Papilloedema

Overview

Papilloedema describes swelling of the optic disc due to increased intracranial pressure (ICP). It is almost always bilateral if due to increased ICP. Unilateral papilloedema suggests disease in the eye rather than increased ICP, such as optic nerve inflammation or tumours.

Pathophysiology

The optic nerve sheath is continuous with the subarachnoid space of the brain. Therefore, increased ICP leads to increased pressure in the optic nerve sheath. Since the optic nerve stops suddenly at the eye, retinal neurone fibres in the optic disc bulge and become engorged. It is thought that this leads to mechanical compression and/or ischaemia which leads to the loss of these nerve fibres and visual impairment.

Causes

• Intracranial causes – any cause of increased ICP – more likely to cause bilateral papilloedema:
  • Tumours
  • Intracranial haemorrhages
  • Idiopathic intracranial hypertension
  • Malignant hypertension
  • Cerebral abscess
  • Cerebral inflammation/infection
  • Chiari malformations
  • Hypercapnia
• Optic nerve pathology – more likely to cause unilateral papilloedema:
  • Anterior ischaemic optic neuropathy – the most common cause of unilateral optic nerve swelling
  • Optic neuritis
  • Neoplasms (either primary or metastatic)

Presentation

Patients may have visual blurring and features of Elevated Intracranial Pressure.

Assessment

A neurological and ophthalmic examination should be performed. The following features may be seen on fundoscopy:

• Blurring of the optic disc margin
• Engorgement of retinal veins – often the first sigh
• Elevation of the optic disc
• Absent venous pulsations – this can be normal in ~20% of unaffected patients
• Paton’s lines – radial retinal lines extending out from the optic disc

Investigations

Overview

• Urgent neuroimaging (CT/MRI brain):
  • To screen for space-occupying lesions and venous sinus thrombosis