bubble_chart Overview

It was previously believed that swelling of the optic disc caused solely by increased intracranial pressure was referred to as optic disc edema, a non-inflammatory obstructive edema of the optic disc, with approximately 80% of cases resulting from intracranial space-occupying lesions, while other causes such as inflammation, trauma, or congenital cranio-orbital deformities could also lead to it. Since the term "optic disc edema" does not accurately reflect its clinical signs and pathology, it has been suggested to replace it with "swelling of the optic disc." Hayern's research findings do not support the use of "papilledema" (optic disc edema) to specifically denote cases caused by intracranial hypertension, and "optic disc edema" for those caused by other reasons, as there is no essential difference between the two.

bubble_chart Etiology

Due to the numerous causes of optic disc edema, the underlying mechanisms can sometimes differ. Hypertensive encephalopathy may not be due to increased intracranial pressure but rather local optic disc ischemia, where the renin-angiotensin-aldosterone system plays a significant role. Anterior ischemic optic neuropathy results from disrupted blood supply to the optic disc, leading to blockage of axoplasmic flow in both fast and slow phases.

I. Increased Intracranial Pressure

*1. Intracranial space-occupying lesions (brain tumors, subdural hematoma, epidural hematoma, etc.)

*2. Pseudotumor cerebri

⑴ Primary pseudotumor cerebri

⑵ Secondary (severe head trauma, *subarachnoid hemorrhage)

3. Inflammation

*⑴ Meningitis, encephalitis, brain abscess

⑵ Guillain-Barré syndrome

4. Uremia

5. Craniosynostosis

*6. Cerebral arteriovenous malformation

7. Severe chronic obstructive pulmonary disease with elevated CO₂ levels

8. Severe allergic brain disorders, such as bee stings

9. Increased cerebrospinal fluid protein with spinal tumors

II. Normal Intracranial Pressure

1. Congenital optic disc anomalies

2. Leber's hereditary optic neuropathy

3. Inflammatory optic neuropathy

⑴ Optic neuritis

⑵ Perineuritis

*4. Ischemic optic neuropathy

5. Toxic optic neuropathy, such as lead poisoning, methanol poisoning, etc.

6. Compressive optic neuropathy in the orbit (e.g., thyroid optic neuropathy)

7. Infiltrative optic neuropathy

⑴ Leukemia

⑵ Lymphoma

⑶ Multiple myeloma

⑷ Paraproteinemia

8. Local vascular neuropathies

⑴ Malignant hypertension

⑵ Central retinal vein occlusion

⑶ Venous stasis retinopathy (ischemic)

⑷ Optic disc vasculitis

⑸ Juvenile diabetic optic neuropathy

⑹ Hypotony

⑺ Vitreous traction

⑻ Uveitis

9. Mucopolysaccharidosis

bubble_chart Pathogenesis

It is generally believed that intracranial hypertension can be transmitted to the optic nerve sheath through the subarachnoid space of the cerebrospinal fluid, leading to increased pressure within the optic nerve. This disrupts the pressure gradient between intraocular pressure and intraneural pressure, which is essential for normal axoplasmic transport in the optic nerve. Increased pressure in the subarachnoid space of the optic nerve sheath may also cause deformation and displacement of the lamina cribrosa, resulting in compression of the optic nerve axons within the lamina. Additionally, axoplasmic transport in the optic nerve is obstructed at the lamina cribrosa region, leading to swelling and dilation of axons anterior to the lamina, causing optic disc edema. The primary cause is not interstitial edema (gliosis or tissue space abdominal mass), but rather the obstruction of fast and slow phases of axoplasmic flow at the lamina cribrosa, leading to axoplasmic abdominal mass, producing microsomes and dense bodies abdominal mass, causing the axons themselves to swell.

Optic disc edema only occurs in individuals with clear cerebral membrane cavities surrounding the optic nerve and intracranial structures. If these cerebral membrane cavities are adherent or obstructed by tumors, optic disc edema will not occur on the obstructed side. If the optic nerve has already atrophied before the onset of optic disc edema, and there are no edematous nerve fibers, optic disc edema will not occur. However, if there are still a significant number of residual nerve fibers, optic disc edema can still occur. Unilateral optic disc edema may be related to congenital or acquired local optic nerve sheath abnormalities, and is more commonly caused by local lesions such as inflammation, ischemia, or compression of the intraorbital optic nerve. There are also cases of so-called unilateral optic disc edema, which are actually bilateral optic disc edema with asymmetry, and can be easily overlooked during routine fundus examination.

bubble_chart Clinical Manifestations

Normal vision or grade I blurring, transient amaurosis can last for a few seconds, often occurring when moving the eyes, known as fixation amaurosis. The classification varies based on the speed of optic disc edema development and clinical formation. Holy categorizes it into early type, fully developed type, chronic type, and post-edema atrophy type. Wang Hongqi divides it into initial stage [first stage] type, stage of progress type, malignant phase type, and terminal stage type, which are described as follows:

1. Initial stage [first stage] type: The pathological changes are based on nerve fiber swelling, extracellular fluid abdominal mass, and optic disc vascular dilation. Using color stereoscopic fundus photography and stereoscopic ophthalmoscopy, swelling and turbidity of the peripapillary nerve fiber layer can be observed, with loss or bending of straight white reflective streaks. The color deepens and becomes blurred. Optic disc congestion or superficial hemorrhage is due to the dilation or rupture of superficial capillaries on the optic disc. Generally, fundoscopy can distinguish this, but it is best to use a contact lens with a slit lamp for examination, which is extremely valuable for diagnosing this type. The blurring of the optic disc margin usually starts from the lower to the upper part, then extends to the nasal margin, and finally the temporal side becomes blurred, due to the varying density of the nerve fiber layer in different parts of the optic disc, with denser areas swelling earlier. The presence or absence of spontaneous retinal vein pulsation has some significance in judging this type. However, 12-20% of normal people may lack venous pulsation, and intracranial pressure often fluctuates. If venous pulsation is observed between two peaks of intracranial pressure rise, and intracranial pressure drops below 26.7kPa (200mmHg), retinal vein pulsation may reappear, leading to misdiagnosis. Therefore, its exact significance is still debated, but the observation is convenient and easy to perform, and it remains a meaningful reference indicator. Fundus fluorescein angiography may show fine vascular dilation, fluorescein leakage, fistula disease, and small stirred pulse formation, even peripapillary fistula disease, due to increased capillary permeability. Late stage [third stage] shows strong fluorescence. The characteristic of an enlarged physiological blind spot in the horizontal diameter aids in diagnosis. In this type, diagnosis cannot be based solely on one sign; it must rely on a comprehensive analysis of several signs, and suspicious cases should be followed up.

2. Stage of progress type: The surface of the optic disc is significantly raised, up to 3-4D, resembling a mushroom shape. Microaneurysms and capillary dilation on the optic disc surface are very obvious, with dot or flame-shaped hemorrhages around the disc, and significant blurring of the disc margin. The veins passing through the margin are dilated and curved, possibly appearing intermittent. If intracranial pressure rises rapidly, large flame-shaped hemorrhages and cotton wool exudates may be seen, even subvitreous hemorrhage. Hard exudates and hemorrhages may also be seen in the macula. In severe cases, Paton's line may be seen, usually on the temporal side of the optic disc, appearing as a semi-arc, due to swelling of the optic disc tissue pushing and displacing the retinal membrane at the temporal margin, causing folds and wrinkles in the retina, with varying degrees of reflection in the inner retinal membrane. In cases of prolonged optic disc edema, new blood vessels may be seen under the peripapillary retina.

3. Malignant phase type: This type differs from the stage of progress type only in degree. If intracranial pressure rises sharply and suddenly, the optic disc tissue and retinal vessels cannot adapt, leading to massive sheet-like hemorrhages and exudates. The optic disc edema can be raised up to 5D or more, but there may also be cases without hemorrhage or exudate. Vision often decreases to some extent, and the visual field may show concentric narrowing (excluding the characteristic visual field of brain disease).

4. Terminal stage type: Also known as the atrophy type. Regardless of the type, if optic disc edema does not subside for a long time, it can transition to this type. The optic disc becomes round, grade I raised, with the central white cup-shaped depression disappearing. The color of the optic disc changes from red to gray-white, the stirred pulse becomes thinner, the veins slightly thicker or normal, the retinal vessels sheathed, and peripapillary retinal edema absorbed. Small round, smooth, shiny hard exudates may be seen in the superficial tissue of the optic disc, resembling embedded warts. This type is characterized by decreased vision, color vision impairment, and visual field defects. If intracranial decompression surgery is performed, there is a risk of sudden or gradual loss of vision.

The classification of optic disc edema has certain clinical significance in differentiating between benign and malignant intracranial tumors. Benign intracranial tumors are often associated with the initial stage [first stage] or stage of progress type of optic disc edema. Benign tumors develop slowly, with lesions mostly localized, and the supratentorial region is relatively broad, with less or mild involvement of the ventricles. For example, in the case of infratentorial benign tumors, although the infratentorial region is narrower than the supratentorial region, most benign tumors are small in size. If the growth site is far from the ventricular system, the increase in intracranial pressure is generally not abrupt. Malignant intracranial tumors mostly occur in the malignant phase due to their infiltrative and diffuse growth pattern, with extensive tumor invasion involving the ventricular system, leading to acute obstruction of cerebrospinal fluid circulation, resulting in a sudden increase in intracranial pressure and causing optic disc edema.

The frequency and location of optic disc edema are closely related. Tumors located below the tentorium and midline, such as those in the cerebellum, posterior third ventricle, and fourth ventricle, almost always cause optic disc edema early on due to direct obstruction of cerebrospinal fluid flow. In contrast, tumors in the frontal, parietal, temporal lobes, and brainstem develop more slowly. Pituitary adenomas typically cause unilateral optic nerve atrophy and rarely result in optic disc edema. Optic disc edema caused by increased intracranial pressure should be treated as an emergency, indicating severe neurological and systemic diseases.

bubble_chart Auxiliary Examination

Strive to identify the cause of the disease and treat it promptly. Brain tumors should be surgically removed at an early stage. Symptomatic treatment includes hypertonic dehydrating agents. If intracranial space-occupying sexually transmitted disease changes can be ruled out and the diagnosis is confirmed as optic disc vasculitis with optic disc edema type, corticosteroids can achieve good results. For cases accompanied by severe headaches and optic neuropathy, if treatments such as dehydrating agents are ineffective, decompression surgery or shunt surgery can be considered, especially for pseudotumor cerebri. In the past, continuous lumbar puncture, subtemporal decompression, and external orbital optic nerve sheath decompression were used, which only provided temporary pressure relief. Currently, lumbar-peritoneal shunting is more commonly advocated. To monitor visual function, Farnsworth-Munsell 100 hue test and VEP can be used.

bubble_chart Complications

Strive to identify the cause of the disease and treat it promptly. Brain tumors should be surgically removed at an early stage. Symptomatic treatment includes hypertonic dehydrating agents. If intracranial space-occupying sexually transmitted disease changes can be ruled out and optic disc vasculitis with optic disc edema is confirmed, corticosteroids can yield good results. For cases accompanied by severe headache and optic neuropathy, where dehydrating agents and other treatments are ineffective, decompression or shunt surgery may be considered, especially for pseudotumor cerebri. In the past, continuous lumbar puncture, subtemporal decompression, and external orbital optic nerve sheath decompression were used, which only provided temporary pressure relief. Currently, lumbar-peritoneal shunt surgery is more commonly advocated. To monitor visual function, Farnsworth-Munsell 100 hue test and VEP (Visual Evoked Potential) can be used.