Papilledema

Papilledema is optic disc swelling caused by raised intracranial pressure. Pressure in the subarachnoid space around the optic nerve slows axoplasmic flow at the lamina cribrosa, producing axonal swelling, venous congestion and disc elevation. The term excludes disc swelling from other causes, which is called optic disc edema.

Idiopathic intracranial hypertension has an incidence of about 1 in 100,000 in the general population and 15 to 20 in 100,000 in women aged 20 to 44 with a BMI above 30. Almost every patient with it has papilledema. Other causes:

• Intracranial mass lesions and hydrocephalus
• Cerebral venous sinus thrombosis
• Chronic meningitis, including cryptococcal
• Subarachnoid hemorrhage
• Craniosynostosis in children
• Drugs: tetracyclines, retinoids, vitamin A excess, lithium, nalidixic acid, growth hormone, and corticosteroid withdrawal

The staging is descriptive:

• grade 0: normal disc
• grade 1: C-shaped halo with nasal blurring
• grade 2: circumferential halo
• grade 3: obscuration of one or more major vessel segments at the disc margin
• grade 4: obscuration of a vessel segment on the disc
• grade 5: total obscuration of vessels

Chronic papilledema progresses to a champagne cork disc with loss of hyperemia, then to optic atrophy with narrowed fields. Central acuity is spared until late, but fulminant cases lose vision within days.

Complications are permanent field constriction, optic atrophy and blindness.

• Headache that is daily, worse on waking, on lying flat or with Valsalva
• Transient visual obscurations lasting seconds, triggered by posture change
• Pulsatile tinnitus, nausea, vomiting
• Horizontal diplopia from sixth nerve palsy (a false localizing sign)
• Photopsias and, in advanced disease, blurred vision

Examination findings:

• Visual acuity is usually normal early.
• Perimetry shows an enlarged blind spot, then arcuate and inferonasal loss.
• Color vision is lost late.
• The fundus shows hyperemic disc, blurred margins, loss of spontaneous venous pulsation (absent in about 20% of normal eyes), peripapillary flame hemorrhages, cotton wool spots, Paton folds and hard exudates.
• Unilateral or markedly asymmetric swelling is uncommon.

Red flags: sudden visual loss, thunderclap headache, focal neurological deficit, reduced consciousness, fever with neck stiffness, and papilledema in a patient with cancer or immunosuppression.

• Dilated fundus examination is first line. Document disc appearance with photographs.
• Neuroimaging before lumbar puncture. MRI brain with MR venography. If MRI is unavailable, use contrast CT with CT venography. IIH imaging signs: empty sella, posterior globe flattening, optic nerve sheath distension, transverse sinus stenosis.
• Lumbar puncture in the lateral decubitus position with legs extended. Adult opening pressure above 25 cmH2O is raised and 20 to 25 is equivocal. In children, above 28 cmH2O is raised (above 25 if not sedated or obese). CSF composition is normal in IIH. Send cell count, protein, glucose, cryptococcal antigen and culture when infection is possible.
• Visual function: automated perimetry (24-2 or 30-2) as baseline, OCT of the retinal nerve fiber layer to track thickness.
• Fluorescein angiography to separate papilledema (late disc leakage) from drusen (early nodular hyperfluorescence). B-scan ultrasound detects buried calcified drusen.

Differentials: pseudopapilledema (drusen, tilted disc, myelinated fibers), optic neuritis (pain on eye movement, afferent pupillary defect, reduced acuity), anterior ischemic optic neuropathy, malignant hypertension, central retinal vein occlusion, infiltrative optic neuropathy, diabetic papillopathy. IIH is diagnosed when papilledema is present, neurological examination is normal apart from cranial nerve palsy, imaging shows no mass or thrombosis, CSF composition is normal and opening pressure is raised.

Treat the cause. Papilledema is an indicator of risk to vision, and the aim is to normalize pressure and protect the field.

Mass lesion or hydrocephalus:

• Urgent neurosurgical referral.
• Dexamethasone 10 mg IV once, then 4 mg IV or orally every 6 hours for vasogenic edema.
• CSF diversion by external ventricular drain, ventriculoperitoneal shunt or endoscopic third ventriculostomy.

Cerebral venous sinus thrombosis: enoxaparin 1 mg/kg SC every 12 hours, then warfarin to INR 2 to 3 for 3 to 12 months (or a direct oral anticoagulant). Hemorrhagic infarction is not a contraindication.

Idiopathic intracranial hypertension:

• Weight loss of 5 to 15% of body weight through a low energy diet. Bariatric surgery for BMI 35 or above that is refractory.
• Acetazolamide, extended release 500 mg orally twice daily, titrated by 500 mg weekly to 1 g twice daily (maximum 4 g/day). Adverse effects: paresthesia, taste change, fatigue, metabolic acidosis, nephrolithiasis. Monitor bicarbonate and potassium. Contraindicated in sulfonamide allergy and severe renal or hepatic impairment. Avoid in the first trimester.
• Topiramate 25 mg twice daily, increasing to 50 mg twice daily, as an alternative or addition. It causes cognitive slowing and is teratogenic.
• Furosemide 20 to 40 mg orally daily as an adjunct, with potassium monitoring.
• Do not use corticosteroids, because of weight gain and rebound. Avoid repeated therapeutic lumbar puncture.
• Treat headache with amitriptyline 10 to 50 mg at night or propranolol 40 mg twice daily. Limit simple analgesics to 2 days a week.

Progressive visual loss on maximal medical therapy or fulminant presentation:

• Optic nerve sheath fenestration via the medial approach. Complications: transient diplopia, tonic pupil, rare retinal artery occlusion. Long term failure in 10 to 25%.
• Lumboperitoneal or ventriculoperitoneal shunt, with revision rates of 40 to 50%.
• Venous sinus stenting when the transverse sinus pressure gradient exceeds 8 mmHg, followed by dual antiplatelet therapy for 3 to 6 months.

Children: acetazolamide 25 mg/kg/day in 2 to 3 divided doses, increasing to a maximum of 100 mg/kg/day (not above 2 g/day).

Pregnancy: weight gain monitoring, acetazolamide after the first trimester if needed, vaginal delivery with no restriction on the second stage.

Follow up: acuity, perimetry and fundus photographs at 2 to 4 weeks, then every 3 months, with OCT each visit. Papilledema resolves over 6 to 8 weeks to several months after pressure normalizes. Counsel on driving restrictions while fields are impaired, avoidance of vitamin A supplements and retinoids, and weight maintenance. About 10 to 20% relapse, mostly with weight regain.