SCRN common mistakes
SCRN · Understand the traps and how to avoid them.
When a vignette describes vertigo, diplopia, dysarthria, or crossed sensory findings, the candidate assigns the lesion to the MCA or labels it a benign peripheral process rather than localizing to the posterior circulation (vertebrobasilar) territory.
Candidates memorize the 'big three' cortical syndromes (MCA/ACA/PCA) and default to cortical localizing language; posterior circulation syndromes are less visually obvious on the classic 'face-arm-speech' frame and are frequently described with vague symptoms like dizziness.
What to do instead
Build a territory checklist and apply it to every item: brainstem/cerebellum = vertigo, diplopia, dysarthria, dysphagia, ataxia, crossed signs, 'herald' symptoms; PCA = isolated homonymous hemianopia without weakness; MCA = face/arm-predominant plus aphasia or neglect. Explicitly ask 'is there any cranial nerve or crossed finding?' before choosing a cortical territory.
Leg-predominant weakness with urinary incontinence and abulia is attributed to the MCA, or face/arm-predominant weakness with neglect is attributed to the ACA.
Candidates anchor on the most frequently tested artery (MCA) and on the presence of weakness rather than the distribution of weakness, and they under-weight the cortical behavioral signs that separate the two territories.
What to do instead
Anchor on the homunculus: ACA supplies the medial surface (contralateral leg > arm, abulia, incontinence, contralateral grasp); MCA supplies the lateral surface (face/arm > leg, aphasia if dominant, neglect if nondominant). Practice sorting vignettes strictly by 'which limb is worst' plus behavioral signs.
NIHSS items are scored as '0' when they cannot be assessed (e.g., ataxia in a patient who cannot ambulate, dysarthria in an intubated patient), or ataxia is scored 'present' in a patient with hemiparesis who simply cannot move the limb.
Candidates want to complete every item and treat a blank as a zero; they also do not distinguish motor weakness from true incoordination, and they have not internalized the 'UN = untestable' convention and the coma-scoring rules.
What to do instead
Memorize the untestable rules: score UN only where the scale permits it (ataxia in a patient who cannot ambulate or is paralyzed is UN, not 0), and score 0 only when the function is genuinely normal. Remember that in a patient with hemiparesis, ataxia is judged in the unaffected limb; in coma, follow the mandated default scores for each item rather than guessing.
On the 'best language' item, the candidate scores a patient with slurred but fluent, correctly-named speech as aphasic, or scores a patient with fluent but empty, paraphasic speech as dysarthric only.
Both present as 'abnormal speech' and candidates use the words interchangeably; they do not systematically test naming, repetition, and comprehension separately from articulation.
What to do instead
Separate the constructs explicitly: dysarthria is a motor articulation problem with intact language content (ask the patient to repeat words and assess clarity); aphasia is a language deficit (test object naming, comprehension of commands, repetition). Score the aphasia item on language content and the dysarthria item on articulation, and never let one contaminate the other.
The candidate applies a uniform 3-hour thrombolysis window to every ischemic stroke vignette and excludes a patient with a large vessel occlusion who is 12 hours from last known well and meets perfusion/clinical mismatch criteria from any reperfusion therapy.
Older teaching and single-drug memorization dominate; candidates conflate the IV alteplase window with the thrombectomy window and do not track which patients require advanced imaging selection.
What to do instead
Memorize the two decisions separately: IV alteplase within 4.5 hours of last known well (with selected extended-window/wake-up patients eligible only via imaging selection), and endovascular thrombectomy 0–6 hours for anterior large vessel occlusion, extending to 6–24 hours when DAWN/DEFUSE-3 clinical-imaging mismatch criteria are met. Before answering, state last known well and whether imaging selection criteria are satisfied.
The candidate either gives alteplase to a patient with a blood pressure of 190/105 without first lowering it, or aggressively drives an acute ischemic stroke patient's pressure down to normotensive targets in the first 24 hours.
Candidates remember 'blood pressure must be controlled' without remembering which number applies to which situation, and they misapply chronic hypertension targets to the acutely ischemic brain.
What to do instead
Learn the thresholds as paired rules: before alteplase, lower to <185/110 and keep <180/105 for 24 hours post-treatment; without reperfusion therapy, permissive hypertension is generally allowed unless there is another indication (e.g., concomitant myocardial ischemia, aortic dissection, ICH). In spontaneous ICH, target systolic 130–150 and avoid dropping below 130.
The candidate orders oral medications, food, or a diet order before a documented dysphagia screen, or omits the swallow screen entirely because the patient 'looks alert.'
Attention is on the clot and the clock, and swallowing is treated as a nursing formality rather than a determinant of aspiration pneumonia; alertness is incorrectly used as a proxy for swallowing safety.
What to do instead
Treat a documented dysphagia screen as a hard gate on anything by mouth (including pills, which may need to be held or given by an alternative route). Know that screening should occur before the first oral intake and that a failed screen triggers speech-language pathology evaluation, nil per os status, and aspiration precautions.
The candidate attributes a new flat affect, poor participation, or refusal of therapy after stroke to 'expected post-stroke fatigue' or 'noncompliance' and does not screen for post-stroke depression or anxiety.
Mood symptoms overlap with the motor and cognitive consequences of stroke, and rehabilitation settings reward physical progress, so emotional and cognitive barriers are under-recognized and under-documented.
What to do instead
Build mood and cognition into the assessment reflex: screen with a validated tool, recognize that depression and anxiety are common after stroke and independently impair rehabilitation participation and outcomes, and treat them as a clinical finding requiring referral rather than a motivational problem. Differentiate fatigue, apathy, and depression rather than lumping them.
After a minor noncardioembolic stroke or high-risk TIA, the candidate continues dual antiplatelet therapy indefinitely instead of transitioning to single antiplatelet therapy, or uses dual therapy for a cardioembolic stroke.
The landmark short-course dual-antiplatelet trials are remembered as 'dual therapy is better than aspirin' without the duration limit or the population restriction, and candidates do not check stroke mechanism before selecting an agent.
What to do instead
Tie duration and mechanism together: dual antiplatelet therapy (aspirin plus clopidogrel, or aspirin plus ticagrelor) for 21–90 days is for minor noncardioembolic stroke (NIHSS ≤3) or high-risk TIA, followed by single antiplatelet therapy; cardioembolic stroke from atrial fibrillation requires anticoagulation timed to infarct size and bleeding risk, not antiplatelet therapy. Always name the mechanism before naming the drug.
When a patient with aphasia or significant cognitive impairment refuses a recommended intervention, the candidate either declares the patient decisively capable ('the patient said no') or decisively incapable and hands the decision to the family, without assessing capacity or identifying the appropriate surrogate and standard.
Candidates confuse the ability to express a preference with decision-making capacity, and they are uncomfortable with the ambiguity, so they default to whichever shortcut feels more respectful or more protective.
What to do instead
Apply the four capacity elements explicitly - understanding, appreciation, reasoning, and expression of choice - using communication supports (yes/no boards, interpreter, speech-language pathology) before concluding incapacity. If incapacity is established, identify the legally authorized surrogate and apply the surrogate's substituted-judgment or best-interest standard, rather than assuming the family or the clinician decides.