Nystagmus_Dr. M. Sharma Flashcards
Where is the probable location of a upbeat nystagmus?
Posterior fossa (medulla most common)
Where is the probable location of a periodic alternating nystagmus?
Cerebellar nodulus
Where is the probable location of a ocular bobbing?
Pontine destructive lesion
Where is the probable location of a ocular flutter/opsoclonus?
Pons (pause cells); cerebellum (connections to pons)
Where is the probable location of a convergence-retraction nystagmus?
Pretectum (dorsal midbrain)
Where is the probable location of a see-saw nystagmus?
Paraellar/diencephalon
Where is the probable location of a monocular nystagmus of childhood?
optic nerve/chiasm/hypothalamus
central vestublar nystagmus is a mixed __________ trajectory?
horizontal-torsional
Central vestibular nystagmus usually beats away or towards the side of the vestibular lesion?
away
Does central vestibular nystagmus associates with neurologic signs and symptoms?
Yes
How is the VA of the people who has central vestibular nystagmus?
VA may be normal small amplitude outside primary position
Which nystagmus is the most common form of central vestibular nystagmus?
downbeat nystagmus
What is a downbeat nystagmus look like?
results from lesions that produce defective vertical gaze holding characterized by an upward drift of the eyes, which is then corrected with a downward saccade.
Does downbeat nystagmus follow the ALEXANDER’S LAW?
Yes
In what position does the downbeat nystagmus usually accentuated?
downgaze, especially to either side.
T/F In downbeat nystagmus, the lesion is in vestibulocerebellum and diminish the tonic output from the anterior semicircular canals to the ocular motoneurons.
True
What is the most common structural lesion of a downbeat nystagmus?
Arnold-Chiari Type 1 malformation. Lesion of the foramen magnum
What are the treatments for downbeat nystagmus?
- Common treatments are “off label” include Clonazepam, Baclofen and Gabapentin
- Base-Out prisms (induce convergence)
- Memantine, 4-Aminopyridine and 3,4-Diaminopyridine
where is the probable location of lesion with downbeat nystagmus?
Cervical-medullary junction
upbeat nystagmus is caused y lesions in the posterior fossa of which part?
Brainstem (often medulla) and The anterior cerebellar vermis
The most common causes of upbeat nystagmus are _______, _______, ________, and ________.
Demyelination
Stroke
Cerebellar degeneration
Tobacco smoking
Purely torsional nystagmus indicates a _______ lesion.
central lesion, associates with a medullary lesion (eg. syingobulbia, lateral medullary infarction)
Periodic alternating nystagmus oscillates predictably in ________, ______ and ______.
direction, amplitude and frequency
Is periodic alternating nystagmus congenital or acquired?
can be both
Periodic alternating nystagmus is typically associated with dysfunction of the _______ and _______.
cerebellar nodulus and uvula
What is the drug of choice to effectively treat acquired form of nystagmus?
Baclofen
Acquired pendular nystagmus with both vertical and horizontal components produces ________ (if the components are in phase) or ________ or ________ nystagmus (if the components are out of phase).
oblique, circular, elliptical
The eye movements in acquired pendular nystagmus may be conjugate or disconjugate and are often _________.
dissociated
Oculopalatal myoclonus or tremor is an acquired _________ plus ________.
pendular nystagmus, myoclonus
Oculopalatal myocolonus usually arises several months after a lesion occus that involves the _________.
Guillain-mollaret triangle
Which kind of nystagmus produces an inferior olivary hypertrophy?
Oculopalatal myoclonus. When the lesion is within central tegmental tract, it can disrupt transmission between the cerebellum, specifically the flocculus,, and the inferior olive.
See-saw nystagmus is a form of disconjugate nystagmus in which 1 eye _____ and _____ while the other eye ______ and ______.
elevates, intorts
depresses, extorts
See-Saw nystagmus is most commonly observed in patients with large tumors of the parasellar region that impinge on the ______ ventricle.
third
Craniopha-Ryngioma is a frequent cause
Other parasellar-diencephalic tumors and trauma may als produce see-saw nystagmus
See-Saw nystagmus may be associated with vision loss and often looks like ________ hemianopia.
bitemporal
In dissociated nystagmus, the most common form of this disorder is one that is associated with lesions of the __________, which produce an internuclear ___________.
medial longitudinal fasciculus (MLF)
Ophthalmoplegia (paralysis of the muscles within or surrounding the eye)
How does dissociated nystagmus look like?
isolated slowing of adduction of the eye isilateral to an MLF lesion, which create excessive saccadic movements in the contralateral rectus muscle (abduction). That’s according to Hering’s Law.
What are the Gaze-holding deficiency nystagmus (neural integrator)?
- eccentric gaze nystagmus ( and associated rebound nystagmus)
- Gaze instability (“Run-away”) nystagmus.
What is eccentric gaze nystagmus?
It develops becaue of an inability to maintain fixation in eccentric gaze. Eyes drift back to the midline and a corrective saccades reposition the eyes on the eccentric target with a fast phase.
What law is Eccentric gaze nystagmus follows?
Alexander’s law. Nystagmus increases in intensity (amplitude and frequency) as the eyes are moved in the direction of the fast phase.
Eccentric gaze nystagmus is caused by dysfunction of the ________ integrator.
neural
- For horizonal gaze, the neural integrator include the nucleus prepositus hypoglossi and the medial vestibular nuclei
- For vertical gaze the interstitial nucleus of Cajal serves as the neural integrator
- The flocculus and nodulus of the cerebellum also play a role in maintaining an eccentric position of gaze.
Rebound nystagmus is often a manifestation of _________ disease.
cerebellar
what is gaze instability (run-away) nystagmus look like?
ocillation slow phases are directed away from central position
Gaze instability (run-away) nystagmus is associated with ________ signs and symptoms.
neurologic
In gaze instability nystagmus, ocular motility recording show slow phase that are accelerating or decelerating?
accelerating
What is the treatment for superior oblique myokymia?
Carbamazepine
What are the treatment for downbeat and other central vestibular forms of nystagmus?
occasionally be helped by clonazepam, A GABA agonists
What would you use that may improve visual acuity in patients with congenital nystagmus?
contact lenses
What are the non-medical treatments for nystagmus?
- Prisms such as base out prisms to induce convergence if nystagmus diminishes with convergence
- contact lenses to improve VA in patients with congenital nystagmus
What are the other eye movement disorders?.
- voluntary flutter (“nystagmus”)
- convergence-retraction nystagmus
- superior oblique myokymia
- oculomasticatory myorhythmia
- ocular bobbing
What is the motion you see with voluntary flutter (“nystagmus”)?
rapidly oscillating eye movement (almost always horizontal) that can be induced volitionally.
The movement lack slow phases, so it’s not a form of nystagmus.
Voluntary flutter appear as high-frequency, conjugate, back to back saccades without an ___________.
intersaccadic interval
Voluntary flutter is associated with convergence and often with eyelid flutter and ________.
facial grimacing
is Convergence-retraction nystagmus a true nystagmus?
no because it doesn’t have a slow phase
Convergence-retraction nystagmus is often associated with paresis of what gaze?
upgaze
What is the Collier sign and which nystagmus has this?
Near dissociation, skew deviation and bilateral eyelid retraction
Superior Oblique Myokymia produces ________, _______, ________ bursts of contraction of the superior oblique muscle.
paroxysmal, monocular, high frequency
Does Superior Oblique Myokymia shows large or small amplitude?
small amplitude and magnification is usually required.
Is Superior Oblique Myokymia malignant or benign?
It is almost always benign, although there are rare reports of its association with MS and posterior fossa tumor
What is oculomasticator myorhythmia?
It develops pendular, vergence oscillations that occur with contractions of the masticatory muscles.
What is an early neurologic finding in whipple disease?
vertical saccadic palsy
What is the eye movements you see with ocular bobbing?
rapid downward movement of both eyes, followed by a slow return of the eyes to the midline position.
Where is the lesion that causes ocular bobbing?
Usually in the pons, secondary to infarction or hemorrhage.
