Brainstem Syndromes Flashcards
Note that a common thread to most of the brainstem syndromes is what?
a pattern of contralateral body weakness or sensory loss coupled with ipsilateral cranial nerve weakness or sensory loss.
This pattern is a consequence of brainstem nuclei/fascicle involvement simultaneous with long tract (corticospinal, spinothalamic, medial lemniscus). Since the long tracts in the brainstem have not crossed over to the opposite side, lesions in the brainstem will cause contralateral signs and symptoms. In contrast, lesions of the brainstem nuclei and fascicle will cause ipsilateral signs and symptoms.
Stroke/vascular lesion of the base of the Midbrain (aka Weber’s Syndrome) most likely affects what blood supply?
the tip of the basilar artery and/or branches of the PCA
Stroke/vascular lesion of the base of the Midbrain (aka Weber’s Syndrome) most likely affects what structures?
CN III fascicles
Cerebral peduncle
How might Stroke/vascular lesion of the base of the Midbrain (aka Weber’s Syndrome) present?
ipsilateral 3rd nerve paresis
contralateral hemiparesis
Stroke/vascular lesion of the tegmentum of the Midbrain (aka Claude’s Syndrome) most likely affects what blood supply?
tip of the basilar artery and/or branches of the PCA
Stroke/vascular lesion of the tegmentum of the Midbrain (aka Weber’s Syndrome) most likely affects what structures?
CN III fascicles
red nucleus
superior cerebellar peduncle
How might stroke/vascular lesion of the tegmentum of the Midbrain (aka Weber’s Syndrome) present?
ipsilateral 3rd nerve paresis
contralateral tremor and ataxia
Stroke/vascular lesion of the base AND tegmentum of the Midbrain (aka Benedikt’s Syndrome) most likely affects what structures?
CN III fascicles
red nucleis
superior cerebellar peduncle
Substantia nigra
How might Stroke/vascular lesion of the base AND tegmentum of the Midbrain (aka Weber’s Syndrome) present?
ipsilateral 3rd nerve paresis
contalateral paresis, tremor, and ataxia
The Weber Syndrome features a lesion of what area? Presentation?
the cerebral peduncle and the oculomotor nerve fascicles passing just medial of the peduncle.
This produces an ipsilateral oculomotor paralysis with a wide fixed pupil, contralateral hemiplegia, contralateral facial weakness with the lower face weaker than the upper face and contralateral weakness of the tongue. The tongue protrudes toward the weaker side.
Claude’s syndrome is a relatively uncommon midbrain syndrome in its pure form. It is characterized by what?
ipsilateral oculomotor nerve palsy and contralateral cerebellar ataxia.
Due to vascular variation, the exact location and extent of the midbrain lesion responsible for Claude’s syndrome has not been completely resolved. However, the lesion most commonly affects where?
the fascicle of the oculomotor nerve and the fibers from the superior cerebellar peduncle passing below and medial to the red nucleus.
The figure on the left is taken from their article.
The hatched area represents the lesion common to all six studied cases.
The right figure shows a typical MRI ischemic stroke affecting the medial midbrain. It would produce elements of Claude’s syndrome but the red nucleus also appears affected and might contribute a “rubral tremor” to the ataxia. Some of the ascending arousal system (reticular activating system) appears involved causing some drowsiness. That’s the problem with these named syndromes; they are seldom “pure” or “classic” in the real world.
In Benedikt’s syndrome, the structures affected include what?
the root fibers (fascicles) of the oculomotor nerve,
the medial lemniscus and
the red nucleus including some of the cerebellar fibers passing nearby.
The neurological signs of Benedikt’s syndrome are:
ipsilateral oculomotor paresis (including a wide fixed pupil),
reduced position and vibration sense in the contralateral body, and
contralateral tremor, chorea, athetosis and ataxia. The latter movement disorder may be dominated by evident ataxic movements of the limbs.
Benedikt syndrome resembles Weber syndrome but with the main difference between the two being:
that Weber’s is associated with hemiplegia (i.e. contralateral paralysis), and Benedikt’s with hemi-ataxia (i.e. disturbed coordination of movements on the contralateral side).
Again, these syndromes in the real world can overlap depending on the extent of the lesion in which case paralysis may conceal the underlying movement disorder.
The location of the lateral medullary lesion causing Wallenberg’s syndrome. In addition, the central sympathetic tract lying just lateral of the nucleus ambiguous may be affected to produce an ipsilateral Horner’s syndrome (small pupil, ptosis of upper eyelid).
If the inferior vestibular nucleus is affected as well, vertigo and nystagmus will develop. If the reticular formation is affected in the area, hiccup may resultt.
