CSF, Blood-Brain Barrier and Cerebral Circulation MCQs

Physiology · 44 free questions with answers & explanations.

  1. A 35-year-old woman on lithium therapy for bipolar disorder develops headache, nausea, and papilledema. CSF opening pressure is 32 cmH2O with normal cell count and protein. The CSF absorption pathway normally responsible for maintaining ICP homeostasis involves:
  2. A researcher administers a drug that inhibits Na+/K+-ATPase specifically in the choroid plexus. The expected primary effect on CSF composition is:
  3. Cerebral autoregulation maintains constant cerebral blood flow (CBF) over a mean arterial pressure (MAP) range of approximately 60–160 mmHg. A patient with chronic hypertension (MAP 130 mmHg for years) undergoes antihypertensive therapy, rapidly lowering MAP to 90 mmHg. The patient develops confusion and visual disturbances. The explanation is:
  4. The blood-brain barrier (BBB) prevents passage of certain substances into the CNS. Which of the following statements about BBB transport is MOST accurate?
  5. Which property of the blood-brain barrier explains why lipid-soluble drugs (e.g., thiopental) reach the brain rapidly while water-soluble drugs (e.g., aminoglycosides) do not?
  6. CSF is reabsorbed primarily at the arachnoid villi. Which pressure gradient drives this reabsorption?
  7. Cerebral autoregulation maintains constant cerebral blood flow (CBF) over a mean arterial pressure (MAP) range of approximately:
  8. A patient with cryptococcal meningitis has elevated CSF opening pressure of 45 cm H2O. CSF protein is 120 mg/dL and glucose is 35 mg/dL (serum 110 mg/dL). The primary site of CSF reabsorption in normal physiology — and its impairment in this context — involves:
  9. Cerebral autoregulation maintains relatively constant cerebral blood flow (CBF) over a range of mean arterial pressures. The primary mechanism of myogenic autoregulation in cerebral vessels involves:
  10. The blood-brain barrier (BBB) selectively restricts entry of substances into the CNS. The component of the BBB that provides the primary physical barrier to paracellular diffusion of hydrophilic solutes is:
  11. A patient with bacterial meningitis has CSF glucose of 20 mg/dL with simultaneous serum glucose of 90 mg/dL (CSF:serum ratio 0.22). Which mechanism PRIMARILY accounts for hypoglycorrhachia in bacterial meningitis?
  12. Cerebral perfusion pressure (CPP) is maintained at 70 mmHg by autoregulation. If mean arterial pressure suddenly drops to 50 mmHg and ICP is 15 mmHg, what is the CPP and what autoregulatory response is expected?
  13. A neurosurgeon installs an intracranial pressure monitor following severe TBI. The ICP waveform shows Lundberg B waves (rhythmic pressure waves every 0.5–2 minutes peaking at 20–50 mmHg). What is the physiological basis of these waves?
  14. Which drug class exploits the fact that the blood-brain barrier expresses high levels of P-glycoprotein (P-gp) efflux pump to PREVENT CNS penetration and thus limit CNS side effects?
  15. A 30-year-old man has normal blood glucose of 90 mg/dL but his CSF glucose is 20 mg/dL (CSF:plasma ratio 0.22; normal ≥0.6). CSF protein is 80 mg/dL. CSF opening pressure is 120 mmH2O (normal). What is the MOST likely diagnosis, and which transport mechanism is impaired?
  16. A head injury patient has an ICP of 28 mmHg and a mean arterial pressure of 80 mmHg. His cerebral perfusion pressure is calculated as 52 mmHg. On CT, there is no significant midline shift. Cerebral autoregulation is intact. Which of the following interventions will MOST specifically reduce ICP without reducing CPP further?
  17. Which of the following correctly explains the Monro-Kellie doctrine and its application to intracranial hypertension?
  18. Normal CSF production rate is approximately 0.35 mL/min (500 mL/day), yet total CSF volume is only 150 mL. This implies CSF turns over approximately _____ times per day.
  19. A patient develops bacterial meningitis with markedly elevated CSF protein (250 mg/dL), low glucose (25 mg/dL with serum glucose 90 mg/dL), and >1000 PMNs/µL. The low CSF glucose primarily results from:
  20. Cerebral blood flow (CBF) is autoregulated between mean arterial pressures (MAP) of approximately 50–150 mmHg. Which cellular mechanism is primarily responsible for myogenic autoregulation of CBF?
  21. Which of the following substances is actively excluded by the blood-brain barrier (BBB) via efflux transport, and deficiency of this transporter is implicated in increased CNS drug toxicity?
  22. A 30-year-old woman presents with persistent headache, papilloedema, and elevated CSF opening pressure of 28 cm H2O on lumbar puncture; CSF composition is normal. She has no intracranial mass. The diagnosis of idiopathic intracranial hypertension (pseudotumour cerebri) is suspected. Which is the primary mechanism for CSF pressure elevation in this condition?
  23. Cerebral blood flow (CBF) is tightly autoregulated between mean arterial pressures of 60 and 160 mmHg. In chronic hypertension, this autoregulatory range is shifted to the right. What is the primary mechanism of myogenic autoregulation of cerebral vessels?
  24. The blood-brain barrier (BBB) is formed by tight junctions between cerebral endothelial cells expressing claudins-3, -5, and -12. Which of the following substances crosses the BBB most readily under physiological conditions?
  25. A patient with bacterial meningitis has CSF findings: protein 200 mg/dL, glucose 20 mg/dL (serum glucose 80 mg/dL), cells 1500/mm3 (90% neutrophils). The CSF:serum glucose ratio is 0.25. Which factor most directly causes the low CSF glucose in bacterial meningitis?
  26. Cerebral autoregulation maintains constant cerebral blood flow (CBF) over what mean arterial pressure (MAP) range, and which of the following conditions impairs this autoregulation?
  27. The blood-brain barrier (BBB) restricts entry of most hydrophilic molecules into the CNS. Which of the following most accurately explains the structural basis of the BBB?
  28. Hypercapnia causes cerebral vasodilation and increases CBF. The primary mechanism mediating this response is:
  29. Cerebrospinal fluid (CSF) is primarily produced by the choroid plexus of the lateral, third, and fourth ventricles. The normal rate of CSF production and total volume are approximately:
  30. Normal CSF composition differs from plasma. Which of the following accurately describes normal lumbar CSF values?
  31. Cerebral blood flow (CBF) is autoregulated between mean arterial pressures of approximately 60–160 mmHg. The primary local vascular mechanism responsible for cerebral autoregulation is:
  32. The blood-brain barrier (BBB) is formed primarily by which structural element?
  33. Cerebrospinal fluid is produced at approximately 500 mL/day, yet the total CSF volume is only 150 mL. At what rate is CSF produced, and where is it primarily absorbed?
  34. The blood-brain barrier (BBB) is formed primarily by cerebral endothelial cells with tight junctions. Which substance is NOT reliably excluded by the intact BBB?
  35. Cerebral autoregulation maintains a constant cerebral blood flow (CBF) over a range of mean arterial pressures. What is the normal autoregulatory range, and what mediates this response?
  36. Normal adult lumbar CSF pressure is 6–18 cmH2O. A patient with idiopathic intracranial hypertension (IIH) has a CSF pressure of 30 cmH2O. Which of the following correctly explains how elevated ICP manifests as papilledema?
  37. CSF is produced primarily by the choroid plexus via an active secretory process. Which ion transport mechanism is the rate-limiting step in CSF secretion?
  38. Normal adult CSF pressure measured by lumbar puncture in the lateral decubitus position is 7–18 cmH2O. A patient has a pressure of 28 cmH2O with normal CSF composition. Which condition most commonly causes raised CSF pressure with normal composition?
  39. The blood-brain barrier (BBB) is maintained by tight junctions between cerebral capillary endothelial cells. Which substance crosses the BBB most readily by simple passive diffusion?
  40. Cerebral autoregulation maintains constant cerebral blood flow (CBF) over a MAP range of approximately 60–160 mmHg. A patient with chronic hypertension has a rightward shift of this autoregulatory curve. What is the immediate clinical implication when their MAP drops to 70 mmHg (e.g., after aggressive antihypertensive therapy)?
  41. Cerebrospinal fluid (CSF) is produced primarily by the choroid plexus. What is the approximate rate of CSF production and total volume in an adult?
  42. Cerebral blood flow (CBF) is maintained at approximately 50 mL/100g/min over a wide range of mean arterial pressures (50–150 mmHg). The primary mechanism responsible for this autoregulation is:
  43. The blood-brain barrier (BBB) is primarily formed by the tight junctions of cerebral capillary endothelial cells. Which of the following substances crosses the intact BBB most readily?
  44. In normal pressure hydrocephalus (NPH), CSF pressure is paradoxically normal. The mechanism causing ventriculomegaly despite normal CSF pressure is:
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