Lec 31 Brainstem Syndromes Flashcards
Localization principle: what do anterior [ventral] brainstem lesions affect vs posterior?
anterior = affect descending motor pathways posterior = affect ascending sensory pathways
Localization principle: what do left brain hemisphere lesions affect?
right side of body
Do cranial nerves exit ipsilateral or contralateral to their symptoms?
ipsilateral
What CN defines the midbrain?
CN 3
What CNs defines the pons?
CN 6 and CN 7
What CNs defines the medulla?
CN 9, 10, 12
Man presents with double vision and left sided weakness. On exam, his right eye is deviated down and out. His right eye will not move medially and ptosis is present. He is weak on the left side, arm and leg/ He cannot walk or lift his left arm
where is the lesion?
- crossed signs [right eye + left side] –> brainsteam
- motor signs –> anterior [ventral] and affects corticospinal tract on right
- eye –> CN 3 involved –> midbrain
right side anterior midbrain!
What are symptoms of a lesion in anterior midbrain?
- ipsilateral ptosis
- defect in adduction and vertical movement of eye
- diplopia
- contralateral hemiplegia
Case: Man presents with double vision and left sided weakness. On exam, his right eye will not abduct. His diplopia worsens when he looks to the right, but is better when he looks to the left. He is weak on the left side, arm and leg. He cannot walk or lift his left arm
left side weakness –> right side lesion
right eye will not abduct –> problem with lateral rectus on right –> abducens = pons
motor –> anterior
right side anterior pons!
Case: Man presents with right facial weakness and left sided weakness. On exam, his right nasolabial fold is flat. He cannot move the corner of his right mouth he is drooling from the right side of this mouth. His speech is slurred. He is weak on the left side, arm and leg and he cannot walk or lift his left arm.
right facial weakness = right side lesion
right nasolabial fold is flat –> facial nerve –> pons
lefst side weakness –> right anterior
right side anterior pons [lateral pontine syndrome]
Case: Woman presents with slurred speech, imbalance, and numbness. On exam, her speech is dysarthric and she’s drooling. Her gag reflex is diminished on the right. Her right face is numb to pain and temperature. Her left body is numb to pain and temperature. She is imbalanced and clumsy
right face numb –> right side trigeminal
left body numb –> sensory/dorsal on right side
lateral medullary syndrome = wallenberg syndrome
What are sypmtoms of wallenberg syndrome? what is it?
- lateral medullary syndrome
- – ipsilateral loss of facial pain and temp
- – ipsilateral loss of direct corneal reflex, preservation of consensual response
- – contralateral loss of pain and temp below the neck
- – inhibited gag reflex, drooling, dysarthric
Why do lesions in brainstem/spinal cord cause more symptoms than in cerebrum?
its a funnel –> all of the info has to pass through much smaller brainstem so its much more densely packed with info traveling to and from body
Case: Man presents with slurred speech and left sided weakness. On exam, his speech is dysarthric with a lingual quality. Tongue protrudes to the right and cannot move to the left. His left side is weak, both arm and leg.
- right side lesion
- CN 12 problem –> medulla
right side medulla lesion
Case: Man collapses in the grocery store, unresponsive, gets intubated, brought to Emergency Dept. On exam, he makes no attempt to speak or move. He follows no commands and doesn’t track left or right with his eyes. His face is motionless. He does not withdraw any limb to painful stimuli. He does not improve. Weeks later he is transferred to a long-term care facility, where a therapist notes that he seems to blink his left eye to command. He is quadriplegic, aphonic, has no horizontal eye movement and his blinking is intact.
CN3 is lowest nerve still functioning –> rest are not –> lesion in pons
locked in syndrome == bilateral transaction at level of pons
