Supranuclear Disorders

Question 1

clinically distinguishing factors of supra- v infra-nuclear disorders

Answer 1

supranuclear: affect both eyes similarly and rarely cause diplopia
infranuclear: affect eyes differently and often cause diplopia

Question 2

Name the responsible ocular motor tracking system:

1. Holds stationary object image steady by correcting for ocular drift
2. Rapidly brings objects of interest to fovea
3. Holds retinal image steady during sustained head rotation
4. Holds retinal image steady during brief head rotation
5. Holds target image steady during linear rotation of object or self, up to speed of 30 degrees per second
6. Moves eyes in opposite directions so a single image is simultaneously centered on both foveas

Answer 2

1. microsaccadic refixation movements
2. saccades
3. optokinetic (OKN)
4. vestibular ocular reflex VOR
5. smooth pursuit
6. vergence

Question 3

what structures provide the excitatory burst neurons and neural integrators for horizontal and vertical saccades, respectively?

Answer 3

horizontal: PPRF burst, median vestibular nucleus and nucleus prepositus hypoglosus for integration
vertical: riMLF for burst, interstitial nucleus of Cajal for integration

Question 4

what does the OKN drum actually test

Answer 4

pursuit and saccade systems, not OKN

Question 5

the larger the saccade, the ____ the speed

Answer 5

faster

Question 6

from where is a leftward saccade generated?

Answer 6

right frontal eye fields

Question 7

from where is leftward smooth pursuit generated?

Answer 7

left parietal lobe

Question 8

difference between pendular nystagmus and square-wave jerk

Answer 8

pendular nystagmus only has a slow phase and is larger amplitude. SWJs only have a fast phase, are smaller in amplitude, and lack periodicity

Question 9

disease states with increased frequency of square-wave jerks?

Answer 9

progressive supranuclear palsy, smoking, cerebellar disease

Question 10

patient presents with right-sided miosis, ptosis, and decreased sensation to right side of face. Patient also with ataxia and decreased sensation to left side of body. diagnosis and cause?

Answer 10

lateral medullary syndrome (Wallenberg); usually from vascular insult to right PICA or right vestibular artery

Question 11

80 yo male with stiff gait, rigid face, and inability to look down volitionally or with saccades. what maneuver(s) can you do to help localize the pathology?

Answer 11

this patient likely has PSP. to localize the problem as supranuclear and not infranuclear (i.e., third nerve, inferior rectus, etc.), you can do the doll’s head maneuver. jerking the patient’s head up while having him maintain primary fixation will excite the vestibular pathway and allow the patient to look down. this will localize the pathology to supranuclear (although, may be difficult to do with patient’s overall body rigidity)

Question 12

hypometria and hypermetria

Answer 12

under- and over-shooting of saccades

Question 13

distinguish central and peripheral lesions with regards to saccadic dysfuntion

Answer 13

central: slow saccades with good accuracy
peripheral: slow saccades with hypometria

Question 14

horizontal saccadic dysfunction may localize pathology to ___ while vertical to ____

Answer 14

horizontal: pons
vertical: midbrain

Question 15

1. obviously slowed saccades with rigidity
2. hypermetric saccades
3. unidirectional hypermetric saccades with ocular tilt reaction

Answer 15

1. PSP
2. cerebellar dysfunction
3. Wallenberg (lateral medullary) syndrome

Question 16

inability to move eyes volitionally but eye movement attained by inducing VOR through rapid head thrusts?

Answer 16

ocular motor apraxia

• -congenital: ataxia-telangiectasia, Niemann-Pick, Gaucher, Tay-Sachs, Joubert, abetalipoproteinemia, Wilson’s
• -acquired: large anoxic encephalopathy affecting frontal and parietal lobes (i.e. post AAA repair)

Question 17

Will frontal stroke lead to tonic deviation towards or away from the side of the lesion? What about brainstem lesion?

Answer 17

cortex: eyes drift towards
brainstem: eyes drift away

Question 18

bilateral pontine injuries?

Answer 18

inability to generate any horizontal movement (including VOR), but vertical movements intact

Question 19

ipsilateral gaze palsy and bilateral facial paresis?

Answer 19

Mobius syndrome (aplasia of ipsilateral sixth nerve nucleus)

Question 20

findings in dorsal midbrain syndrome (Parinaud syndrome)

Answer 20

conjugate limitation of vertical gaze (esp. upgaze), mid-dilated pupils with light-near dissociation, retraction nystagmus on attempted upgaze, retraction of the lids in primary position (Collier’s sign), skew, disruption of convergence, and square-wave jerks

Question 21

conjugate vertical gaze palsy with eyelid retraction?

Answer 21

setting sun sign, common in Parinaud syndrome affecting children

Question 22

workup for isolated convergence insufficiency, convergence spasm, or divergence insufficiency?

Answer 22

none

Question 23

typical patient with convergence spasm?

Answer 23

early-onset esotropia with high AC/A ratio