‣
DDx 🏳️🌈
‣
- Physical Misalignment
- Orbital mass (e.g. pseudo-tumor)
- Trauma & Entrapment
- Neurologic Weakness
- Brainstem
- Stroke
- Demyelination
- Malignancy
- Nerve
- CN III
- Ptosis, pupil spared: small vessel ischemic disease (e.g. diabetes)
- Ptosis, dilated/unreactive pupil: compression (PComm vs. ICA aneurysm, cavernous sinus thrombosis), continuous inflammation (meningitis)
- CN IV
- Symptoms worsen on down & out
- CN VI
- Horizontal diplopia worse at distance (e.g. driving)
- Neuromuscular junction
- Myasthenia Gravis & Lambert-Eaton Syndrome
- Organophosphate poisoning
- Muscle
- Thyroid eye disease
- Vascular
- GCA
- AL amyloidosis
‣
- Single eye affected
- Corrects w/ pinhole test: Cornea/lens refractive issue
- Doesn’t: Retinal disease
- Both eyes affected
- Bilateral single eye diseases above
- Cortical diplopia
- Psychogenic
‣
Principles❗️
Can’t miss 🚨
- GCA: Emergency Medicine guidelines recommend obtaining an ESR/CRP for all patients > 50 years old with new onset diplopia
- Enlarging vs. Ruptured PComm Aneurysm: compressive CNIII palsy + concurrent thunderclap headache should prompt concern
Localizing factors 👉
👉 “Crossed” neurologic signs → brainstem
👉 Multiple “CN palsies” → anatomic bundling (III, IV, V1/V2, VI, sympathetic fibers in cavernous sinus), multifocal vascular fingerprint (GCA)
👉 Worse on sustained lateral gaze → neuromuscular junction
👉 Proptosis → orbital mass
👉 Direct eye pain → intra-orbital pathology
👉 Pain on eye movement → myopathy vs. intra-orbital pathology
👉 Non-specific inflammatory symptoms, ↑ ESR/CRP, Age > 50 → GCA
👉 Small-vessel vasculopathy risk factors (e.g. uncontrolled DM) → cranial nerve infarction
Anatomy 👀
‣
References 📚
- “Eye Movement: a Hero’s Quest” by mikearcieri.bsky.social
- Framework adapted from @CPSolvers
