Papilledema is defined as swelling of the optic nerve head secondary to raised intracranial pressure (RICP). (When intracranial pressure is not raised, the appropriate term is ‘disc swelling’ or ‘disc edema’.) Although the mechanism is imperfectly understood, experiments suggest that RICP is transmitted through the optic nerve sheath, compressing nerve fibres particularly at the lamina cribosa, where the optic nerve passes through the sclera. This impairs intracellular transport within nerve axons (axoplasmic stasis) resulting in leakage and swelling, vascular obstruction and dilatation, and eventual retinal and optic nerve ischemia.
Causes Of Raised Intracranial Pressure
- Intracranial space-occupying lesions (e.g., tumor, hemorrhage, abscess)
- Cerebral edema from head trauma
- Increased cerebrospinal fluid (CSF) production (e.g., choroid plexus tumor)
- Decreased CSF absorption (e.g., meningitis, subarachnoid hemorrhage)
- Obstruction of CSF flow within the central nervous system (congenital or acquired)
- Increased cerebral blood volume (vascular malformations)
- Obstruction of cranial venous outflow (e.g., venous sinus thrombosis)
- Pseudotumor cerebri.
Transient visual obscurations (e.g., dimmed vision lasting seconds) are common with early papilledema. RICP classically produces headache, nausea and vomiting, which is most severe in the morning. The conscious state may also be affected, particularly with severe or sudden increases in intracranial pressure. Double vision with sixth nerve palsy is a nonspecific feature of intracranial pathology.
Differentiating papilledema from ‘pseudopapilledema’
- Visual acuity is usually intact with early papilledema. It is usually affected acutely in several other differential diagnoses (e.g., optic neuritis, arteritic ischemic optic neuropathy).
- Optic disc morphology is informative to the experienced clinician. For example, with optic disc drusen, the disc margin may be irregular, with effacement of the optic cup and abnormal branching of blood vessels. Peripapillary haemorrhages, exudates and cotton wool spots are common with papilledema.
- Venous pulsation at the disc is present in approximately 80 percent of normal eyes, and absent in 20 percent. The presence of venous pulsation suggests that raised CSF pressure is unlikely.
- While often asymmetrical, papilledema is almost always bilateral. (As a rare counterexample, optic atrophy may prevent disc swelling in one eye despite RICP.)
Clinical features of papilledema are described in more detail in the next condition, ‘Papilledema – Evolution & Sequelae’.
Many causes of RICP are potentially life-threatening and require urgent evaluation. Untreated papilledema can result in optic atrophy and permanent loss of vision.
Optic Disc Drusen, Myelinated Nerve Fibers, Hypertensive Retinopathy (malignant hypertension), Anterior Ischemic Optic Neuropathy, Optic Neuritis, Neuroretinitis, Diabetic Papillopathy, Central Retinal Vein Occlusion, Intraocular Lymphoma, Intraorbital Tumors.
Papilledema – Evolution & Sequelae, Pseudotumor Cerebri, Chorioretinal Folds and Retinal Folds.
Treatment is needed for the underlying cause of the papilledema.
Urgent, Additional investigations, Blood tests
Urgent imaging of the brain and optic nerves is required (computed tomography and/or magnetic resonance imaging). Following imaging studies, lumbar puncture may be performed to confirm elevated intracranial pressure, and for CSF analysis. Other blood tests will be influenced by the clinical presentation.
Hyperemic disc swelling; cotton wool spots affecting axons; small hemorrhages; surrounding ring of retinal edema