Seeing as my day job is meant to be anatomy I figure a few posts focused on anatomy with relevance to EM might be nice. For me at least.
[Image from Nautiyal A, Singh S, DiSalle M, O’Sullivan J (2005) Painful Horner Syndrome as a Harbinger of Silent Carotid Dissection. PLoS Med 2(1): e19 doi:10.1371/journal.pmed.0020019 via Wikipedia Commons]
Horner’s syndrome in med school means
- some kind of dissection originating or extending to the carotids (spont or trauma)
- cavernous sinus thrombosis
- small pupil on the side of the lesion
- droopy lid on the side of the lesion
no one cares that your face doesn’t sweat so forget about it
- The sympathetic supply to the eye has been disrupted
- it supplies the dilator pupillae muscle (makes the pupil big)
- it supplies the fairly puny Muller’s muscle that helps keep the eyelid raised
- Potentially this can be anywhere between brainstem and the eye but for our purpose we’re talking about a third-order lesion (if you can’t remember all that first, second order neurone thing then don’t worry too much) meaning the fibres from the sympathetic trunk to their final destination.
- These are carried as a plexus in the wall of the carotid artery. This is where they tend to get disrupted in any of the dissections or neck trauma.
- The other spot we’re interested in is in the cavernous sinus itself. In that case you’ll be looking for ipsilateral funny eye movements as well as the Horners (probably the most useful sign)
- turn off the lights – tell your patient first. When the lights are off the pupils should dilate up. If there’s a Horner’s syndrome the normal pupil will get bigger and the affected one will remain fairly unchanged. A patient I saw told me that he noticed the pupil big when he looked in the mirror when he got up to go to the loo in the middle of the night but it was normal when he looked in the morning
- light reflex should be intact – the efferent part of this is mediated by the parasympathetics so should be unaffected in Horners
- get your sides right – a patient (or referring doc) might tell you they have a dilated left pupil when in reality it’s a constricted left pupil
- the classic (in a conscious patient at least) differential for pupil asymmetry includes a posterior circulation aneurysm that’s putting pressure on the oculomotor nerve (III) in it’s rather taut course across the floor of the brain
- the parasympathetic fibres that control pupil contraction run in the peripheral part of the nerve so this is lost before the central fibres, controlling eye movements, are affected
- the more substantial levator palpebrae superioris is supplied by the oculomotor (III) nv on a somatic not an autonomic basis
- if you get your sides right (as mentioned above) you’ll be fine
- stroke – while stroke is the end consequence of untreated carotid dissection, it’s important to know to make the diagnosis as you need contrast for the scan to pick it up
- headache – a headache and horner’s should make you at least think about a diagnosis of carotid dissecton
- CT angio probably the test you’ll get. There are lots of other ways to look for it too
- treatment is probably best with anti-coagulation. I’m not sure whether there’s a definite answer of warfarin vs heparin vs aspirin. The important point is to know that it’s different from aortic dissection where you definitely don’t want to anti-coagulate.