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ACTIVE TREATMENT OF CONGENITAL NYSTAGMUS: RATIONALE & RESULTS. LIONEL KOWAL LOTS of assistance from Drs Elaine Wong, Steven Bush, Joanne Dondey & Larry Abel SQUINT CLUB 2006. OVERVIEW OF THIS TALK. 1. Overview of cong N 2. Treatments 3. Audit of recordings 4. Audit of surgeries.

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active treatment of congenital nystagmus rationale results

ACTIVE TREATMENT OFCONGENITAL NYSTAGMUS:RATIONALE & RESULTS

LIONEL KOWAL

LOTS of assistance from Drs Elaine Wong, Steven Bush, Joanne Dondey & Larry Abel

SQUINT CLUB 2006

overview of this talk
OVERVIEW OF THIS TALK
  • 1. Overview of cong N
  • 2. Treatments
  • 3. Audit of recordings
  • 4. Audit of surgeries

Squint Club 2006

apogolies for difficlut ternimology
APOGOLIES FOR DIFFICLUT TERNIMOLOGY
  • Congenital Aperiodic Periodic Alternating Nystagmus  PAN
  • Latent Manifest Latent Nystagmus  LMLN, aka Fusion Maldevelopment Syndrome or FMS
  • Dual Jerk nystagmus : Not a personal insult - combination pendular plus jerk nystagmus

Nystagmus usu referred to as N

Squint Club 2006

in office assessment of congenital nystagmus

IN OFFICE ASSESSMENT OF CONGENITAL NYSTAGMUS

Types of congenital nystagmus - how to differentiate them in the office

2 main types of c ongenital n

2 Main types of congenital N:

Lower case ‘cN’ = congenital N = any sort of very early onset N

1.Congenital N

Upper case ‘CN’ - a specific type of cN

Synonyms:

Congenital Motor N

Idiopathic Infantile N

IIN

2 main types of congenital n

2 Main types of congenital N:

2. LMLN

Latent Manifest Latent N

Synonyms:

Manifest Latent N

Fusion Maldevelopment N

FMNS

congenital n
Congenital N
  • Result of abnormal bilateral symmetric acuity development @ a CRITICAL PERIOD in very early visual devpt.
  • Hence frequent association with : OCA [foveal ± disc dys- / hypo-plasia], high refractive errors, bilateral optic n hypoplasia, PVL, bilateral cong cataracts, …..

Squint Club 2006

slide9
LMLN
  • Result of Asymmetric acuity development and/or abnormal development of binocularity @ a CRITICAL PERIOD in very early visual devpt hence associated with CET, early monocular visual loss, PVL, …

Squint Club 2006

slide10
CN
  • Involuntary, bilateral, conjugate [RE = LE] oscillation beginning ≤ 6 mo
  • Usually horizontal ± torsional
  • Decreased at certain angle[s] = null zone NZ
  • Blocked with convergence [also NZ]

Squint Club 2006

slide11
CN

Commonly gaze evoked:

  • R beating in R gaze
    • actually to R of NZ
  • L beating in L gaze
    • actually to L of NZ

Usual CN waveform [decreasing velocity slow phase] is UNIQUE

Squint Club 2006

acuity in cn foveation
Acuity in CN : FOVEATION

When eye changes direction, speed of oscillation slows down in order to reverse direction = foveation period

[velocity < 5 º/sec; flat part of the EMR]

Squint Club 2006

acuity in cn foveation13
Acuity in CN : FOVEATION
  • BCVA depends on:
    • Duration of foveation period
    • Persistence and effect of factors that initiated the CN [foveal hypoplasia, optic n hypoplasia, high cyls, …]

Squint Club 2006

cn 2 nzs little no n
CN: 2 NZs LITTLE / NO N
  • ECCENTRIC NZ : drives AHP
  • Usu stable / ‘hard wired’
  • but can vary time / age
  • Can be turn, tip, tilt [T3] or combo.
  • Same with either eye fixing
  • CONVERGENCE NZ
  • near acuity better than distance
  • medial recti ‘brake’ the CN

Squint Club 2006

cn natural history 3 phases over the first 12mo
CN Natural history: 3 phases over the first 12mo

Phase I : first 2-3 mo of life

  • Purposeless eye mvmts - as if blind
  • No jerk N
  • large amp, low frequency ‘triangular’
  • No voluntary horizontal pursuit / saccades
  • Normal vertical OKN, pursuit and saccades - excludes apparent blindness & avoids MRI

Squint Club 2006

natural history phase ii pendular
Natural history : Phase II pendular

Age 6-12 mo

Symmetrical, low-amplitude, pendular N

May remain phase II without proceeding to phase III

Squint Club 2006

natural history phase iii adult waveform
Natural history: Phase III adult waveform
  • Age 12+ mo
  • ‘Adult’ jerk waveform
  • development of eccentric null zone with AHP
  • ± compensatory head nodding
  • Phases are per Reinecke
  • Hertle does not show same evolution
  • Difference: ?sampling ?selection bias

Squint Club 2006

cn variant p a n
CN variant : P A N
  • Relatively common
  • VERY under diagnosed
  • Melbourne: ?30% of albinos
  • FAT SCAN IMPORTANT - are there ANY photos that shows a face turn the other way?

Squint Club 2006

cn variant p a n19
CN variant : P A N
  • Oscillates between 2 NZs approx 90° apart
  • O/wise identical to CN
  • NZ changes : cycle of 1 to 10 min

Acquired PAN : cycle usu 2 min

  • Usu Aperiodic e.g. 8 min to L & 1 min to R

Squint Club 2006

latent manifest latent nystagmus lmln
Latent Manifest Latent Nystagmus LMLN
  • Main EMR feature:

Decreasing velocity slow phase

[not unique - also gaze paretic N]

Squint Club 2006

latent manifest latent n lmln
Latent Manifest Latent N LMLN
  • Main clinical feature:

Fast phase to fixing eye - UNIQUE

LMLN : is a conjugate bilateral monocularly ‘driven’ N - waveform depends on which eye is fixing, and whether that eye is in the AD- or AB- ducted position

Slit lamp: T component common

Squint Club 2006

lmln can resemble cn
LMLN can resemble CN

Null in adduction for each eye [less N, vision better] - can look like CN conv null

Nystagmus on lateral gaze:

  • LE in LG: BE have N  L
  • RE in RG: BE have N  R

SUPERFICIALLY SIMILAR TO GAZE EVOKED N OF CN

Squint Club 2006

lmln face turn to fixing eye
LMLN Face turn to fixing eye
  • 2 NZs improve VA:H & Thence 2 types of AHP
  • NZs in LMLN are monocular
  • NZ for blocking the H component of LMLN: fixation in adduction
  • Medial rectus acts as a ‘brake’
    • Face turn to fixing eye - can superficially resemble PAN

Squint Club 2006

lmln head tilt to fixing eye
LMLN Head tilt to fixing eye
  • NZ for blocking T component of LMLN : in intorsion
  • sup oblique acts as a ‘brake’

Head tilt to fixing eye

Same mechanism causes DVD of other eye

Squint Club 2006

cn pan lmln
CN / PAN & LMLN
  • RECAP ….

Squint Club 2006

congenital n26
Congenital N
  • Result of abnormal bilateral symmetric acuity development

Squint Club 2006

why lmln
WHY LMLN?
  • Result of Asymmetric acuity development &/or abnormal development of binocularity
  • BOTH LMLN & CN seen together in very early onset Cong ET

Squint Club 2006

both cn lmln may have
Both CN & LMLN may have:
  • N greater in lateral gaze
  • Latent component

N worse with monocular cf binocular fixation

different mechanisms in CN / LMLN

  • Strabismus

CN: some. LN: nearly all

Squint Club 2006

both cn pan lmln may have
Both CN/PAN & LMLN may have:
  • Conv null

different mechanisms

  • Alternating face turns

different mechanisms

Squint Club 2006

cn vs lmln in office guidelines
CN vs. LMLNIN OFFICE GUIDELINES
  • T: prob LMLN
  • OCA :  bilateral VA  CN
  • N  fixing eye: LMLN

Squint Club 2006

cn vs lmln in office guidelines 2
CN vs. LMLNIN OFFICE GUIDELINES 2
  • Pref for fixation in ABduction : CN
  • Smooth pursuit asymmetry: LMLN

Squint Club 2006

p a n
P A N
  • Prolonged in- office exam - check AHP while talking to parents for PAN [show age appropriate DVD]
  • FAT scan to determine consistency

Squint Club 2006

slit lamp exam
SLIT LAMP EXAM
  • Look for TIDs of iris with decentred beam in a darkened room
  • Makes OCA likely
  • Hermansky Pudlak looks just like OCA : ask re: any possible bleeding diathesis

Squint Club 2006

slit lamp exam34
SLIT LAMP EXAM
  • The ‘Designs for Vision’ examination paddle with reduced Snellen chart is a good way to
    • determine conv null
    • any T component [usu LMLN]
    • fast phase to fixing eye
    • Smooth pursuit asymmetry [usu accompanies LMLN]

Squint Club 2006

does everyone with wiggly eyes need to be recorded
Does everyone with wiggly eyes need to be recorded?
  • Usually - not if you’re absolutely certain about the diagnosis and have all the information you need for management
  • EMR is to cN today what ECG was to arrhythmia 50 y ago - would you dream of managing an arrhythmia without ECG?

Squint Club 2006

what if you re not sure
What if you’re not sure?
  • CN waveforms are unique - can confirm diagnosis

Can save patient expensive imaging studies (esp. small children)

Squint Club 2006

what if you re not sure38
What if you’re not sure?
  • What distinctions can you make?
    • Acquired vs. cong types N
    • CN vs. cong PAN
    • CN vs. LMLN
    • N vs. saccadic oscillations

Squint Club 2006

cn waveforms
CN waveforms
  • Pathognomonic for CN
  • Approx 15 waveforms described
  • ‘Jerk’ or ‘pendular’ on basis of slow component

Jerk waveforms may appear pendular clinically

  • Analysis of waveform may  prognostic information about potential VA

Squint Club 2006

latent nystagmus
Latent nystagmus
  • EMR often required to determine whether LN is due to CN or LMLN
  • “The eye is quicker than the eye”

Squint Club 2006

assessing effects of treating cn
Assessing effects of treating CN
  • CN’s variability makes clinical assessment of change difficult
  • Recording can objectively document
    • Changes in foveation
      • Can facilitate better VA
    • Shift in null position
      • Will reduce or eliminate AHP
    • Broadening of null
      • having best possible vision over a wider range of gaze angles improves patients’ functionalfield of vision

…all best demonstrated with EMR

Squint Club 2006

summary
Summary
  • EMR can provide clinicians with two major forms of assistance:
  • 1) establishing / confirming a diagnosis when the clinical presentation is atypical or ambiguous
  • 2) Document outcome of treatment

Squint Club 2006

treatment goals in cn 1
Directly Improve VA

Treat refractive error

Treat amblyopia

Stabilize/ reduce intensity N (increase “foveation”) to improve VA

Prisms

CLs

Surgery

Treatment goals in CN 1

Squint Club 2006

treatment goals in cn 2
Normalize head posture

Prisms

Surgery

Broaden NZ to expand effective visual field

Prisms

CLs

Surgery

Treatment goals in CN 2

Squint Club 2006

medical treatments
Drugs - barely explored

New epilepsy drugs Lyrica, Memantine, Neurontin

Medical treatments

Squint Club 2006

prisms for convergence null
Prisms - for convergence null
  • Induce fusional convergence
  • 7 ∆ base out prisms with -1 DS OU to compensate for convergence induced accommodation [CA/C ratio]
  • Can be used long term
  • Useful preop test for suitability for artificial divergence surgery

Squint Club 2006

contact lenses
Contact lenses
  •  VA ≥ optical effect alone
  • CL sometimes expands NZ & improves foveation time
  • ? Stimulates conjunctival proprioceptors

Dell’Osso 1988. Contact lenses and congenital nystagmus.

Clin. Vision. Sci. 3:229-232

Squint Club 2006

surgical treatments
#1: ARTIFICIAL DIVERGENCE

#2: KESTENBAUM / ANDERSON

#3: HERTLE TENOTOMY

#3A: 4 MUSCLE RECESSION

#4: LMLN SURGERY

Surgical treatments

Squint Club 2006

1 artificial divergence surgery
#1: ARTIFICIAL DIVERGENCE SURGERY
  • Cuppers,1970’s. Popularised by Spielman 1990’s. >100 cases to AAPOS 10y ago
  • If there is a conv null for distance with ∆, BMR creates an exophoria that ‘drives’ a conv null
  • INDICATIONS
        • CN / PAN
        • Convergence null for distance
        • Some sensory and motor fusion or BMR  constant XT

Squint Club 2006

artificial divergence surgery
ARTIFICIAL DIVERGENCE SURGERY

COMPLICATIONS AND EXPECTATIONS

  • 10% consec XT
  • Improved VA & field
  • Decreased AHP & nystagmus

BEST OPERATION FOR NYSTAGMUS

Squint Club 2006

2 horizontal null position surgery kestenbaum anderson
#2: HORIZONTAL NULL POSITION SURGERYKESTENBAUM / ANDERSON

50y history!

Rc/Rs OU for face turn

13mm OU for 15º - 25º face turn

Anderson* : only the Rc component

1. INDICATIONS

CN with consistent Eccentric NZ

R/O APAN

INADEQUATE CONVERGENCE DAMPING

>12 mo old (Child is walking)

* Hugh Taylor’s grandfather

Squint Club 2006

complications and expectations of kestenbaum anderson surgery
COMPLICATIONS AND EXPECTATIONS OF KESTENBAUM / ANDERSON SURGERY
  • Improves AHP
  • Improves VA in many
  • Expands NZ & effective field of vision
  • Small Under- > Over- Corrections frequent
  • Consecutive Strabismus infrequent but difficult
  • Limitation of Gaze - pseudo Gaze Palsy - may never fully recover

Squint Club 2006

non specific ve effect of cn surgery
Non- specific +ve effect of CN surgery

K’baum operation usu:

  • Expanded null zone *
  • Improved acuity **

IRRESPECTIVE of whether the K’Baum achieved the desired goal

*Dell'Osso,L,Flynn, J.T.: Congenital Nystagmus Surgery: A Quantitative Evaluation of the Effects.Arch. Ophthalmol.97:462-469, 1979

** John Norton Taylor, RVEEH in Aust NZ J Ophthal, and many others

Squint Club 2006

intriguing question
Intriguing Question

Does K’baum surgery have a non-specific +ve effect that we can exploit ?

Squint Club 2006

hertle research
HERTLE RESEARCH
  • In beagles with cong SSN tenotomy & resuture improves the features of the EMR that correlate with improved VA

2. Proprioceptors in ‘Enthesis’ [where tendon inserts into sclera] are abnormal in human CN pts [?cause ?effect]

Squint Club 2006

slide57

ACHIASMATIC BELGIAN SHEEP DOGS WITH CONGENITAL SEE SAW NYSTAGMUS

Lakota

Copper

Squint Club 2006

3 hertle tenotomy operation
#3: HERTLE TENOTOMY OPERATION
  • If K’baum and artificial divergence surgery not appropriate “Tenotomy & resuture back to insertion” improves foveation on EMR in nearly all CN pts and improves VA in about 50%

Hertle RW.

Horizontal Rectus Tenotomy in Patients with Congenital Nystagmus.

Ophthalmology. 2003;110:2097-2105

Squint Club 2006

3 tenotomy only indications
#3: TENOTOMY ONLY INDICATIONS
  • CN
  • No alternative surgery appropriate

No Convergence or Eccentric Null

  • ≥12 mo old
  • ≤10% of CN Patients appropriate

Squint Club 2006

3a large rc all horizontal recti
#3A: Large Rc all horizontal recti

Bietti / Bagolini 50y history

  • Recess all muscles +++ : to suppress the CN  improve vision, cosmesis, face turns
  • Largely abandoned in Europe - resurrected in USA / Mexico in 80’s

Reinecke

  • improves VA only in PAN

Squint Club 2006

4 surgery for lmln
4. Surgery for LMLN

Reinecke

  • Corrrect ET or XT perfectly and convert LMLN to LN
  • Improved face turns
  • Improved VA

Squint Club 2006

audit methods
Audit methods
  • Files of 79 LK private patients with presumed cN reviewed
  • 55 patients had EMR
  • Recordings and clinical diagnosis were compared

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the population studied
The population studied

Squint Club 2006

emr versus clinical assessment
EMR versus clinical assessment

n=55

Squint Club 2006

emr diagnosis indeterminate clinical diagnosis 33
EMR diagnosis, Indeterminate clinical diagnosis – 33%
  • PG, 18 presented requesting treatment of N.
  • Vision was R 6/24 L6/30, bin 6/10.
  • ET, Direction of fast phase unclear, convergence null
  • Oscillopsia
  • Uncertain office diagnosis
  • EMR : CN

Squint Club 2006

office diagnosis incorrect 16
Office diagnosis incorrect -16%
  • CS, age 5, presents with a L FT and tilt. Had undergone surgery previous year for XT.
  • R6/18 L 6/15.
  • Fast beat in direction of fixation, no convergence null, no eccentric null.
  • Office diagnosis LMLN
  • EMR demonstrates CN

Squint Club 2006

emr indeterminate 11
EMR indeterminate – 11%
  • 4 patients with APAN, all correctly diagnosed as having a CN waveform. Unable to demonstrate EMR features of APAN
  • 1 patient with very asymmetric pendular nystagmus – CN confidently excluded but no definite diagnosis made

Squint Club 2006

limitations of emr
Limitations of EMR
  • Not readily available
  • Equipment limitations limit assessment of vertical nystagmus and positions of extreme gaze
  • Cooperation of patients - v. difficult under 12 mo, difficult under 2y
  • Melbourne: LUCKY to have Larry Abel

Squint Club 2006

limitations of emr70
Limitations of EMR

THANK YOU LARRY!

Squint Club 2006

accuracy of clinical signs
Accuracy of clinical signs
  • Clinical signs evaluated:
    • Direction of N ? in direction of gaze or ? to fixing eye
    • Convergence null
    • Eccentric null
  • Final diagnosis after serial clinical assessment, FAT, EMR, and clinical conferences

Squint Club 2006

conclusions 1
Conclusions 1
  • 3 tests with >95% specificity
    • Eccentric null in CN
    • Conv. null and jerk to gaze direction in CN
    • Jerk to fixing eye in LMLN

Diagnosis made with these signs is likely to

be accurate

Squint Club 2006

conclusions 2
Conclusions 2
  • Although a good “stand alone” test, jerk to fixing eye will still miss ~25% of LMLN
  • Convergence null and jerk to gaze direction will miss most CN

Squint Club 2006

conclusions 3
Conclusions 3
  • EMR valuable in evaluation of cN, and will become more important if / as surgery becomes more popular
  • Serial clinical assessment helpful esp. F.A.T in APAN – EMR may miss this diagnosis
  • Be aware of limitations of office exam

Squint Club 2006

audit of lk surgeries seen during 2003 5
AUDIT OF LK SURGERIES seen during 2003-5
  • n=20
  • 16 : EMR confirmation
  • 10 ‘pure’ CN
  • 3 PAN
  • 5 LMLN [EMR 4]
  • 2 CN + LMLN [EMR 1]

Squint Club 2006

kestenbaum n 6
KESTENBAUM n=6
  • 2 with ≥ 1 line improvement
    • #1: 6/12 OU to 6/6, 6/9
    • #2: 6/18 OU to 6/12 OU
  • 5/6: AHP fixed
  • 3/6 need 2nd surgery:

1. AHP over corrected

2. Consec XT

3. Pre-existing strab not fixed

Squint Club 2006

strabismus hertle n 6
Strabismus + Hertle n=6
  • 5 for ET & 1 for XT + Hertle on other horizontal recti
  • 1/6 improved VA
    • From 6/15 OU to 6/9 OU
  • 1/6 VA worse
    • From 6/30, 6/60 to 6/45, HM

Comorbidities: midline brain anomalies

Squint Club 2006

strabismus hertle n 680
Strabismus + Hertle n=6
  • 1/6: fixation switch : problems
  • 1/6 PAN. E + conv null for D confirmed with ∆ glasses. Sx: NO effect on FT. 2nd surgery to augment BMR - some improvement

Squint Club 2006

artificial divergence hertle n 2
Artificial divergence + Hertle n=2
  • #1: PAN with alternating FT
    • Corrected
  • #2: PAN and albinism
    • VA 6/36 OU to 6/22 OU
    • Consec XT* : 2nd op to advance one MR
    • Alt FTs much improved

* +ve Kappa of OCA makes this look worse

Squint Club 2006

large 4 muscle rc n 1
Large 4 muscle Rc n=1

PAN with no face turns - null zone in primary position

  • Surgery
    • MRRc 9 OU, LRRc 10 OU
  • VA improved
    • 6/30 to 6/19 OU

Squint Club 2006

surgery for lmln n 2
Surgery for LMLN n=2
  • #1: 35∆ XT with oscillopsia
    • MRsOU previous LR Rc OU
    • No oscillopsia
    • VA: from R6/22, L6/25, BE 6/9 to R6/12, L 6/9, BE 6/9
  • #2: 45 ∆ ET
    • BMMRc
    • Residual 35 ∆ ET
    • No VA improvement

Squint Club 2006

summary effect on va
Summary : Effect on VA
  • 5/20 improved VA ≥ 1 line
    • 2/5: .. to 6/12
    • 2/5: 2 line improvement
    • 6/30 to 6/19
    • 6/12 to 6/6
  • 1/20 : VA worse no explanation

Squint Club 2006

summary effect on ahp
Summary : Effect on AHP

Any sensible surgery usu effective for AHP in CN and PAN

  • 9/12 : improved AHP
  • 5 require 2nd op
  • 3 were for residual / induced strabismus
  • 2 required 2nd op to improve residual AHP

Squint Club 2006

summary effect on oscillopsia
Summary Effect on oscillopsia

Excellent

  • 2/2 with resolution of symptoms

Squint Club 2006

becoming an expert
Becoming an expert
  • Read the following authors:

1. Hertle

2. Reinecke

3. Spielman

4. Abadi

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a lot of work for little benefit
A LOT OF WORK!!FOR LITTLE BENEFIT?
  • Ask the patients!
  • When a snail gets a ride on the back of a tortoise, the observer isn’t impressed. The snail thinks it’s fantastic!*

* Tychsen

Squint Club 2006

last slide
LAST SLIDE!!

THANK YOU FOR YOUR TIME AND PERSEVERANCE

Squint Club 2006

for more effective conference lectures

FOR MORE EFFECTIVE CONFERENCE LECTURES

From New Scientist, 26 January 2006, page 17

Stuart Brody [Paisley, UK] compared effects of different sexual activities on BP when a person is later stressed.

24 F & 22 M kept diaries of when they had penile-vaginal intercourse (PVI) & non- coital sex.

They then underwent a stress test involving public speaking and mental arithmetic out loud.

The PVI group were least stressed; their BP normalised faster than the non-coital group. Abstainers had the highest BP response to stress.

The effects are not attributable to short-term relief from orgasm, but endure for at least a week. Release of oxytocin might account for the effect.