Vestibular System Flashcards
What are the 2 things that the vestibular system can detect?
Static and kinetic movement of the head
A proprioceptive system that influences axial and proximal limb muscle tone and the oculomotor system
Vestibular system
What Vestibuloocular Response (VOR) would you perform on an unconscious patient?
Doll’s Eye Maneuver
What are the contraindications for Doll’s Eye Maneuver?
CANNOT HAVE A Cervical Injury!!!! And they must be unconscious
Describe the Doll’s Eye maneuver and the expected response
Side-to-side movement of the patient’s head results in their eyes turning gaze to the opposite direction
If you are performing the Doll’s Eye maneuver and the head is turned right, what is wrong if the left eye remains neutral and the right eye is correctly ADducted?
Left CN VI palsy
If you are performing the Doll’s Eye maneuver and the head is turned right, what is wrong if the right eye remains neutral and the left eye is ABducted correctly?
Right CN III palsy
If you are performing the Doll’s Eye maneuver and the gaze is neutral and forward, what is wrong?
Possible midbrain damage
For Doll’s Eye maneuver, if the head is turned left where should the eyes go?
Right side gaze
What Vestibuloocular Response (VOR) can you perform on a conscious patient?
Ice or Warm water caloric test
Describe the Ice/Warm water caloric test
Injecting ice water or warm water into the patients external acoustic meatus
What is the expected response of an ice cold water caloric test?
Eyes turn TOWARD the affected ear and then have nystagmus AWAY
What is the expected response of a warm water caloric test?
Eyes turn AWAY from the affected ear and then have nystagmus TOWARD
What is the pneumonic to remember the direction of the nystagmus in the water caloric test for conscious patients?
COWS -
Cold water = Opposite
Warm water = Same
What are the vestibular receptors?
Neuroepithelial cells in the cristae ampullaris and maculae of the ear
What is the vestibular ganglion?
Bipolar neurons near the membranous labyrinth
What nuclei does the vestibular nerve terminate into after getting signal from the vestibular receptors/ganglion?
Vestibular nucleus, Fastigial nucleus and Flocculo-nodular lobe
What nuclei make up the vestibulocerebellum?
Fastigial nucleus and Flocculo-nodular lobe
What are the tracts/areas of the Vestibular nucleus?
Medial Longitudinal Fasciculus (MLF)
Medial Vestibulospinal Tract (MVST)
Lateral Vestibulospinal Tract (LVST)
Reticular formation (RF)
Some fibers of CN VIII do not go to the vestibular nucleus; where do they go directly?
Vestibulocerebellum (Fastigial nucleus and Flocculo-nodular lobe)
Medial longitudinal fasiculus
Eyes turn toward stimulus
Medial Vestibulospinal tract
Head turns toward stimulus
Lateral Vestibulospinal tract
Body turns toward stimulus
Reticular formation
Nausea, vertigo, visceral disturbances
PPRF
Paramedian Pontine Reticular Formation
What is the PPRF involved in?
Coordination of horizontal gaze
What pathway is involved with the Doll’s Eye maneuver and the oculocaloric testing?
Medial longitudinal Fasciculus (MLF) - horizontal gaze
Where does the MVST terminate?
Intermediate grey matter at the cervical and upper thoracic levels ONLY in the spinal cord
What type of pathways are the MVST and the LVST?
Descending
What is the function of the MVST?
Controls positioning of head relative to the eye movements by influencing the muscles of the neck, upper back and proximal upper limb
Where does the LVST terminate?
Intermediate grey matter at ALL levels of the spinal cord
What does the LVST fibers descend in?
Lateral funiculus of the spinal cord
What is the function of the LVST?
Control extensor tone and reflexes of the axial and appendicular musculature (body)
What test would you perform to test for lesions of the vestibular system?
Romberg’s Test
Describe the Romberg’s Test
Have patient close their eyes and stand still. If they sway or when gently touched they almost fall over, that is a positive finding.
What is a lesion of the Median longitudinal Fasciculus (MLF) called?
Internuchlear Opthalmoplegia
If there is a unilateral lesion on the right side of the MLF, what are the results?
Horizontal gaze to the right is normal
Horizontal gaze to the left shows the following:
- Right eye unable to ADduct
- Left eye exhibits nystagmus
If there is a lesion on the PPRF, what will be lost?
Horizontal gaze to the affected side!
If a patient is unable to look to the right, where is the likely lesion?
Right PPRF
A PPRF lesion destroys fibers that are going where?
Ipsilateral Abducens nucleus and contralateral oculomotor nucleus
