A 35-year-old man is brought to the emergency department with a 2-week history of progressive headache, morning vomiting, and blurred vision. He denies eye pain or photophobia. On examination, visual acuity is 6/9 bilaterally. Fundoscopy shows bilateral disc swelling with blurred margins, obscuration of vessels at the disc, and retinal folds (Paton's lines) around the disc. Visual fields show enlargement of the blind spot. Lumbar puncture shows opening pressure of 35 cm H₂O. MRI brain reveals a 3 cm pineal region mass compressing the third ventricle. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Papilloedema from Raised Intracranial Pressure ### Key Distinguishing Features **Key Point:** Papilloedema is bilateral optic disc swelling caused by raised intracranial pressure (ICP). It is characterised by **painless vision loss, bilateral presentation, and elevated ICP on LP**. ### Clinical Presentation Analysis | Feature | Papilloedema | Papillitis (Optic Neuritis) | |---------|-------------|---------------------------| | **Onset** | Insidious (weeks to months) | Acute (hours to days) | | **Bilaterality** | Always bilateral | Monocular (rare bilateral) | | **Pain** | Absent | Present, especially with eye movements | | **Vision loss** | Initially none; late if severe | Marked and early | | **Colour vision** | Preserved until late | Severely impaired | | **Blind spot enlargement** | Characteristic | Central scotoma | | **ICP** | Elevated (>25 cm H₂O) | Normal | | **Retinal folds (Paton's lines)** | Present | Absent | | **Cause** | Space-occupying lesion, hydrocephalus, idiopathic intracranial hypertension | Demyelination, inflammation | ### Why This Patient Has Papilloedema 1. **Bilateral disc swelling** — papilloedema is always bilateral; optic neuritis is monocular 2. **Painless presentation** — papilloedema is painless; optic neuritis causes pain with eye movements 3. **Elevated ICP (35 cm H₂O)** — diagnostic of papilloedema; normal in optic neuritis 4. **Retinal folds (Paton's lines)** — specific sign of chronic papilloedema from raised ICP 5. **Enlarged blind spot** — papilloedema enlarges the blind spot; optic neuritis causes central scotoma 6. **Structural lesion on MRI** — pineal mass causing hydrocephalus and raised ICP **High-Yield:** The **triad of papilloedema** = bilateral disc swelling + elevated ICP + space-occupying lesion or hydrocephalus. **Clinical Pearl:** Paton's lines (retinal folds radiating from the disc) and obscuration of vessels at the disc margin are hallmarks of papilloedema. They indicate chronic raised ICP and warrant urgent neuroimaging. **Mnemonic — Papilloedema Signs (DISC):** - **D**isk swelling (bilateral) - **I**CP elevated (>25 cm H₂O) - **S**pace-occupying lesion or hydrocephalus - **C**hronic headache, vomiting, blurred vision (painless) ### Stages of Papilloedema (Frisén Scale) 1. **Stage 0** — Normal optic disc 2. **Stage 1** — C-shaped blurring of nasal margin 3. **Stage 2** — Complete circumferential blurring 4. **Stage 3** — Obscuration of major vessels at disc 5. **Stage 4** — Complete obscuration of vessels; disc appears as a mound 5. **Stage 5** — Optic atrophy with gliosis (chronic papilloedema) This patient is at **Stage 3–4**, indicating chronic raised ICP.