Red flags in fever US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Red flags in fever. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Red flags in fever US Medical PG Question 1: A 2-year-old boy presents for a routine checkup. The patient’s mother says that he has been ‘under the weather’ for the past few days. She did not measure his temperature at home but states that he has felt warm. She denies any episodes of diarrhea or vomiting. No significant past medical history or current medications. The patient attends daycare. He is due for a hepatitis A vaccine. The patient was born at term with no prenatal or perinatal complications. The vital signs include: temperature 37.8°C (100.1°F), blood pressure 112/62 mm Hg, pulse 80/min, respiratory rate 18/min, and oxygen saturation 99% on room air. The patient is alert and responsive. The physical exam is unremarkable. Which of the following is the most appropriate next step in the management of this patient?
- A. Order a complete blood count
- B. Order liver function tests
- C. Strep rapid antigen detection test
- D. Administer the hepatitis A vaccine (Correct Answer)
- E. Delay the hepatitis A immunization until next visit
Red flags in fever Explanation: ***Administer the hepatitis A vaccine***
- The patient has a **low-grade fever** (37.8°C), which is generally **not considered a contraindication** for vaccination, especially if the child is otherwise well and active.
- The patient's presentation of being "under the weather" with an unremarkable physical exam and stable vitals suggests a **mild illness**, allowing for routine vaccinations to proceed.
*Order a complete blood count*
- A **CBC is not indicated** at this time, as the patient displays only mild, non-specific symptoms and has a normal physical exam.
- This would be reserved for cases with more concerning signs of infection or systemic illness, such as persistent high fever, lethargy, or specific clinical findings.
*Order liver function tests*
- **Liver function tests are not warranted** as the patient has no symptoms or signs suggestive of liver disease (e.g., jaundice, right upper quadrant pain, dark urine).
- While the patient is due for a hepatitis A vaccine, there is no clinical evidence of active hepatitis or liver dysfunction requiring diagnostic workup.
*Strep rapid antigen detection test*
- The patient has **no symptoms consistent with streptococcal pharyngitis**, such as sore throat, tonsillar exudates, or cervical lymphadenopathy.
- Given the lack of specific symptoms, testing for strep throat would be inappropriate and potentially lead to unnecessary antibiotic use.
*Delay the hepatitis A immunization until next visit*
- Delaying vaccination is only recommended for **moderate to severe acute illnesses** with or without fever, or for certain contraindications.
- A mild illness with low-grade fever, as in this case, is generally **not a reason to postpone** routine immunizations, as per CDC guidelines.
Red flags in fever US Medical PG Question 2: A 22-year-old female is brought to the emergency department by her roommate with a one day history of fever and malaise. She did not feel well after class the previous night and has been in her room since then. She has not been eating or drinking due to severe nausea. Her roommate checked on her one hour ago and was alarmed to find a fever of 102°F (38.9°C). On physical exam temperature is 103°F (40°C), blood pressure is 110/66 mmHg, pulse is 110/min, respirations are 23/min, and pulse oximetry is 98% on room air. She refuses to move her neck and has a rash on her trunk. You perform a lumbar puncture and the CSF analysis is shown below.
Appearance: Cloudy
Opening pressure: 180 mm H2O
WBC count: 150 cells/µL (93% PMN)
Glucose level: < 40 mg/dL
Protein level: 50 mg/dL
Gram stain: gram-negative diplococci
Based on this patient's clinical presentation, which of the following should most likely be administered?
- A. Ceftriaxone (Correct Answer)
- B. Dexamethasone
- C. Rifampin
- D. Acyclovir
- E. Erythromycin
Red flags in fever Explanation: ***Ceftriaxone***
- The patient presents with classic signs of **bacterial meningitis** (fever, neck stiffness, rash, altered mental status) and CSF analysis confirms, showing **cloudy appearance**, **elevated opening pressure**, **high WBC count with PMN predominance**, **low glucose**, and **gram-negative diplococci** on Gram stain, typical for *Neisseria meningitidis*.
- **Ceftriaxone** is a third-generation cephalosporin, a first-line antibiotic for treating bacterial meningitis, particularly effective against *Neisseria meningitidis*.
*Dexamethasone*
- While **dexamethasone** can be used as an adjunct in bacterial meningitis, particularly when caused by *Streptococcus pneumoniae*, it's administered *before or with* the first dose of antibiotics to mitigate inflammation.
- It is not the primary treatment to *eradicate* the infection and is less critical than immediate antibiotic therapy.
*Rifampin*
- **Rifampin** is primarily used for chemoprophylaxis in close contacts of individuals with meningococcal meningitis, or as part of a multi-drug regimen for tuberculosis.
- It is not the recommended first-line monotherapy for acute bacterial meningitis.
*Acyclovir*
- **Acyclovir** is an antiviral medication used to treat herpes simplex virus (HSV) meningitis or encephalitis.
- The CSF analysis showing **gram-negative diplococci** clearly indicates a bacterial etiology, not viral, making acyclovir inappropriate.
*Erythromycin*
- **Erythromycin** is a macrolide antibiotic with a narrower spectrum of activity and is not typically used as first-line treatment for bacterial meningitis, especially not for *Neisseria meningitidis*.
- Its use is often limited by resistance and side effects compared to third-generation cephalosporins.
Red flags in fever US Medical PG Question 3: A 67-year-old man presents to the emergency department with confusion. The patient is generally healthy, but his wife noticed him becoming progressively more confused as the day went on. The patient is not currently taking any medications and has no recent falls or trauma. His temperature is 102°F (38.9°C), blood pressure is 126/64 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a confused man who cannot participate in a neurological exam secondary to his confusion. No symptoms are elicited with flexion of the neck and jolt accentuation of headache is negative. Initial laboratory values are unremarkable and the patient's chest radiograph and urinalysis are within normal limits. An initial CT scan of the head is unremarkable. Which of the following is the best next step in management?
- A. CT angiogram of the head and neck
- B. Vancomycin, ceftriaxone, ampicillin, and dexamethasone
- C. Acyclovir (Correct Answer)
- D. PCR of the cerebrospinal fluid
- E. MRI of the head
Red flags in fever Explanation: ***Acyclovir***
- This patient presents with **acute confusion and fever** without an obvious infectious source, negative meningeal signs, and normal initial imaging, highly suggestive of **herpes simplex encephalitis (HSE)**.
- HSE is a **medical emergency** with high mortality (70-80%) if untreated, but mortality drops to 20-30% with early acyclovir therapy.
- **Empiric acyclovir must be started immediately** upon clinical suspicion of HSE, **without waiting for diagnostic confirmation**.
- Standard management includes obtaining CSF for PCR **concurrently** with starting acyclovir, but treatment should never be delayed for diagnostic testing.
- The best next step in **management** is initiating acyclovir; CSF PCR is obtained for confirmation but does not delay treatment.
*PCR of the cerebrospinal fluid*
- **CSF PCR for HSV** is the gold standard **diagnostic test** for HSE with high sensitivity (96%) and specificity (99%).
- While lumbar puncture should be performed to obtain CSF for PCR, this is a **diagnostic step** that should be done **concurrently** with starting acyclovir, not instead of it.
- The question asks for best next step in **management**, not diagnosis—acyclovir therapy takes precedence.
- Delaying acyclovir while awaiting diagnostic confirmation significantly increases morbidity and mortality.
*Vancomycin, ceftriaxone, ampicillin, and dexamethasone*
- This broad-spectrum antibiotic regimen is empiric therapy for **bacterial meningitis** and should be considered in patients with fever and altered mental status.
- However, the **absence of meningeal signs** (negative nuchal rigidity, negative jolt accentuation) makes bacterial meningitis less likely.
- In practice, when HSE is suspected but bacterial meningitis cannot be excluded, both antimicrobial regimens may be initiated empirically, but the primary concern here is HSE given the clinical presentation.
*MRI of the head*
- **MRI with FLAIR sequences** is highly sensitive for HSE and typically shows **temporal lobe involvement** (especially medial temporal lobes).
- However, MRI findings may be **normal early in the disease course** (first 48-72 hours).
- MRI is useful for supporting the diagnosis but should **not delay empiric acyclovir therapy**.
- Obtaining MRI before treatment would be inappropriate given the time-sensitive nature of HSE.
*CT angiogram of the head and neck*
- CT angiography evaluates vascular structures and is indicated for suspected **stroke, aneurysm, or vascular dissection**.
- This patient lacks focal neurological deficits, signs of acute stroke, or vascular risk factors that would prioritize vascular imaging.
- The presentation with fever and diffuse encephalopathy points toward an infectious/inflammatory process rather than a vascular etiology.
Red flags in fever US Medical PG Question 4: A 4-year-old boy is brought to the emergency department with difficulty breathing. His mother reports that he developed a fever last night and began to have trouble breathing this morning. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is unvaccinated (conscientious objection by the family) and is meeting all developmental milestones. At the hospital, his vitals are temperature 39.8°C (103.6°F), pulse 122/min, respiration rate 33/min, blood pressure 110/66 mm Hg, and SpO2 93% on room air. On physical examination, he appears ill with his neck hyperextended and chin protruding. His voice is muffled and is drooling. The pediatrician explains that there is one particular bacteria that commonly causes these symptoms. At what age should the patient have first received vaccination to prevent this condition from this particular bacteria?
- A. At birth
- B. At 2-months-old (Correct Answer)
- C. Between 9- and 12-months-old
- D. At 6-months-old
- E. Between 12- and 15-months-old
Red flags in fever Explanation: ***At 2-months-old***
- The clinical presentation with **high fever**, **difficulty breathing**, **neck hyperextension**, **muffled voice**, and **drooling** in an unvaccinated child strongly suggests **epiglottitis**, likely caused by *Haemophilus influenzae type b* (Hib).
- The **Hib vaccine** is routinely given starting at **2 months of age** as part of the multi-dose primary series to protect against this life-threatening condition.
*At birth*
- While some vaccines like **Hepatitis B** are given at birth, the Hib vaccine is not typically administered at this age.
- Vaccinating at birth would not align with the standard immunization schedule for *Haemophilus influenzae type b*.
*Between 9- and 12-months-old*
- This age range typically corresponds to the **measles, mumps, and rubella (MMR)** and **varicella** vaccines, or a booster dose of other vaccines, not the initial primary series for Hib.
- Delaying the first Hib vaccination until this age would leave infants vulnerable during a critical period.
*At 6-months-old*
- By 6 months, a child should have already received at least **two doses** of the Hib vaccine if following the recommended schedule.
- Administering the first dose at 6 months would significantly delay protection against invasive Hib disease.
*Between 12- and 15-months-old*
- This age range is typically when the **final booster dose** of the Hib vaccine is given, not the initial vaccination.
- The primary series for Hib should have been completed much earlier to provide timely protection.
Red flags in fever US Medical PG Question 5: A 65-year-old man presents to the emergency department due to an episode of lightheadedness. The patient was working at his garage workbench when he felt like he was going to faint. His temperature is 98.8°F (37.1°C), blood pressure is 125/62 mmHg, pulse is 117/min, respirations are 14/min, and oxygen saturation is 98% on room air. Laboratory values are ordered as seen below.
Hemoglobin: 7 g/dL
Hematocrit: 22%
Leukocyte count: 6,500/mm^3 with normal differential
Platelet count: 197,000/mm^3
The patient is started on blood products and a CT scan is ordered. Several minutes later, his temperature is 99.5°F (37.5°C), blood pressure is 87/48 mmHg, and pulse is 180/min. The patient's breathing is labored. Which of the following is also likely to be true?
- A. Anaphylactic reaction (Correct Answer)
- B. Febrile non-hemolytic transfusion reaction
- C. Acute hemolytic transfusion reaction
- D. Transfusion-related acute lung injury (TRALI)
- E. Bacterial contamination of blood products
Red flags in fever Explanation: ***Anaphylactic reaction***
- The rapid onset of **hypotension**, **tachycardia**, and **respiratory distress** immediately following blood product administration is highly suggestive of an anaphylactic reaction.
- This severe allergic reaction occurs within **minutes** of exposure and can rapidly progress to **shock** and **airway compromise**.
- The profound cardiovascular collapse with respiratory distress is the hallmark presentation.
*Febrile non-hemolytic transfusion reaction*
- Characterized by **fever** and **chills** within several hours of transfusion.
- Typically does **not** cause the profound **hypotension** and severe **respiratory distress** seen here.
- While a slight temperature elevation occurred, the overwhelming cardiovascular collapse is not typical.
*Acute hemolytic transfusion reaction*
- Usually presents with **fever**, **chills**, **flank pain**, **dark urine** (hemoglobinuria), and sometimes hypotension due to **ABO incompatibility**.
- Onset can be rapid but typically includes more evidence of **hemolysis** (jaundice, hemoglobinuria).
- The immediate and severe respiratory compromise is less typical compared to anaphylaxis.
*Transfusion-related acute lung injury (TRALI)*
- Presents primarily with **acute respiratory distress**, **hypoxemia**, and **bilateral pulmonary infiltrates** within six hours of transfusion.
- Usually occurs **1-6 hours** post-transfusion, not within minutes.
- While respiratory distress is present, the immediate and profound circulatory collapse with such rapid onset points toward anaphylaxis rather than TRALI.
*Bacterial contamination of blood products*
- Can present with **septic shock**: fever, hypotension, and tachycardia following transfusion.
- However, the **respiratory distress** and **immediate onset** within minutes are more characteristic of anaphylaxis.
- Bacterial contamination typically has a slightly more gradual onset and may show signs of sepsis.
Red flags in fever US Medical PG Question 6: A 27-year-old woman comes to the physician because of a 3-day history of a sore throat and fever. Her temperature is 38.5°C (101.3°F). Examination shows edematous oropharyngeal mucosa and enlarged tonsils with purulent exudate. There is tender cervical lymphadenopathy. If left untreated, which of the following conditions is most likely to occur in this patient?
- A. Rheumatic fever (Correct Answer)
- B. Rheumatoid arthritis
- C. Erythema multiforme
- D. Toxic shock syndrome
- E. Post-streptococcal glomerulonephritis
Red flags in fever Explanation: ***Rheumatic fever***
- The patient presents with classic symptoms of **streptococcal pharyngitis** (sore throat, fever, tonsillar exudate, tender cervical lymphadenopathy), which, if left untreated, is a major risk factor for developing **acute rheumatic fever**.
- **Acute rheumatic fever** is a serious inflammatory disease that can affect the **heart valves**, joints, brain, and skin, occurring in approximately **3% of untreated cases** of Group A Streptococcal pharyngitis.
*Rheumatoid arthritis*
- This is a **chronic autoimmune inflammatory disease** primarily affecting the synovial joints, not typically associated with an acute streptococcal infection.
- It involves a different pathophysiological mechanism and is not a direct complication of untreated streptococcal pharyngitis.
*Erythema multiforme*
- This is an **acute, self-limiting skin condition** often triggered by infections (e.g., Herpes simplex virus) or medications, resulting in target lesions.
- While infections can cause it, **streptococcal pharyngitis** is not a common or direct cause, and it's not a systemic complication similar to rheumatic fever.
*Toxic shock syndrome*
- This is a **rapidly progressing infectious disease** characterized by fever, rash, hypotension, and multi-organ failure, most often caused by toxins produced by *Staphylococcus aureus* or *Streptococcus pyogenes*.
- While *Streptococcus pyogenes* (Group A Strep) can cause it, toxic shock syndrome is an **acute complication** rather than a late sequela of untreated infection, making **rheumatic fever** the more characteristic delayed complication.
*Post-streptococcal glomerulonephritis*
- While this is another serious immune-mediated complication of **streptococcal infections**, it **more commonly follows skin infections (impetigo)** than pharyngitis.
- **Rheumatic fever** is the most characteristic and clinically significant late complication of untreated streptococcal **pharyngitis** specifically, with greater emphasis in clinical practice due to its potential for permanent cardiac valve damage.
Red flags in fever US Medical PG Question 7: A previously healthy 40-year-old woman comes to the physician because of a 3-day history of fever, headaches, and fatigue. She also reports a persistent tingling sensation in her right hand and numbness in her right arm that started this morning. Physical examination shows pallor, mild scleral icterus, and petechiae on her forearms and legs. On mental status examination, she appears confused and is only oriented to person. Laboratory studies show:
Hemoglobin 11.1 g/dL
Platelet count 39,500/mm3
Bleeding time 9 minutes
Prothrombin time 14 seconds
Partial thromboplastin time 35 seconds
Serum
Creatinine 1.7 mg/dL
Total bilirubin 2.1 mg/dL
A peripheral blood smear shows fragmented erythrocytes. Which of the following is the most likely underlying cause of this patient's condition?
- A. Antibodies against double-stranded DNA
- B. Mutation of the PIGA gene
- C. Antibodies against GpIIb/IIIa
- D. Antibodies against ADAMTS13 (Correct Answer)
- E. Absence of platelet GpIIb/IIIa receptors
Red flags in fever Explanation: ***Antibodies against ADAMTS13***
- This patient presents with a classic pentad of symptoms: **fever**, **neurologic symptoms** (confusion, tingling, numbness), **renal failure** (creatinine 1.7 mg/dL), **thrombocytopenia** (platelet count 39,500/mm3), and **microangiopathic hemolytic anemia** (pallor, scleral icterus, fragmented erythrocytes on smear). This constellation of findings is highly suggestive of **Thrombotic Thrombocytopenic Purpura (TTP)**.
- TTP is primarily caused by a deficiency of the **ADAMTS13 enzyme**, often due to **autoantibodies** that inhibit its activity. ADAMTS13 is responsible for cleaving large **von Willebrand factor (vWF) multimers**, and its deficiency leads to the accumulation of these large multimers, promoting platelet aggregation and microthrombi formation.
*Antibodies against double-stranded DNA*
- Antibodies against double-stranded DNA (**anti-dsDNA antibodies**) are characteristic of **Systemic Lupus Erythematosus (SLE)**, which can present with various systemic symptoms.
- While SLE can cause thrombocytopenia and renal involvement, it typically does not cause the severe **microangiopathic hemolytic anemia** with schistocytes or the combination of symptoms seen in this patient to the extent of TTP.
*Mutation of the PIGA gene*
- A **mutation of the *PIGA* gene** is responsible for **Paroxysmal Nocturnal Hemoglobinuria (PNH)**, a clonal stem cell disorder characterized by hemolytic anemia, thrombosis, and bone marrow failure.
- While PNH involves hemolysis, it typically lacks the prominent neurological symptoms, severe thrombocytopenia with microangiopathic features, and renal failure seen in TTP.
*Antibodies against GpIIb/IIIa*
- **Antibodies against GpIIb/IIIa** (glycoprotein IIb/IIIa) receptors are the hallmark of **Immune Thrombocytopenic Purpura (ITP)**, causing accelerated platelet destruction.
- ITP primarily causes **isolated thrombocytopenia** and mucocutaneous bleeding, but it does not cause microangiopathic hemolytic anemia, renal failure, or neurological symptoms that are prominent in this patient.
*Absence of platelet GpIIb/IIIa receptors*
- The **absence of platelet GpIIb/IIIa receptors** is characteristic of **Glanzmann's thrombasthenia**, a rare inherited disorder of platelet function.
- Glanzmann's thrombasthenia leads to **mucocutaneous bleeding** due to impaired platelet aggregation, but it does not cause thrombocytopenia, hemolytic anemia, renal failure, or neurological symptoms.
Red flags in fever US Medical PG Question 8: A 21-year-old man presents with fever, headache, and clouded sensorium for the past 3 days. His fever is low-grade. He says his headache is mild-to-moderate in intensity and associated with nausea, vomiting, and photophobia. There is no history of a sore throat, pain on urination, abdominal pain, or loose motions. He smokes 1–2 cigarettes daily and drinks alcohol socially. Past medical history and family history are unremarkable. His vital signs include: blood pressure 120/80 mm Hg, pulse 106/min, temperature 37.3°C (99.2°F). On physical examination, he is confused, disoriented, and agitated. Extraocular movements are intact. The neck is supple on flexion. He is moving all his 4 limbs spontaneously. A noncontrast CT scan of the head is within normal limits. A lumbar puncture is performed, and cerebrospinal fluid results are still pending. The patient is started on empiric intravenous acyclovir. Which of the following clinical features favors encephalitis rather than meningitis?
- A. Photophobia
- B. Clouded sensorium (Correct Answer)
- C. Headache
- D. Fever
- E. Nausea and vomiting
Red flags in fever Explanation: ***Clouded sensorium***
- **Altered mental status**, including confusion, disorientation, agitation, and clouded sensorium, is the hallmark feature that distinguishes **encephalitis** from meningitis
- **Encephalitis** involves direct inflammation of the **brain parenchyma**, leading to impaired brain function and altered consciousness
- While meningitis can cause irritability, profound changes in consciousness like disorientation and confusion are characteristic of **brain tissue involvement** rather than isolated meningeal inflammation
- The patient's confusion, disorientation, and agitation indicate parenchymal dysfunction, making encephalitis the more likely diagnosis
*Photophobia*
- Photophobia is a common symptom in **both meningitis and encephalitis**, reflecting meningeal irritation
- It results from inflammation of the meninges and does not indicate brain parenchymal involvement
- This symptom is **not a differentiating factor** between the two conditions
*Headache*
- Headache is a prominent symptom in **both meningitis and encephalitis** due to meningeal inflammation and increased intracranial pressure
- While often severe in meningitis, it can also occur in encephalitis when meningeal irritation is present (meningoencephalitis)
- Headache alone **does not specifically favor** one diagnosis over the other
*Fever*
- Fever is a systemic response to infection and inflammation, present in **both meningitis and encephalitis**
- It reflects the body's immune response to the infectious agent
- The presence of fever **does not help distinguish** between inflammation of the meninges alone versus inflammation involving the brain parenchyma
*Nausea and vomiting*
- Nausea and vomiting can occur in **both meningitis and encephalitis**, often associated with meningeal irritation and increased intracranial pressure
- These symptoms result from stimulation of the vomiting center and are common in many CNS infections
- These symptoms are **not specific enough to differentiate** between the two conditions
Red flags in fever US Medical PG Question 9: A 43-year-old woman was admitted to the hospital after a fall. When the emergency services arrived, she was unresponsive, did not open her eyes, but responded to painful stimuli. The witnesses say that she had convulsions lasting about 30 seconds when she lost consciousness after a traumatic event. On her way to the hospital, she regained consciousness. On admission, she complained of intense headaches and nausea. She opened her eyes spontaneously, was responsive but confused, and was able to follow motor commands. Her vital signs are as follows: blood pressure, 150/90 mm Hg; heart rate, 62/min; respiratory rate, 13/min; and temperature, 37.3℃ (99.1℉). There are no signs of a skull fracture. The pupils are round, equal, and poorly reactive to light. She is unable to fully abduct both eyes. Ophthalmoscopy does not show papillary edema or retinal hemorrhages. She has nuchal rigidity and a positive Kernig sign. An urgent head CT does not show any abnormalities. Which of the following is a proper investigation to perform in this patient?
- A. Lumbar puncture (Correct Answer)
- B. Angiography
- C. Sonography
- D. Brain MRI
- E. EEG
Red flags in fever Explanation: ***Lumbar puncture***
- The patient's symptoms, including **severe headache**, **nuchal rigidity**, **positive Kernig sign**, and **abnormal oculomotor findings** (poorly reactive pupils, inability to abduct eyes), despite a normal head CT, are highly suggestive of **subarachnoid hemorrhage**. A lumbar puncture is essential to look for **xanthochromia** (yellowish discoloration of CSF due to bilirubin from lysed red blood cells), which confirms the diagnosis, especially when CT is negative in the first 6-12 hours.
- The history of a "traumatic event" followed by convulsions and transient loss of consciousness, along with a "lucid interval" then renewed symptoms (headache, confusion), raises suspicion for head injury leading to hemorrhagic event. The **elevated BP and bradycardia** (Cushing's reflex components), though not fully developed, also suggest increased intracranial pressure, further warranting investigation for hemorrhage.
*Angiography*
- While angiography (CTA or conventional) is performed **after a subarachnoid hemorrhage is confirmed** to identify the source of bleeding (e.g., aneurysm), it is not the *initial* diagnostic test to *confirm* the hemorrhage itself when CT is negative.
- Doing an angiography before ruling out significant hemorrhage via LP (when CT is negative) is premature and could expose the patient to unnecessary risks without a confirmed diagnosis.
*Sonography*
- **Sonography** (ultrasound) has **no role** in the acute diagnosis of subarachnoid hemorrhage or other intracranial pathology in adults.
- It is used for imaging the brain in neonates through the open fontanelles but is ineffective through the adult skull.
*Brain MRI*
- While an **MRI is more sensitive than CT for detecting subarachnoid hemorrhage** (especially subacute hemorrhage or small bleeds missed by CT), it is generally **less readily available** in an emergency setting than CT and LP.
- In cases where CT is negative but clinical suspicion for SAH is high, **lumbar puncture is typically the next step** as it can detect early SAH via xanthochromia, which might not be immediately visible on MRI. MRI may be used later to identify causes or small bleeds not picked up by CT.
*EEG*
- An **EEG (electroencephalogram)** is used to **evaluate seizure activity** and other types of brain dysfunction related to electrical activity.
- While the patient had convulsions, the primary concern given her overall presentation (severe headache, meningeal signs, altered mental status, and cranial nerve palsies) is **subarachnoid hemorrhage**, not solely seizure. An EEG would not help diagnose the underlying cause of her acute neurological deterioration.
Red flags in fever US Medical PG Question 10: A 47-year-old male with a medical history significant for hypertension, recurrent urinary tract infections, mitral valve prolapse, and diverticulosis experiences a sudden, severe headache while watching television on his couch. He calls 911 and reports to paramedics that he feels as if "someone shot me in the back of my head." He is rushed to the emergency room. On exam, he shows no focal neurological deficits but has significant nuchal rigidity and photophobia. Of the options below, what is the most likely etiology of this man's headache?
- A. Temporal Arteritis
- B. Brain Tumor
- C. Carotid Dissection
- D. Migraine
- E. Subarachnoid Hemorrhage (Correct Answer)
Red flags in fever Explanation: ***Subarachnoid Hemorrhage***
- The sudden onset of a "thunderclap" headache, often described as the "worst headache of my life" or feeling like "someone shot me in the back of my head", is a classic presentation of **subarachnoid hemorrhage (SAH)**.
- **Nuchal rigidity** (neck stiffness) and **photophobia** are common signs of meningeal irritation due to blood in the subarachnoid space.
*Temporal Arteritis*
- Typically presents in older individuals (usually >50 years old) with headache, **scalp tenderness**, jaw claudication, and visual disturbances, often associated with elevated inflammatory markers.
- The sudden, extremely severe nature and the patient's age (47) make this less likely.
*Brain Tumor*
- Headache associated with a brain tumor usually has a more **gradual onset** and progressive worsening, often accompanied by **focal neurological deficits** or seizures.
- The acute, severe "thunderclap" nature described here is not typical for a brain tumor headache.
*Carotid Dissection*
- Carotid dissection can cause a sudden headache, often unilateral, and may be associated with **neck pain**, neurological deficits (e.g., Horner's syndrome, transient ischemic attacks, stroke symptoms), or cranial nerve palsies.
- While it can present with acute headache, the description of "worst headache of my life" and prominent nuchal rigidity without focal deficits points more strongly to SAH.
*Migraine*
- Migraines typically have a **prodrome** or a more gradual onset, often accompanied by aura, photophobia, phonophobia, and nausea; they are usually recurrent.
- While migraines can be severe, the description of a sudden, explosive headache with associated nuchal rigidity is more characteristic of a serious underlying vascular event like SAH.
More Red flags in fever US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
