High-Yield Lesions

Question 1

Answer 1

Paramedian: infarction of paramedian branches of the basilar a.

• I/L oculomotor palsy (oculomotor nucleus or radiations)
• B/L downgaze palsy (commissural fibers connecting both oculomotor nuclei)
• B/L ataxia (decussation of SCP)
• C/L ataxia (cerebellothalamic fibers rostral to SCP)

**If lesion extends to posterior thalamus:

• confusions
• amnesia
• sleep disturbance

Question 2

Answer 2

Short circumferential territory: branches of the basilar a.

• I/L oculomotor palsy (oculomotor nucleus or radiations)
• C/L spasticity (CST in CC0

Question 3

Answer 3

Caudal Long Circumferential

• I/L oculomotor palsy (oculomotor nucleus or radiations)
• C/L loss of discriminative sensory from UE (inferior ML)
• C/L UE & LE ataxia (cerebellothalamic fibers above the level of decussation)
• C/L choreoathetotic movement (palladiothalamic fibers passing through the base of the internal capsule)

Question 4

Answer 4

Rostral Long Circumferential

• I/L oculomotor palsy (oculomotor nucleus or radiations)
• C/L discriminative sensory loss LE>UE (rostral ML)
• C/L UE & LE ataxia (cerebellothalamic fibers rostral to decussation)
• C/L UE & LE choreoathetotic movement (palladiothalamic fibers passing through the rostral aspect of internal capsule)

Question 5

Answer 5

Parinaud’s Syndrome

• B/L upgaze palsy (commissural fibers between oculomotor nuclei crossing above cerebral aqueduct)

Question 6

Answer 6

Thalamus: Paramedian territory

• confusion & dementia (DM nucleus)
• amensia with confabulation (mamillary bodies and mammillothalamic tract)
• sleep disturbance (hypothalamus)

Question 7

Answer 7

Anterolateral thalamic lesion: tuberothalamic branches from posterior communicating artery

• Neuropsych changes: language, intellect, memory
• dysphasias, neglect, abulia (anterior and ventral anterior nuclei of thalamus)
• C/L emotional facial paralysis (median forebrain bundle)

Question 8

Answer 8

Lateral thalamus lesion

• C/L homonymous hemianopia (optic radiations)
• C/L spastic paresis/paralysis (CST in CC)

Question 9

Answer 9

Posterolateral thalamic lesion (posteromedial choroidal vessels from the PCA and posterior communicating arteries)

• C/L hemibody sensory loss (ventroposterior nuclei or ML)
• C/L homonymous hemianopia (optic tract, LGB)
• C/L hemipelegia/paresis (CST in IC)
• C/L hemichorea or athetosis (VL and VA nuclei or palladiothalamic fibers)