Diplopia Flashcards
What questions do you need to ask about diplopia?
Determine what is being describe as diplopia
is it horizontal or vertical?
Is it fatiguable or does it come and go?
Is it worse in a specific gaze position (e.g. looking to the side cause diplopia might suggest problem with lateral rectus of one eye or medial rectus of the other eye)
Is there any associated pain or tiredness or other symptoms?
What does unconjugation mean neurologically speaking
Misalignment of the eye
Where would the problem be if there was sudden onset diplopia and left leg and arm weakness?
Sudden onset -> vascular
Brainstem problem (nuclei for CN go from brainstem, plus corticospinal tracts go through it)
What’s the syndrome called for third nerve palsy and contralateral hemiparesis?
Weber’s syndrome
Medical vs surgical third nerve palsy - explain
Medical - pupil sparing
Surgical - pupil involvement
Parasympathetic fibres run on outside of nerve, so something pressing on the nerve will cause PNS fibres to be affected before the motor weakness of eye, so eye dilates (pupil involvement)
Causes of surgical third nerve palsy?
Posterior communicating artery aneurysm
What might you see with a partially constricted pupil?
Partial ptosis
Anhydrosis
(Horner’s syndrome)
What is the pathophysiology of Horner’s?
Disruption of sympathomimetic innervation of the pupil, hence unopposed PNS pupil constriction
Raised calcium plus Horner’s syndrome - what might be the cause?
Pancoast’s tumour - affects brachial plexus and presses on sympathomimetic chain hence Horner’s
What might you get if you have a pancoasts tumour there?
Might also get some local pain and muscle weakness in arm/hand
What other location can cause horner’s?
Common carotid artery thrombosis/dissection can push upon sympathomimetic fibres as they ascend into cranium
If the pt has muscle fatiguability in the eye, e.g. when they look up the eye droops down, what could the problem be?
Myasthenia gravis
What is Myasthenia Gravis?
Most commonly affects occular,
???
Diagnosing
Nerve conduction studies ANtibody testing (MUSK, AChR)
CXR - thioma ?
