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Third nerve palsy
From WikEM
(Redirected from CN III palsy)
Contents
Background
- Third (oculomotor) nerve, innervates eyelid muscles and external ocular muscles (except lateral rectus and superior oblique) [1]
- Nerve also carries parasympathetic fibers on external surface allowing for pupillary constriction
- Palsy causes diplopia except in lateral gaze (lateral rectus innervated by CN VI)
- Ptosis, headache
Causes
- Posterior Communicating Artery (PCOM) Aneurysm (compresses nerve)
- Ischemia
- Trauma
- Temporal lobe herniation through tentorium
- Myasthenia Gravis[2]
- Cavernous Sinus Thrombosis
- often associated with other cranial nerve defecits
- Neurosyphillis
- Autoimmune vasculitis (Lupus)
- Aneurysm [3]
- Carotid cavernous fistula
- Mass
- Ischemia
- Myasthenia gravis
- Thyroid associated orbitopathy
- Internuclear opthalmoplegia
- Giant cell arteritis
Clinical Features
- Eye deviates laterally and down
- Pupil exam:
- If dilated/nonreactive likely secondary to space occupying lesion
- If pupil is spared likely ischemic etiology
- Loss of accommodation
Differential Diagnosis
Monocular Diplopia
- Cataract
- Lens Dislocation
- Macular Disruption
Binocular Diplopia
- Basilar Artery Thrombosis
- Posterior Communicating Artery (PCOM) Aneurysm
- Vertebral Artery Dissection
- Myasthenia Gravis[4]
- Lambert-Eaton Syndrome
- Botulism
- Cavernous Sinus Thrombosis
- Brainstem Mass
- Intracranial Mass
- Miller Fischer variant Guillain-Barré[5]
- MS
- Hyperthroid Proptosis
- Basilar Meningitis
- CVA
- Muscular Entrapment from Trauma
- Third nerve palsy
Evaluation
- If complete CNIII involvement with ptosis, mydriasis, and ophtalmoplegia:
- assume a compressive etiology from an intracraneal anurysm.
- Proceed to a CTA brain
- If complete oculomotor nerve palsy without pupil involvement then strongly favor an ischemic process
- Consider a CTA brain
- Coronal reconstruction on CT will allow visualization of orbits to rule out compressive process
- If associated with other neurologic deficits:
- CTA brain followed by MRI/MRA brain
Management
- If ischemic cause
- Medical management with most self resolving in 6-8 wks
- Ophthalmology follow up
- If aneurysm/mass
- Neurosurgery consult
- If diplopia
- No driving or operating heavy machinery
See Also
References
- ↑ Capo, H., M.D., Warren, F., M.D., Kupersmith, M. , M.D. Evolution of Oculomotor Nerve Palsies. J Clin Neuroophthalmol. 1992 Mar;12(1):21-5. (12)1:21-25, 1992.
- ↑ Appenzeller S, Veilleux, M. Clarke, A. Lupus. Third cranial nerve palsy or pseudo 3rd nerve palsy of myasthenia gravis? A challenging diagnosis in systemic lupus erythematosus. 2009 Lupus. Aug;18(9):836-40.
- ↑ Chaudhary,N. et al Imaging of Intracranial Aneurysms Causing Isolated Third Nerve Palsy. J. Neuro-Ophthalmol 2009;29:238-244
- ↑ Kusner LL, Puwanant A, Kaminski HJ: Ocular myasthenia: Diagnosis, treatment, and pathogenesis. Neurologist 2006; 12:231-239
- ↑ Bushra JS: Miller Fisher syndrome: An uncommon acute neuropathy. J Emerg Med 2000; 18:427-430
