Mechanical thrombectomy indications US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Mechanical thrombectomy indications. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Mechanical thrombectomy indications US Medical PG Question 1: A researcher is investigating the risk of symptomatic intracerebral hemorrhage associated with tissue plasminogen activator (tPA) treatment in severe ischemic stroke. The outcomes of a large randomized controlled trial of ischemic stroke patients, some of whom were randomized to tPA, is shown:
Symptomatic intracerebral hemorrhage No symptomatic intracerebral hemorrhage
Received tPA 12 188
Did not receive tPA 25 475
Based on this data, how many patients with severe ischemic stroke would need to be treated with tPA, on average, to contribute to one case of symptomatic intracerebral hemorrhage?
- A. 13
- B. 6
- C. 0.01
- D. 1.2
- E. 100 (Correct Answer)
Mechanical thrombectomy indications Explanation: ***100***
- To calculate the number needed to harm (NNH), first determine the **absolute risk reduction/increase (ARR/ARI)** for symptomatic intracerebral hemorrhage.
- The **risk in the tPA group** is 12 (hemorrhages) / (12 + 188) (total tPA patients) = 12/200 = 0.06. The **risk in the control group** is 25 (hemorrhages) / (25 + 475) (total control patients) = 25/500 = 0.05.
- The **ARI = Risk in tPA group - Risk in control group = 0.06 - 0.05 = 0.01**.
- The NNH is the reciprocal of the ARI: **NNH = 1 / ARI = 1 / 0.01 = 100**. This means 100 patients need to be treated for one additional case of symptomatic intracerebral hemorrhage due to tPA.
*13*
- This value does not represent the correct calculation for the **Number Needed to Harm (NNH)**.
- It likely results from an incorrect application of the data or a misinterpretation of the NNH formula.
*6*
- This number is incorrect and does not reflect the **NNH** based on the provided data.
- It might represent a calculation based on a different metric or a miscalculation of the **absolute risk increase**.
*0.01*
- This value represents the **absolute risk increase (ARI)** (0.06 - 0.05 = 0.01) of symptomatic intracerebral hemorrhage with tPA, not the **Number Needed to Harm (NNH)**.
- The NNH is the reciprocal of the ARI, which would be 1/0.01 = 100.
*1.2*
- This value is not derived from the standard calculation of **Number Needed to Harm (NNH)**.
- It may be the result of a miscalculation or an attempt to compare the relative risks, rather than addressing the question of treatment impact per case.
Mechanical thrombectomy indications US Medical PG Question 2: A 6-month-old male presents to the emergency department with his parents after his three-year-old brother hit him on the arm with a toy truck. His parents are concerned that the minor trauma caused an unusual amount of bruising. The patient has otherwise been developing well and meeting all his milestones. His parents report that he sleeps throughout the night and has just started to experiment with solid food. The patient’s older brother is in good health, but the patient’s mother reports that some members of her family have an unknown blood disorder. On physical exam, the patient is agitated and difficult to soothe. He has 2-3 inches of ecchymoses and swelling on the lateral aspect of the left forearm. The patient has a neurological exam within normal limits and pale skin with blue irises. An ophthalmologic evaluation is deferred.
Which of the following is the best initial step?
- A. Genetic testing
- B. Complete blood count and coagulation panel (Correct Answer)
- C. Ensure the child's safety and alert the police
- D. Peripheral blood smear
- E. Hemoglobin electrophoresis
Mechanical thrombectomy indications Explanation: ***Complete blood count and coagulation panel***
- The unusual amount of **bruising** after minor trauma, along with a family history of an unknown blood disorder, strongly suggests a potential **bleeding disorder**. A **CBC** and a **coagulation panel** (PT, aPTT, fibrinogen) are essential initial steps to evaluate for abnormalities in platelets, clotting factors, or other hematologic conditions.
- These tests can help narrow down the differential diagnosis between **platelet dysfunction**, **coagulopathies** (like hemophilia or von Willebrand disease), or other less common bleeding disorders, guiding further specific investigations.
- **Important consideration:** The presence of **blue sclera** (described as "blue irises") raises concern for **osteogenesis imperfecta (OI)**, a connective tissue disorder causing bone fragility. However, initial hematologic screening is still appropriate given the family history of blood disorder and presentation of excessive bruising. If coagulation studies are normal, imaging and further workup for OI would be indicated.
*Genetic testing*
- While a genetic component is plausible given the patient's family history and clinical presentation (blue sclera may suggest osteogenesis imperfecta), **genetic testing** is typically performed *after* initial laboratory workup has identified a specific type of bleeding or inherited disorder.
- Starting with genetic testing without basic hematologic parameters is not the most efficient or cost-effective initial diagnostic approach.
*Ensure the child's safety and alert the police*
- While child abuse should always be considered in cases of unexplained or excessive bruising, the presence of a **family history of a blood disorder** and the **blue sclera** (suggesting possible osteogenesis imperfecta) make **medical causes** more immediate concerns for initial investigation.
- Pursuing a medical workup first often clarifies whether abuse is the primary explanation, although child protective services should be notified if suspicion remains high after medical evaluation.
*Peripheral blood smear*
- A **peripheral blood smear** provides information on red blood cell morphology, platelet size and number, and white blood cell differential. While useful in assessing for some hematologic conditions, it is often performed *after* a CBC has indicated abnormalities or in conjunction with specialized testing.
- It would not be the *best initial step* as it doesn't directly assess clotting factor function, which is critical in evaluating significant bruising severity.
*Hemoglobin electrophoresis*
- **Hemoglobin electrophoresis** is used to diagnose **hemoglobinopathies** like sickle cell anemia or thalassemia.
- The patient's symptoms (easy bruising) are not characteristic of hemoglobinopathies, and while he has pale skin, this test would not be the initial step to investigate a bleeding disorder.
Mechanical thrombectomy indications US Medical PG Question 3: A 60-year-old male is admitted to the ICU for severe hypertension complicated by a headache. The patient has a past medical history of insulin-controlled diabetes, hypertension, and hyperlipidemia. He smokes 2 packs of cigarettes per day. He states that he forgot to take his medications yesterday and started getting a headache about one hour ago. His vitals on admission are the following: blood pressure of 160/110 mmHg, pulse 95/min, temperature 98.6 deg F (37.2 deg C), and respirations 20/min. On exam, the patient has an audible abdominal bruit. After administration of antihypertensive medications, the patient has a blood pressure of 178/120 mmHg. The patient reports his headache has increased to a 10/10 pain level, that he has trouble seeing, and he can't move his extremities. After stabilizing the patient, what is the best next step to diagnose the patient's condition?
- A. Doppler ultrasound of the carotids
- B. CT head with intravenous contrast
- C. MRI head without intravenous contrast
- D. CT head without intravenous contrast (Correct Answer)
- E. MRI head with intravenous contrast
Mechanical thrombectomy indications Explanation: ***CT head without intravenous contrast***
- The sudden onset of severe headache, visual disturbances, and neurological deficits (inability to move extremities), coupled with uncontrolled severe hypertension despite initial treatment, is highly suggestive of an **intracranial pathology**, most likely a **hemorrhagic stroke**.
- A **non-contrast CT scan of the head** is the **gold standard** for rapidly identifying acute intracranial hemorrhage, as it can be performed quickly and is readily available in emergency settings.
*Doppler ultrasound of the carotids*
- This test is primarily used to evaluate **carotid artery stenosis** due to atherosclerosis, which can lead to ischemic stroke.
- While the patient has risk factors for atherosclerosis, his acute presentation with severe central neurological symptoms points more towards an acute intracranial event rather than carotid disease.
*CT head with intravenous contrast*
- While a contrast CT can be useful for identifying tumors, abscesses, or vascular malformations, it is **contraindicated in the initial assessment of acute stroke** if an intracranial hemorrhage is suspected.
- Contrast can sometimes obscure subtle bleeds or complicate the interpretation of acute hemorrhage, and it also carries a risk of **contrast-induced nephropathy**, especially in a patient with diabetes.
*MRI head without intravenous contrast*
- An MRI provides superior soft tissue resolution compared to CT and is excellent for detecting ischemic strokes in later stages, as well as subtle hemorrhages, tumors, and other conditions.
- However, it is **less available, takes longer to perform**, and is often not the first choice in an acute neurological emergency where time is critical, particularly when differentiating between ischemic and hemorrhagic stroke.
*MRI head with intravenous contrast*
- Similar to a contrast CT, an MRI with contrast is generally **not the initial imaging choice for acute stroke** due to time constraints and the need to quickly rule out hemorrhage before considering contrast administration.
- Contrast agents for MRI, such as gadolinium, have their own risks, including **nephrogenic systemic fibrosis** in patients with renal impairment, which is a concern in a diabetic patient.
Mechanical thrombectomy indications US Medical PG Question 4: A 78-year-old man is brought in to the emergency department by ambulance after his wife noticed that he began slurring his speech and had developed facial asymmetry during dinner approximately 30 minutes ago. His past medical history is remarkable for hypertension and diabetes. His temperature is 99.1°F (37.3°C), blood pressure is 154/99 mmHg, pulse is 89/min, respirations are 12/min, and oxygen saturation is 98% on room air. Neurologic exam reveals right upper and lower extremity weakness and an asymmetric smile. Which of the following is the next best step in management?
- A. Alteplase
- B. MRI brain
- C. CT head (Correct Answer)
- D. Aspirin
- E. CTA head
Mechanical thrombectomy indications Explanation: ***CT head***
- A **non-contrast CT head** is the immediate priority to differentiate between ischemic and hemorrhagic stroke, which is critical for guiding subsequent treatment decisions.
- Given the patient's acute neurological deficits (slurred speech, facial asymmetry, weakness) and vascular risk factors (hypertension, diabetes), **stroke is highly suspected**, and identifying intracerebral hemorrhage is crucial before considering thrombolytic therapy.
*Alteplase*
- **Alteplase** (tPA) is a thrombolytic agent used for acute ischemic stroke, but its administration is **contraindicated in hemorrhagic stroke**.
- Initiating alteplase without first ruling out hemorrhage with a CT scan could lead to catastrophic bleeding.
*MRI brain*
- While an **MRI brain** can provide more detailed imaging of stroke, it is typically **not the initial imaging modality** in the emergency setting due to longer acquisition times and limited availability, especially when emergent differentiation between ischemic and hemorrhagic stroke is needed.
- Its use is usually reserved for cases where the CT is inconclusive or for later evaluation.
*Aspirin*
- **Aspirin** is an antiplatelet agent used in the management of ischemic stroke, but it should **not be given until a hemorrhagic stroke has been ruled out** via CT head.
- Administering aspirin in the context of an intracerebral hemorrhage could worsen bleeding.
*CTA head*
- A **CT angiography (CTA) head** is used to visualize the cerebral vasculature and identify large vessel occlusions, which can guide thrombectomy decisions in ischemic stroke.
- However, performing a **non-contrast CT head is a prerequisite** to rule out hemorrhage before proceeding with CTA or any other advanced imaging or therapeutic interventions.
Mechanical thrombectomy indications US Medical PG Question 5: A 30-year-old man with history of intravenous drug use and methamphetamine-associated chronic thromboembolic pulmonary hypertension (CTEPH) is brought to the emergency department by his girlfriend for worsening abdominal pain and fevers. The patient said the pain was initially around his umbilicus, but he is now experiencing intense tenderness near his groin. He was initially prescribed rivaroxaban, but due to insurance issues, he was switched to warfarin for management of CTEPH two weeks ago. His temperature is 102°F (38.9°C), blood pressure is 95/60 mmHg, pulse is 95/min, respirations are 22/min. He states that his blood pressure usually runs low. His physical exam is notable for an unremarkable cardiac exam, bibasilar crackles, and RLQ tenderness with rebound tenderness when the LLQ is palpated. Laboratory results are shown below:
Hemoglobin: 11 g/dL
Hematocrit: 35 %
Leukocyte count: 16,000/mm^3 with normal differential
Platelet count: 190,000/mm^3
Serum:
Na+: 137 mEq/L
Cl-: 100 mEq/L
K+: 3.7 mEq/L
HCO3-: 23 mEq/L
BUN: 40 mg/dL
Glucose: 110 mg/dL
Creatinine: 0.8 mg/dL
Ca2+: 9.1 mg/dL
AST: 34 U/L
ALT: 45 U/L
International normalized ratio (INR): 6.2
Prothrombin time (PT): 40 seconds
Partial thromboplastin time: 70 seconds
Blood type: O
Rhesus: Positive
Antibody screen: Negative
A clinical diagnosis is made and supported by the surgical consult team in lieu of imaging. The next operating room for an add-on procedure will not be available for another 5 hours. Appropriate medical therapy is initiated. What is the best next step for surgical optimization?
- A. Fresh frozen plasma
- B. Prothrombin complex concentrate (Correct Answer)
- C. Protamine
- D. Do nothing
- E. Phytonadione
Mechanical thrombectomy indications Explanation: ***Prothrombin complex concentrate***
- The patient has **warfarin over-anticoagulation (INR 6.2)** and requires **emergency surgery** for suspected appendicitis with peritonitis, necessitating rapid reversal of anticoagulation.
- **Prothrombin complex concentrate (4-factor PCC)** contains concentrated factors II, VII, IX, and X (and proteins C & S), providing **rapid and complete reversal** of warfarin's anticoagulant effects within minutes, which is crucial in emergency surgical situations.
- PCC is **preferred over FFP** per current guidelines (ACCP, AHA) for urgent warfarin reversal due to faster administration, smaller volume, and more predictable INR correction.
- **Vitamin K should be administered concurrently** to provide sustained reversal (takes 12-24 hours), but PCC is essential for immediate correction before surgery.
*Fresh frozen plasma*
- While FFP contains all coagulation factors and can reverse warfarin, it requires **larger volumes (4-6 units)**, takes longer to thaw and administer, and is **less effective** in rapidly correcting INR to normal range compared to PCC.
- Administering large volumes of FFP can lead to **volume overload** (especially concerning in CTEPH patients) and **transfusion-related complications**.
- PCC is superior for urgent reversal in patients requiring emergency surgery.
*Protamine*
- **Protamine** is used to reverse the anticoagulant effects of **unfractionated heparin** (and partially reverses low molecular weight heparin), not warfarin.
- It would have **no effect** on the patient's elevated INR due to warfarin use.
- Note: The elevated PTT (70s) in this case may suggest concurrent heparin bridging therapy or other factor deficiency, but the primary issue requiring reversal is the critical warfarin over-anticoagulation.
*Do nothing*
- This patient has **surgical peritonitis** (appendicitis with peritoneal signs) and requires emergency surgery with an INR of 6.2, creating **high risk of surgical bleeding**.
- Proceeding to surgery without reversing anticoagulation would result in **life-threatening hemorrhage**.
- Delaying treatment would likely result in further **clinical deterioration** with possible perforation and sepsis.
*Phytonadione*
- **Phytonadione (Vitamin K)** reverses warfarin's effects by restoring hepatic synthesis of vitamin K-dependent clotting factors, but its onset of action is **slow (12-24 hours for full effect)**, making it unsuitable as the sole agent for immediate reversal in patients requiring emergent surgery.
- While **Vitamin K should be administered** alongside PCC to provide sustained reversal, it is **not sufficient alone** for rapid correction in surgical emergencies.
Mechanical thrombectomy indications US Medical PG Question 6: A 77-year-old man with a history of hypertension and a 46 pack-year smoking history presents to the emergency department from an extended care facility with acute onset of headache, nausea, vomiting, and neck pain which started 6 hours ago and has persisted since. He is alert, but his baseline level of consciousness is slightly diminished per the nursing home staff. His temperature is 99.0°F (37.2°C), blood pressure is 164/94 mmHg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 98% on room air. The patient's neurological exam is unremarkable with cranial nerves II-XII grossly intact and with stable gait with a walker. He is immediately sent for a head CT which is normal. What is the most appropriate next step in management?
- A. Ultrasound
- B. Lumbar puncture (Correct Answer)
- C. Alteplase
- D. Ibuprofen, acetaminophen, metoclopramide, and diphenhydramine
- E. MRI
Mechanical thrombectomy indications Explanation: ***Lumbar puncture***
- The patient's symptoms (acute severe headache, nausea, vomiting, neck pain) and risk factors (hypertension, smoking history) are highly suggestive of a **subarachnoid hemorrhage (SAH)**, even with a normal initial **non-contrast head CT**.
- A **lumbar puncture (LP)** is the next critical diagnostic step to detect **xanthochromia** (due to bilirubin degradation from red blood cells) or elevated red blood cell count in the cerebrospinal fluid (CSF), which would confirm SAH.
- CT has approximately **95% sensitivity in the first 6 hours**, but sensitivity decreases over time, making LP essential when clinical suspicion remains high.
*Ultrasound*
- **Ultrasound** is not a standard diagnostic tool for acute neurological symptoms like severe headache or suspected SAH.
- It is primarily used for evaluating soft tissues, abdominal organs, and vascular structures like carotid arteries, but offers limited utility for intracranial bleeding.
*Alteplase*
- **Alteplase** (tissue plasminogen activator, tPA) is a thrombolytic agent used in acute ischemic stroke, characterized by focal neurological deficits due to arterial occlusion.
- Administering alteplase in the setting of headache and neck pain without focal deficits, while SAH is suspected, could be fatal as it would worsen bleeding.
*Ibuprofen, acetaminophen, metoclopramide, and diphenhydramine*
- This combination of medications is used for **symptomatic relief** of headache and nausea but does not address the underlying potentially life-threatening cause.
- Treating symptoms without a definitive diagnosis in suspected SAH could lead to delayed intervention and worse outcomes.
*MRI*
- While **MRI with specific sequences (FLAIR, GRE, SWI)** has high sensitivity for detecting SAH and is increasingly used in clinical practice, **lumbar puncture remains the traditional and most widely recommended next step** after a negative CT in suspected SAH.
- LP directly detects **xanthochromia** (present 6-12 hours after bleeding) and RBCs in CSF, providing definitive evidence of SAH.
- MRI may not always be readily available in the emergency setting, takes longer to perform, and requires patient stability and cooperation.
- For standardized exams, **LP is the classic correct answer** when CT is negative but clinical suspicion for SAH remains high.
Mechanical thrombectomy indications US Medical PG Question 7: A 65-year-old man presents to the emergency department for sudden weakness. He was doing mechanical work on his car where he acutely developed right-leg weakness and fell to the ground. He is accompanied by his wife, who said that this has never happened before. He was last seen neurologically normal approximately 2 hours prior to presentation. His past medical history is significant for hypertension and type II diabetes. His temperature is 98.8°F (37.1°C), blood pressure is 177/108 mmHg, pulse is 90/min, respirations are 15/min, and oxygen saturation is 99% on room air. Neurological exam reveals that he is having trouble speaking and has profound weakness of his right upper and lower extremity. Which of the following is the best next step in management?
- A. Thrombolytics
- B. Noncontrast head CT (Correct Answer)
- C. CT angiogram
- D. MRI of the head
- E. Aspirin
Mechanical thrombectomy indications Explanation: ***Noncontrast head CT***
- A **noncontrast head CT** is the most crucial initial step in managing acute stroke symptoms because it can rapidly rule out an **intracranial hemorrhage**.
- Distinguishing between ischemic stroke and hemorrhagic stroke is critical, as the management strategies are vastly different and administering thrombolytics in the presence of hemorrhage can be fatal.
*Thrombolytics*
- **Thrombolytics** can only be administered after an **intracranial hemorrhage** has been excluded via noncontrast head CT.
- Administering thrombolytics without imaging could worsen a hemorrhagic stroke, causing significant harm or death.
*CT angiogram*
- A **CT angiogram** is used to identify large vessel occlusions in ischemic stroke and is typically performed after a noncontrast CT rules out hemorrhage.
- This imaging is crucial for determining eligibility for **endovascular thrombectomy** but is not the very first diagnostic step.
*MRI of the head*
- An **MRI of the head** is more sensitive for detecting acute ischemic changes but takes longer to perform and is often not readily available in the acute emergency setting.
- It is not the initial imaging of choice for ruling out hemorrhage due to its longer acquisition time compared to CT.
*Aspirin*
- **Aspirin** is indicated for acute ischemic stroke but should only be given after an **intracranial hemorrhage** has been ruled out.
- Like thrombolytics, aspirin could exacerbate a hemorrhagic stroke and is thus deferred until initial imaging is complete.
Mechanical thrombectomy indications US Medical PG Question 8: A 77-year-old man is brought to the emergency department by his wife because of headache, nausea, and vomiting for 24 hours. His wife says that over the past 2 weeks, he has been more irritable and has had trouble remembering to do routine errands. Two weeks ago, he fell during a skiing accident but did not lose consciousness. He has coronary artery disease and hypertension. He has smoked one pack of cigarettes daily for 50 years. He has had 2 glasses of wine daily since his retirement 10 years ago. Current medications include atenolol, enalapril, furosemide, atorvastatin, and aspirin. He appears acutely ill. He is oriented to person but not to place or time. His temperature is 37°C (98.6°F), pulse is 99/min, respirations are 16/min, and blood pressure is 160/90 mm Hg. During the examination, he is uncooperative and unable to answer questions. Deep tendon reflexes are 4+ on the left and 2+ on the right. Babinski's sign is present on the left. There is mild weakness of the left iliopsoas and hamstring muscles. A CT scan of the head without contrast shows a high-density, 15-mm crescentic collection across the right hemispheric convexity. Which of the following is the most appropriate next step in the management of this patient?
- A. Recombinant tissue plasminogen activator administration
- B. Obtain an Electroencephalography
- C. Obtain an MRI of the head
- D. Surgical evacuation (Correct Answer)
- E. Observation
Mechanical thrombectomy indications Explanation: ***Surgical evacuation***
- The CT scan reveals a **high-density, crescentic collection**, strongly indicative of an **acute subdural hematoma**, which is causing significant neurological deficits and mass effect (e.g., increased intracranial pressure symptoms like headache, nausea, vomiting, and altered mental status, and focal neurological signs).
- Given the patient's **acute neurological decline**, significant mass effect from the 15-mm hematoma, and age, prompt **surgical evacuation** is the definitive treatment to relieve pressure and prevent further brain injury.
*Recombinant tissue plasminogen activator administration*
- **tPA** is indicated for **acute ischemic stroke**, not hemorrhagic stroke or subdural hematoma. Administering tPA in this context would be harmful, potentially worsening the hemorrhage.
- The patient's CT scan clearly shows a **hemorrhagic lesion**, not an ischemic event.
*Obtain an Electroencephalography*
- **EEG** is primarily used to evaluate **seizure disorders** or certain types of encephalopathy. While the patient has altered mental status, the primary issue identified on CT is a subdural hematoma requiring immediate intervention.
- EEG would not provide information relevant to the immediate management of an **acute subdural hematoma**.
*Obtain an MRI of the head*
- An **MRI** can provide more detailed imaging, but in the context of an **acute subdural hematoma** with significant neurological compromise, it would delay crucial and time-sensitive surgical intervention.
- The **CT scan** has already provided sufficient diagnostic information to warrant immediate surgical planning.
*Observation*
- **Observation** is not appropriate for a patient with a rapidly expanding **acute subdural hematoma** causing significant neurological deficits and a 15-mm collection, especially given the patient's age and clinical presentation.
- Delaying treatment would likely lead to further neurological deterioration, **herniation**, and potentially death.
Mechanical thrombectomy indications US Medical PG Question 9: A 48-year-old woman presents with acute stroke symptoms 18 hours ago. MRI shows a right MCA M1 occlusion with large penumbra on perfusion imaging (mismatch ratio >1.8) and small infarct core (25 mL). Her NIHSS is 16. She has no significant comorbidities. Her family is concerned about disability but wants to pursue treatment if reasonable chance of benefit exists. Synthesize the evidence and evaluate the treatment approach.
- A. Intravenous alteplase as salvageable tissue is present
- B. Intra-arterial thrombolysis combined with mechanical device
- C. No intervention as she is outside the standard treatment window
- D. Mechanical thrombectomy based on perfusion imaging criteria (Correct Answer)
- E. Medical management with antiplatelet and early rehabilitation
Mechanical thrombectomy indications Explanation: ***Mechanical thrombectomy based on perfusion imaging criteria***
- For patients with large vessel occlusion (LVO) in the extended 6–24 hour window, **DAWN** and **DEFUSE-3** trials demonstrated significant functional benefit when clinical-core mismatch is present.
- This patient satisfies criteria with an **M1 occlusion**, a **small infarct core (<70 mL)**, and a **large mismatch ratio (>1.8)**, indicating substantial salvageable penumbra.
*Intravenous alteplase as salvageable tissue is present*
- The therapeutic window for **IV alteplase** is strictly limited to within **4.5 hours** of symptom onset; it is not recommended at 18 hours due to high hemorrhage risk.
- While salvageable tissue exists, chemical thrombolysis is less effective than mechanical intervention for **proximal M1 occlusions** and is unsafe in this late window.
*Intra-arterial thrombolysis combined with mechanical device*
- **Intra-arterial thrombolysis** is generally superseded by modern **stent retrievers** and aspiration catheters which provide faster and more complete recanalization.
- Current guidelines prioritize standalone **mechanical thrombectomy** in the late window to minimize procedural risks and intracranial hemorrhage.
*No intervention as she is outside the standard treatment window*
- The "Time is Brain" concept has evolved into "Tissue is Brain," where **perfusion imaging** identifies candidates who benefit regardless of the traditional 6-hour clock.
- Denying treatment based solely on the 18-hour timeframe ignores high-level evidence from the **DAWN** trial showing benefit up to 24 hours.
*Medical management with antiplatelet and early rehabilitation*
- Standard **medical management** (aspirin/heparin) for an M1 occlusion with a high **NIHSS score (16)** usually results in poor functional outcomes and severe disability.
- While rehabilitation is essential, it does not address the underlying **large vessel occlusion** which can be reversed with mechanical intervention to prevent infarct expansion.
Mechanical thrombectomy indications US Medical PG Question 10: A 55-year-old man undergoes successful thrombectomy for left MCA occlusion. Post-procedure, he develops progressive lethargy and his blood pressure increases to 180/100 mmHg. CT shows hyperdensity in the treated territory without hemorrhage, and his symptoms worsen over 4 hours despite blood pressure control. Evaluate the most likely diagnosis and management priority.
- A. Hemorrhagic transformation; reverse anticoagulation immediately
- B. Cerebral edema from large infarction; emergent decompressive hemicraniectomy
- C. Reperfusion injury; start high-dose corticosteroids and osmotic therapy
- D. Contrast extravasation from blood-brain barrier disruption; supportive care and avoid aggressive BP lowering (Correct Answer)
- E. Recurrent arterial occlusion; emergent repeat angiography and thrombectomy
Mechanical thrombectomy indications Explanation: ***Contrast extravasation from blood-brain barrier disruption; supportive care and avoid aggressive BP lowering***
- Post-thrombectomy **hyperdensity** on CT often represents contrast that leaked through an ischemic **blood-brain barrier**, which can mimic hemorrhage but lacks significant **mass effect**.
- Management is **supportive care** because the contrast is typically reabsorbed within 24–48 hours; avoiding aggressive **blood pressure lowering** prevents secondary ischemia in the penumbra.
*Hemorrhagic transformation; reverse anticoagulation immediately*
- While **hemorrhagic transformation** is a risk, true blood usually demonstrates higher density earlier and is associated with rapid clinical decline and **midline shift**.
- Reversing anticoagulation without confirming blood on a follow-up **dual-energy CT** or MRI may lead to **stent thrombosis** or re-occlusion.
*Cerebral edema from large infarction; emergent decompressive hemicraniectomy*
- **Cerebral edema** typically peaks between 72–96 hours post-stroke; a presentation within 4 hours is too acute for **malignant MCA syndrome**.
- While edema causes lethargy, the hyperdensity on CT more specifically points toward **contrast staining** or blood rather than simple cytotoxic edema.
*Reperfusion injury; start high-dose corticosteroids and osmotic therapy*
- **Corticosteroids** are not indicated for stroke-related edema or reperfusion injury as they do not improve outcomes and may increase **infection risk**.
- **Osmotic therapy** is reserved for patients with clear clinical or radiologic signs of **elevated intracranial pressure**, not isolated hyperdensity on CT.
*Recurrent arterial occlusion; emergent repeat angiography and thrombectomy*
- **Recurrent occlusion** usually presents with a sudden recurrence of the original **focal neurological deficits** (e.g., hemiplegia, aphasia) rather than progressive lethargy.
- The presence of **hyperdensity** in the stroke territory on CT is specifically indicative of material (contrast or blood) being present, which is not a feature of a simple **re-occlusion**.
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