery (MCA) is not part of the Circle of Willis; it is a major branch of the internal carotid artery.

Question 73

17. An early sign of ischemic stroke on a CT scan includes: A. Cytotoxic edema B. Vasogenic edema C. Hyperdense MCA sign D. Subfalcine herniation

Answer 73

C. Hyperdense MCA sign Rationale: The hyperdense MCA sign is an early indicator of MCA occlusion, appearing as an abnormally bright artery due to clot formation.

Question 74

18. Which imaging modality is the choice for evaluating gunshot wounds? A. Skull X-ray B. Non-contrast cranial CT scan C. Contrast-enhanced cranial CT scan with angiography D. Plain cranial MRI with angiography

Answer 74

B. Non-contrast cranial CT scan Rationale: Non-contrast CT is the preferred initial imaging modality for gunshot wounds, as it quickly detects fractures, hemorrhage, and bullet trajectory.

Question 75

19. Inferior cerebellar displacement and fullness of the foramen magnum are indicative of: A. Subfalcine herniation B. Tonsillar herniation C. Uncal herniation D. Transtentorial herniation

Answer 75

B. Tonsillar herniation Rationale: Tonsillar herniation occurs when the cerebellar tonsils herniate through the foramen magnum, compressing the brainstem and causing respiratory failure.

Question 76

20. What is the most common site of aneurysm in the Circle of Willis? A. Anterior communicating artery B. Posterior cerebral artery C. Middle cerebral artery bifurcation/trifurcation D. Tip of the basilar artery

Answer 76

A. Anterior communicating artery Rationale: The anterior communicating artery is the most common site of intracranial aneurysms, due to high hemodynamic stress at this bifurcation.

Question 77

21. Ventricular dilatation secondary to intraventricular extension of hemorrhage and subarachnoid hemorrhage is classified as which type of hydrocephalus? A. Non-communicating B. Communicating C. Obstructive D. Normal pressure

Answer 77

B. Communicating Hydrocephalus

Question 78

22. Encephalomalacia typically becomes visible on imaging studies at approximately ____ post-infarction. A. Less than 24 hours B. 2-7 days C. 7-14 days D. 30-90 days

Answer 78

D. 30-90 days Rationale: Encephalomalacia (brain softening due to infarction) is typically visible 30-90 days post-infarction as hypodense areas with volume loss and gliosis on imaging.

Question 79

23. Which imaging modality is the best choice for evaluating CNS infections? A. X-ray B. CT scan C. MRI D. Ultrasound

Answer 79

C. MRI Rationale: MRI is the best imaging modality for evaluating CNS infections, as it provides superior soft tissue contrast and detects meningeal inflammation, abscesses, and encephalitis.

Question 80

24. Which lobe is most commonly affected by sinus disease? A. Parietal lobe B. Frontal lobe C. Temporal lobe D. Occipital lobe

Answer 80

B. Frontal lobe Rationale: Frontal sinus infections can extend into the frontal lobe, causing cerebritis or abscess formation, especially in untreated sinusitis.

Question 81

25. Which lobe is most commonly affected by otomastoiditis? A. Parietal lobe B. Frontal lobe C. Occipital lobe D. Temporal lobe

Answer 81

D. Temporal lobe Rationale: Otomastoiditis can spread to the temporal lobe via direct extension or venous drainage pathways, leading to temporal lobe abscesses.

Question 82

26. In which stage of brain abscess may a CT scan appear normal or show an area of low density? A. Late capsule B. Early capsule C. Late cerebritis D. Early cerebritis

Answer 82

D. Early cerebritis Rationale: In the early cerebritis stage, CT scans may be normal or show a low-density area due to initial infection and inflammation.

Question 83

27. Which stage of brain abscess is characterized by thick irregular contrast enhancement at the edges of the lesion? A. Late capsule B. Early capsule C. Late cerebritis D. Early cerebritis

Answer 83

C. Late cerebritis Rationale: Late cerebritis is characterized by thick, irregular contrast enhancement at the lesion edges, indicating necrosis and inflammation.

Question 84

28. In which stage of brain abscess does CT and MRI typically show a well-defined rim of enhancement? A. Late capsule B. Early capsule C. Late cerebritis D. Early cerebritis

Answer 84

B. Early capsule Rationale: Early capsule formation occurs when the immune response walls off the infection, and CT/MRI show a well-defined rim of enhancemen

Question 85

29. Which stage of brain abscess is characterized by a thin and well-defined rim of enhancement? A. Late capsule B. Early capsule C. Late cerebritis D. Early cerebritis

Answer 85

A. Late capsule Rationale: In the late capsule stage, the rim of enhancement becomes thinner and better defined, indicating a mature abscess wall with reduced inflammation.

Question 86

30. What is the imaging appearance of a tuberculoma? A. Target appearance B. Wheel-spoke appearance C. Onion skin appearance D. Popcorn cluster appearance

Answer 86

A. Target appearance Rationale: Tuberculomas can show a "target appearance" on imaging, characterized by a central area of necrosis, surrounded by an enhancing rim.

Question 87

31. What is the typical imaging appearance of most fungal granulomas? A. Large mass-like density B. Wheel-spoke appearance C. Large nodular density D. Small with solid or thick rim enhancement

Answer 87

D. Small with solid or thick rim enhancement Rationale: Most fungal granulomas appear as small lesions with solid or thick rim enhancement on imaging, reflecting chronic inflammation and necrosis.

Question 88

32. Which is the most frequently reported CNS fungal infection? A. Mucormycosis B. Cryptococcosis C. Candidiasis D. Histoplasmosis

Answer 88

B. Cryptococcosis Rationale: Cryptococcus neoformans is the most frequently reported CNS fungal infection, particularly in immunocompromised patients (e.g., AIDS), often presenting with gelatinous pseudocysts and basal meningeal enhancement.

Question 89

33. In cysticercosis, the small marginal nodule within the cyst represents what structure of the parasite? A. Tail B. Body C. Scolex D. Neck

Answer 89

C. Scolex Rationale: In cysticercosis, the scolex is the small nodular structure within the cyst, representing the head of the parasite, and it enhances with contrast.

Question 90

34. What is the characteristic imaging finding of echinococcosis? A. Multiple cysts B. Large solitary unilocular cyst C. Multiple nodules D. Mass-like lesion

Answer 90

B. Large solitary unilocular cyst Rationale: Echinococcosis (hydatid disease) is characterized by a large, unilocular cyst with a well-defined wall, typically affecting the liver and brain.

Question 91

35. Which viral infection is associated with CT findings of multiple periventricular calcifications? A. Congenital cytomegalovirus B. Herpes simplex encephalitis C. Varicella-zoster virus D. Rubella

Answer 91

A. Congenital cytomegalovirus Rationale: Congenital CMV infection classically causes multiple periventricular calcifications, leading to neurodevelopmental abnormalities.

Question 92

36. Which viral infection has a predilection for the temporal lobe? A. Congenital cytomegalovirus B. Herpes simplex encephalitis C. Varicella-zoster virus D. Rubella

Answer 92

B. Herpes simplex encephalitis Rationale: Herpes simplex virus (HSV-1) preferentially affects the temporal lobes, causing necrotizing encephalitis with edema and hemorrhage on imaging.

Question 93

37. What is the typical imaging finding of tuberculous meningitis? A. Marked contrast enhancement in the cerebellum B. Marked contrast enhancement along the brainstem C. Marked contrast enhancement near the base of the brain and basal cisterns D. Marked contrast enhancement in the cortical regions

Answer 93

C. Marked contrast enhancement near the base of the brain and basal cisterns Rationale: Tuberculous meningitis typically presents with enhancement of the basal meninges and cisterns, along with hydrocephalus and infarcts.

Question 94

38. One of the basic principles in the interpretation of CNS imaging is: A. CSF spaces, particularly the basal cisterns, create a mass-like effect on the brain parenchyma B. Loss of sulci should be presumed to be due to a mass lesion C. A mass lesion is presumed whenever there is a shift in midline structures D. The sulci and gyri pattern of the cerebrum depends on the age of the patient

Answer 94

C. A mass lesion is presumed whenever there is a shift in midline structures Rationale: Midline shift on imaging is a key indicator of mass effect, which suggests the presence of a tumor, hematoma, or large infarct.

Question 95

39. What is the characteristic quadrigeminal plate cistern pattern seen on imaging? A. Smile appearance B. Pentagon or Jewish star appearance C. Spoke-wheel appearance D. Butterfly appearance

Answer 95

A. Smile appearance Rationale: The quadrigeminal plate cistern has a characteristic "smile" appearance on axial imaging. This symmetrical pattern is formed by the midbrain and surrounding CSF spaces. Any asymmetry, effacement, or opacification of this cistern can indicate brainstem mass, transtentorial herniation, or subarachnoid hemorrhage. The pentagon or Jewish star appearance is associated with the suprasellar cistern, not the quadrigeminal plate cistern.

Question 96

40. Which imaging modality is the best study to perform when intracranial hemorrhage is suspected? A. CT scan without contrast B. CT scan with contrast C. MRI without contrast D. MRI with contrast

Answer 96

A. CT scan without contrast Rationale: Non-contrast CT is the best initial imaging modality for intracranial hemorrhage, as blood appears hyperdense and can be quickly identified. Contrast may obscure acute bleeding.

Question 97

41. Which imaging modality is the best study to perform for a patient presenting with memory loss? A. CT scan without contrast B. CT scan with contrast C. MRI without contrast D. MRI with contrast

Answer 97

C. MRI without contrast **Explanation:** - **Memory loss** is often associated with **neurodegenerative disorders** (e.g., Alzheimer's disease, vascular dementia) or **chronic structural brain changes**. - **MRI without contrast** is the **best study** for assessing **brain atrophy, white matter changes, and vascular pathology**. - **Contrast is not necessary** unless there is suspicion of an underlying tumor, infection, or inflammation. **Why not the other options?** - **A. CT scan without contrast** → Can detect gross atrophy but is **not detailed enough** for early neurodegenerative changes. - **B. CT scan with contrast** → Used mainly for detecting tumors or infections, **not ideal for dementia evaluation**. - **D. MRI with contrast** → Reserved for suspected malignancy, inflammation, or vascular pathology with contrast enhancement.

Question 98

42. Which imaging modality is the best study to perform for a patient presenting with a sudden severe headache? A. CT scan without contrast B. CT scan with contrast C. MRI without contrast D. MRI with contrast

Answer 98

A. CT scan without contrast Rationale: Non-contrast CT is the first-line imaging for sudden severe headache, especially to rule out subarachnoid hemorrhage.

Question 99

43. Which of the following is an example of an intra-axial mass? A. Arachnoid cyst B. Glioma C. Meningioma D. Subarachnoid hemorrhage

Answer 99

B. Glioma Rationale: Intra-axial masses originate within the brain parenchyma, and gliomas are primary brain tumors arising from glial cells.

Question 100

44. Which of the following is an example of an extra-axial mass? A. Astrocytoma of the cerebellum B. Glioma C. Ependymoma D. Meningioma

Answer 100

D. Meningioma Rationale: Extra-axial masses originate outside the brain parenchyma, and meningiomas arise from the meninges, making them extra-axial.

Question 101

45. Which of the following intracranial tumors characteristically spreads through the corpus callosum? A. Astrocytoma of the brainstem B. Glioblastoma multiforme C. Meningioma D. Oligodendroglioma

Answer 101

B. Glioblastoma multiforme Rationale: Glioblastoma multiforme (GBM) is highly invasive and spreads through the corpus callosum, forming a "butterfly glioma" appearance.

Question 102

46. Despite involving a significant volume of the brain, true multicentric tumors are rare in which of the following intracranial tumors? A. Craniopharyngioma B. Glioblastoma multiforme C. Meningioma D. Metastasis

Answer 102

B. Glioblastoma multiforme Rationale: Although GBM affects large brain volumes, true multicentric tumors (independent origins) are rare in GBM but more common in metastases.

Question 103

47. Cystic elements may predominate in the pathologic and radiographic appearance of which of the following intracranial tumors? A. Glioblastoma multiforme B. Low-grade astrocytoma C. Ependymoma D. Metastasis

Answer 103

B. Low-grade astrocytoma Rationale: Low-grade astrocytomas, especially pilocytic astrocytomas, frequently present with cystic components with an enhancing mural nodule.

Question 104

48. Which of the following intracranial tumors characteristically parasitizes the vasculature of adjacent brain tissue as seen on angiography? A. Craniopharyngioma B. Meningioma C. Oligodendroglioma D. Pituitary macroadenoma

Answer 104

B. Meningioma Rationale: Meningiomas parasitize the vasculature of adjacent brain tissue, showing a characteristic "dural tail sign" on angiography.

Question 105

49. Which of the following intracranial tumors arise from cell nests at the margins of the lateral ventricles? A. Craniopharyngioma B. Ependymoma C. Pituitary macroadenoma D. Schwannoma

Answer 105

B. Ependymoma Rationale: Ependymomas arise from ependymal cells, which line the ventricles, commonly occurring near the lateral or fourth ventricle.

Question 106

50. Which of the following intracranial tumors arise from remnants of Rathke’s pouch? A. Craniopharyngioma B. Ependymoma C. Pilocytic astrocytoma D. Schwannoma

Answer 106

A. Craniopharyngioma Rationale: Craniopharyngiomas originate from Rathke’s pouch remnants, typically found in the suprasellar region.

Question 107

51. Which of the following intracranial tumors characteristically produce erosion of the floor of the sella turcica? A. Craniopharyngioma B. Pilocytic astrocytoma C. Pituitary adenoma D. Acoustic schwannoma

Answer 107

C. Pituitary adenoma Rationale: Pituitary adenomas grow within the sella turcica and can erode its floor, particularly in macroadenomas.

Question 108

52. Which of the following tumors characteristically involve the gray-white matter junction? A. Cerebellopontine angle schwannoma B. Metastasis C. Pilocytic astrocytoma of the cerebellum D. Trigeminal schwannoma

Answer 108

B. Metastasis Rationale: Metastatic tumors frequently lodge in the gray-white matter junction due to embolization and abrupt vascular caliber changes.

Question 109

53. A large enhancing mass lesion obliterating the cerebellopontine angle and displacing the fourth ventricle is most likely due to: A. Acoustic schwannoma B. Astrocytoma of the brainstem C. Fibrillary astrocytoma D. Trigeminal schwannoma

Answer 109

A. Acoustic schwannoma Rationale: Acoustic (vestibular) schwannomas arise in the cerebellopontine angle, often displacing the fourth ventricle.

Question 110

54. A clinical presentation with amenorrhea and galactorrhea is most likely to have which tumor on contrast MRI of the brain? A. Pituitary microadenoma B. Ependymoma C. Low-grade astrocytoma D. Oligodendroglioma

Answer 110

A. Pituitary microadenoma Rationale: Prolactin-secreting pituitary microadenomas cause hyperprolactinemia, leading to amenorrhea and galactorrhea.

Question 111

55. Which anatomic landmark divides the frontal and parietal lobes? A. Rolandic fissure B. Sylvian fissure C. Calcarine fissure D. Interhemispheric fissure

Answer 111

A. Rolandic fissure Rationale: The Rolandic fissure (central sulcus) separates the frontal and parietal lobes, dividing the motor and sensory cortices.