DIPLOPIA + CN III - NEUROLOGY + NEUROSURGERY

PromptDescribe examination findings in 3rd nerve palsy

ResponseBinocular horizontal, vertical or oblique diplopia
Paralysis of adduction, elevation and depression - eye looks “Down and out”
Ptosis
+/- Pupil dilation

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PromptOther features to localise CN III lesion

ResponseBrainstem - vertigo, ataxia, aphasia. Contralateral cerebellar deficics/hemiparesis
Intracranial course - Involvement of CN IV, V, VI
Orbital (SOF, orbital apex) - orbital signs (chemosis, injection, proptosis), visual loss, IV +VI nerves signs.

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PromptPupillary involvement in 3rd nerve palsy - significance

ResponsePupillary constriction is mediated by parasympathetic fibres that accompany CNIII - they travel peripherally and are more susceptible to compression resulting in pupillary dilation (from unopposed sympathetic supply)

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PromptCauses of CNIII palsy

ResponseCompression from PCOM aneurysm - CTA shows aneurysm
Demyelination - Plaques on MRI
Tumour - SOL on contrast CT/MRI
Cavernous sinus thrombosis - Flow deficit on venous phase CT head
Stroke - MRI

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PromptCauses of Anisocoria (different pupil sizes)

ResponseRaised ICP (Coning)
3rd nerve palsy
Physiologic (ie: normal for them - 20% of the population!)
Structural defect of eye - congenital iritis, surgical, traumatic
Acute closed angle glaucoma
Horner’s syndrome
Pharmacologic - cycloplegics (Atropine, tropicamide), Atrovent (ipratropium) in eye
Plants - deadly nightshade (Belladona)

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PromptList causes of diplopia, clinical findings, and investigations

ResponseMysthenia Gravis

Fatiguability, ptosis
CT thymus, tensilion test, resp monitoring, Ice pack test (60 sec of ice pack on eyes resolves diplopia/ptosis)

Guillaine barre syndrome

Hyporeflexia, ascending weakness, Miller Fischer eye signs
Mostly clinical, LP - raised protein (but not always)

MS

Cerebellar signs, hyperreflexia, optic neuritis
MRI, LP

Toxins (Unintentional - Lead)

Evidence of other ingestions
Lead level, FBC + Film (Basophilic stippling)

CVA

Sudden onset, unilateral/localising signs
CTB, MRI

Cord problems (syrinx, transverse myelitis)

Hyperreflexia, central cord findings, spasticity
MRI

Infection - botulism

Global weakness
Cultures

Snake bite

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PromptFACIAL NERVE PALSY/BELLS

Response

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PromptFeatures of PERIPHERAL CN VII (Facial N.) palsy

ResponseUpper and lower facial musculature (ie: includes forehead = LMN lesion)
Decreased taste anterior ⅔ tongue (Same side)
Ipsilateral hyperacusis (phonophobia)
Ipsilateral reduced tear production
Unable to completely close eye on affected side
Facial numbness/hyperasthesia

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PromptCauses of isolated peripheral CN VII lesion

ResponseThis list was VAST. I have included ones i’ve heard of. NSW 2017.2-7 for ref.
Cerebelopontine angle tumour - Eg: acoustic neuroma
Temporal bone #
Guillaine barre syndrome
Sarcoid
Bell’s Palsy
Ramsay Hunt syndrome
Diabetes
Botulism
Viral - EBV, HIV
Acute otitis media/externa
Migraine without aura
Focal seizure

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PromptTreatment of idiopathic bells palsy

ResponseEye care - prevents corneal exposure - artificial tear 1-2 hourly + lubricating ointment at night
Steroid therapy - High dose Prednisone 60 mg/day fro 5/7 then taper
Antivirals (controversial)

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PromptPrognosis of idiopathic Bells

Response86% complete recovery at 2 months.
Incomplete paralysis favours better outcome

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PromptFactors associated with poorer outcome

ResponsePregnancy
Diabetes
Associated taste disorder
Older age

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