IV Nerve Palsy

1
IV Nerve Palsy
A presentation
2
Case History

• Initial Orthoptists Observations (aspects to
  look out for)
• Head tilt/turn to opposite side of affected eye
• Facial asymmetry (common in congenital fourth
  nerve palsy)
• Affected eye-hypertropia

3
Case History

• General Health
• Any illness/meds
• Diabetes, Myasthenia Gravis, hypertension,
• Intracranial tumour
• Any injury/trauma-recent bump to the head
• Family History
• For suspected congenital fourth nerve palsy,
  there is evidence that it can be inherited in an
  autosomal dominant form (Botelho Giangiacomo,
  1996, pg. 374)

4
Case History

• Previous Ocular History
• Treatment for diplopia or other eye related
  problems, glasses
• With congenital fourth nerve palsy, patient may
  report always having had a head posture or may be
  unaware of it but on looking through old
  photographs notice that it was there in
  childhood

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Case History

• Questions to ask further as a basis for
  investigation
• Reason for visit-diplopia?
• Vertical/horizontal?
• How far apart images are?
• Any torsion?
• How long they have had it?
• When does it occur? Constant/ intermittent?
• Worse when reading?
• Neck pain?

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Aetiology-Nerve pathway (Origin)

• The trochlear nerve is the smallest (in diameter)
  of the 12 cranial nerves. It is the only nerve to
  originate in the brainstem (medulla).
• The Trochlear is situated within the brainstem at
  the level of the inferior colliculus.

http//www.sgul.ac.uk/depts/histopathology/ssm_arc
hive/ssmpteresh/trochlear1.JPG
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Aetiology-Nerve pathway (Intracranial)

• From its origin it decussates and exits the
  brainstem dorsally before passing temporally
  around the brainstem and projecting superiorly
  through the arachnoidal space. The trochlear
  pierces the arachnoid and enters the subdural
  space of the cavernous sinus. The trochlear then
  passes through the superior orbital fissure

http//www.netterimages.com/images/vpv/000/000/020
/20654-0550x0475.jpg
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Aetiology-Nerve pathway (Intraorbital)

• The trochlear does not traverse through the
  Common Tendonous ring (annulus of Zinn). It
  projects anteriorly superiorly and medially to
  the Common Tendonous ring, traveling inferiorly
  and temporally to the superior oblique. The
  Trochlear finally pierces the belly of the
  superior oblique.

http//www.elsevierimages.com/images/vpv/000/000/0
35/35653-0550x0475.jpg
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Aetiology-Eye Movements
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Aetiology-Children

• Leading cause would be a congenital superior
  oblique palsy
• Will usually develop an abnormal head posture
• Holmes JM et al found that the main cause of 4th
  nerve palsy in children was Congenital. ( Holmes
  JM et al 1999)

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Aetiology-Adults

• Leading cause of isolated 4th nerve palsy is
  trauma, specifically CHI
• CHI Closed head injury blunt force damage that
  doesnt cause a break in the scalp or mucous
  membranes (Medical Dictionary Online 2012)
• 4th nerve palsies are rarely due to aneurism and
  it is unlikely that a cavernous sinus fistula
  would cause an isolated 4th nerve palsy as it is
  much more likely that various palsies would
  occur, due to the proximity of the cranial nerves
  in the cavernous sinus.

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Clinical Characteristics

• When first presenting to the clinic the following
  information should be gained by simple
  observation
• The type of deviation present
• Any abnormal head posture

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Clinical Characteristics cont.

• Observed deviation
• http//www.pedseye.com/strabismus_hypertropia.htm
  LSO palsy RSO palsy

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Clinical Characteristics cont.

• Abnormal Head Posture
• The patient may present with chin depression and
  a face turn or head tilt away from the affected
  side, to reduce their diplopia.
• (Ansons and Davis 2001)
• http//www.aao.org/publications/eyenet/200409/am_r
  ounds.cfm

Asymmetry of the face may be observed in cases of
congenital IV nerve palsies. Typically a
reduction in distance between the lateral canthus
and the corner of the mouth on the side of the
head tilt.
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Clinical Characteristics cont.

• Diplopia
• Patients with a IV nerve palsy typically
  experience vertical diplopia and in some cases
  may be aware of cyclotorsion.
• http//galeri.uludagsozluk.com/r/vertical-diplopia
  -143415/ http//www.freakingnews.com/Double-Visi
  on-Pictures--1762-0.asp

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Expected Findings from Investigations

• Visual Acuity
• Cover Test
• for near and distance, with and without abnormal
  head posture
• Investigating Cyclotorsion Using Synoptophore and
  Double Maddox Rod.
• Can be seen objectively on fundus examination if
  asymptomatic.
• Bielschowsky Head Tilt Test
• Past-pointing
• Prism Fusion Range
• Ocular Movements

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Expected Findings from Investigations

• Hess Chart Using Lees Screen
• Right superior oblique palsy
• Ipsilateral inferior oblique overaction

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Expected Findings from Investigations
Congenital Acquired
Intermittent diplopia can occur later in childhood or in adult life as first symptom of decompensating palsy. Recent onset of diplopia common
Awareness of abnormal head posture more common in acquired
Usually absent of symptoms of torsion Patient more aware of torsion in acquired
Vertical prism fusion range gt 10? Vertical prism fusion range 2-4?
Hess charts will be similar in size Deviation more concomitant Hess chart of affected eye will be significantly smaller as muscle sequelae will not have developed
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Examples

• Is this congenital or acquired?
• 74 Year old male presented with a three day
  history of sudden onset vertical diplopia. This
  was worse when reading. He had had a mild left
  cerebral vascular accident (CVA) one week
  previously resulting in hand weakness which later
  resolved (Fiona Rowe, Clinical Orthoptics, 2nd
  edition, page 344)

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Example

• Is this congenital or acquired?
• A 36-year-old woman has been bothered by a
  deviating right eye since early childhood. She
  has had diplopia for as long as she can remember
  but was able to tilt her head to relieve it. She
  has worn prism glasses for many years. Her
  friends and associates at work comment on the
  fact that she tilts her head constantly.
  (http//telemedicine.orbis.org)

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References

• Ansons, A. M. and Davis, H. (2001) Diagnosis and
  Management of Ocular Motility Disorders.
  Blackwell Publishing Oxford.
• Botelho Giangiacomo, 1996. Cited in Ansons,
  A. M. and Davis, H. (2001) Diagnosis and
  Management of Ocular Motility Disorders pg. 374)
• Holmes JM et al. (199) Pediatric third, fourth
  and sixth nerve pasies A population based study.
  Am J Opthalmol, 127, 388-392
• The Medical Dictionary Online, accessed on
  11/09/12 at http//medical-dictionary.thefreedict
  ionary.com/closedheadinjury
• Rowe, F. (2004) Clinical Orthoptics, 2nd edition.
  Blackwell Publishing Oxford.