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Flashcards in Brainstem Deck (16):

Which arteries supply the brainstem?

PCA, SCA, and branches of Basilar


Which artery supplies the midbrain?



What is Parinaud Syndrome (lesion to dorsal tectum of midbrain)?

Sup. Colliculus--> paralysis of upward gaze, pupillary disturbances, absence of convergence
Cerebral Aqueduct--> obstruction leads to noncommunicating hydrocephalus
Pineal Gland--> inadequate melatonin (possible insomnia)


Describe Benedikt Syndrome (lesion to tegmentum of midbrain)?

CNIII--> ptosis, eye "down and out"
Dentatothalamic fibers--> contralateral cerebellar ataxia, intention tremor
Medial Lemniscus--> contralateral loss of fine touch and proprioception


Which artery supplies the pons?

Paramedian branches of Basilar and AICA


What is the function of the Medical Longitudinal Fasciculus? What is MLF syndrome?

Conjugate gaze
MLF Syndrome (Internuclear Ophthalmoplegia): Medial rectus palsy on attempted lateral gaze and Nystagmus


What is the Charcot triad of Multiple Sclerosis?

1) scanning speech
2) intention tremor
3) nystagmus (MLF syndrome)


What can happen from Basilar Artery occlusion? Which part of the pons is affected?

Medial pons affected
CN VI--> lateral rectus
CN VII--> Ipsilateral Bell palsy w/o forehead sparing
Medial Lemniscus--> loss of contralateral light touch/proprioception
Corticospinal tract--> contralateral hemiparesis


What can happen to pons if occlude PICA?

Lateral spinothalamic tract--> loss of contralateral pain/temp
CN VIII--> vertigo, hearing loss, tinnitis, nystagmus
CN VII--> Bell palsy w/o forehead sparing
Middle Cerebellar peduncle--> Ipsilateral ataxia
Spinal Trig. Nucelus/Tract--> Ipsilateral pain/touch
Descending sympathetics--> Ipsilateral Horner syndrome


What is Caloric Nystagmus used to test?

Test brain stem function (Acoustic nerve)


Describe the results of Caloric Nystagmus

Cold Water Irrigation: reduce signaling--> simulates contralateral head turn--> ipsilateral gaze deviation with nystagmus to contralateral side

Warm Water Irrigation: increase signaling--> simulates ipsilateral head turn--> contralateral deviation with nystagmus to ipsilateral side
"COWS= Cold-Opposite, Warm-Same"
Ex) Cold water in LEFT ear--> LEFT eye gaze deviation with RIGHT beating nystagmus
Ex) Warm water in LEFT ear--> RIGHT eye gaze deviation with LEFT beating nystagmus


What is "Locked-in syndrome"?

Lesion to base of pons--> Affects bilateral corticospinal and corticobulbar tracts--> paralysis from head to toe
Spares oculomotor and trochlear nerves--> communicates with eyes
Awake and aware


What is Horner Syndrome? Causes?

Due to damage to descending Sympathetic Tract
Ptosis, miosis, hemianhidrosis (ipsilateral lack of sweating), and apparent enophthalmos (sunken eye ball)

Causes: Lateral medullary (Wallenberg Syndrome)


Which arteries supply the medulla?

PICA, Vertebral Artery, Anterior Spinal Artery


What are the main autonomic functions of the medulla?

1) Vomiting center (base of medulla, samples CSF)--> outputs to nucleus solitary tract and autonomic control centers
2) Respiratory Regulation--> at low pH, activate Reticular Formation--> activate phrenic nerve
3) Consciousness (Reticular Formation)
4) BP regulation--> Carotid bodies and aorta receptors--> sense stretch in vessels


Describe Weber Syndrome (base of midbrain)

CNIII--> ptosis, eye "down and out"
Corticospinal tracts--> contralateral spastic paralysis
Corticobulbar tracts--> weakness of lower face (CN VII), tongue (XII), and palate (X), uvula points AWAY from lesion, and tongue points TOWARD lesion