This document discusses the anatomy and function of the oculomotor nerve (cranial nerve 3). It describes the nucleus and course of the nerve, causes of lesions, clinical features of total oculomotor nerve palsy, treatment options which may include surgery or monitoring, and differential diagnoses. History, examination, and investigations are outlined to evaluate patients presenting with oculomotor nerve palsies.

1. Dr. Mahziba Rahman
MCPS, FCPS
Eye Specialist & Surgeon
Bangladesh Eye Hospital Ltd.

2. 3rd
cranial nerve
Oculomotor nerve
Entirely motor in function
Supplies –
• All the Extraocular muscles except superior
oblique and lateral rectus
• Levator palpebrae superioris
• Intra ocular muscles- Sphincter pupillae and cilliary
muscle

3. Nucleus
Located in midbrain at the level of superior colliculus,
ventral to the Sylvian aquiduct.
Composed of
• Unpaired levator subnucleus
• Paired superior rectus sub nuclei
• Paired medial rectus, inferior rectus and inferior
oblique subnuclei
• Unpaired Edinger-Westphal nucleus

4. Course
Can be divided into –
 Fascicular
 Basilar
 Intracavernous
 Intraorbital part

5. Course

6. Course

7. Intracavernous portion of 3rd
nerve

8. Intraorbital portion of 3rd
nerve

9. Major causes of nuclear complex
lesion of 3rd
nerve palsy
Vascular occlusion – Diabetes & Hypertension
Neoplastic lesions – primary tumour or metastasis
Haemorrhage

10. Major causes of fascicular lesion of
3rd
nerve palsy
Vascular occlusion – Diabetes & Hypertension
Neoplastic lesions – primary tumour or metastasis
Haemorrhage
Demyelination

11. Syndromes of Fascicular lesion
Benedikt syndrome- Ipsilateral 3rd
nerve palsy and
contralateral extrapyramidal signs
Weber syndrome- Ipsilateral 3rd
nerve palsy and
contralateral hemiparesis
Nothnagel syndrome- Ipsilateral 3rd
nerve palsy and
cerebellar ataxia
Claude syndrome-

12. Major causes of lesion in Basilar
region
The 3rd
nerve traverses the basilar part unaccompanied
by any other cranial nerves.
Isolated 3rd
nerve palsies are commonly basilar.
The important causes are
Aneurysm
Head trauma-Extradural or subdural haematoma

13. continued

14. continued

15. Major causes of Intracavernous
lesion
Usually associated with involvement of 4th
, 6th
nerves &
first division of 5th
nerve.
Diabetes – causes pupil sparing 3rd
nerve palsy
Pituitary apoplexy
Others – Aneurysm, Meningeoma, Carotid-cavernous
fistula.

16. Intraorbital causes of 3rd
nerve
palsy
Trauma
Vascular
Neoplasm
Inflammation

17. Pupillomotor fibers
Parasympathetic fibers
Located superficially between the brainstem and the
cavernous sinus
Blood supply derived from the pial blood vessels
Main trunk of 3rd
nerve supplied by the vasa nervorum

18. Continued
Type of lesion affecting
Pupillomotor fibers :Surgical
Main trunk : Medical

19. Causes of isolated 3rd
nerve palsy
Idiopathic – about 25%
Vascular – Hypertension & Diabetes (commonly pupil
sparing)
Aneurysm – posterior communicating artery at its
junction with internal carotid artery
Trauma – subdural haematoma with uncal herniation
Miscellaneous

20. Clinical features of total 3rd
nerve
palsy
SYMPTOMS
Drooping of eyelid
Binocular double vision
Pain (may be present)

21. SIGNS
Ptosis
Abduction of globe
Intortion of the globe which increases on attempted
down gaze
Limitation of adduction
Limitation of elevation
Limitation of depression
Dilated pupil with defective accommodation

23. History of Patient
Onset
Duration
Diplopia
Trauma
Associated systemic disorders

24. Examination
Pupillary reactions
Motility restrictions
Ptosis
Other cranial nerves

25. Investigations
Age < 50 years CT or MRI, Cerebral angiography
Age > 50 years
Pupil sparing FBS and 2HABF, HbA1c, Lipid profile,
Check BP, CBC with ESR, CRP
Pupil involving FBS and 2HABF, HbA1c, Lipid profile,
Check BP, CBC with ESR, CRP, CT or
MRI, Cerebral angiography

26. Investigations
Hess Chart

27. Treatment
Non-surgical
Treatment of underlying cause
Diplopia – Occlusion patch or prism in involved eye
Monitor children for development of amblyopia

28. Treatment
Surgical
Neurosurgery – Aneurysm or haematoma
Strabismus or ptosis surgery – Not earlier than 6
months from time of onset

29. Follow-up
Pupil sparing – Observe daily for 5 days for pupil
involvement
Recheck every 4 to 6 weeks
If secondary to ischemia function usually returns
within 3 months

30. Differential Diagnosis
Myasthenia gravis
Thyroid associated orbitopathy
Chronic progressive external ophthalmoplegia
Idiopathic orbital inflammatory disease

31. Thank
you