Infantile Nystagmus Flashcards
define nystagmus
repetitive , involuntary rhythmic oscillation of 1 or both eyes
can be about one or more axes horizontal/vertical
what is infantile idiopathic nystagmus
caused by no other neurological abnormalities
what are the causes of nystagmus in childhood
infantile idiopathic
albinism associated (achiasma)
associated with ocular diseases e.g. retinal dystrophies , rop
neurological diseases e.g. space occupying lesions , chiari malformation , hydrocephalus, cerebral palsy
spasms nutans
manifest latent nystagmus (infantile et)
fusion maldevelopment syndrome
sensory nystagmus
examples of associated ocular diseases causing nystagmus are..
retinal dystrophies
achromatopisa
congenital stationary night blindness
corneal opacities
optic nerv coloboma
optic nerve atrophy
chorioretinal coloboma
optic nerve hypoplasia
examples of neurological diseases associated with nystagmus are
hydrocephalus
chiari malformation
cerebral palsy
spinocerebellar ataxia
developmental diseases
space occupying lesions
what is the prevalence of nystagmus
24 per 10,000 have infantile nystagmus
what are the features of infantile nystagmus
present at birth/6 months
involuntary, bilateral , conjugate oscillation of the eyes, uniplanar oscillation (only horizontal plane)
no c/o oscillopsia
associated with x Linked recessive disorder (mum is a carrier and so is son) FRMD7 mutation
onset = 3-4 months
how to differentiate between acquired and infantile
acquired tends to be unilateral
infantile tends to be bilateral
what are the two types of albinism
oculotaneous albinism and ocular albinsim (oa) i.e. albinism contained to the eye
Genetically Inherited (recessive/x-linked)
Mutations in TYR/OCA2 (OCA) and GPR143 (OA)
Iris Transillumination- lacking pigmenetation in iris – inbestigated on slit lamp
Hypopigmentation of fundus
No foveal light reflex
Foveal hypoplasia-
Abnormal crossing at the chiasm- in picture more nasal fibres cross over- this results in an increased risk of dvloping strabismus and reduced levels of bsv e.g. stereopsis
Photophobia
what is achromatopsia
High Frequency
Horizontal and vertical nystagmus - eliptical
Severe photophobia
Abnormal Cone structure on OCT
Colour blindness
Refractive Error
Genetically Inherited – Recessive
what are the other common types of ateiology for infantile nystagmus
pax6- where iris dosnt develop normally
congenital stationary night blindness (CSNB) night blindness and myope , x linked , recessive and dominant inheritance patterns reported
retinal dystrophies
affecting the function of rods and cones
what is infantile strabismus syndrome
Causing a particular type of waveform – Manifest Latent Nystagmus (MLN)
Associated with Strabismus and prolonged deprivation of binocular function
Occlusion of one eye significant increases waveform fast phase beats toward fixing eye
Change their AHP
how are nystagmus eye movements classified
intensity
(frequency and amplitude)
waveform I,e, pendularr - backwards and forwards , jerk (slow phase and corrective fast phase)
complex - both jerk and pendular
plane - e.g. torsional, horizontal, vertical
conjugacy - ie.. conjugate - (eyes move together)
disconjugate
foveation periods- when eyes are moving slower
describe the waveforms produced by congenital nystagmus
Congenital nystagmus waveform: has an increasing-velocity slow phase, followed by a corrective fast phase
describe the waveforms produced by manifest latent nystagmus
has a decreasing-velocity slow phase followed by a corrective fast phase. The fast phase beats towards the viewing eye ( so if you cover RE, the fast phase will be to the left). But the waveform can also be linear, in which the slow phase is a straight line, followed by a corrective phase
how to differentiate between congenital nystagmus and manifest latent nystagmus
A way of differentiating MLN from CN is that in MLN the nystagmus intensity usually increase when one eye is covered, which is not usually the case in CN.
describe latent nystagmus waveforms
Latent Nystagmus waveform: is similar to MLN with decreasing-velocity slow phase, but is only present when one eye is covered. True LN occurs infrequently and there is a debate if true LN really exists.
what is periodic alternating nystagmus
Uncommon conjugate, horizontal jerk oscillation c periodic reversals in the direction of the fast phase
Occurs in 25% of patients with IIN
Separated by very short “quiet” phases (usually pendular oscillations of low intensity)
Beats to the left for a period of time then right
PAN cycle is variable (60-360 sec) and can be asymmetrical
what is the null zone
Null Zone (NZ): the gaze angle of min nystagmus intensity- where its theleast & max VA
Neutral Zone: the gaze angle in which the direction of the jerk nystagmus reverses its beat direction
Null Zone = Neutral Zone
where is the null zone
NZ= gaze angle of minimum nystagmus intensity and maximum visual acuity
Subjects with eccentric null zones often adopts a head posture to place their eyes in the NZ position
what compensatory strategies are used
Abnormal head posture (AHP)
Common with CN waveform
Multiple AHPs
Intermittent head nodding/head oscillation
Ghasia and Shaikh (2015) identified
Low frequency oscillation – constant, mainly horizontal
High frequency oscillation – episodic vertical bursts
Not correlated to dampening of nystagmus
\
head posture= adopted if the null zone is in eccentric gaze
can you adopt more than 1 ahp
It is important to be aware that some patients adopt multiple head postures because they have more than 1 NZ.
how is va influenced by nystagmus
Type of nystagmus waveform
Monocular or binocular viewing
Testing distance- important if convergence has an effect
dependent on Aetiology
Use of compensatory strategies
va is tested uniocualrly and binocularly
is manifest strabismus associated with nystagmus
2/3 with CN waveform
Almost 100% with MLN waveform
Majority horizontal strabismus
Esotropia ≈ Exotropia
Common in patients with albinisim
how is refractive error associated with infantile nystagmus
majority have refractive error (80%)
equal chance of having myopia/hypermetropia
may also have astigmatism
what are two rare forms of infantile nystagmus
Spasmus nutans is a rare form of infantile nystagmus.
It is characterised by a triad of nystagmus, head posture and head nodding
It present before 18 months of life
The nystagmus waveform: can be horizontal &/or vertical, monocular or binocular, the amplitude can be different b/w the two eyes
Spasmus nutans is a diagnosis of exclusion and further investigation is required to exclude brain tumours
See-saw nystagmus is characterised by 1 eye elevates and intort and the other depress and extort
Congenital see-saw nystagmus is extremely rare and it is more likely to be acquired.
Possible aetiology include: suprasellar mass lesion, Multiple sclerosis, Arnold-Chiari malformation, head trauma
how to differentiate between acquired nystagmus and infantile nystagmus
When a patient presents with nystagmus it is detrimental to determine if the nystagmus is Neurological (acquired nystagmus) or infantile.
The waveform of neurological nystagmus can be horizontal, vertical, torsional or a combination. It is often different in different positions of gaze. For example up-beat on up-gaze, down-beat on down-gaze and horizontal on versions.
It is frequently disconjugate which means the nystagmus is different in the 2 eyes e.g. horizontal in RE and torsional in LE
A common characteristic for acquired nystagmus is complain of oscillopsia. It is often unwell patients that also feels nauseas and c/o headaches.
Possible aetiology of acquired include Brain tumour, stroke, MS, increased intracranial pressure.
what are the aims of examination
The aims of the examination are:
Determine if the nystagmus is infantile or acquired
Assess maximum level of VA
Diagnose any strabismic amblyopia
Record the type of the nystagmus
what needs to be looked at on investigation
Case History
Age of onset (<6/12)
Symptoms – c/o oscillopsia, nausea, photophobia, night blindness, Colour VA problems
FH of nystagmus
GH -medication
Effect of previous treatment
Observation
AHP/head nodding
Manifest nystagmus
Signs of albinism
Signs of visual handicap
what things need to be noted in the case history
It is important to take a detailed case history to determine the differential diagnosis of infantile versus acquired nystagmus. Is the onset before 6 months? if the patient c/o oscillopsia or feel ill they are more likely to be acquired. If the patient c/o photophobia he/she may be albino. If there is a FH of nystagmus it is unlikely to be acquired.
Observe the patient: do they adopt a head posture or head nod, is the nystagmus manifest and is there any signs of albinism or visual handicap?
what needs to be done in the orthoptic investigation
VA – Binoc and Monoc, Near and distance
AHP – During VA testing may change
CT ~ Manifest strabismus
OM ~ Describe the nystagmus
Saccades, VOR, OKN
Convergence ~ dampening of nystagmus
Assess BSV ~ appropriate to level of VA
Colour Vision
Visual Fields
to patients see better monocularly or binocualry
Often patients with IN see better with both eyes open hence VA testing should be done monocularly and binocularly for near and distance. Also ask for their preferred reading distance to allow for the convergence effect, many sees better at example 15cm instead of 1/3m
what extra things need to be done if a pt has suspected infantile nystagmus
Describe the nystagmus, is it horizontal, vertical, torsional or a combination
Is it jerk or pendular and is it there all the time or increase in intensity when one eye is closed.
Check for any convergence effect
Colour vision is valuable to do to determine if there is any underlying sensory defect
how to describe the directions and types of nystagmus
horizontal/peendular
horizontal jerk with fast phase left
horizontal jerk with fast phase right
torsional
torsional and horizontal jerk with fast phase left
how to describe thee amplitude and frequency of nystagmus
small amplitude, medium amplitude, large amplitude , low frequency
moderate frequency , high frequency , thee null zone is noted at 30 degrees eccentricity
how is nystagmus recored diagrammatically
using grid (same as 9 positions of gaze)
*have to draw two lines not just one line with two arrows to represent the 2 eyes
what further examinations need to be done
Cycloplegic refraction has been advocated because so many of the patients have astigmatism.
The aim is to achieve max VA and allow the patient to use compensatory strategies if it improves VA
Fundus and media should be checked to determine possible underlying cause (Picture: albino c hypopigmentation of fundus (fovea and macular))
Ideally the diagnosis of idiopathic IN should include electrodiagnostic tests to exclude retinal or optic nerve diseases
ERG to identify any retinal disorders, example CSNB, Rod/Cone dystrophies
VEP to diagnose ocular albinism or optic nerve diseases.
Ideally you would like to carry out infrared recording techniques to differentiate b/w the different waveforms of IN, such as CN and MLN. Additionally you can also determine the position of the NZ. EOG is not an accurate technique.
MRI and CT- scan must be performed if there is any doubt the nystagmus may be secondary to neurological diseases.
If still in doubt further investigations may be required.such as MRI and CT scan
further investigation= genetic testing
what are the aims of treatment
The aims of treatment is to achieve max level of VA
Provide genetic counselling
Reduce a mod/mark Ahp
And correct cosmetically poor strabismus
how is optimum va achieved
As orthoptist we will treat amblyopia if it is present this can be done conventionally with patching. Often part-time occlusion is recommended because the nystagmus often increase in intensity when 1 eye is covered as well as VA can reduce with 1 eye covered. Hence atropine and bangert foils have been advocated by some.
A lot of children with nystagmus have multiple disabilities. Therefore you have to weigh up if it is really worth undergoing occlusion.
Optically the VA may improve with CL rather than glasses because CL’s follow the constant movement of the eye
Albino patients are often very photophobic and benefit from tinted lenses
Minus lenses may also be considered if there is a marked dampening effect on convergence. The minus lenses will simply induce accommodation and accommodative-convergence
how is optimum va achieved (optically)
Majoroty of patients will have refractive error and high degrees of astigmatism
Randomised controlled trial in Leicester (( Jayaramachandran et al 2014)
comparing RGPL vs SCL. Thought RGPL would cause greater reduction in nystagmus intensity due to it is likely to cause more feedback of eye movements than the mre pliable and more comfortable material of soft contact lenses
Albino patients are often very photophobic and benefit from tinted lenses
Minus lenses may also be considered if there is a marked dampening effect on convergence. The minus lenses will simply induce accommodation and accommodative-convergence
how are prisms used to correct ahp
Prisms: may be used if there is an eccentric NZ and an associated AHP. The principle is to put the prism BO away from the NZ. If a patient adopts an AHP to the right and the NZ is to the left, you place the prism BO to the right to shift the NZ to the right, and thus reduce the need for an AHP.
If there is a dampening of the nystagmus on convergence, you can place both prisms BO, to induce convergence.
how is medication used to treat nystagmus
Recently, the effect of gabapentin and memantine on idiopathic infantile nystagmus and those with infantile nystagmus due to ocular defects has been examined. Encouraging findings of dampening of nystagmus intensity, extended foveation period associated with improvement in visual acuity have been demonstrated in some patients (Shery et al. 2006; McLean et al. 2007).
Dell’Osso et al.2011 In this subject with INS, topical brinzolamide resulted in improved-foveation INS waveforms over a broadened range of gaze angles. Its therapeutic effects were equivalent to systemic CAI. Although a prospective clinical trial is needed to prove efficacy or effectiveness in other subjects, an eyedrops-based therapy for INS may emerge as a viable addition to optical, surgical, behavioral, and systemic drug therapies.
Clinical trial required
what is the Anderson kestenbaum procedure
The Andersen-Kestenbaum procedure. It is indicated in patients who adopts a large AHP to place eyes in their eccentric NZ.
The principle is to move BE’s in the direction of the AHP and away from the NZ.
So if you have a face turn R and NZ to the L, you would want to resect RLR (8mm) and LMR (6mm) and recess RMR(5mm) and LLR (7mm)
Artificial divergence surgery is considered in cases where the nystagmus intensity reduce markedly on convergence.
The principle is to induce an exophoria by bimedial MR recession and thus make the patient have to exert fusional convergence.
what is the artificial divergence procedure
Nystagmus intensity (NI) on convergence and near VA ↑
Principle: induce exophoria
Bimedial MR recession patient exerts fusional convergence nystagmus & distance VA ↑
Hertle et al. (2010) suggested MR recession and LR tenotomy + reattachment of LR
what is done to the recti muscles to help Improve infantile nystagmus
Maximum recession of all 4 horizontal recti muscles have been advocated. The aim is to symmetrically weaken all 4 horizontal recti muscles which has been found to reduce NI and increase the foveation period which gives improved VA.
It is indicated in patients without an AHP, strabismus or conv effect.
is there a cure for nystagmus
no
