FOURTH NERVE / SUPERIOR OBLIQUE PALSY

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FOURTH NERVE / SUPERIOR OBLIQUE PALSY SIMILAR /
SIMULATING CONDITIONS

• DR LIONEL KOWAL
• RVEEH / CERA
• MELBOURNE

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Types of FNP / SOPused as synonyms

• 1. Definite SOP
• 2. Possible SOP or Resolved SOP
• 3. Fake SOP
• Idiopathic oblique dysfunction other synonyms
  for
• Cyclovertical dysfunction of uncertain cause
  CVD

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Definite/ Possible/ Fake SOP can all ?

• Vertical misalignment
• Disrupt horizontal fusion ? horizontal
  misalignment
• CVD can also be a consequence of loss of
  horizontal fusion - seen in any horizontal strab
• Head tilts
• Vertical greater to one side
• Apparent IO OA, SO UA
• CLINICAL PICTURE CAN BE THE SAME IN ALL TYPES OF
  SOP

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How to tell definite from fake Simonsz

• GA take off SO, inject sux measure L-T curve
• LA take off SO ask pt to look up / down
  measure L-T curve
• When good clinicians made clinical diagnosis of
  real SOP, they were wrong 50 of the time
• Klin Monatsbl Augenheilkd. 1992 Length-tension
  measurement of oblique eye muscles in strabismus
  operations for differentiating trochlear
  paralysis and strabismus sursoadductorius
  German

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How to tell definite from fake Demer

• Joe Demer
• Coronal scans can you see the muscle belly?
• Upgaze to downgaze watch SO belly move back
  increase in size
• When subspecialist clinicians made clinical
  diagnosis of real SOP, they were wrong 50 of the
  time!!
• Demer JL et al MRI of the functional anatomy of
  the sup obl muscle. IOVS. 1995 in 1994 AAPOS /
  ISA joint meeting proceedings

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JOE DEMER

• Coming to SQUINT CLUB 2006
• MELBOURNE
• APRIL 21-22

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R SOP HEAD TILT TO LEFT
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R IO OA
R SO UA
TIGHT RSR RIR UA
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SOP image
LSO OK RSO ?absent
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SOP image
RSO clearly smaller than LSO
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How to tell definite from fake Herzau

• Is congenital SO strabismus a paretic disorder?
  An MRI study German full blown clinical
  picture of a congenital SOP symmetrical muscle
  volumes on both sides in all coronal sections
• CLINICAL PICTURE OF REAL SOP CAN BE WRONG
• Siepmann K, Herzau V Klin Monatsbl Augenheilkd.
  2005 May

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Demer X-sectional area of SO segregates SOP from
normal SO
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Up gaze to down gaze ? x-sectional area of SO
in normals only
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Change in x-sectional area from up to down gaze
segregates SOP from normals
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Real SOP

• Head injury
• ARIX gene
• Vascular disease
• Rare SOP- specific CNS pathology LK 1/500

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Fake SOP

• Abnormal cyclovertical anatomy
• Craniofacial anomalies
• Posteroplaced trochlea Bagolini
• Abnormal physiology
• Brodskys wild pitch

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Telling definite from fake does it matter?

• Anomalous SO tendons clinically are nearly
  always associated with radiologically
  attenuated SO muscle provides explanation for
  the phenomenon of laxity of the SO tendon
• Sato M. Magnetic resonance imaging and tendon
  anomaly associated with congenital superior
  oblique palsy. Am J Ophthalmol. 1999

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Telling definite from fake - does it matter?

• Forewarned / forearmed
• Atrophic SO on scan ? floppy SO tendon on FDT
  may need SO tuck
• SO tuck more difficult / higher morbidity c.f.
  other surgeries
• Real SOP ?less reliable long term prognosis than
  fake SOP

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Possible / Resolved

• Radiological changes may be too subtle for
  routine scans
• SOP may have resolved leaving small permanent
  change in L-T curve of SO
• same mechanism as small ET remaining after 6th n.
  paresis resolves

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Principles of treatment

1. Make it better - dont over correct
2. Trauma look for bilateral SOP
3. Accurate measurements
4. Tighten floppy muscles
5. Rc tight muscles

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Principles of treatment

• Acquired wait 12 mo can Rx earlier if getting
  worse
• Long standing Acquired suppression makes it
  harder to characterise
• Usually have to treat the muscular consequences
  of the SOP rather than the SOP itself hence
  Knapp 1-7

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Principles of treatment IO OA

• Weak SO often ? IO OA as a consequence, and this
  may dominate the clinical picture far more than
  the SO UA of the original SOP
• Fake SOP often manifests as IO OA
• Parks IO Rc for 10-15 ? height in PP
• 20 ? To lateral edge IR
• 25 ? 2mm ant to edge IR

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Principles of treatmentTight SR

• Chronic hypertropia may ? tight SR, spread of
  comitance apparent IR UA wch may come to
  dominate the clinical picture.
• SR Rc required
• Recessing SR will increase extorsion unless it
  is temporally transposed

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Sequelae of SOP IO OA tight SR
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REAL CONG R SOP CONG ET FIXING WITH PARETIC
R EYE ? L HYPO NOT IDIOPATHIC IR FIBROSIS
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R SO atrophic
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R SO atrophic
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TREATMENT MORBIDITY

• Sup Obl
• Browns
• Ptosis
• Inf Obl
• Upgaze restriction
• Lid change

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TREATMENT MORBIDITY

• Sup Rectus
• Ptosis / lid retraction
• Inf Rectus
• Lid retraction
• Progressive over correction

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TREATMENT EXPECTATIONS

• LK audit early 90s n450
• Unilateral SOP all sorts
• 1.3 surgeries
• 90 VG to excellent

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SOP

• Difficult area of strabismus
• Imaging has been under- utilised
• Natural history of different sub types their
  treatments not well defined