What tests are done to investigate papilledema?

Diagnostic Tests for Papilledema

The primary test for investigating papilledema is MRI of the brain and orbits with MR venography, which should be performed urgently to evaluate for causes of increased intracranial pressure.

Initial Imaging Studies

• MRI brain and orbits is the most useful imaging modality for initial evaluation of patients presenting with papilledema and signs of raised intracranial pressure 1, 2
• CT or MR venography is mandatory to exclude cerebral sinus thrombosis within 24 hours 3
• If MRI is unavailable within 24 hours, urgent CT brain should be performed with subsequent MRI if no lesion is identified 3
• Neuroimaging should confirm there is no evidence of hydrocephalus, mass, structural or vascular lesion, and no abnormal meningeal enhancement 3

Key MRI Findings in Papilledema

• Empty or partially empty sella is a typical neuroimaging feature found in raised intracranial pressure 2
• Posterior globe flattening (56% sensitivity, 100% specificity for high ICP) 2
• Intraocular protrusion of the optic nerve (40% sensitivity, 100% specificity) 2
• Horizontal tortuosity of the optic nerve (68% sensitivity, 83% specificity) 2
• Enlarged optic nerve sheath compared to control groups 2
• Dilated optic nerve sheaths and tortuous or enhancing optic nerves 2

Lumbar Puncture

• Following normal imaging, all patients with papilledema should have a lumbar puncture to check opening pressure and ensure CSF contents are normal 3
• The lumbar puncture opening pressure should be measured in the lateral decubitus position 3
• Opening pressure >200 mm H₂O indicates elevated intracranial pressure 4
• CSF composition should be normal in idiopathic intracranial hypertension 5

Ophthalmologic Assessment

• Fundoscopic examination is essential to confirm papilledema and rule out pseudopapilledema 3, 5
• Visual field testing should be performed to assess for visual field defects 6
• Optical coherence tomography (OCT) is useful for distinguishing pseudopapilledema from true papilledema 6
• Color fundus photographs should be taken to document baseline appearance and monitor changes 6

Alternative Diagnostic Approaches

• Transorbital point-of-care ultrasound measuring optic nerve sheath diameter (US-ONSD) and optic disc elevation (US-ODE) can be used as a screening tool, particularly in children 7
• A US-ONSD cut-off value of 5.73 mm has 92% sensitivity and 86.4% specificity for detecting conditions requiring treatment for increased ICP 7

Differential Diagnosis Considerations

• Blood pressure must be measured to exclude malignant hypertension 3
• When there is diagnostic uncertainty regarding papilledema versus pseudopapilledema, an experienced clinician should be consulted early before invasive tests are performed 3
• Neurological examination should be performed to rule out other cranial nerve involvement (typically there should be no cranial nerve involvement other than possible sixth cranial nerve palsy) 3

Clinical Correlation

• Assess for key symptoms including headache (present in nearly 90% of patients with idiopathic intracranial hypertension), transient visual obscurations, pulsatile tinnitus, and diplopia 2, 4
• Papilledema is usually bilateral but may be asymmetric 8
• Visual function is typically normal in the acute phase of papilledema 5

Management Considerations

• If there is evidence of declining visual function, acute management to preserve vision may require surgical intervention 2
• Weight loss is the first-line treatment for pseudotumor cerebri in overweight patients 1
• Acetazolamide is the first-line medication for patients with mild visual loss 1

Remember that papilledema is a serious finding that requires prompt investigation and management to prevent potential vision loss. Joint care between ophthalmologists and neurologists is essential for optimal patient outcomes.