USMLE Step 2 CK Neurology Mnemonics: Stroke Syndromes, TIA, and Reflexes

A ValueMD community study resource, originally shared in our USMLE Step 2 CK forum and preserved here for students preparing for the neurology section of Step 2 CK.

Stroke localization is one of the highest-yield neurology topics on USMLE Step 2 CK. The mnemonics below were contributed by the ValueMD student community to help distinguish lacunar strokes, the major cerebral artery occlusion syndromes, TIA features, and reflex root levels: the patterns most frequently tested in vignette form.

Educational note: these are student-built memory aids for exam preparation, not a substitute for a neurology textbook or clinical guideline. Use them alongside First Aid, UWorld, or your course material rather than in place of them.

Lacunar Infarcts: Risk Factors and Classic Syndromes

Lacunar infarcts are small-vessel strokes caused by occlusion of a single deep penetrating artery, most often in patients with chronic hypertension or diabetes. A simple way to remember the risk-factor profile is GAP:

• G: deep Gray matter structures affected (basal ganglia, thalamus, internal capsule)
• A: Atherosclerosis of small penetrating vessels (lipohyalinosis)
• P: chronic hyPertension is the leading risk factor

The five classic lacunar syndromes, roughly in order of frequency:

A rarer presentation, dysarthria with facial weakness, can occur with lacunae in the anterior limb of the internal capsule.

Anterior Cerebral Artery (ACA) Occlusion

The ACA supplies the medial surface of the frontal and parietal lobes, including the leg-dominant portion of the motor and sensory cortex (the paracentral lobule). Occlusion classically produces:

• Contralateral leg weakness (crural monoplegia), with relative sparing of the face and arm
• Possible contralateral leg sensory loss, from involvement of the same medial cortical strip

Middle Cerebral Artery (MCA) Occlusion

The MCA is the most commonly occluded vessel in ischemic stroke, and its territory covers the lateral surface of the frontal, parietal, and temporal lobes. Look for this pattern:

• Contralateral hemiparesis and hemisensory loss, face and arm affected more than the leg (the reverse of ACA occlusion)
• Contralateral homonymous hemianopsia: the visual field cut affects the same side as the weakness
• Aphasia when the dominant (usually left) hemisphere is involved
• Hemineglect and apraxia when the non-dominant (usually right) hemisphere is involved

Posterior Cerebral Artery (PCA) Occlusion

The PCA supplies the occipital lobe and, via its perforating branches, the thalamus. A useful way to remember the pattern is POST:

• P: Proximal limb tremor/flinging movements can occur when thalamic or subthalamic branches are involved
• O: Occipital lobe infarction causes contralateral homonymous hemianopsia, sometimes with macular sparing
• S: Speech and spelling are preserved, but the patient cannot read fluently. This is alexia without agraphia, seen with dominant-hemisphere PCA infarcts affecting the splenium of the corpus callosum
• T: Thalamic syndrome (contralateral sensory loss, sometimes with pain) from thalamogeniculate artery involvement

Vertebrobasilar (Posterior Circulation) Occlusion: The 4 D’s

Posterior circulation ischemia affecting the brainstem and cerebellum classically presents with:

• Dizziness
• Diplopia
• Dysarthria
• Dysphagia

(Some versions add a fifth D for Drop attacks or Ataxia, so it’s worth knowing both forms if you see this tested.)

Types of Stroke: Stroke Will “HIT” You

• H: Hemorrhagic stroke
• I: Ischemic stroke
• T: TIA (Transient Ischemic Attack)

Transient Ischemic Attack (TIA): SHADED

Patients often describe a TIA affecting vision as a shade being pulled over one eye. Remember the workup and risk profile with SHADED:

• S: Sensory loss; a TIA can herald a full stroke and needs urgent workup
• H: Hypertension and hyperlipidemia are major risk factors
• A: Amaurosis fugax (transient monocular blindness), classically from retinal artery embolism
• D: Differential diagnosis to rule out: seizure, brain tumor, migraine with aura, vertigo
• E: Evaluate carotids for endarterectomy candidacy; if the patient is on warfarin, monitor the INR
• D: Diabetes is an additional risk factor

Deep Tendon Reflex Root Levels

A quick reference for the nerve roots tested by each deep tendon reflex:

Argyll Robertson Pupil

Classically associated with neurosyphilis (tabes dorsalis), the Argyll Robertson pupil is remembered as a pupil that “accommodates but does not react”:

• Accommodation reflex: Present
• Pupillary light reflex: Absent

Frequently Asked Questions

1. What is the most common lacunar stroke syndrome? Pure motor hemiparesis is the most common, accounting for roughly 60% of lacunar strokes, and typically results from a lacune in the posterior limb of the internal capsule or the basis pontis.
2.  What is the difference between ACA and MCA stroke presentations? ACA occlusion primarily affects the leg (leg weakness greater than arm/face), because the ACA supplies the medial motor cortex where the leg is represented. MCA occlusion primarily affects the face and arm, with relative leg sparing, and can also cause aphasia or neglect depending on which hemisphere is involved.
3. What does alexia without agraphia indicate? The inability to read while retaining the ability to write and spell suggests a dominant-hemisphere PCA infarct involving the occipital lobe and splenium of the corpus callosum, a classic finding tested with posterior circulation stroke questions.
4. What is the “4 D’s” mnemonic used for? It’s used to recall the core symptoms of vertebrobasilar (posterior circulation) ischemia: dizziness, diplopia, dysarthria, and dysphagia.

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