Weber Syndrome – Midbrain Infarct — SCE Neurology MCQ

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ModerateCerebrovascular DiseaseWeber Syndrome – Midbrain InfarctSCE Neurology

A 50-year-old woman develops acute onset of a third cranial nerve palsy with pupil involvement (dilated right pupil, complete ptosis, eye in 'down and out' position) and contralateral left hemiplegia. MRI brain shows a right midbrain infarct. What is this syndrome called?

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Correct answer: A — Weber syndrome

Weber syndrome results from a lesion of the cerebral peduncle in the ventral midbrain, damaging the ipsilateral third nerve fascicle (causing ipsilateral CN III palsy with pupil involvement) and the ipsilateral cerebral peduncle/corticospinal tract (causing contralateral hemiplegia). A: Wallenberg is lateral medulla. C: Benedikt syndrome is midbrain but involves the red nucleus (CN III + contralateral tremor/ataxia). D: Millard-Gubler is ventral pons (CN VI/VII + contralateral hemiplegia). E: Parinaud syndrome involves the dorsal midbrain (upgaze palsy, convergence-retraction nystagmus).

Reference: Clinical Neuroanatomy