Doctor, I'm Seeing Two of Everything

Area of Science:

• Neurology
• Ophthalmology
• Emergency Medicine

Background:

• Acute diplopia is an uncommon emergency department presentation with a wide differential diagnosis.
• Effective emergency management relies on key historical and physical examination findings.

Observation:

• A 51-year-old male presented with acute, painless vertical diplopia upon waking.
• Initial emergency department workup was unremarkable, prompting admission for further evaluation.

Findings:

• The patient was diagnosed with fourth cranial nerve (CN IV) neuropathy.
• Differential diagnoses considered included CN IV palsy, acute Parinaud syndrome, and ischemic stroke.

Implications:

• Understanding CN IV palsy and Parinaud syndrome pathophysiology is crucial for emergency physicians.
• A systematic approach integrating history, physical exam, and consultations aids in managing undifferentiated diplopia.