Scenario
A 21yo female presents to your emergency department with visual changes.
You are to take a history, outline your differential diagnosis and discuss what Ix the patient might need. You are NOT to examine the patient.
Domains to be examined
- medical expertise
- communication
Instructions for the actor:
HPI
- for the past 6 days you have noticed ‘blurring’ of your vision
- your vision has steadily been getting worse and now you do not feel safe to drive
- on further questioning, you mean that you have been noticing double vision
- this is present all the time and is worse when looking left/right/down
- during this time you have also noted heaviness of your eyelids which is always present but worse through the day
- find that you have to consciously need to ‘pull your eyelids open with my forehead’
- if specifically asked about limb weakness
- for the past 4 days you have been finding it very tiring to walk around at the end of the day
- also noticed poor performance in cardio at the gym due to rapid fatigue of limbs
- you were recently treated for a kidney infection in the same ED 10 days ago
- presented with classic features of pyelonephritis (fever, right flank pain, dysuria)
- give IV antibiotics overnight and DC’d home from the ED on oral Abx
- all of these symptoms have resolved
- relevant negatives
- no pain on eye movement
- no weakness in the limbs (just returned from a hiking trip in NZ 2 weeks ago)
- no headaches
- no speech changes
- no difficulty swallowing/chewing
- have noticed some weight loss recently, ~5kg over the past 3 months without any dieting/exercise
- occasionally waking up in the night with sweats
B/G:
- asthma
- family Hx of lymphoma
- mother and brother have both had this in their early 20s
- you are very worried that these symptoms mean you have lymphoma
- meds: OCP
- social
- non-smoker
- social etoh
- no illicit drugs
- studying media at university
Questions to ask the candidate:
- what do you think I have? (if they have not reached a differential)
- is that definitely what I’ve got?
- what tests do i need to have?
Assessment:
- this patient presents with a classic history of myasthenia gravis
- exacerbator may be gentamicin which had recently used to treat the patient’s pyelonephritis (for highly performing candidates)
- DDx is certainly difficult:
- note the constitutional symptoms and strong family Hx of lymphoma
- gives the DDx of Eaton-Lambert (this is for highly performing candidates), GBS variant
- Important parts
- identifying primary DDx
- identifying that the symptoms are rapidly progressive, thus the patient needs inpt admission and neurology review
- that some tests can be sent from the ED (need only broad headings)
- bloods: Anti-ACh-R Abs, anti-Musk Abs
- spirometry: given this patient has limb involvement, it is important to identify any potential respiratory muscle weakness
- CXR or CT chest (less urgent): looking for a thymoma
- nerve conduction studies/EMGs
blurry-vision-osce (printable version)