For Medical Students/Ophthalmologists/Neurologists/Neurosurgeons

1. Neurological causes of
Strabsimus
Raed Behbehani , MD FRCSC

2. Strabismus
• Ocualar misalignment of the visual axes.
• Childhood strabimus.
» Congenital strabsimus
» Accomodative esotropia/ refractive non-accomodative
» Abnormal visual development
» Neurologic

3. Neurologic Strabismus
• Pure neurologic strabismus can mimick other
causes of childhood strabismus.
• Diagnostic difficulty.
• Comitant vs incomitant.
• History : Ask about :
» acute onset, head trauma, perinatal history, variability
with ptosis, other neurological signs, old photographs
, previous history of head tilt

4. Neurological Strabismus
• Cranial Nerve Palsies ( III, IV, IV CN Palsy)
• Neurological diseases (
Myasthenia, mitochondrial
encephalomyopthy, Botulism, Miller Fisher
Synrome).
• Posterior Fossa tumors / malformations (
Chiari).
• Raised intracranial pressure
(hydrocephalus, idiopathic, tumor-related).

5. Paralytic Strabismus
Third nerve palsy
• Nucleus in midbrain tectum anterior to
cerebral aqueduct.

6. Third nerve palsy
• Palsy can be complete or partial.
• Complete : complete ptosis, eye is deviated
out and pupillary dilation. No
depression, elevation or adduction.
• Partial : Superior or inferior branch.

7. Third nerve palsy

8. Causes of third nerve palsy
• Ischemia ( diabetis, hypertesnion, hyperlipedemia)
• Vascular
• Pcom artery aneyrysm ( adults with pulillary involvment) , but rare
in children (posteior comunicating artery).
• Inflammatory
• Post-viral , auto-immune , Miller-Fisher syndrome
• Neoplastic
• Astrocytoma , meingioma, schwanommas.
• Congenital
– Forceps deivery , underlying neurinoma of the third nerve , midbrain
hypoplasia.

9. Third NP

10. Differential Diagnosis of Third Nerve
Palsy
• Myasthenia.
• Orbital Fractures.
• Brain stem syndrome (Inter-nuclear
ophthalmoplegia).
• Duane Syndrome.

11. Trochlear Nerve Palsy
• The most common cause of isolated acquired
cranial nerve palsy.
• Congenital or traumatic.
• Vertical diplopia.

12. Anatomy of the Forth Nerve

13. Fourth Nerve Palsy
• Head tilt ( in congenital palsy , it can be
overlooked).

14. Trochlear Palsy
• Look at old photos ! (FAT scan)

15. Trochlear Palsy

16. Postive Head Tilt
• Hypertropia increases when head is tilted to
the ipsilateral side.

17. Trochlear Palsy
• Hypertropia of the affectd eye (eye is higher
than contralateral).
• Facial asymmetry (ipsilateral face less
developed).

18. Superior oblique palsy in Case 1.
Kim J H , Hwang J Br J Ophthalmol 2010;94:346-350
©2010 by BMJ Publishing Group Ltd.

19. Bilateral SO Palsy

20. Torchlear Palsy Causes
• Congenital
• Ischemic (adults)
• Craniofacial anamolies
– Plagiocephaly
• Head trauma.
• Most common cause of acquired unilateral.
• Presume bilateral.
• Brain tumors
• Posteior fossa tumors , post-resection , hydrocepahlus.

21. Abducens Nerve Palsy
• Limited abducation.
• Esotropia.
• Head turn.

22. Abducens Palsy Anatomy
Lateral ponto-meduallary junction

23. Abducens Anatomy

24. Cavernous Sinus

25. Causes of Abducens Palsy
• Ischemic (adults)
• Tumor
• Pontine gliomas
• Extra-axial clival or petrous ridge tumors.
• Raised intra-cranial pressure
• Pseudotumor cerebri
• Hydrocephalus
• Trauma
• Closed head truama , basal skull fractures
• Inflammation.
• Post-viral or vaccination

26. Always examine the fundus

27. Differential Abducens Palsy
• Duane syndrome.
• Myasthenia.
• Long standing esotropia.
• Thyroid eye disease.
• Fractures of the medial orbital wall.

28. Duane Syndrome
• Congenital duction deficit due to absence
innervation of the lateral rectus.
• Co-contraction of the lateral rectus muscle in
adducion.
• Narrowing of the papebral fissure in
adduction and widening in adduction.

29. Duane Syndrome

30. Duane Syndrome
• Sproadic (90%) , familial (10%).
• Females > males.
• Left side > right side.
• Systemic associations
• Hearing loss (10%)
• Cervical malformations (Klippel-Feil anamoly)
• Okihiro syndrome (AD , thenar hypoplasia, deafness)

31. Etiology of Duane Syndrome
• Aberrant innervation of the lateral rectus
muscle by a branch of the third nerve.
• Lateral rectus muscle is fibrotic.
• Absence of the sixth nerve.
• Hypoplasia of the sixth nerve nucleus.

32. Other Neurologic Causes of Strabimus
• Mitochondrial encephalopathy (CPEO, MELAS)
• Brain stem tumors.
• Hydrocephalus.
• Miller-Fisher Syndrome.
• Myasthenia Gravis.
• Botulism

33. Chronic Progressive External
Ophthalmoplegia
• Mitochondrial encephalmoypathies.
• 50% are sporadic , AD and AR in 15%.
• Mutations in the mitochondrial Genome.
• Slowly progressive Ophthalmoplegia and
ptosis.
• Many differenet clinical phenotypes (Kearnes-
Sayer Syndrome, MELAS).
• Most patients do not complain of diplopia.

34. Kearne-Syre Syndrome
CPEO + Pigmentary degeneration of the retina + heart block

35. Myasthenia
• Auto-immune neurologic disease.
• Failure of neuromascular transmission.
• Ophthalmologic symptoms in 50% (Ptosis and
Ophthalmoplegia).
• MG can mimick any ocular motility disorder !
• Fatiguable ptosis, orbicularis
weakenss, variable strabismus.

36. Myasthenia
• Ice test , sleep test
• Tensilon test ( used less often now ).
• Serum Ach-receptor antibodies (50% of ocular MG).
• Anti-MUSK antibodies
• Clinical electophysiological tests
• Reptetive nerve stimulation ( in generalized MG)
• Single fiber EMG ( the most sensitive test for MG)
• CT scan of the chect (thymoam).

37. Myasthenia
Before ice test
After ice test 2 min

38. Botulism
• Total ophthalmoplegia + pupillary dilataion +
dry mouth + descending paralysis +
obstipation - Think of Botulsim.
• Clostridium botulinum produce different
toxins A, B , and E.
• Interfer with release of acetychilne by
preventing exocytosis.
• Food poisoning , contaminated wounds, or
colonization of the GIT “infant botulism”.

39. Hydrocephalus
• Uni- or Bilateral Abducens Palsy.
• Comitant esotropia or exotropia.
• Uni- or Bilateral Trochlear Palsy ( compression
of the superior medullary velum).
• Third Nerve Palsy.
• Dorsal midbrain syndrome (upgaze palsy, lid
retraction, pupillary light-near
dissociation, convergence retraction
nystagmus).

40. Dorsal Midbrain Syndrome

41. Chiari Malformation
• Hernation of the posterior forssa contents
below the foramen magnum.
• Chiari I-III ( I most common).
• Occipital headache (with
coughing), pain, sensory loss and weakness.
• Hydrocephalus (lack of CSF flow between the
spinal and cranial subarachnoid space).
• Nystagmus and ataxia.

42. Chiari

43. Esotropia in Chiari
• Acute comitant esotropia can occur.
• Vertical strabismus.
• Strabimsus improves with sub-occipital
decompression.

44. Miller-Fisher Variant of GBS
• Ataxia, ophthalmoplegia, and arelfexia.
• Viral prodrome , URTI 1-3 weeks prior to onset
of the symptoms.
• Pupillary involevement.
• CSF shows mild protein elevation at 2-3
weeks.
• Resolve spontaneously in 1-3 months.
• Corticosteroids, plasma exchange or IV
immuno-globulins.

45. Miller-Fisher Variant of GBS
• Anti-GQ1b ganglioside antibodies target the
pre-synaptic motor terminal complement-
mediated injury.
• Ganglioside epitopes on C Jeujeni is key to
antibody production.
• Need to rule out posterior fossa
tumors, Botulism, brain stem stroke, and
Wenick Encephalopathy.

46. Summary
• Neurologic causes of strabismus are less
common than other forms of strabismus.
• Can mimick other common types of
childhood strabismus.
• Most cases can be identified by history and
physical examination.
• In certain cases, especially posterior fossa
tumors, hydrocephalus chiari
malforation, ancillary test (MRI) are needed.