Posterior cerebral artery territory US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Posterior cerebral artery territory. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Posterior cerebral artery territory US Medical PG Question 1: A researcher is studying the brains of patients who recently died from stroke-related causes. One specimen has a large thrombus in an area of the brain that is important in relaying many modalities of sensory information from the periphery to the sensory cortex. Which of the following embryologic structures gave rise to the part of the brain in question?
- A. Metencephalon
- B. Diencephalon (Correct Answer)
- C. Mesencephalon
- D. Telencephalon
- E. Myelencephalon
Posterior cerebral artery territory Explanation: ***Diencephalon***
- The **thalamus**, a key relay center for sensory information to the cerebral cortex, develops from the diencephalon.
- A thrombus in this area would severely impair the transmission of **sensory modalities** from the periphery.
*Metencephalon*
- The metencephalon gives rise to the **pons** and the **cerebellum**.
- These structures are primarily involved in motor control, coordination, and respiratory regulation, not direct sensory relay to the cortex.
*Mesencephalon*
- The mesencephalon develops into the **midbrain**.
- The midbrain contains structures involved in visual and auditory reflexes, and motor control, but not the primary sensory relay described.
*Myelencephalon*
- The myelencephalon gives rise to the **medulla oblongata**.
- The medulla is crucial for vital autonomic functions (e.g., breathing, heart rate) and connects the brain to the spinal cord.
*Telencephalon*
- The telencephalon develops into the **cerebral hemispheres** (cerebral cortex, basal ganglia, hippocampus).
- While it processes sensory information, it is not the primary relay center from the periphery; that role belongs to the thalamus.
Posterior cerebral artery territory US Medical PG Question 2: A 66-year-old man undergoes a coronary artery bypass grafting. Upon regaining consciousness, he reports that he cannot see from either eye and cannot move his arms. Physical examination shows bilaterally equal, reactive pupils. A fundoscopy shows no abnormalities. An MRI of the brain shows wedge-shaped cortical infarcts in both occipital lobes. Which of the following is the most likely cause of this patient's current symptoms?
- A. Lipohyalinosis
- B. Atherothrombosis
- C. Amyloid angiopathy
- D. Cardiac embolism
- E. Systemic hypotension (Correct Answer)
Posterior cerebral artery territory Explanation: ***Systemic hypotension***
- **Watershed infarcts** secondary to systemic hypotension often occur in areas supplied by the most distal branches of major arteries, such as the regions between the middle and posterior cerebral arteries that supply the **occipital lobes**.
- **Bilateral occipital lobe infarcts** would explain the blindness (**cortical blindness**) despite normal pupillary reflexes and fundoscopy, as the primary visual cortex is affected, while the brainstem pathway for pupillary reflexes is spared.
*Lipohyalinosis*
- This is a process affecting **small, penetrating arteries**, leading to **lacunar infarcts** and is typically associated with chronic hypertension and diabetes.
- It would not typically cause large, wedge-shaped cortical infarcts in multiple arterial territories like the occipital lobes.
*Atherothrombosis*
- This involves the formation of a **thrombus on an atherosclerotic plaque**, commonly in large or medium-sized arteries.
- While it can cause strokes, atherothrombosis is less likely to cause widespread, bilateral watershed infarcts, which are more indicative of a global hypoperfusion event.
*Amyloid angiopathy*
- This condition involves **amyloid deposition in small and medium-sized cerebral arteries**, primarily causing lobar hemorrhages or microinfarcts.
- It is not a common cause of acute, large bilateral occipital lobe infarcts, especially in the context of perioperative complications.
*Cardiac embolism*
- A cardiac embolus would typically cause an **infarct in a single arterial territory**, often affecting unilateral cerebral hemisphere or a single lobe.
- It is less likely to cause **bilateral, symmetrical watershed infarcts**, which are characteristic of global hypoperfusion rather than focal embolic occlusion.
Posterior cerebral artery territory US Medical PG Question 3: An 85-year-old woman otherwise healthy presents with left-sided weakness. Her symptoms started 4 hours ago while she was on the phone with her niece. The patient recalls dropping the phone and not being able to pick it up with her left hand. No significant past medical history. No current medications. Physical examination reveals decreased sensation on the left side, worse in the left face and left upper extremity. There is significant weakness of the left upper extremity and weakness and drooping of the lower half of the left face. Ophthalmic examination reveals conjugate eye deviation to the right. A noncontrast CT of the head is unremarkable. The patient is started on aspirin. A repeat contrast CT of the head a few days later reveals an ischemic stroke involving the lateral convexity of right cerebral hemisphere. Which of the following additional findings would most likely be seen in this patient?
- A. Homonymous hemianopsia (Correct Answer)
- B. Horner's syndrome
- C. Amaurosis fugax
- D. Profound lower limb weakness
- E. Prosopagnosia
Posterior cerebral artery territory Explanation: ***Homonymous hemianopsia***
- The patient has an ischemic stroke affecting the **right cerebral hemisphere**, specifically the **lateral convexity**. This suggests involvement of the **middle cerebral artery (MCA)** territory.
- The **optic radiations** carrying visual information from the contralateral visual field pass through the parietal and temporal lobes to the occipital cortex. Damage to these radiations in the right hemisphere would result in a **left homonymous hemianopsia**.
*Horner's syndrome*
- Characterized by **ptosis**, **miosis**, and **anhidrosis** on one side of the face.
- It results from damage to the **sympathetic pathway**, typically in the brainstem, spinal cord above T1, or sympathetic chain, which is not the primary location of this stroke.
*Amaurosis fugax*
- This is a **transient monocular vision loss** ("curtain coming down") due to temporary interruption of blood flow to the retina, usually from an **ipsilateral carotid artery embolus**.
- It is typically a symptom of impending stroke or TIA, not a direct neurological deficit resulting from a cerebral hemisphere stroke.
*Profound lower limb weakness*
- The described stroke involves the **lateral convexity of the right cerebral hemisphere**, fed by the **middle cerebral artery (MCA)**.
- The MCA primarily supplies the upper limb and facial motor/sensory cortices, leading to more pronounced **upper limb and facial weakness** rather than profound lower limb weakness, which is more characteristic of an **anterior cerebral artery (ACA)** stroke.
*Prosopagnosia*
- This is the inability to recognize familiar faces, often due to damage to the **fusiform gyrus** in the temporal and occipital lobes, usually on the **right side**.
- While it can occur with right hemisphere strokes, it is a specific higher-order cognitive deficit and not the *most likely* additional finding in this presentation focused on motor and sensory deficits and conjugate eye deviation.
Posterior cerebral artery territory US Medical PG Question 4: A 78-year-old left-handed woman with hypertension and hyperlipidemia is brought to the emergency room because of sudden-onset right leg weakness and urinary incontinence. Neurologic examination shows decreased sensation over the right thigh. Muscle strength is 2/5 in the right lower extremity and 4/5 in the right upper extremity. Strength and sensation in the face are normal but she has difficulty initiating sentences and she is unable to write her name. The most likely cause of this patient’s condition is an occlusion of which of the following vessels?
- A. Right vertebrobasilar artery
- B. Right middle cerebral artery
- C. Left posterior cerebral artery
- D. Left anterior cerebral artery (Correct Answer)
- E. Right anterior cerebral artery
Posterior cerebral artery territory Explanation: ***Left anterior cerebral artery***
- Stroke in the **left anterior cerebral artery (ACA)** territory typically causes **contralateral leg weakness** (right leg in this case) and **urinary incontinence** due to involvement of the paracentral lobule.
- The patient's difficulty writing her name (agraphia) and initiating sentences (transcortical motor aphasia, which can manifest as difficulty initiating speech) is consistent with damage to the supplemental motor area in the dominant (left) hemisphere, provided by the ACA.
*Right vertebrobasilar artery*
- Occlusion of the vertebrobasilar artery typically presents with a wide range of symptoms including **vertigo**, **ataxia**, **dysarthria**, and bilateral or alternating sensory/motor deficits.
- It would not selectively cause isolated right leg weakness, urinary incontinence, and dominant hemisphere language difficulties without other brainstem or cerebellar signs.
*Right middle cerebral artery*
- A stroke in the **right middle cerebral artery (MCA)** would cause **left-sided deficit**, not right-sided.
- Although it can cause motor and sensory deficits, it typically affects the arm and face more than the leg, and would not cause the specific language deficits of the dominant hemisphere seen here.
*Left posterior cerebral artery*
- Occlusion of the **left posterior cerebral artery (PCA)** typically leads to issues like **contralateral homonymous hemianopia**, visual field defects, and potentially memory impairment or alexia without agraphia if the splenium of the corpus callosum is involved.
- It directly affects posterior brain regions, so it would not cause the anterior cerebral artery specific symptoms such as prominent contralateral leg weakness, urinary incontinence, or the described language difficulties.
*Right anterior cerebral artery*
- Occlusion of the **right anterior cerebral artery (ACA)** would cause **left leg weakness** and **left-sided sensory deficits**, not the right-sided deficits observed in this patient.
- While it could cause urinary incontinence, the combination of right-sided weakness and dominant hemisphere language deficits points against a right ACA occlusion.
Posterior cerebral artery territory US Medical PG Question 5: A 75-year-old woman presents with sudden loss of vision. She says that she was reading when suddenly she was not able to see the print on half of the page. Her symptoms started 4 hours ago and are accompanied by a severe posterior headache. Vital signs reveal the following: blood pressure 119/76 mm Hg, pulse 89/min, SpO2 98% on room air. The patient was unable to recognize her niece when she arrived to see her. A noncontrast CT of the head shows no evidence of hemorrhagic stroke. What is the most likely diagnosis in this patient?
- A. Lacunar stroke
- B. Middle cerebral artery stroke
- C. Vertebrobasilar stroke
- D. Subarachnoid hemorrhage
- E. Posterior cerebral artery stroke (Correct Answer)
Posterior cerebral artery territory Explanation: ***Posterior cerebral artery stroke***
- The sudden severe posterior headache along with **unilateral vision loss** and **prosopagnosia** (inability to recognize familiar faces) are characteristic signs of a **posterior cerebral artery (PCA) stroke**.
- PCA occlusion often affects the **occipital lobe** (vision) and can extend to the **temporal lobe** (facial recognition).
*Lacunar stroke*
- This type of stroke results from the occlusion of small penetrating arteries and typically causes **pure motor** or **pure sensory deficits**, not complex visual or recognition problems.
- While headache can occur, the specific combination of symptoms points away from a lacunar infarct.
*Middle cerebral artery stroke*
- MCA stroke commonly presents with **contralateral hemiparesis**, **aphasia** (if dominant hemisphere), and **hemianopia** but usually not isolated unilateral vision loss or severe posterior headache with prosopagnosia.
- The symptoms are more consistent with involvement of the posterior circulation.
*Vertebrobasilar stroke*
- A vertebrobasilar stroke can cause **visual disturbances**, but it is typically associated with other **brainstem symptoms** like vertigo, ataxia, or cranial nerve deficits, which are not described here.
- The specific presentation of unilateral vision loss and prosopagnosia is less typical for a vertebrobasilar stroke affecting widespread brainstem structures.
*Subarachnoid hemorrhage*
- While a **sudden severe headache (thunderclap headache)** is a hallmark of SAH, it usually presents with meningeal irritation symptoms like **neck stiffness** and often altered mental status, and the visual deficits are usually different (e.g., oculomotor nerve palsy).
- The patient's focal neurological deficits, specifically prosopagnosia and unilateral visual field loss, are more indicative of an ischemic event in a specific vascular territory.
Posterior cerebral artery territory US Medical PG Question 6: A 47-year-old woman comes to the emergency department after coughing up 2 cups of bright red blood. A CT angiogram of the chest shows active extravasation from the right bronchial artery. A coil embolization is planned to stop the bleeding. During this procedure, a catheter is first inserted into the right femoral artery. Which of the following represents the correct subsequent order of the catheter route?
- A. Thoracic aorta, right superior epigastric artery, right bronchial artery
- B. Thoracic aorta, right bronchial artery (Correct Answer)
- C. Thoracic aorta, left ventricle, left atrium, pulmonary artery, right bronchial artery
- D. Thoracic aorta, brachiocephalic trunk, right subclavian artery, right internal thoracic artery, right bronchial artery
- E. Thoracic aorta, right subclavian artery, right internal thoracic artery, right bronchial artery
Posterior cerebral artery territory Explanation: ***Thoracic aorta, right bronchial artery***
- The **femoral artery** leads directly into the **aorta**. From the aorta, the catheter can be navigated to the **thoracic aorta**, where the **bronchial arteries** typically originate.
- The **bronchial arteries** usually arise directly from the **descending thoracic aorta** (most commonly T5-T6 vertebral level) to supply the lung parenchyma and airways.
*Thoracic aorta, right superior epigastric artery, right bronchial artery*
- The **superior epigastric artery** is a terminal branch of the **internal thoracic artery**, supplying the anterior abdominal wall, and is not a direct path to the bronchial arteries.
- Navigating from the superior epigastric artery to the main bronchial artery without passing through intermediary large vessels would be anatomically incorrect and impractical.
*Thoracic aorta, left ventricle, left atrium, pulmonary artery, right bronchial artery*
- This path describes the venous and then pulmonary circulation (right heart, lungs), which is incorrect for reaching the **arterial system** of the bronchial arteries.
- A catheter inserted via the **femoral artery** remains within the arterial system and would not cross into the pulmonary circulation or the left heart chambers in this manner.
*Thoracic aorta, brachiocephalic trunk, right subclavian artery, right internal thoracic artery, right bronchial artery*
- This pathway involves ascending from the **thoracic aorta** to the **brachiocephalic trunk** and subsequently into the **right subclavian** and **internal thoracic arteries**, which is a route primarily to the upper limb and chest wall.
- While the internal thoracic artery can sometimes have small anastomoses, it is not the primary or direct route for embolizing a bronchial artery, which typically originates directly from the descending thoracic aorta.
*Thoracic aorta, right subclavian artery, right internal thoracic artery, right bronchial artery*
- Similar to the previous incorrect option, this route involves navigating through the **subclavian** and **internal thoracic arteries**, which is an indirect and unnecessarily complex path to the bronchial arteries.
- The **bronchial arteries** are direct branches of the **thoracic aorta**, making this a much more convoluted and less likely route for therapeutic embolization.
Posterior cerebral artery territory US Medical PG Question 7: A 65-year-old man presents with facial weakness. He says he noticed that his face appeared twisted when he looked in the bathroom mirror this morning. He is otherwise well and does not have any other complaints. He denies any facial pain or paresthesia. No significant past medical history. The patient is afebrile and vital signs are within normal limits. Neurological examination reveals difficulty shutting the right eye tight and inability to bring up the right corner of his mouth when asked to smile. Remainder of the exam, including the left side of the face, is unremarkable. Which of the following is the most likely diagnosis in this patient?
- A. Idiopathic facial paralysis (Correct Answer)
- B. Right hemisphere stroke
- C. Left middle cerebral artery stroke
- D. Facial nerve schwannoma
- E. Acoustic neuroma
Posterior cerebral artery territory Explanation: ***Idiopathic facial paralysis***
- The sudden onset of **unilateral facial weakness** affecting both the upper and lower face (inability to shut eye and inability to smile on the same side) without other neurological symptoms is characteristic of **Bell's palsy**.
- It is a diagnosis of exclusion, and the absence of other symptoms and normal vital signs support this benign, self-limiting condition.
*Right hemisphere stroke*
- A stroke typically causes **upper motor neuron facial weakness**, primarily affecting the **lower half of the contralateral face**, sparing the forehead.
- Would likely present with other neurological deficits such as **hemiparesis** or sensory changes, which are absent here.
*Left middle cerebral artery stroke*
- Similar to a right hemisphere stroke, a left MCA stroke would typically cause **contralateral facial weakness**, predominantly in the **lower face**.
- Would also likely present with additional symptoms such as **aphasia** (if the dominant hemisphere is affected) or right-sided motor/sensory deficits, which are not described.
*Facial nerve schwannoma*
- This condition tends to cause a **slowly progressive facial weakness**, not the acute onset described.
- Often associated with other symptoms such as **persistent facial pain** or paresthesia, which this patient denies.
*Acoustic neuroma*
- Primarily causes **hearing loss** and **tinnitus**, and later, **vestibular symptoms** like dizziness or imbalance.
- While it can eventually compress the facial nerve causing weakness, the onset would be gradual and accompanied by **auditory symptoms**, which are absent here.
Posterior cerebral artery territory US Medical PG Question 8: A 36-year-old woman, gravida 1, para 1, has back pain and numbness in her lower extremities after an emergency cesarean delivery of a healthy 3856-g (8-lb, 8-oz) newborn male. She had a placental abruption and lost approximately 2000 ml of blood. During the procedure, she received two units of packed red blood cells and intravenous fluids. She has no history of serious illness and takes no medications. She is sexually active with one male partner, and they use condoms inconsistently. She is alert and oriented to person, place, and time. Her temperature is 37.2°C (98.9°F), pulse is 90/min, respirations are 15/min, and blood pressure is 94/58 mm Hg. Examination shows decreased sensation to temperature and pinprick below her waist and 0/5 muscle strength in her lower extremities. She feels the vibrations of a tuning fork placed on both of her great toes. Deep tendon reflexes are absent in the lower extremities and 2+ in the upper extremities. Which of the following is the most likely diagnosis?
- A. Posterior spinal artery syndrome
- B. Brown-Séquard syndrome
- C. Anterior spinal artery syndrome (Correct Answer)
- D. Guillain-Barré Syndrome
- E. Tabes dorsalis
Posterior cerebral artery territory Explanation: ***Anterior spinal artery syndrome***
- This syndrome is characterized by the sudden onset of **bilateral motor paralysis** below the level of the lesion, accompanied by a dissociated sensory loss (**loss of pain and temperature sensation**) while **proprioception and vibratory sensation are preserved**.
- The patient's history of **significant blood loss** and hypotension during delivery makes her susceptible to spinal cord ischemia, particularly in the anterior spinal artery territory, which supplies the anterior two-thirds of the spinal cord.
*Posterior spinal artery syndrome*
- This syndrome primarily affects the **dorsal columns**, leading to a loss of **proprioception and vibratory sensation**, with preservation of motor function and pain/temperature sensation.
- The patient's preserved vibratory sensation and significant motor deficits rule out posterior spinal artery syndrome.
*Brown-Séquard syndrome*
- This syndrome results from **hemitransverse lesion of the spinal cord**, causing **ipsilateral motor paralysis** and loss of proprioception/vibration below the lesion, and **contralateral loss of pain and temperature sensation**.
- The patient's **bilateral motor and sensory deficits** are inconsistent with the unilateral presentation of Brown-Séquard syndrome.
*Guillain-Barré Syndrome*
- GBS typically presents as an **ascending paralysis** with **areflexia**, but sensory loss is usually stocking-glove distribution and often involves proprioception, and it is a **peripheral neuropathy** not a spinal cord infarction.
- The acute, localized nature of the sensory and motor loss below the waist, along with preserved vibratory sensation, differentiates it from the more diffuse presentation of GBS.
*Tabes dorsalis*
- This is a late manifestation of **syphilis** affecting the **dorsal columns** and dorsal roots, characterized by ataxia, lancinating pains, and loss of proprioception and vibration sense.
- The acute onset of symptoms following a hypotensive episode, along with motor paralysis and preserved vibratory sensation, does not fit the chronic, dorsal column pathology of tabes dorsalis.
Posterior cerebral artery territory US Medical PG Question 9: A morbidly obese 43-year-old man presents for elective bariatric surgery after previously failing several non-surgical weight loss plans. After discussing the risks and benefits of several different procedures, a sleeve gastrectomy is performed. During the surgery, the surgeon begins by incising into the right half of the greater curvature of the stomach. Which of the following arteries most likely directly provides the blood supply to this region of the stomach?
- A. Short gastric arteries
- B. Right gastric artery
- C. Right gastroduodenal artery
- D. Right gastroepiploic artery (Correct Answer)
- E. Splenic artery
Posterior cerebral artery territory Explanation: ***Right gastroepiploic artery***
- The **right gastroepiploic artery** (also known as the **right gastroomental artery**) is a branch of the **gastroduodenal artery** that runs along the **greater curvature of the stomach** from right to left.
- This artery is the primary blood supply to the **right portion of the greater curvature**, which corresponds to the region where an incision into the right half of the greater curvature would be made during a sleeve gastrectomy.
- It anastomoses with the left gastroepiploic artery along the greater curvature.
*Short gastric arteries*
- The **short gastric arteries** supply the **fundus** and a small portion of the superior body of the stomach, specifically to the left of the midline.
- They originate from the **splenic artery** and supply the left superior portion of the greater curvature, not the right half described in the question.
*Right gastric artery*
- The **right gastric artery** primarily supplies the **pyloric part of the stomach** and a portion of the **lesser curvature**.
- It arises from the **hepatic artery proper** and is not the main supply to the greater curvature.
*Right gastroduodenal artery*
- The **gastroduodenal artery** supplies the **duodenum** and the **head of the pancreas**.
- This artery is located inferior to the stomach and gives rise to the right gastroepiploic artery but does not directly supply the greater curvature itself.
*Splenic artery*
- The **splenic artery** is a large artery that primarily supplies the **spleen** and gives off branches like the **short gastric arteries** and the **left gastroepiploic artery**.
- While it contributes indirectly via its branches to the left portion of the greater curvature, it does not directly supply the right half of the greater curvature.
Posterior cerebral artery territory US Medical PG Question 10: A 47-year-old woman presents to the emergency department with a fever and a headache. Her symptoms started yesterday and have rapidly progressed. Initially, she was experiencing just a fever and a headache which she was treating with acetaminophen. It rapidly progressed to blurry vision, chills, nausea, and vomiting. The patient has a past medical history of diabetes and hypertension and she is currently taking insulin, metformin, lisinopril, and oral contraceptive pills. Her temperature is 104°F (40.0°C), blood pressure is 157/93 mmHg, pulse is 120/min, respirations are 15/min, and oxygen saturation is 98% on room air. Upon further inspection, the patient also demonstrates exophthalmos in the affected eye. The patient's extraocular movements are notably decreased in the affected eye with reduced vertical and horizontal gaze. The patient also demonstrates decreased sensation near the affected eye in the distribution of V1 and V2. While the patient is in the department waiting for a CT scan, she becomes lethargic and acutely altered. Which of the following is the most likely diagnosis?
- A. Acute closed angle glaucoma
- B. Cavernous sinus thrombosis (Correct Answer)
- C. Brain abscess
- D. Periorbital cellulitis
- E. Intracranial hemorrhage
Posterior cerebral artery territory Explanation: ***Cavernous sinus thrombosis***
- The rapid progression of symptoms, **exophthalmos**, decreased extraocular movements (involving cranial nerves III, IV, and VI that pass through the cavernous sinus), and V1/V2 sensory deficits (trigeminal nerve branches) are classic signs of **cavernous sinus thrombosis**. The patient's acute alteration and lethargy point to CNS involvement.
- The patient's oral contraceptive use is a risk factor for **thrombosis**, and her diabetic and hypertensive status may contribute to her vulnerability to infections, which can lead to cavernous sinus thrombosis.
*Acute closed angle glaucoma*
- Acute closed-angle glaucoma typically presents with sudden, severe eye pain, blurred vision, and halos, often without systemic symptoms like fever or rapid progression to altered mental status.
- While it causes blurry vision, it does not typically cause **exophthalmos**, multiple extraocular muscle palsies, or deficits in V1/V2 sensation.
*Brain abscess*
- A brain abscess can cause fever, headache, and altered mental status, but it less commonly presents with the specific combination of **exophthalmos**, multiple cranial nerve palsies affecting eye movement, and V1/V2 sensory deficits.
- It would typically cause focal neurological deficits related to the specific brain region affected, rather than a constellation of orbital and systemic symptoms like this.
*Periorbital cellulitis*
- Periorbital cellulitis causes eyelid swelling, redness, and pain, and can be associated with fever, but it typically does not cause **exophthalmos**, decreased extraocular movements, or sensory deficits in the V1/V2 distribution as seen in this patient.
- Infection is limited to tissues anterior to the orbital septum and generally resolves with antibiotics without progression to severe neurological symptoms.
*Intracranial hemorrhage*
- Intracranial hemorrhage can cause sudden headache, altered mental status, and focal neurological deficits, but it rarely presents with **fever**, **exophthalmos**, or the specific cranial nerve palsies described without other clear signs of a stroke (e.g., sudden weakness or speech changes).
- The presence of fever and the constellation of orbital signs make hemorrhage less likely as the primary diagnosis.
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