Papilledema

Papilledema refers to swelling of the optic disc related to increased intracranial pressure.

Terminology

Care must be taken to not use the term papilledema for all causes of optic nerve head elevation. Although papilledema literally means swelling of the optic disc (nerve head/papilla), in ophthalmological parlance, it is only one of many causes of optic disc edema ^8-10. Furthermore, it should also be distinguished from causes of pseudo-edema from optic disc drusen ⁹.

Pathology

Etiology

• idiopathic intracranial hypertension (pseudotumor cerebri)

• hydrocephalus

• intracranial masses, e.g. primary CNS tumors (e.g. gliomas), cerebral metastases, cerebral abscesses

• extra-axial fluid collection, e.g. subdural hemorrhages, subdural empyemas

• meningeal disease

  • meningioma(s), leptomeningeal carcinomatosis, tuberculosis

Radiographic features

Ultrasound

Ultrasound can be used to detect optic disc elevation into the vitreous cavity.

The optic nerve sheath diameter posterior to the globe can also be measured ¹¹.

CT and MRI

The CT and MRI appearance relates to the dural anatomy of the optic nerve, which is continuous with the subarachnoid space, thereby allowing increased intracranial pressure (ICP) to be transmitted to the optic disc. In most cases, the papilledema is bilateral. However, it can be unilateral in Foster Kennedy syndrome and its pseudovariants.

With the advent of motion correction sequences or higher resolution 3D aquisitions, CSF in the dural sheath over the optic nerve is much more frequently seen, and caution should be shown when reporting this to avoid false positives ⁷. Flattening or bulging of the optic nerve head is probably a more specific sign ⁷.

Differential diagnosis

The differential for papilledema includes other causes of optic disc edema (e.g. optic neuropathy, hypertensive retinopathy, papillitis, and orbital tumors) as well as pseudoedema (pseodupapilledema) from optic disc drusen ^2,3.