Brainstem

Question 0

Which artery supplies the midbrain?

Answer 0

PCA and SCA

Question 1

Which arteries supply the brainstem?

Answer 1

PCA, SCA, and branches of Basilar

Question 3

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

Answer 3

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

Question 4

Describe Benedikt Syndrome (lesion to tegmentum of midbrain)?

Answer 4

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

Question 5

Which artery supplies the pons?

Answer 5

Paramedian branches of Basilar and AICA

Question 6

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

Answer 6

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

Question 7

What is the Charcot triad of Multiple Sclerosis?

Answer 7

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

Question 8

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

Answer 8

Medial pons affected
MLF–> INO
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

Question 9

What can happen to pons if occlude PICA?

Answer 9

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

Question 10

What is Caloric Nystagmus used to test?

Answer 10

Test brain stem function (Acoustic nerve)

Question 11

Describe the results of Caloric Nystagmus

Answer 11

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

Question 12

What is “Locked-in syndrome”?

Answer 12

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

Question 13

What is Horner Syndrome? Causes?

Answer 13

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)

Question 14

Which arteries supply the medulla?

Answer 14

PICA, Vertebral Artery, Anterior Spinal Artery

Question 15

What are the main autonomic functions of the medulla?

Answer 15

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

Question 16

Describe Weber Syndrome (base of midbrain)

Answer 16

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