It is mainly caused by a midbrain infarction as a result of occlusion of a branch of posterior cerebral artery most commonly or the paramedian branches of basilar bifurcation perforating arteries. This lesion is usually unilateral and affects several structures in the midbrain including: Structure damaged Effect substantia nigra contralateral parkinsonism because it's dopaminergic projections to the basal ganglia innervate the ipsilateral hemisphere motor field, leading to a movement disorder of the contralateral body. corticospinal fibers contralateral hemiparesis (if lateral corticospinal tract is only affected) & contralateral hemiplegia (if both lateral & anterior corticospinal tracts are affected) and typical upper motor neuron findings. It is contralateral because it occurs before the decussation in the medulla. corticobulbar tract difficulty with contralateral lower facial muscles and hypoglossal nerve functions. oculomotor nerve fibers ipsilateral lower motor neuron type oculomotor nerve palsy with a drooping eyelid (partial ptosis) and fixed wide pupil pointed down and out (mydriasis). This leads to diplopia. Human brainstem blood supply description. Posterior cerebral artery is #6, and midbrain is behind it.
Weber's syndrome
Grisel's syndrome
Fowler's syndrome
Löffler's syndrome
Nicolaides–Baraitser syndrome
Renpenning's syndrome
complications of Cat-scratch disease
Satchmo's syndrome