Chapter 16. Eye Movement Disorders : Diplopia, Nystagmus, and Other Ocular Oscillations Flashcards
Question 16-1: Which is the most common cause of monocular diplopia? A. Retinal detachment B. Lens dislocation C. Refractive error D. Conversion reaction
Answer 16-1: C.
Refractive error is the most common cause of
monocular diplopia. Psychogenic may be the
next most common cause. The others are also
potential causes, but much less common.
Refractive error can be tested not only by
corrective lens placemc:nt. but more quickly
by pin bole testing with the pin hole. the
optical distonion is eliminated and the
monocular diplopia is not apparent
Question 16-2: Head tilt is commonly seen in superior oblique palsy. With right superior oblique palsy, which type of head tilt is expected? A. Forward and left B. Forward and right C. Backward and left D. Backward and right
Answer 16-2: A.
A right superior oblique palsy causes the head
to tilt forward and to the left. In general, the
head tilts in the direction of action of the weak
muscle. A right SO palsy results in extortion
of the right eye relative to the left, so tilt of the
head to the left causes intortion of the left eye
so that the retinal fields are again congruent.
The loss of depressor action of the right SO
causes slight elevation of the right eye, which
is then compensated for by tilting the head
forward (down).
Question 16-3: Which of the following would not be expected to produce vertical diplopia? A. Superior oblique palsy B. Myasthenia C. Thyroid orbitopathy D. Sixth nerve palsy E. Third nerve palsy
Answer 16-3 D.
Sixth nerve palsy produces horizontal diplopia
which is exacerbated by gaze towards the side
of the lesion. The others are potential causes
of vertical diplopia. Superior oblique palsy,
myasthenia, and thyroid orbitopathy are the
most common causes, along with brainstem
lesions which would produce skew deviation.
Third nerve palsy is also common
Questions 16-4:
What is the purpose of forced ductions?
A. Determine which muscle is weak
B. Detennine whether ocular muscle weakness is due to neural defect or neuromuscular transmission defect
C. Detennine whether there is a mechanical restriction of eye muscle action
D. To force a repair of ocular motor dysfunction
Answer 16-4: C.
Forced auctions are performed to determine
whether there is mechanical restriction in eye
muscle action. Some important disorders
which can produce restrictive defects include
entrapment by fracture, thyroid
ophthalmopathy, congenital or acquired ocular
muscle fibrosis, and Duane’s syndrome. Longstanding ocular muscle paresis can result in
restrictive contracture of the antagonist.
However, forced ductions are not intended to
be therapeutic.
Question 16-5:
A patient with nystagmus is found to have a paradoxical response to optokinetic testing. where the fast phase in the direction of movement of the tape. Which is the most likely explanation?
A. Midbrain involvement of multiple sclerosis
B. Congenital nystagmus
C. Wernicke’s encephalopathy
D. Ocular myasthenia
Answer 16-5: B.
Congenital nystagmus is often associated with
a paradoxical response to optokinetic testing,
with the fast phase of the nystagmus in the
direction of movement of the tape or drum.
Most structural abnormalities of the brainstem
produce disorders of ocular motility but not
this type of paradoxical reaction. Elucidation
of an internuclear ophthalmoplegia is the most
common use ofOKN testing for brainstem
disorders
Question 16-6: A patient presents with diplopia which was suddenly noticed. Ocular motor testing shows defective adduction of the left eye with right lateral gaze. The right eye abducts normally but has nystagmus with the fast phase to the Ieft. Which is the most likely cause for these findings ? A. Multiple sclerosis B. Thyroid ophthalmopathy C. Myasthenia D. Superior oblique myokymia E. Lithium intoxication
Answer 16-6: A.
This patient has an internuclear
ophthalmoplegia which is most likely due to
demyelinating disease or vascular disease,
only the former of which is presented as an
option. All of the other listed conditions can
produce diplopia, but with differing features.
Thyroid ophthalmopathy produces restrictive
defects of the ocular muscles. Myasthenia produces any combination of ptosis and ocular
motor defects which do not all fall within
single neural distributions. Superior oblique
myokymia produces monocular blurring or
torsional or vertical oscillopsia or diplopia.
select the most likely syndrome from the following list: A. Congenital nystagmus B. Spasmus nutans C. Vestibular nystagmus D. Downbeat nystagmus E. Periodic alternating nystagmus F. Seesaw nystagmus G. Superior oblique myokymia H. Gaze-paretic nystagmus
Question 16-7:
Peudular oscillation in which one eye rises and intorts while the other eye falls and extorts. The actions alternate.
Answer 16-7: F.
This is a classic description of seesaw
nystagmus. The appearance is quite
remarkable and often obvious to the examiner
without special testing. The precise
neurophysiology is not known but may be
related to dysfunction of the normal ocular
counter-rolling reflex. Bitemporal hemianopia
from chiasmallesions as well as other intraaxial
lesions, especially of the midbrain, can
produce this
select the most likely syndrome from the following list: A. Congenital nystagmus B. Spasmus nutans C. Vestibular nystagmus D. Downbeat nystagmus E. Periodic alternating nystagmus F. Seesaw nystagmus G. Superior oblique myokymia H. Gaze-paretic nystagmus
Question 16-8:
A 2-year-old is brought in for evaluation of titubation and is found to have torticollis plus a high-frequency pendular nystagmus.
Answer 16-8: B.
Spasmus nutans develops in children between
the ages of 6 and 12 months and lasts
approximately 2 years. It is characterized by a
high-frequency, low-amplitude pendular
nystagmus. Torticollis and titubation form the
other components of the spasmus nutans triad.
The titubation is not of the same frequency as
the nystagmus, so it is not merely a
compensatory nystagmus
select the most likely syndrome from the following list: A. Congenital nystagmus B. Spasmus nutans C. Vestibular nystagmus D. Downbeat nystagmus E. Periodic alternating nystagmus F. Seesaw nystagmus G. Superior oblique myokymia H. Gaze-paretic nystagmus
Question 16-9:
A 30-year-old man presents with no nystagmus in the primary position but has symmetrical nystagmus with gaze to either side. It has a jerk appearance with the fast phase in the direction of gaze.
Answer 16-9: H. Gaze-paretic nystagmus is the most common type of nystagmus. Common causes are alcohol and drug effects, including anticonvulsants. These non-structural causes cause symmetric nystagmus whereas structural causes would cause asymmetric nystagmus.
select the most likely syndrome from the following list: A. Congenital nystagmus B. Spasmus nutans C. Vestibular nystagmus D. Downbeat nystagmus E. Periodic alternating nystagmus F. Seesaw nystagmus G. Superior oblique myokymia H. Gaze-paretic nystagmus
Question 16-10:
Horizontal jerk nystagmus with a fast phase which changes direction after 1-2 minutes.
Answer 16-10: E
Periodic alternating nystagmus is a horizontal
Jerk nystagmus which alternates sides. The
nystagmus fades, then starts in the opposite
direction. The complete cycle lasts about 3
minutes. Periodic alternating nystagmus rnay
coexist with downbeat nystagmus and has the
same clinical implications with a wide .
differential diagnosis
