CGA 27 Med Brain Brawl 2025

Pathology

100

1. A 72-year-old man with chronic hypertension presents with sudden-onset left-sided weakness and slurred speech. MRI shows an infarct in the right internal capsule. What is the most likely underlying pathology?

A) Atherosclerotic plaque rupture and thrombus formation
B) Lipohyalinosis and small vessel occlusion
C) Embolism from the left atrium
D) Charcot-Bouchard aneurysm rupture
E) Arteriovenous malformation

Answer: (B) Lipohyalinosis and small vessel occlusion

📌 Explanation:

• The internal capsule is a common location for lacunar infarcts, which occur due to hypertensive small vessel disease.
• Lipohyalinosis and fibrinoid necrosis cause occlusion of small penetrating arteries.
• Lacunar infarcts present with pure motor or sensory deficits without cortical signs.

200

2. A 45-year-old woman presents with an enlarging, firm breast mass. Biopsy reveals malignant cells with overexpression of HER2/neu. Which of the following best describes the mechanism of HER2/neu in tumorigenesis?

A) Tumor suppressor gene inactivation
B) DNA mismatch repair deficiency
C) Proto-oncogene activation via tyrosine kinase signaling
D) Chromosomal translocation activating anti-apoptotic proteins
E) Impaired nucleotide excision repair

Answer: (C) Proto-oncogene activation via tyrosine kinase signaling

📌 Explanation:

• HER2/neu (ERBB2) is a proto-oncogene encoding a tyrosine kinase receptor.
• Overexpression leads to unregulated cell proliferation and aggressive tumor growth.
• HER2+ breast cancer responds well to Trastuzumab (HER2 inhibitor).

300

4. A 62-year-old man presents with generalized fatigue and unintentional weight loss. Physical exam reveals splenomegaly. Peripheral blood smear shows numerous smudge cells. Flow cytometry detects CD5 and CD20 co-expression. Which of the following best describes the pathogenesis of this disease?

A) Clonal expansion of mature B cells with defective apoptosis
B) Overproduction of immature myeloid precursors
C) Excessive erythrocyte production due to JAK2 mutation
D) Chromosomal translocation involving the BCL-2 gene
E) Proliferation of plasma cells with excess monoclonal IgG

 Answer: (A) Clonal expansion of mature B cells with defective apoptosis

📌 Explanation:

• The patient has Chronic Lymphocytic Leukemia (CLL), characterized by:
  • CD5+/CD20+ B cells
  • Smudge cells on blood smear
  • Splenomegaly & lymphocytosis
• Pathogenesis: Defective apoptosis (BCL-2 overexpression) leads to accumulation of mature but dysfunctional B cells.

400

3. A 28-year-old woman presents with fatigue, weight loss, and recurrent fevers. Physical exam reveals a malar rash, oral ulcers, and mild arthritis. Laboratory testing shows a positive ANA and anti-dsDNA, decreased C3 and C4 levels, and proteinuria. A kidney biopsy is performed. Which of the following is the most likely finding?

A) Mesangial IgA deposition
B) Wire-loop lesions with subendothelial immune complex deposition
C) Onion-skinning of arterioles
D) Linear IgG and C3 deposits along the basement membrane
E) Granulomatous inflammation with multinucleated giant cells

Answer: (B) Wire-loop lesions with subendothelial immune complex deposition

📌 Explanation:

• The patient has systemic lupus erythematosus (SLE) with lupus nephritis (proteinuria, low complement).
• Diffuse proliferative glomerulonephritis (DPGN) is the most severe form of lupus nephritis.
• "Wire-loop lesions" are due to subendothelial immune complex deposits (IgG & C3).

500

A 7-year-old boy presents with progressive behavioral changes, cognitive decline, and myoclonic jerks. He had measles infection 6 years ago but was never vaccinated. MRI shows white matter demyelination, and CSF analysis reveals elevated measles antibodies without IgG in serum. What is the most likely diagnosis?

A) Subacute sclerosing panencephalitis (SSPE)
B) Progressive multifocal leukoencephalopathy (PML)
C) Acute disseminated encephalomyelitis (ADEM)
D) Creutzfeldt-Jakob disease
E) Cytomegalovirus encephalitis

Answer: (A) Subacute sclerosing panencephalitis (SSPE)

📌 Explanation:

• SSPE is a rare, fatal complication of measles caused by persistent mutated measles virus in the CNS.
• Symptoms: Cognitive decline, myoclonus, and progressive neurological deterioration.
• Pathognomonic finding: CSF measles IgG antibodies with no serum IgG (intrathecal synthesis).
• Demyelination on MRI is due to viral-induced neuronal destruction.

Anatomy/Physio

100

1. A 25-year-old athlete is running a marathon. During exercise, which of the following compensatory physiological changes occurs in skeletal muscle to increase oxygen delivery?

A) Decreased capillary recruitment
B) Decreased arteriolar resistance
C) Decreased oxygen extraction
D) Decreased cardiac output
E) Decreased venous return

Answer: (B) Decreased arteriolar resistance

📌 Explanation:

• During exercise, skeletal muscle arterioles dilate (decreased resistance) to increase blood flow and oxygen delivery.
• Increased capillary recruitment and oxygen extraction further enhance oxygen utilization.
• Cardiac output and venous return increase to meet metabolic demands.

200

A 72-year-old man with a history of heart failure presents with worsening shortness of breath and bilateral leg swelling. Which of the following best describes his left ventricular end-diastolic pressure (LVEDP) and pulmonary capillary wedge pressure (PCWP)?

A) LVEDP ↑, PCWP ↓
B) LVEDP ↓, PCWP ↓
C) LVEDP ↑, PCWP ↑
D) LVEDP ↓, PCWP ↑
E) LVEDP normal, PCWP normal

Answer: (C) LVEDP ↑, PCWP ↑

📌 Explanation:

• In left-sided heart failure, the left ventricle cannot adequately pump blood forward, leading to increased LVEDP.
• This backups pressure into the left atrium and pulmonary circulation, increasing PCWP (a measure of left atrial pressure).
• Increased PCWP → Pulmonary congestion → Dyspnea & edema.

300

4. A 62-year-old man presents with generalized fatigue and unintentional weight loss. Physical exam reveals splenomegaly. A peripheral blood smear shows numerous smudge cells. Flow cytometry detects CD5 and CD20 co-expression, confirming chronic lymphocytic leukemia (CLL). Which of the following anatomical structures is responsible for destroying these abnormal cells?

A) Liver sinusoids
B) Red pulp of the spleen
C) White pulp of the spleen
D) Bone marrow sinusoids
E) Thymic medulla

 Answer: (B) Red pulp of the spleen

📌 Explanation:

• The red pulp of the spleen functions to filter aged and abnormal blood cells (including CLL cells).
• The white pulp is involved in immune function, particularly adaptive immunity.
• Splenomegaly in CLL occurs due to excessive clearance of abnormal lymphocytes in the red pulp.

400

A 65-year-old man with a history of hypertension and coronary artery disease presents to the emergency department with crushing substernal chest pain radiating to his left arm. His ECG shows ST-segment elevations in leads II, III, and aVF, consistent with an inferior myocardial infarction (MI).

Which of the following anatomical structures is most likely occluded, and what physiological effect would be expected due to this occlusion?

A) Left anterior descending artery (LAD); decreased contractility of the anterior wall of the left ventricle
B) Left circumflex artery (LCX); impaired perfusion of the lateral wall of the left ventricle
C) Right coronary artery (RCA); bradycardia due to involvement of the sinoatrial (SA) node
D) Posterior descending artery (PDA); decreased conduction through the right bundle branch
E) Right marginal artery; reduced blood flow to the right atrium and atrioventricular (AV) node

Correct Answer: (C) Right coronary artery (RCA); bradycardia due to involvement of the sinoatrial (SA) node

📌 Explanation:

• ST-segment elevations in leads II, III, and aVF indicate an inferior wall MI, which is most commonly caused by occlusion of the right coronary artery (RCA).
• The RCA supplies blood to the SA node (~60% of people) and the AV node (~80% of people via the PDA).
• Inferior MI can lead to bradycardia due to ischemia of the SA node, affecting pacemaker function and causing sinus bradycardia or heart block.

500

A 55-year-old man presents with difficulty swallowing, hoarseness, and deviation of the uvula to the left. He also reports loss of gag reflex on the right side and mild dizziness when turning his head to the right. On physical examination, his right shoulder appears slightly drooped, and he has difficulty elevating it against resistance. Neurological examination reveals no tongue deviation.

Which of the following best localizes the lesion?

A) Right medulla affecting the nucleus ambiguus and spinal accessory nerve
B) Left jugular foramen affecting cranial nerves IX, X, and XI
C) Right cerebellopontine angle compressing cranial nerves VII and VIII
D) Right hypoglossal canal affecting cranial nerve XII
E) Left cavernous sinus compressing cranial nerves III, IV, V1, V2, and VI

Correct Answer: (B) Left jugular foramen affecting cranial nerves IX, X, and XI

• The jugular foramen transmits cranial nerves IX (glossopharyngeal), X (vagus), and XI (spinal accessory). A lesion in this area results in Jugular Foramen Syndrome (Vernet Syndrome).
• Key findings in this patient:
  • Dysphagia & hoarseness → Vagus nerve (CN X) dysfunction
  • Uvula deviation to the left → Right-sided CN X lesion (uvula deviates away from the lesion)
  • Absent right gag reflex → Right CN IX lesion
  • Right shoulder droop & difficulty elevating it → Right spinal accessory nerve (CN XI) lesion

Because these symptoms all localize to the right CN IX, X, and XI, the lesion is most likely in the right jugular foramen.

Micro

100

A 63-year-old man presents with rapidly progressive dementia, personality changes, and myoclonus over the past 3 months. His family reports that he was previously healthy but has developed difficulty with coordination and memory loss. On physical examination, he has startle myoclonus and signs of cerebellar dysfunction. MRI of the brain shows cortical ribboning and basal ganglia hyperintensities. EEG reveals periodic sharp wave complexes, and cerebrospinal fluid (CSF) analysis is positive for 14-3-3 protein.

Which of the following best describes the pathophysiology of this disease?

A) Misfolding of α-synuclein leading to Lewy body deposition
B) Abnormal spongiform transformation of gray matter due to misfolded prion protein (PrPSc)
C) Accumulation of β-amyloid plaques and neurofibrillary tangles
D) Demyelination due to JC virus reactivation in oligodendrocytes
E) Autoimmune-mediated destruction of NMDA receptors in the limbic system

Correct Answer: (B) Abnormal spongiform transformation of gray matter due to misfolded prion protein (PrPSc)

• The patient presents with rapidly progressive dementia, myoclonus, and ataxia, which are classic features of Creutzfeldt-Jakob Disease (CJD).
• CJD is a prion disease, caused by the abnormal conversion of normal prion protein (PrPc) into its misfolded form (PrPSc).
• This leads to spongiform degeneration of the gray matter, giving a "spongy" appearance to the brain.

200

 A 6-year-old boy presents with a sore throat, fever, and difficulty swallowing. On examination, his tonsils are erythematous with white exudates. A rapid streptococcal antigen test is positive. Which of the following best describes the causative organism?

A) Gram-negative rod, oxidase-positive
B) Gram-positive cocci in clusters, catalase-positive
C) Gram-positive cocci in chains, beta-hemolytic
D) Gram-negative diplococci, maltose fermenter
E) Gram-positive rod, spore-forming

Answer: (C) Gram-positive cocci in chains, beta-hemolytic

📌 Explanation:

• The patient has streptococcal pharyngitis (strep throat) caused by Streptococcus pyogenes (Group A Strep, GAS).
• GAS is Gram-positive, forms chains, and is β-hemolytic on blood agar.
• Early treatment with penicillin prevents rheumatic fever, but not post-streptococcal glomerulonephritis.

300

A 7-year-old girl presents with sudden onset vomiting and profuse, watery diarrhea 6 hours after eating potato salad at a picnic. She has no fever. Which of the following best explains the pathogenesis of her symptoms?

A) Bacterial invasion of the intestinal mucosa
B) Heat-labile and heat-stable toxin production
C) Preformed enterotoxin-mediated illness
D) Shiga-like toxin-induced cytotoxicity
E) Attachment to intestinal epithelium via Type III secretion system

(C) Preformed enterotoxin-mediated illness

📌 Explanation:

• Rapid-onset vomiting & diarrhea within 6 hours after food ingestion suggests Staphylococcus aureus food poisoning.
• S. aureus produces a preformed enterotoxin (heat-stable), which directly stimulates the vagus nerve and intestinal lining, causing nausea and diarrhea.
• Self-limited illness; no antibiotics needed.

400

A 32-year-old man presents for a routine checkup. He reports no symptoms but mentions that his wife was recently diagnosed with chronic hepatitis B. His vaccination history is unclear. His lab results are as follows:

Marker Result

HBsAg (Hepatitis B surface antigen)Negative

Anti-HBc (Hepatitis B core antibody)Negative

Anti-HBs (Hepatitis B surface antibody)Positive

Which of the following is the most likely interpretation of these results?

A) Acute Hepatitis B infection
B) Chronic Hepatitis B infection
C) Prior Hepatitis B infection with immunity
D) Vaccinated against Hepatitis B
E) Window period of Hepatitis B infection

(D) Vaccinated against Hepatitis B

📌 Explanation:

• HBsAg negative → No active infection.
• Anti-HBc negative → No history of prior natural infection.
• Anti-HBs positive → Immunity is present, but since Anti-HBc is negative, this immunity is due to vaccination, not past infection.
• Vaccination results in Anti-HBs positivity without Anti-HBc, whereas past infection would show both Anti-HBc and Anti-HBs positivity.

500

A 36-year-old woman presents with fever, malaise, and a widespread maculopapular rash that involves the palms and soles. She also reports a sore throat and patchy hair loss over the past few weeks. She has a history of multiple sexual partners and does not use barrier protection. Physical exam reveals generalized lymphadenopathy, and mucous patches are seen on the oral mucosa. Darkfield microscopy of a lesion exudate reveals spiral-shaped motile organisms.

Which of the following is the most important virulence factor responsible for the pathogenesis of this disease?

A) Exotoxin A
B) Lipooligosaccharide (LOS)
C) Endoflagella (Periplasmic flagella)
D) M protein
E) Capsular polysaccharide

Correct Answer: (C) Endoflagella (Periplasmic flagella)

• The patient presents with secondary syphilis, caused by Treponema pallidum, which is a spirochete.
• Key signs: Maculopapular rash on the palms and soles, generalized lymphadenopathy, condylomata lata, mucous patches, and patchy alopecia.
• Treponema pallidum uses endoflagella (periplasmic flagella) for motility and tissue invasion, allowing it to disseminate through the bloodstream, which is key to the systemic spread seen in secondary syphilis.

Pharm

100

1. A 24-year-old woman is diagnosed with a urinary tract infection caused by Escherichia coli. She is prescribed an antibiotic that inhibits bacterial DNA gyrase. Which of the following best describes the mechanism of action of this drug?

A) Inhibits transpeptidase enzyme in bacterial cell wall synthesis
B) Inhibits DNA-dependent RNA polymerase
C) Binds to 50S ribosomal subunit, blocking protein synthesis
D) Inhibits bacterial topoisomerase II and IV, preventing DNA replication
E) Blocks folate synthesis by inhibiting dihydropteroate synthase

Answer: (D) Inhibits bacterial topoisomerase II and IV, preventing DNA replication

📌 Explanation:

• Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) inhibit DNA gyrase (topoisomerase II) and topoisomerase IV, preventing bacterial DNA replication.
• Used for gram-negative UTIs, respiratory infections, and some GI infections.

200

A 67-year-old man with atrial fibrillation is started on an antiarrhythmic drug that prolongs the action potential duration and increases the QT interval. The drug has a risk of causing torsades de pointes. Which of the following drugs was most likely prescribed?

A) Lidocaine
B) Metoprolol
C) Amiodarone
D) Verapamil
E) Digoxin

Answer: (C) Amiodarone

📌 Explanation:

• Class III antiarrhythmics (K+ channel blockers, e.g., Amiodarone, Sotalol, Dofetilide) prolong repolarization → increased QT interval.
• Amiodarone is the most commonly used but has less torsades risk compared to other Class III drugs like Sotalol.

300

A 75-year-old woman with atrial fibrillation is started on an anticoagulant that directly inhibits Factor Xa. Which of the following drugs was most likely prescribed?

A) Warfarin
B) Heparin
C) Rivaroxaban
D) Alteplase
E) Aspirin

 Answer: (C) Rivaroxaban

📌 Explanation:

• Rivaroxaban, Apixaban, Edoxaban → Direct Factor Xa inhibitors (DOACs).
• Used for stroke prevention in atrial fibrillation and DVT/PE treatment.
• Unlike warfarin, no need for INR monitoring

400

A 35-year-old woman with moderate persistent asthma is prescribed a medication that acts as a long-acting beta-2 agonist (LABA) to provide sustained bronchodilation. Which of the following best describes the mechanism of action of this drug?

A) Inhibits phosphodiesterase, increasing cAMP levels
B) Increases intracellular cGMP via nitric oxide activation
C) Blocks muscarinic receptors in bronchial smooth muscle
D) Activates adenylyl cyclase, increasing cAMP and promoting bronchodilation
E) Inhibits leukotriene receptors, reducing bronchoconstriction

Answer: (D) Activates adenylyl cyclase, increasing cAMP and promoting bronchodilation

📌 Explanation:

• Beta-2 agonists (e.g., Albuterol [short-acting], Salmeterol, Formoterol [long-acting]) stimulate adenylyl cyclase, increasing cAMP, leading to bronchodilation.
• LABAs (e.g., Salmeterol, Formoterol) are used for long-term control in asthma and COPD but are NOT used as monotherapy (always combined with ICS).

500

 A hospitalized patient with ventilator-associated pneumonia grows Klebsiella pneumoniae resistant to cephalosporins and carbapenems. A last-resort antibiotic is given that disrupts bacterial membrane integrity by acting as a cationic detergent. Which of the following drugs was most likely administered?

A) Linezolid
B) Vancomycin
C) Polymyxins (Colistin, Polymyxin B)
D) Daptomycin
E) Tigecycline

Answer: (C) Polymyxins (Colistin, Polymyxin B)

📌 Explanation:

• Polymyxins (Colistin, Polymyxin B) act as cationic detergents, disrupting bacterial membranes (especially gram-negative bacteria).
• Used for multidrug-resistant (MDR) gram-negative infections (e.g., Klebsiella, Pseudomonas, Acinetobacter).
• High nephrotoxicity & neurotoxicity, limiting use.

OMM

100

A 30-year-old woman presents with neck stiffness after sleeping in an awkward position. OMM exam reveals a diagnosis of C4 ESRRR. Which of the following best describes the setup for facilitated positional release (FPR)?

A) Extend, sidebend right, and rotate right, then apply compression
B) Extend, sidebend left, and rotate left, then apply compression
C) Flex, sidebend right, and rotate right, then apply traction
D) Flex, sidebend left, and rotate right, then apply compression
E) Neutralize, then apply counterforce while the patient moves against resistance

 Answer: (A) Extend, sidebend right, and rotate right, then apply compression

📌 Explanation:

• Facilitated Positional Release (FPR) is an indirect technique where you place the vertebra in its diagnosis (ease of motion), then apply compression to facilitate release.
• C4 ESRRR → You set up extension, right sidebending, and right rotation, then apply compression to enhance the technique.

200

A 55-year-old man with a history of coronary artery disease presents with chest pain. His cardiac workup is negative, and OMM assessment is performed. Palpation reveals a tender, firm nodule at the 2nd intercostal space, just lateral to the sternum bilaterally. This Chapman’s reflex point is most associated with dysfunction in which organ?

A) Lungs
B) Heart
C) Liver
D) Adrenals
E) Esophagus

Answer: (B) Heart

📌 Explanation:

• Chapman’s points are viscerosomatic reflexes indicating organ dysfunction.
• Heart Chapman’s point is located at the 2nd intercostal space, lateral to the sternum.
• Lung points are in the 3rd & 4th intercostal spaces, liver is in the 5th & 6th right intercostal spaces, and adrenals are above the umbilicus bilaterally.

300

A 60-year-old man with chronic obstructive pulmonary disease (COPD) presents with increased shortness of breath and mild peripheral edema. Physical exam reveals restricted motion of the thoracic cage, and palpation of the right clavicle reveals a firm, immobile barrier over the supraclavicular fossa. Which of the following is the most appropriate initial OMM treatment?

A) Rib raising to improve sympathetic tone
B) Thoracic inlet release to improve lymphatic drainage
C) Counterstrain for the sternocleidomastoid muscle
D) High-velocity, low-amplitude (HVLA) for the right clavicle
E) Doming the diaphragm to improve venous return

B) Thoracic inlet release to improve lymphatic drainage

📌 Explanation:

• The thoracic inlet (cervicothoracic junction) is the main drainage site for lymphatic flow into the venous system (subclavian vein).
• Restriction in this area can impair drainage, leading to fluid retention, peripheral edema, and worsened respiratory function.
• Thoracic inlet release should always be done first in lymphatic treatments to clear the pathway for fluid movement.

400

A 34-year-old woman presents with right-sided chest pain after a coughing episode. You palpate Rib 4 on the right and find that it moves more freely with exhalation and is restricted in inhalation. What is the best initial muscle energy treatment?

A) Have the patient push her head forward while resisting motion
B) Ask the patient to take a deep breath while resisting inhalation
C) Instruct the patient to contract the pectoralis minor muscle while inhaling
D) Resist exhalation motion while engaging the serratus anterior muscle
E) Apply direct myofascial release to the diaphragm

Answer: (C) Instruct the patient to contract the pectoralis minor muscle while inhaling

📌 Explanation:

• Key finding: Rib 4 moves freely in exhalation but is restricted in inhalation → This is an exhalation dysfunction (stuck down).
• To treat exhalation dysfunction, you engage the key muscle that lifts the specific rib during inhalation.
  • Ribs 1-2 → Scalenes
  • Ribs 3-5 → Pectoralis minor
  • Ribs 6-9 → Serratus anterior
  • Ribs 10-12 → Latissimus dorsi

500

A 40-year-old man presents with low back pain after standing for long periods at work. OMM exam reveals a positive seated flexion test on the right, a deep sacral sulcus on the left, and a posterior/inferior ILA on the right. What is the most likely sacral diagnosis?

A) Left-on-left sacral torsion
B) Left-on-right sacral torsion
C) Right-on-right sacral torsion
D) Right-on-left sacral torsion
E) Unilateral sacral extension on the right

Answer: (D) Right-on-left sacral torsion

📌 Explanation:

• Seated flexion test positive on the right → Dysfunction is on the right side.
• Deep sacral sulcus on the left & posterior ILA on the right → Suggests leftward sacral base rotation.
• Axis is always opposite the seated flexion test → Left oblique axis.
• Sacral rotation is opposite the axis → Right rotation on a left axis = Right-on-left backward torsion.