Clinical Correlations in Neuroanatomy

Clinical Correlations in Neuroanatomy

Clinical Correlations in Neuroanatomy

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Cerebral Vascular Syndromes - Stroke Strikes

Homunculus representation is key for localization. All deficits contralateral unless specified.

ArteryTerritory (Homunculus Focus)Motor/Sensory Loss EmphasisKey Specific Signs
ACAMedial cortex (Leg/Foot)Lower Limb > Upper/FaceUrinary incontinence, abulia, grasp reflex.
MCALateral cortex (Face/Arm/Speech)Upper Limb/Face > LowerDominant: Aphasia (Broca's/Wernicke's). Non-dominant: Hemineglect. Homonymous hemianopia.
PCAOccipital, medial temporalPrimarily VisualCortical blindness (macular sparing), alexia without agraphia, memory loss.

⭐ Gerstmann syndrome (acalculia, agraphia, finger agnosia, right-left disorientation) can occur with dominant parietal lobe lesions, often involving the angular gyrus supplied by MCA territory.

Brainstem Syndromes - Brainstem Blues

📌 Rule of 4s: For lesion localization.

  • Midbrain Syndromes:
    • Weber's: Ipsilateral CN III palsy; contralateral hemiplegia (corticospinal tract).
    • Benedikt's: Ipsilateral CN III palsy; contralateral ataxia & tremor (red nucleus, medial lemniscus).
    • Parinaud's (Dorsal Midbrain): Vertical gaze palsy (esp. upward), light-near dissociation, convergence-retraction nystagmus.
  • Pontine Syndromes:
    • Millard-Gubler: Ipsilateral CN VI & CN VII palsy; contralateral hemiplegia (corticospinal tract).
  • Medullary Syndromes:
    • Wallenberg's (Lateral Medullary): Ipsilateral: ataxia, Horner's syndrome, loss of facial pain/temp (CN V), dysphagia, hoarseness (CN IX, X). Contralateral: loss of body pain/temp (spinothalamic tract). Midbrain cross-section with labeled structures

⭐ Wallenberg's syndrome (PICA occlusion) classically spares the corticospinal tract, hence no contralateral hemiplegia is a key distinguishing feature.

Cranial Nerve Lesions - Nerve Wrecks

  • CN III (Oculomotor): Eye "down & out", ptosis, mydriasis.
  • CN IV (Trochlear): Vertical diplopia (worse looking down/inward), head tilt away from lesion.
  • CN VI (Abducens): Horizontal diplopia, failed eye abduction (lateral gaze palsy).
    • 📌 Mnemonic (extraocular muscles): $LR_6SO_4R_3$.
  • CN VII (Facial) Palsy:
    • LMN (e.g., Bell's Palsy): Ipsilateral entire half of face paralyzed.
    • UMN: Contralateral lower face paralysis; forehead spared.
  • Other Key Lesions:
    • CN V: Trigeminal neuralgia (severe, lancinating facial pain).
    • CN IX/X: Bulbar signs (dysphagia, dysarthria, absent gag reflex, uvula deviates away from lesion).
    • CN XII: Tongue deviates towards side of LMN lesion on protrusion.
  • Localizing Value: Patterns of combined CN palsies help pinpoint lesion site (e.g., cavernous sinus, cerebellopontine angle).

Cranial Nerve Lesions: Anatomic Site, Findings, Causes

⭐ Pupil-sparing CN III palsy often suggests ischemic microvascular damage, whereas pupil involvement (mydriasis) typically indicates a compressive lesion, such as a posterior communicating artery (PCOM) aneurysm, requiring urgent investigation.

Spinal Cord Syndromes - Spinal Shockers

  • Brown-Séquard Syndrome (Hemisection):
    • Ipsilateral: UMN paralysis, loss of proprioception/vibration below lesion.
    • Contralateral: Loss of pain/temperature sensation, 2-3 segments below lesion.
  • Anterior Cord Syndrome (ASA Occlusion):
    • Bilateral loss: Motor function (corticospinal), pain/temperature (spinothalamic) below lesion.
    • Preserved: Proprioception/vibration (dorsal columns).
  • Central Cord Syndrome (Hyperextension Injury, common in elderly):
    • Motor impairment: Upper limbs > lower limbs (sacral sparing often present).
    • Sensory loss variable; often pain/temperature affected at level of lesion (cape-like distribution).
  • Posterior Cord Syndrome (e.g., Tabes Dorsalis, Vitamin B12 deficiency):
    • Bilateral loss of proprioception, vibration, and discriminative touch below lesion.
    • Motor function, pain/temperature preserved.
  • Sacral Sparing: Indicates incomplete lesion; peripheral fibers of spinothalamic tract (sacral) are spared. Common in central cord syndrome; good prognostic sign.

Spinal cord tracts and lesion locations

⭐ The anterior spinal artery (ASA) supplies the anterior two-thirds of the spinal cord, including the corticospinal and spinothalamic tracts. Occlusion leads to Anterior Cord Syndrome. 📌 Mnemonic: "A" for Anterior, "A" for Artery, "A"ll motor and pain/temp gone (mostly).

High‑Yield Points - ⚡ Biggest Takeaways

  • Broca's area lesion: expressive aphasia; Wernicke's area lesion: receptive aphasia.
  • Subarachnoid hemorrhage: "worst headache of life", often ruptured berry aneurysm.
  • Brown-Séquard syndrome: ipsilateral motor/proprioception loss, contralateral pain/temperature loss.
  • Parkinson's disease: dopamine depletion in substantia nigra causes TRAP symptoms.
  • Horner's syndrome: ptosis, miosis, anhidrosis due to sympathetic chain lesion.
  • Bell's palsy (LMN CN VII): ipsilateral facial paralysis; UMN lesion spares forehead.
  • Optic chiasm lesion: bitemporal hemianopia.

Practice Questions: Clinical Correlations in Neuroanatomy

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Not seen in case of hemorrhage in MCA territory is:

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Flashcards: Clinical Correlations in Neuroanatomy

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Scalp bleeding is predominantly _____

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Scalp bleeding is predominantly _____

arterial

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