brainstem syndrome

Claude's syndrome is caused by midbrain infarction as a result of occlusion of a branch of the posterior cerebral artery. This lesion is usually a unilateral infarction of the red nucleus and cerebral peduncle, affecting several structures in the midbrain including:

Structure damaged	Effect
dentatorubral fibers	contralateral ataxia
corticospinal tractfibers	contralateral hemiparesis
corticobulbar tractfibers	contralateral hemiplegia of lower facial muscles, tongue, and shoulder
oculomotor nerve fibers	ipsilateral oculomotor nerve palsy with a drooping eyelid and fixed wide pupil pointed down and out; probablediplopia

Bnedikt:
It is characterized by the presence of an CN III oculomotor nerve palsy and cerebellar ataxia including tremor. Neuroanatomical structures affected include CNIII nucleus, Red nucleus, corticospinal tracts, brachium conjunctivum, and cerebellum. It is very similar in etiology, morphology and clinical presentation to Weber's syndrome; the main difference between the two being that Weber's is more associated with hemiplegia (i.e. paralysis), and Benedikt's with hemiparesis (i.e. weakness).

Foville's syndrome is caused by the blockage of the perforating branches of the basilar artery in the region of the brainstem known as thepons.^[1]

Structures affected by the infarct are the PPRF, nuclei of cranial nerves VI and VII, corticospinal tract, medial lemniscus, and the medial longitudinal fasciculus.

Millard-Gubler syndrome

Symptoms result from the functional loss of several anatomical structures of the pons, including the sixth and seventh cranial nerves and fibers of the corticospinal tract. Paralysis of the abducens (CN VI) leads to diplopia, internal strabismus, and loss of power to rotate the affected eye outward), and disruption of the facial nerves (CN VII) leads to symptoms including flaccid paralysis of the muscles of facial expression and loss of the corneal reflex. Disruption of the corticospinal tract leads to contralateral hemiplegia of the extremities.

It is a form of "crossed hemiplegia," as the paralysis of muscles controlled by the facial nerve occurs on the same side as the lesion, while the hemiplagia of muscles below the neck occurs on the opposite side as the lesion.