Nystagmus ✅ Flashcards
What is nystagmus?
Rhythmic oscillation of the eyes
In what terms can nystagmus be described?
- Type
- Direction
- Plane
- Amplitude
- Rate
- Conjugacy
- Null zone
What are the types of nystagmus? -
- Pendular
- Jerk
What is meant by pendular nystagmus?
Phases of equal velocity
What is meant by jerk nystagmus?
Phases of unequal velocity
What is described in the ‘direction’ of nystagmus?
The direction of the fast component
What are the ‘planes’ of nystagmus?
- Horizontal
- Vertical
- Rotatory
What are the ‘amplitudes’ of nystagmus?
- Coarse
- Medium
- Fine
What are the ‘rates’ of nystagmus?
- Slow
- Fast
What is meant by conjugacy in nystagmus?
Both eyes demonstrate the same movement
What is meant by null zone in nystagmus?
A point of gaze in which the nystagmus intensity is minimal
What are the types of physiological nystagmus?
- Optokinetic
- Rotational
- Caloric
- End-point
Where is end-point nystagmus seen?
Extremes of gaze, or after sustained deviation of the eyes
When is gaze-evoked nystagmus often seen?
As a consequence of therapeutic doses of anti-convulsants
What are the major categories of causes of pathological nystagmus?
- Infantile sensory nystagmus
- Infantile idiopathic motor nystagmus
- Acquired nystagmus secondary to neurological disease
- Acquired vestibular nystagmus
What causes infantile sensory nystagmus?
Poor vision or afferent sensory problems, e.g. aniridia, albinism
What is the most common cause of pathological nystagmus?
Infantile idiopathic motor nystagmus
What is infantile idiopathic motor nystagmus associated with?
Otherwise normal ocular and neurological function
When is infantile nystagmus noticed?
In the first few months of life
What are the characteristic features of infantile nystagmus?
- Usually horizontal (can be vertical or rotatory) and uniplanar
- Usually jerk (but may be pendular)
- Conjugate and similar in amplitude in both eyes
- May have associated head oscillation
- Null point of gaze where nystagmus is less marked
- Usually dampened by convergence
- Worsens when one eye covered
What is meant by uniplanar nystagmus?
Does not change plane in different positions of gaze
What is the result of infantile nystagmus having a null point of gaze?
The child will often adopt a head position to put their eyes in that position of gaze
What is the result of infantile nystagmus being dampened by convergence?
Near vision is better than distance vision
Why do infants with nystagmus need to be seen by an ophthalmologist?
To exclude a causative ocular abnormality
When can idiopathic motor nystagmus (IMN) be diagnosed?
If child’s visual development, eye examination, visual electrodiagnostics, and general development are normal
What might X-linked IMN result from?
Gene mutations from FRMD7
What kind of nystagmus should trigger concern about potential neurological disease?
Disconjugate nystagmus
What is the importance of the pattern of nystagmus in acquired nystagmus due to neurological disease?
It can help localise the pathology
What are the patterns of nystagmus seen by acquired nystagmus due to neurological disease?
- See-saw nystagmus
- Upbeat nystagmus
- Downbeat nystagmus
- Periodic alternating nystagmus
- Spasmus nutans
- Convergence-retraction nystagmus
- Opsoclonus
- Ocular bobbing
- Cerebellar system disease
What is see-saw nystagmus?
Pendular - one eye elevates and rotates inwards, while the other eye depresses and rotates outwards
What causes see-saw nystagmus?
Supra-sellar and rostral midbrain lesions
What is upbeat nystagmus?
Jerk, vertical with fast phase downwards
What causes upbeat nystagmus?
Lesions of cerebellar vermis and brainstem
What is downbeat nystagmus?
Jerk, vertical with fast phase downwards
What causes downbeat nystagmus?
Lesions of the cervico-medullary junction at the level of the foramen magnum, e.g. Arnold-Chiari malformation
What is periodic alternating nystagmus?
Jerk, horizontal with fast phase alternating from one side to the other after a short rest period
What causes periodic alternating nystagmus?
- Arnold-Chiari malformation
- Spinocerebellar degeneration
- Trauma
- Posterior fossa tumours
What is spastic nystagmus?
Triad of head turn, head nodding, and nystagmus
At what age does spasmus nutans occur?
Starts within first 18 months, and resolves by 3 years
Is spasmus nutans benign?
Yes
What are the features of the nystagmus in spasmus nutans?
Can be horizontal, vertical, pendular, or dysconjugate
What can the features of spasmus nutans be mimicked by?
Chiasmal, suprachiasmal, or third ventricle tumours
What is convergence-retraction nystagmus?
Jerk convergence-eye retraction movements on attempts of upgaze
What is convergence-retraction nystagmus usually associated with?
Defective upgaze and light-near dissociation as part of dorsal midbrain syndrome
What is opsoclonus?
Bursts of rapid, multivectorial, chaotic and conjugate eye movement abnormality
What might opsoclonus be associated with?
Myoclonus
What can cause opsoclonus?
- Infectious encephalopathy
- Non-metastatic feature of occult neural crest tumours, e.g. neuroblastoma
What is ocular bobbing?
Fast conjugate vertical movements with fast phase downwards
When might ocular bobbing be seen?
- Metabolic encephalopathy
- Obstructive hydrocephalus
What constitutes cerebellar system disease?
- Gaze-evoked nystagmus
- Ocular dysmetria
- Visual fixation instability
What is acquired vestibular nystagmus usually associated with?
Other symptoms such as deafness, tinnitus, and vertigo
What kind of nystagmus is produced by vestibular disease?
Horizontal-rotatory primary position uni-directional jerk nystagmus
In what direction is the fast beat stage in nystagmus caused by vestibular disease?
It beats away from the diseased vestibular system
