Pseudopapilledema

What is Pseudopapilledema?

Swelling of the optic disc, also known as optic disc edema, and another condition called papilledema are important to diagnose early because they can be the initial signal for a variety of diseases that could lead to vision loss, harm to the nervous system, or even death. To clarify, optic disc edema occurs when a part of the eye called the optic nerve head swells due to a range of potential diseases affecting the optic nerve, including inflammation and compression, among others. On the other hand, papilledema refers specifically to optic disc edema resulting from increased pressure inside the skull.

It’s crucial to differentiate true disc edema from a condition called pseudopapilledema, which only mimics the swollen appearance of the optic nerve head without the actual swelling of the nerve fibers – these two conditions lead to vastly different health implications. Some eye abnormalities such as optic disc drusen (tiny rock-like formations in the optic nerve), congenital disc anomalies (birth defects), myelinated nerve fibers (nerves with an abnormal protective coating), and certain growths surrounding the optic disc, like astrocytic hamartomas, can give a false impression of pseudopapilledema.

This review will mainly concentrate on optic disc drusen. Careful eye check-up and some additional diagnostic tests can typically assist in distinguishing these causes of pseudopapilledema.

What Causes Pseudopapilledema?

Pseudopapilledema is a condition where there seems to be swelling of the optic nerve in the back of your eye. Many different factors can cause pseudopapilledema. For example, people born with small nerves and a crowded optic nerve area, typically seen in farsighted eyes (or those with shorter axial lengths – the measure from the front to the back of the eye), can show mild elevation of the optic nerve. On the other hand, in nearsighted eyes (with longer axial lengths), the optic nerve can be inserted into the eye at a slanted angle which can make one side appear higher than the other.

Sometimes, an incomplete, naturally occurring condition called Burgmeister’s papillae, which forms from a not fully vanished artery in the eye, can cover the optic nerve and mimic the look of papilledema or optic nerve swelling. Even migrated nerve fibers, which are abnormal, can obscure the optic nerve margin and give a similar appearance.

Optic disc drusen (ODD), another cause, are deposits consisting of calcium and proteins located at the back of the retina. The creation of ODD is thought to be related to abnormal axoplasmic flow – the transport within the nerve cell – resulting in the pushing out of the drusen or decay of the retina’s nerve fibers. Over time, these drusen deposits can rise from the deep, hidden zones to the surface and increase the optic nerve head elevation.

Any other irregularities around the optic nerve that can blur the nerve’s boundaries or elevate the nerve can cause pseudopapilledema. This includes issues like vitreopapillary traction, non-mineralized peripapillary astrocytic hamartomas (a rare, benign growth in the eye), or other tumors near the optic nerve.

Risk Factors and Frequency for Pseudopapilledema

Optical disc drusen (ODD) are not very common, affecting around 0.2 to 3.1% of the population. Their prevalence tends to be higher when examined in post-mortem studies. It’s been observed that there can be a genetic component, as ODD often runs in families, but no specific gene has been identified as the cause yet. This condition has been found to be associated with other conditions, such as retinitis pigmentosa, Alagille syndrome, and pseudoxanthoma elasticum (also known as Grönblad–Strandberg syndrome).

• Optical disc drusen (ODD) are found in about 0.2 to 3.1% of people.
• The rate of ODD tends to be higher in post-mortem studies.
• There seems to be a familial link to ODD, but no specific causative gene has been discovered yet.
• ODD is associated with other conditions including retinitis pigmentosa, Alagille syndrome, and pseudoxanthoma elasticum (Grönblad–Strandberg syndrome).

Signs and Symptoms of Pseudopapilledema

Diagnosing pseudopapilledema can be tricky as its appearance is similar to true papilledema, a condition where the optic nerve swells due to pressure. Identifying this condition involves understanding symptoms, which can include headaches that worsen with position changes, nausea, a pulsing sound in the ears, temporary vision disturbances, and double vision. However, these symptoms can also occur in other conditions, making it difficult to interpret. Also, vision loss linked to pseudopapilledema is often gradual and painless, and may not be easily noticed by the patient. In some cases, patients may experience brief vision disturbances, even without increased pressure in the brain, due to temporary insufficient blood supply caused by the pressure of the drusen—the deposits found in pseudopapilledema.

Examining the back of the eye reveals that the optic nerves in pseudopapilledema appear raised. In some cases, the drusen causing this condition can be seen as shiny bodies or yellow deposits. But sometimes, these drusen are located deep in the nerve and hidden by the overlying nerve fiber layer, making them hard to see. Despite the blurred edges of the optic nerves, in cases with buried drusen, the blood vessels are not obscured, and there shouldn’t be any microvascular changes such as hemorrhages or small deposits known as exudates. The optic nerves tend to be small and lack the “cup” that is usually seen, with atypical branching of the retinal blood vessels.

A natural rhythmic flow in the veins at the back of the eye (known as spontaneous venous pulsations) is usually a good sign that there is no increased pressure in the brain. However, these pulsations are not always visible in everyone, so their absence does not necessarily mean there’s increased pressure. Additionally, conditions associated with pseudopapilledema, such as retinitis pigmentosa, pseudoxanthoma elasticum, and Alagille syndrome should be ruled out.

Testing for Pseudopapilledema

The most reliable test for diagnosing swelling of the optic nerve also known as optic disc edema or papilledema, is intravenous fluorescein angiography (IVFA). This test involves injecting a special dye intravenously which will leak from the nerve if true disc edema is present. However, this test is invasive, requires an intravenous (IV) line, and the patient’s cooperation with repeated photography of the inner surface of the eye, which isn’t often readily available in clinics. Staff usually resort to IVFA only when other tests can’t provide a clear result. Absence of leakage doesn’t completely rule out that optic disc drusen (deposits in the optic nerve) are present since the swollen appearance of the optic nerve could be due to other causes of pseudopapilledema (false appearance of swelling).

There are several other tests used to detect optic disc drusen (ODD) that are too deep to be seen during an examination of the inner surface of the eye. Although CT scans aren’t usually done to diagnose ODD, they might show an increased density at the optic nerve head associated with calcified drusen if the scan was performed for some other reason. Advanced techniques like autofluorescence imaging can highlight drusens that are closer to the surface that glow under special light. B-scan ultrasonography, a type of ultrasound, can also detect drusen, showing them as bright signals at the nerve head that creates a shadow effect and an artifact (error in image)

A technology called optical coherence tomography (OCT) can measure the thickness of a layer in the retina, but can’t reliably differentiate between disc edema and pseudopapilledema. New OCT technologies allow for imaging of deeper structures of the optic nerve, including deep drusen which appear as darker masses with brighter borders.

However, it’s also important to remember that other conditions can produce similar image characteristics, so this evidence should always be carefully interpreted. It has been suggested that enhanced depth imaging OCT (EDI-OCT) may be the most sensitive testing method for optic disc drusen, and unlike ultrasonography, it can show the location of the drusen within the nerve head which can help understand any visual field defects.

Treatment Options for Pseudopapilledema

In simple terms, pseudopapilledema caused by ODD, a condition of the eye, doesn’t have any widely known cure or treatment options. One study did describe a procedure called radial optic neurotomy that showed some promise in improving or stabilizing vision in six patients, but the procedure carries certain risks. So, it’s only considered for those with very severe vision loss, which is not typical for this condition. Trying to remove the drusen, small yellow deposits that may form, has been attempted, but this led to poor results and is generally not advised.

Other complications that arise due to this condition should be treated as they happen, unfortunately, there’s no known way to prevent these complications from occurring in the first place.

On another note, if pseudopapilledema is a natural occurrence from birth (a congenital variant), no specific treatment is necessary. However, if what appears to be pseudopapilledema is actually due to a tumor near the optic nerve, the focus should be on treating the tumor itself. In cases where it’s caused by a pulling force on the optic nerve due to certain changes in the eye’s vitreous gel (known as vitreopapillary traction), it might resolve on its own over time. But, if it’s causing symptoms and doesn’t resolve itself, a surgical procedure called a pars plana vitrectomy could be considered as a potential treatment.

What else can Pseudopapilledema be?

When an optic nerve appears raised, it can be due to various conditions. These can be grouped into two categories: actual disc swelling (disc edema) or a condition that mimics this swelling (pseudopapilledema).

The potential causes for disc swelling include:

• Papilledema, which is caused by increased pressure inside the skull,
• Inflammation of the optic nerve due to multiple causes such as demyelination, granulomas, uveitis, or inflammation of the tissue around the nerve,
• Blockage or limitation of blood supply to the optic nerve,
• Tumors or other masses that press or grow into the optic nerve,
• Lower than normal pressure inside the eye or around the brain and spinal cord,
• Inherited conditions, like Leber hereditary optic neuropathy.

Conditions that may mimic optic disc swelling include:

• Optic disc drusen, which are deposits in the optic nerve,
• Having a nerve that’s crowded due to farsightedness or tilted due to nearsightedness,
• Bergmeister papilla, which is a leftover piece of tissue from when the eye was developing,
• A nerve that’s covered in a layer of myelin, which is unusual outside the brain and spinal cord,
• A condition where the vitreous, the gel that fills most of the eye, pulls on the optic nerve,
• A mass close to the optic nerve.

It’s also crucial to remember that a patient can have more than one condition at the same time. For example, they could have optic disc drusen and also be experiencing actual disc swelling.

What to expect with Pseudopapilledema

The outlook for pseudopapilledema, a condition often confused with true optic nerve inflammation, when Optic Disc Drusen (ODD) is present, is generally very good. ODD is characterized by little yellowish deposits (drusen) in the optic nerve. As people with drusen age, they sometimes develop issues with their visual fields – the total area one can see without moving the eyes. The prevalence of these visual field defects ranges from 11% in children to a full 100% in older adults.

The vision changes caused by these defects are usually minor, affect the edges of your sight (called peripheral vision), and progress very slowly. They often manifest as enlarged blind spots, peripheral constriction (a narrowing of the field of vision), or issues with the nerve fibers in the eyes that appear similar to those seen in glaucoma, a group of diseases damaging the eye’s optic nerve.

The severity of the vision loss is linked with the amount of drusen present in the optic nerve and is more severe in patients with drusen closer to the surface, drusen larger than 500 micrometers, or clusters of drusen. Despite this, losing central visual acuity – the sharpness or clarity of your straight-ahead vision – is a rare occurrence with this condition.

Possible Complications When Diagnosed with Pseudopapilledema

People with ODD (Optic disc drusen), apart from experiencing peripheral vision loss due to presumed compression of the nerve fibers in the retina, are also susceptible to other eye conditions. For instance, they have a higher likelihood of developing Non-arteritic ischemic optic neuropathy (NAION) which results in stroke of the eye. The risk of developing this condition in the other eye is also elevated. In addition, ODD puts individuals at risk of blockages in the arteries or veins of the retina or abnormal blood vessels around the optic nerve.
Common Ocular Conditions associated with ODD include:

• Peripheral vision loss
• Non-arteritic ischemic optic neuropathy (stroke of the eye)
• Retinal artery occlusions (blockage in the arteries of the retina)
• Retinal vein occlusions (blockage in the veins of the retina)
• Peripapillary CNV (abnormal blood vessels around the optic nerve)

Preventing Pseudopapilledema

Pseudopapilledema and ODD are conditions that a person is born with, and right now, there’s no known way to prevent or treat them. The most helpful thing one can do for a patient diagnosed with ODD is to make sure that they and their health care team are fully aware of the condition. Knowledge is crucial in managing these conditions.