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Stephens Brainstem Lesions > M5 > Flashcards

Flashcards in M5 Deck (23):
1

unconscious patient: cold water in Right external auditory meatus. Head turns what direction?

what does the absence of nystagmus/horizontal eye movement suggest?

1) to the Right (to the side of the stimulus); phenomena occurs when the brainstem is intact

2) "the fast phase of nystagmus will be absent in a comatose patient as nystagmus is controlled by the cerebellum"

3) no caloric response = brainstem impairment = increased impairment

2

VOR

vestibuloocular response (doll's head maneuver)

3

unconscious patient: hot water in Right external auditory meatus. Head turns what direction?

1) to the left. if the brainstem is intact, warm water causes the eyes to turn away from the stimulus with horizontal nystagmus toward the side of the stimulus

4

absent VOR

ipsilateral vestibular impairment of the stimulated lateral semicircular duct

5

normal HOT water response: slow and fast component

the eyes turn AWAY from the stimulus with the nystagmus TOWARD the stimulus

6

normal COLD water response: slow and fast component

the eyes turn horizontally TOWARD the side of the stimulus while the nystagmus is away from the side of the stimulus.

7

in comatose patients with cerebral damage, cold water irritation will result in...

deviation of the eyes toward the ear being irrigated.

if responses are bilaterally absent and there is no nystagmus---> indicates midbrain damage/poor prognosis in 92%.

8

After entering the brainstem, the central process of the primary neuron bifurcates into ascending and descending branches that terminate in what four nuclei?

Vestibular nuclei: superior, inferior, medial and lateral

Fastigial nuclei (bilaterally)

Flocculo-nodular lobe

9

a key link in coordinating the positioning of the head relative to eye movements.

mostly comprised of uncrossed descending fibers, MVST terminates in the intermediate gray of the cervical and upper thoracic levels of the spinal cord and influences the muscles of the neck, upper back and proximal upper limbs

10

MVST

head turns to side of stimulus

mostly comprised of uncrossed descending fibers, MVST terminates in the intermediate gray of the cervical and upper thoracic levels of the spinal cord and influences the muscles of the neck, upper back and proximal upper limbs

11

LVST

body turns to side of stimulus

The lateral vestibulospinal tract coordinates the positioning of the
body relative to head position and gaze. The LVST facilitates the
tone and reflexes of the antigravity axial and appendicular musculature.
extensor

12

reticular formation

nausea/vertigo/visceral disturbances

vestibular nuclei have strong, bilateral projections into the reticular formation. These connections affect the somatic motor system (postural tone), and providing a mechanism for the visceral autonomic disturbances associated with vestibular stimulation (pallor, nausea, vertigo, vomiting, etc.).

13

vestibular connection to the cerebellum

form the restiform bodies, also called the juxtarestiform body

courses through the medial portion of the inferior cerebellar peduncle.

14

the oldest part of the cerebellum

vestibulo-cerebellum, called in normal parlance "flocculo nodular lobe"

receives input from reticular formation and vestibular nuclei

15

inputs to the flocculo nodular lobe and their outputs

inputs: vestibular nerve (directly), vestibular nucleus, fastigial nucleus, somato-sensory from axial and proximal limbs.

outputs: fastigial nucleus and vestibular nucleus

16

These connections affect the somatic motor system (postural tone), and providing a mechanism for the visceral autonomic disturbances associated with vestibular stimulation (pallor, nausea, vertigo, vomiting, etc.).

reticular formation

17

Vestibulo-thalamo-cortical pathway (reduced to three interconnected formulas from the picture on slide 12)

1) vestibular nv --> vestibular nuc --> ventral lateral nucleus of thalamus (VLN)

2) vestibular nuc vestibulocerebllum

3) cortical areas --> striatum --> globus pallidus --> VLN

two converging systems

18

Vestibulo-thalamo-cortical pathway (reduced to three interconnected formulas from the picture on slide 12)

1) vestibular nv --> vestibular nuc --> ventral lateral nucleus of thalamus (VLN)

2) vestibular nuc vestibulocerebllum

3) cortical areas --> striatum --> globus pallidus --> VLN

two converging systems

19

The vestibular nerve has direct connections to which the following?

A. Dentate nucleus
B. Flocculo-nodular lobe
C. Paramedian pontine RF
D. Abducens nucleus

i believe it is the paramedian pontine RF

20

When attempting horizontal to the left, the right eye does not adduct; the left eye exhibits nystagmus, this is a right INO due to a lesion of the left MLF

a right INO due to a lesion of the left MLF

[NOTE: The lesion is ipsilateral to the non-adducting eye.]

21

When attempting horizontal to the right, the left eye does not adduct; the right eye exhibits nystagmus, this
is

a left INO due to a lesion of the right MLF

[NOTE: The lesion is ipsilateral to the non-adducting eye.]

22

In about 80% of the cases of INO are either _____ with bilateral INO and multiple sclerosis or _____ with unilateral INO due to vascular disease.

young adults; ms; INO bilateral
older folks; vascular disease; unilateral INO

23

lesion of the right PPRF would result in

lesion of the right PPRF would result in the patient's inability to move both eyes in conjugate horizontal gaze to the right. Their gaze preference would be to the left.