A 28-year-old man is referred with bilateral disc swelling and blurred margins noted on routine fundoscopy. He is asymptomatic with normal visual acuity and no eye pain. Pupillary responses are normal. Which investigation is most appropriate to confirm the diagnosis of papilloedema and identify the underlying cause?

Explanation

## Diagnostic Approach to Papilloedema **Key Point:** Papilloedema is a sign of raised intracranial pressure (ICP), not a disease itself. The investigation of choice must identify the underlying cause of elevated ICP. ### Clinical Features of Papilloedema | Feature | Papilloedema | Papillitis | |---------|--------------|----------| | Bilateral | Yes (almost always) | No (usually unilateral) | | Vision loss | Late and mild | Early and marked | | Eye pain | Absent | Present | | RAPD | Absent | Present | | Disc appearance | Blurred margins, hyperemia, peripapillary hemorrhages | Hyperemia, flame hemorrhages at disc margin | | Symptoms | Often headache, diplopia, transient visual obscurations | Eye pain, vision loss | ### Why Neuroimaging is the Investigation of Choice **High-Yield:** Neuroimaging (MRI brain ± contrast or CT head) is essential because: 1. **Confirms papilloedema** — Shows obliteration of subarachnoid spaces, flattening of posterior globe, distension of optic nerve sheath 2. **Identifies the cause** — Brain tumors, hydrocephalus, venous sinus thrombosis, pseudotumor cerebri, infection, hemorrhage 3. **Guides management** — Treatment depends on the underlying etiology 4. **Assesses urgency** — Differentiates benign from life-threatening causes **Clinical Pearl:** **Idiopathic intracranial hypertension (IIH)** is the most common cause of papilloedema in young women. Neuroimaging must exclude secondary causes before diagnosing IIH. ### Diagnostic Algorithm for Papilloedema ```mermaid flowchart TD A[Bilateral disc swelling + blurred margins]:::outcome --> B{Asymptomatic or symptomatic?}:::decision B -->|Asymptomatic, normal VA, no pain| C[Likely papilloedema]:::outcome B -->|Eye pain, vision loss, RAPD| D[Likely papillitis]:::outcome C --> E[MRI brain ± contrast or CT head]:::action E --> F{Structural lesion found?}:::decision F -->|Yes: tumor, hydrocephalus, etc.| G[Treat underlying cause]:::action F -->|No: normal imaging| H[Suspect IIH]:::outcome H --> I[Lumbar puncture for opening pressure]:::action D --> J[MRI optic nerves with contrast]:::action J --> K[Confirm optic nerve enhancement]:::outcome ``` ### Why Other Options Are Incorrect **Perimetry** — Useful for monitoring visual field loss in chronic papilloedema but does not identify the cause of raised ICP. **OCTA** — Shows structural vascular changes but cannot assess intracranial pathology or confirm the etiology of papilloedema. **Carotid Doppler** — Relevant only if venous sinus thrombosis is suspected; not a first-line investigation for papilloedema. **Mnemonic:** **BRAIN-FIRST** — When papilloedema is suspected, image the BRAIN first to identify the cause of raised intracranial pressure.