Oculomotor nerve
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The oculomotor nerve (3rd cranial nerve) is entirely motor and supplies several extraocular muscles and the levator palpebrae superioris muscle. It has nuclei located in the midbrain and courses through the fascicular, basilar, intracavernous, and intraorbital regions. Common causes of oculomotor nerve palsy include vascular issues like aneurysms and diabetes, neoplasms, trauma, and idiopathic cases. A complete oculomotor nerve palsy presents with ptosis, limitation of eye movements, and potentially a dilated pupil. Evaluation involves assessing pupil involvement and testing for underlying causes. Management consists of treating any identified cause as well as addressing diplopia.
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Oculomotor nerve
- 1. Oculomotor Nerve 23rd July 2020 DR M SAQUIB Vice Principal MBBS,MS , FSCEH DELHI,FHVDESAI PUNE, EX REGISTRARA JNMCH,AMU CONSULTANT OPHTHALMOLOGIST HOD D/O OPHTHALMOLOGY G.S .MEDICAL COLLEGE Founder sec: MEDICS India , Mail-dms2k5@gmail.com , 9634123800
- 2. 3 rd cranial 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 2
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- 4. ▸ 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
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- 6. Course ▸ Can be divided into – ▸ Fascicular ▸ Basilar ▸ Intracavernous ▸ Intraorbital part 6
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- 11. Major causes of nuclear complex lesion of 3rd nerve pals ▸ Vascular occlusion – Diabetes & Hypertension ▸ Neoplastic lesions – primary tumour or metastasis ▸ Haemorrhage 11
- 12. Major causes of fascicular lesion of 3 rd nerve palsy ▸ Vascular occlusion – Diabetes & Hypertension ▸ Neoplastic lesions – primary tumour or metastasis ▸ Haemorrhage ▸ Demyelination 12
- 13. 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 13
- 14. 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 14
- 15. Posterior communicating artery aneurysm 3rd nerve palsy 15
- 17. ▸ 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. 17 Major causes of Intracavernous lesion
- 18. Intraorbital causes of 3rd nerve palsy ▸ Trauma ▸ Vascular ▸ Neoplasm ▸ Inflammation 18
- 19. ▸ 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 19 Pupillomotor fibers
- 20. ▸ The pupil rule :The pupil is spared in 75% of ischemic III nerve palsies, but involved in over 90% of aneurysmal palsies . 20
- 22. 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 22
- 23. ▸ Clinical features of total 3rd nerve palsy SYMPTOMS Drooping of eyelid Binocular double vision Pain (may be present) 23 Clinical features of total 3rd nerve palsy
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- 25. 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 25
- 26. History of Patient ▸ Onset ▸ Duration ▸ Diplopia ▸ Trauma ▸ Associated systemic disorders 26
- 27. Examination ▸ Pupillary reactions ▸ Motility restrictions ▸ Ptosis ▸ Other cranial nerves 27
- 28. ▸ 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 angiography28 ▸ Investigations
- 29. HESS CHART ▸ Treatment ▸ Surgical ▸ Neurosurgery – Aneurysm or haematoma ▸ Strabismus or ptosis surgery – Not earlier than 6 months from time of onset 29
- 30. ▸ Treatment ▸ Non-surgical ▸ Treatment of underlying cause ▸ Diplopia – Occlusion patch or prism in involved eye ▸ Monitor children for development of amblyopia 30
- 31. ▸ 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 31
- 32. ▸ Differential Diagnosis ▸ Myasthenia gravis ▸ Thyroid associated orbitopathy ▸ Chronic progressive external ophthalmoplegia ▸ Idiopathic orbital inflammatory disease 32