4.5 Practice Drills and Readiness Markers

Numbers You Must Recall Instantly

The CEN rewards speed. Build automaticity on these figures so you do not burn time on the test deriving them. Drill them aloud until each comes in under ten seconds.

The most common arithmetic item on the exam is CPP. Practice: if MAP is 85 and ICP is 22, CPP = 63 mmHg — adequate but the ICP still needs treatment. If MAP is 70 and ICP is 25, CPP = 45 mmHg — critically low and the brain is being starved.

Discriminator Drills and the Missed Posterior Stroke

Most wrong answers come from confusing look-alikes. Rehearse the discriminator for each pair until it is reflexive:

• Ischemic vs hemorrhagic stroke: hemorrhage is more likely with severe early headache, vomiting, very high blood pressure, and rapid depressed consciousness — and CT shows blood. Thrombolytics are only for ischemic strokes with a clean (no-blood) CT.
• Neurogenic vs hypovolemic shock: bradycardia and warm skin point to neurogenic; tachycardia and cool, clammy skin point to hypovolemic.
• Meningitis vs encephalitis: nuchal rigidity dominates meningitis; altered behavior, seizures, and focal deficits dominate encephalitis.
• TIA vs stroke: TIA deficits resolve with no infarct on imaging; a stroke leaves an infarct.
• Spinal shock vs neurogenic shock: spinal shock is areflexia/flaccidity (neurologic); neurogenic shock is hypotension with bradycardia (hemodynamic).

The most frequently missed stroke is posterior-circulation (vertebrobasilar), because it does not give classic face/arm weakness. Memorize the 5 D's: Dizziness, Diplopia, Dysarthria, Dysphagia, and Dystaxia (ataxia), often with sudden vertigo, nausea, and balance loss. A patient written off as having vertigo or intoxication may be infarcting the brainstem or cerebellum.

Readiness Markers and Test-Day Behavior

You are ready for this domain when you can do four things without hesitation. 5 hours, and thrombectomy evaluation to 24 hours. Second, run the timed status epilepticus staircase — stabilize, benzodiazepine, second-line agent, then anesthetic infusion — naming the drug for each phase. Third, recognize rising ICP early, acting on a declining level of consciousness rather than waiting for the terminal Cushing's triad, and reach for head-of-bed elevation and hyperosmolar therapy. Fourth, identify the discriminating finding that separates each look-alike pair above.

On test day, anchor every neurological item to its time window or its single discriminating sign. When a stem buries a time in the history ("symptoms began 5 hours ago"), that number is usually the answer key — it pushes you from thrombolysis to thrombectomy or rules reperfusion out entirely. When a stem lists vital signs, scan first for the shock pattern (bradycardia vs tachycardia) and the Cushing reflex. Treat the rapidly reversible threat — glucose, airway, naloxone, oxygen — before chasing the exotic diagnosis. That disciplined, threat-first reasoning is exactly what the CEN measures in this domain.

Rapid-Fire Self-Check

Use these one-line prompts as a final cram. Cover the answer, recall it, and move on; anything you cannot produce in seconds is a gap to close before test day.

• What is the IV thrombolytic window? 4.5 hours from last-known-well.
• What BP must precede tPA? Below 185/110 mmHg.
• When does thrombectomy still help? Up to 24 hours for anterior LVO with favorable imaging.
• First drug for status epilepticus? A benzodiazepine (lorazepam or midazolam).
• Define status epilepticus. Seizure 5 minutes or longer, or repeated seizures without recovery.
• Normal ICP? Treat above? 7-15 mmHg; treat above 20-22 mmHg.
• CPP formula and target? MAP minus ICP; 60-70 mmHg.
• Earliest sign of rising ICP? Declining level of consciousness.
• Cushing's triad? Hypertension with widening pulse pressure, bradycardia, irregular respirations.
• Neurogenic shock pattern? Hypotension with bradycardia and warm skin.
• GBS killer to monitor? Respiratory failure (vital capacity).
• Thunderclap headache means? Subarachnoid hemorrhage until excluded.
• Meningitis golden rule? Do not delay antibiotics.
• Forehead spared on facial droop? Central (stroke); forehead involved is Bell's palsy.

If every prompt above produced an instant, confident answer, you have reached readiness for the Neurological Disorders domain. Where you hesitated, return to that section, re-read the rule and its single discriminating sign, and re-drill until recall is automatic — that automaticity is what protects your time and accuracy on exam day. The candidates who pass this domain are not the ones who memorize the most facts but the ones who retrieve the right rule fastest under pressure.

Neuro rapid-recall

• Suspected stroke: check glucose immediately, get a non-contrast CT to rule out bleed, and establish last-known-well before any tPA decision.
• Status epilepticus = a seizure ≥5 minutes or back-to-back seizures without recovery; first-line is a benzodiazepine, then levetiracetam or fosphenytoin.
• Rising ICP: elevate the head of bed to 30°, keep the neck midline, treat with hypertonic saline or mannitol, and watch for Cushing triad (hypertension, bradycardia, irregular respirations).