Case Presentation of a Swollen Optic Disc

A 58 year old Caucasian male with type II diabetes and hypertension is an established patient who presents with one swollen optic disc and spots in his vision when he woke up. There are no other abnormal findings on examination. Questions facing the clinician include: What are the possible causes of the swollen optic disc, and how can the list of causes be narrowed down based on the history and examination findings? What further testing is required and which tests should be performed first? What is the initial management of this patient? These questions will be addressed by the following article.

Proceed by:

1. Addressing Increased Intracranial Pressure and Giant Cell Arteritis

The limits of the swelling seen inside the eye must be characterized. Two important conditions to address during the history are the acutely life-threatening condition of increased intracranial pressure and the acutely blinding condition of giant cell arteritis. Increased intracranial pressure can be a result of many processes, including malignant hypertension (so blood pressure and vital signs are required). It is not known for certain why the optic disc swells in hypertension, but the two main theories are constriction of the blood vessels supplying the nerve and another is the forcing of spinal fluid through the optic disc/lamina cribrosa (1, 5). Signs of increased intracranial pressure correspond to exit points from the cranial and meningeal compartments which include the optic disc (causing bilateral optic disc swelling (for which the term “papilledema” is reserved) and the more subtle transient visual obscuration), the auditory canal (causing tinnitus), and the foramen magnum (2). Herniation of the brainstem through the foramen magnum can cause compression of medullary centers for wakefulness (causing somnolence and loss or altered consciousness), vomiting, and reducing activity of vital organs (causing death). Also, increased intracranial pressure can cause clival compression of cranial nerve six (causing diplopia). Headache is a nonspecific symptom, but the “worst headache of my life” may point to a ruptured aneurysm which could increase intracranial pressure and compress cranial nerve three, causing a fixed dilated pupil. Neck stiffness causing pain (in someone without a history of neck problems) upon attempting to touch the chin to the chest can be a sign of meningitis or giant cell arteritis (10). Headaches in conjunction with jaw and/or scalp pain in a patient older than 55 should be investigated for giant cell arteritis. Giant cell arteritis is a medium size blood vessel inflammation affecting the head and neck, mainly the external branches of the carotid artery (1, 7). The ophthalmic and central retinal artery can become completely infiltrated very quickly in giant cell arteritis, causing severe irreversible vision loss in both eyes sequentially or simultaneously.

2. Performing a Cranial Nerve Exam (3, 6, 8)

Anytime one cranial nerve has been affected, the other cranial nerves are tested to determine whether cranial nerve dysfunction is isolated or multiple. If the brain has been affected in an area common to the connecting sites of any two or more cranial nerves to the brain, then the cranial nerve exam would help to localize the problem, and in the as-yet-uninvestigated case

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compel the clinician to seek emergent neuroimaging. Isolated cranial nerve problems need not necessarily involve the brain. A study by Savino et al in 2011 helps the clinician in that decision making (13). Savino states that neuroimaging of an isolated cranial nerve 3, 4, or 6 palsy in a patient with vascular risk factors who does not fall into any of the following categories is not necessary. The categories are: age <50 years old, history of cancer of any type at any time, other neurologic signs or symptoms, pupil-involving or partial cranial nerve III palsy, and no resolution 3 mo after initial visit. If any of the categories apply then neuroimaging should be performed to rule out nonvascular and potentially treatable causes of cranial nerve 3, 4, and 6 palsy. Cranial nerve 3, 4, and 6 are examined clinically with motility testing with the transilluminator as well as with cover testing in multiple positions of gaze.Evaluation of the optic disc of the fellow eye offers clues to the cause of the optic disc swelling. For example, if the fellow eye of a swollen optic disc is similarly swollen then the criteria above would be met and the patient should get neuroimaging (possibly followed by a lumbar puncture) to rule out optic disc swelling secondary to increased intracranial pressure, otherwise known as papilledema. There are numerous causes of papilledema, of which hypertension is just one.Another important point to consider is whether or not what is being viewed funduscopically is truly optic nerve swelling. Pseudoswelling of the optic disc or pseudopapilledema is discussed below (1, 4).

3. Obaining Vital SignsAs stated before, the finding of normal blood pressure and vital signs is an important step in ruling out malignant hypertension, as well as other conditions. A fever, for example, could suggest the body’s attempt to fight off infection, as can occur with some types of meningitis (1).

4. Imaging the posterior pole

Ocular imaging modalities expediently quantify or record intraocular parameters, especially around the changing papillary area in a case of a swollen optic disc, and can be repeated at subsequent visits to monitor for progression.

5. Scheduling the visual field and follow-up appointment

The patient with a swollen optic disc should get blood work done more emergently than a visual field, which can be scheduled at the time of the follow up appointment.

6. Educating the patient to “Swollen Optic Disc” and that an emergency visit is possible

The patient with a swollen optic disc should not be educated to the cause of the swelling, because further investigations have yet to be conducted, but should be educated to the possibility of emergent care in the event of the (diagnosis or) presumed diagnosis of giant cell arteritis or other acutely life or vision threatening conditions.

7. Getting the release of information for the primary care physician’s exam notes

8. Obtaining blood work, especially ESR and CRP, within a few hours

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Negative tests and negative symptoms rules out giant cell arteritis. Positive tests or symptoms may require treatment with steroids until a temporal artery biopsy can provide a definitive diagnosis.

In differentiating two important causes of swollen optic nerves, Biousse offers the following table (2):

Anterior Optic Neuropathy Papilledema

OCULAR SIGNS:

decrease in visual acuity

decrease in color vision

Central/Arcuate/Altitudinal visual field defects

Disc edema more often unilateral

____________________________

SYSTEMIC SIGNS:

Often isolated (or associated with symptoms/signs related to underlying disease – like GCA symptoms)

OCULAR SIGNS:

Normal VA’s til late

Normal color

Enlarged blindspot, nasal defect, and constriction on visual field testing

Disc edema almost always bilateral

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SYSTEMIC SIGNS:

Other symptoms or signs of increased ICP, HA, Nausea, Vomiting, Diplopia, 6th nerve palsy, Pulsatile Tinnitus, TVO’s,(Fever,Seizure,Stiffness)

The most notable feature of the above table is the unilaterality of anterior optic neuropathy and the bilaterality of papilledema. Another notable feature of the above table is the solely ocular findings in nonarteritic ischemic optic neuropathy and the predominantly systemic findings of papilledema. Arteritic ischemic optic neuropathy, unlike the nonarteritic form, includes systemic signs and symptoms including headache, jaw pain, scalp tenderness, malaise, weight loss, polymyalgia rheumatica, and amaurosis fugax.

Lui offers the following differential list (1), categorized from most to least common, for swollen optic discs. With each type of swollen optic disc listed, helpful distinguishing characteristic features are mentioned, when available.

Differential diagnosis of a swollen optic disc: causes according to frequency (1)

Most common a. Papilledema is characterized by bilateralityb. Optic neuritis is characterized by pain on eye movement

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c. Anterior ischemic optic neuropathy (if due to giant cell arteritis would have headache, jaw pain, scalp tenderness, other symptoms, and/or elevated ESR and CRP) (if nonarteric, the condition would lack the symptoms and signs of giant cell arteritis, but often includes common vascular risk factors, including hypertension)

d. Pseudopapilledema (includes discs with buried optic nerve drusen, hypoplasticity or myelination)Common

e. Central retinal vein occlusion is characterized by retinal and peripapillary hemorrhages

f. Diabetic papillopathy is bilateral and often accompanied by diabetic retinopathyUncommon

g. Ocular hypotony is characterized by low intraocular pressureh. Intraocular inflammation (uveitis) is characterized by vitreal cells i. Malignant hypertension is characterized by significantly elevated blood pressure

and hypertensive retinopathyj. Optic perineuritis is characterized by pain on eye movement k. Papillitis is characterized by bilateralityl. Intrinsic optic disc tumors exhibit no improvement and requires further

investigation to rule out, including neuroimagingm. Leber’s hereditary optic neuropathy occurs in youth n. Optic nerve infiltration by:

i. sarcoidosis is characterized by pain on eye movement ii. lymphoma may exhibit vitritis and retinal findings

iii. leukemia may exhibit retinopathyiv. plasma cell dyscrasias exhibits retinopathy

o. Meningioma optic neuropathy is characterized by slow onset and no improvementp. Paraneoplastic optic neuropathy is characterized by slow onset and no

improvementq. Infection by Bartonella hensalae, cat-scratch fever, is characterized by history of

cat exposure

In the case presented at the beginning of this article, no other ocular (or systemic) findings other than a swollen optic disc and a visual field defect were present at the initial visit to suggest any other diagnosis other than nonarteritic ischemic optic neuropathy. The unilaterality, lack of pain (including pain on eye movement and jaw pain), lack of signs of pseudoswelling, presence of signs of true swelling, lack of nonpapillary retinopathy, presence of vascular risk factors (including hypertension), normal intraocular pressures, older age of the patient, acute onset of symptoms, and as will be seen normal blood work and improvement in vision over time—all of these factors confirm the diagnosis of nonarteritic ischemic optic neuropathy. NAION is a condition which has been noted by some to be “diagnosed in the negative .”

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Because all of the information just presented is not available at the time of the initial visit, and because giant cell arteritis is a potentially preventable cause of bilateral blindness, the diagnostic consideration of nonarteritic anterior ischemic optic neuropathy (NAION) is secondary to the arteritic variety. Giant cell arteritis (GCA) is the most common form of vasculitis in adults and its most feared complication is irreversible loss of vision. (Aside: Another unrelated condition in which optic nerve damage is the most feared consequence is pseudotumor cerebri). The diagnostic criteria of GCA is defined in rheumatological literature by the presence of any three of five criteria in the patient who is already diagnosed with vasculitis. The information about the presence or absence of vasculitis is often not available at the time of ocular manifestations of GCA, so the eye doctor must probe for the generalized as well as specific symptoms of vasculitis and the associated condition of polymyalgia rheumatica. Generalized symptoms could be as broadly defined as any new onset neurological symptoms in a patient over 50 years old, but also includes fever, malaise, weakness, weight loss, headache, neck pain. Specific symptoms include: amaurosis fugax, jaw pain, and scalp tenderness. The five criteria are listed in the table below (7):

The following two important points relate to the finding that the complete absence of certain criteria in proven cases of GCA is almost always accompanied by the presence of other criteria. This would be the reason why the multiple criteria are not required to be coexistent with each other. First, when the erythrocyte sedimentation rate (ESR) is normal, systemic symptoms are almost always

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present. Second, in the 16-26% of individuals WITHOUT systemic symptoms the ESR is almost always elevated (1). In the case presented here, GCA symptoms were absent and the ESR (and the C reactive protein, a test of other inflammatory markers) was not elevated, so GCA was not suspected. With GCA safely ruled out, NAION can be considered for this patient.

At this point an interesting comparison can be made between NAION, (the visual aspects of) GCA, and Ocular Ischemic Syndrome (OIS). Though all three are ischemic in nature, NAION is distinguished by the absence of any other findings (including those associated with the other two). GCA is distinguished by the potential involvement of nonorbital visual structures, like the occipital cortex, as well as the lack of association with embolic disease. Alternatively OIS is localized to the orbit and the carotid and ophthalmic arteries which feed the orbit. Both OIS and GCA can include amaurosis fugax as well as several other orbital based findings shown below (9,10,11):

Finally, the discussion of NAION will focus more on the clinical characteristics of this condition which is diagnosed by the absence of findings associated with other conditions. The pathogenesis of NAION is unknown. NAION is associated with common vascular risk factors like hypertension, diabetes, and hypercholesterolemia, and is common in the 60 to 70 year old age group, though any age can be

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affected. Caucasians more than African Americans or Hispanic Americans are affected by NAION. One possible precipitating risk factor is hypertensive therapy which is believed to cause nocturnal hypotension. Two features present in NAION seem to support the role of nocturnal hypotension as the risk factor that causes the condition to begin. One is vision loss noted in the morning and the other is the progressive nature of some cases of NAION. Both of these features are present in the case presented here. In this case the patient wakes up noting black spots in his vision, and as will be seen, his visual fields worsened over a few weeks, instead of showing maximal loss at onset. Other possible risk factors include the “disc at risk,” which is a crowded disc with small cupping, often due to a smaller scleral canal that will not allow the optic disc tissue to spread outwards. It has been said that in cases of suspected NAION, a cupped fellow eye should call the diagnosis of NAION into question. Interestingly, in this case of NAION, the patient’s disc was medium sized and moderately cupped. Other conditions which would contribute to ischemia and which are possible risk factors for NAION include: sleep apnea, smoking, and Viagra use.

The symptoms of NAION were studied in the Ischemic Optic Neuropathy Decompression Trial (IONDT), which was a major trial funded by the National Eye Institute. IONDT found that 40% of NAION patients noted monocular vision loss upon awakening. Other symptoms included maximal vision loss at onset and the absence of other signs or symptoms, most significantly the absence of pain. (Pain is the characteristic of an inflammatory process, and pain on eye movement is very characteristic of optic neuritis).

The signs of NAION were similarly studied by IONDT (14). IONDT found that visual acuity loss was moderate with 50% of NAION patients seeing better than 20/64 and 67% of NAION patients seeing better than 20/200. In this case the patient had painless peripheral vision loss and maintained a visual acuity of 20/20 in both eyes throughout. Contrast the moderate visual acuity loss of NAION with arteritic anterior ischemic optic neuropathy from GCA where the visual acuity loss is often much more severe. Interestingly papilledema may not be associated with any visual acuity loss. Returning to NAION, the presence of a positive afferent papillary defect and a positive red cap test within affected areas of the visual field can occur in NAION, as they occur with other optic nerve disorders. Interestingly, this case did not show an afferent papillary defect or positive red cap test in its early stages. Any visual field defect may occur, but classically inferior altitudinal defects are found with NAION. The optic nerve is classically sectorally or diffusely hyperemic or pale disc edema with hemorrhages. (Pallid swelling has been associated with the more profoundly ischemic arteritic variety of ischemic optic neuropathy. Disc hemorrhages are rare in optic neuritis). This case has sectoral hyperemic optic disc swelling with hemorrhages.

The education of the NAION patient would occur after the diagnosis of NAION has been appropriately confirmed. The condition may improve or worsen over the first month, but afterwards vision should remain relatively stable with respect to NAION. The IONDT found that 43% of patients with NAION improve with no treatment. The IONDT also found that there is a 14.7% risk of fellow eye involvement within 5 years. Therefore, patients should be educated to take their evening blood pressure medicines earlier in the evening and to avoid Viagra.

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Most of the features of the case have been discussed, already. One important feature yet to be mentioned is the ocular history of a microvascular sixth nerve palsy that occurred and resolved completely about 5 years prior to the onset of NAION in the patient. Another interesting feature of is that usually after ischemic optic neuropathy, pallor of the optic nerve can be found. In this case, mild pallor has been noted at times, but not at other times after the onset of NAION.

The following visual fields show that NAION involved both eyes of this patient, with the second eye becoming involved just as the first eye, the left eye, was improving. Note that both eyes improve after the initial decline in vision, an important feature of NAION, which is generally nonprogressive with maximal visual loss at onset. A progressively worsening visual field in the setting of optic disc swelling, even in the absence of other findings, would not be consistent with NAION, and imaging must be performed to rule out occult neoplasia.

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The following two diagrams show the sectoral involvement over time in pictures as well as with optic nerve fiber thickness measures for the same patient with NAION.

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The following diagram shows the optic nerve fiber thickness measures, actual for the right eye and suspected for the left eye, for the NAION involved sectors of the optic disc in the same pt. The diagram also shows that four to five months time was all that elapsed between fellow eye, right eye, NAION involvement. The rapid swelling and deswelling of the involved sector of the optic nerve befits the acute, nonchronic, and noninflammatory ischemic nature of NAION.

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When the optic nerve swelling and visual field information is combined in the same diagram, the strongly simultaneous time association between the two features is appreciated. Again, sudden vision loss that is generally maximal at onset, with improvement afterwards, are important features of NAION, and deviation from this pattern should prompt further investigation.

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The following pictures of optic nerves (4) show some of the differences in appearances which are helpful in determining the presence of and possible causes for optic disc edema. The first two pictures are from this case and show the sectoral hyperemic disc swelling with hemorrhages that can be seen in NAION. The pictures of papilledema do show true optic disc edema, the bilaterality of which would be the most suggestive feature of papilledema. The picture of arteritic ischemic optic neuropathy (AION) shows pallid diffuse edema.

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The pictures of pseudopapilledema include buried optic disc drusen in which all vessels at the disc margin are unobscured as well as the hypoplastic disc which is both flat and distinct.

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The final diagram (12) is drawn from the works of Dr. Hayreh, and shows the watershed zone boundaries between distinct choroidal vascular distribution areas. Significantly the optic disc is sectorally fed by different posterior ciliary arteries (which are the main contributors to the choroidal distribution as well), and temporary loss of perfusion to one sector of the optic nerve, as can be found in NAION, could localize the pathology behind NAION to the posterior ciliary vessels. The boundaries between distinct choroidal distribution areas in the macula and periphery are associated by Dr. Hayreh with the following conditions: macular degeneration, peripheral reticular degeneration, peripheral vitreoretinal degeneration, and midperipheral hemorrhages as found in OIS.

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In conclusion, a 58 year old male with vascular risk factors presents with one swollen disc and spots in his vision when he woke up. Many possible causes of the swelling, particularly life and vision threatening conditions, as well as the most common, common, and uncommon causes, need to be explored and ruled out during the work up. Characterizing the limits of the swelling includes a survey of symptoms, a cranial nerve exam, vital signs, ocular imaging, and blood work. Suspicion of papilledema or occult neoplasia would warrant neuroimaging and would include features like bilaterality and poor course, respectively, which deviate from the unilaterality and improved course of NAION. In the setting of optic disc edema, symptoms of headache, jaw pain, and scalp tenderness (even without corroborating blood work) necessitate initial treatment for and further work up for GCA. The diagnosis of NAION follows after the above considerations have been explored and ruled out. NAION is diagnosed in the presenting patient based on the history, clinical exam, and test results as followed over time. Consultation with a referral center’s ophthalmology department further confirmed the diagnosis. The NAION patient is advised on the information from the IONDT regarding what to expect from the condition as well as ways to reduce the risk of fellow eye involvement.

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References:

1. Liu, G et al. “Visual Loss: Optic Neuropathies and Optic Disc Swelling: Papilledema and Other Causes.” Neuro-Ophthalmology. 2nd ed. Chapters 5 and 6.

2. Biousse, V. Neuro-Ophthalmology Illustrated. Thieme, 2009.

3. Castillo, R. (Conversations with Dr. Richard Castillo). Professor, Northeastern State University College of Optometry, 2012.

4. Kanski, J et al. Illustrated Tutorials in Clinical Ophthalmology (with CD-ROM). Boston: Butterworth-Heinemann, 2001.

5. Sadun, AA et al. “Topical Diagnosis of Acquired Optic Nerve Disorders.” Walsh & Hoyt's Clinical Neuro-Ophthalmology, 6th Edition. Chpt 4. 198.

6. Rosenberg GA. “Brain Edema and Disorders of Cerebrospinal Fluid Circulation” Bradley Neurology in Clinical Practice. Chpt 59. 1389.

7. Hellmann, DB. “Giant Cell Arteritis, Polymyalgia Rheumatica, and Takayasu’s Arteritis.” Kelley's Textbook of Rheumatology. 9th ed. Chapter 88. 1461.

8. Keane JR. Multiple cranial nerve palsies: analysis of 979 cases. Arch Neurol. 2005 Nov;62(11):1714-7.

9. Purvin V. Neuro-ophthalmic emergencies for the neurologist. Neurologist. 2005 Jul;11(4):195-233.

10. Glaser, J. “Topical Diagnosis: Prechiasmal Visual Pathways.” Duane’s ophthalmology online. http://www.oculist.net/downaton502/prof/ebook/duanes/pages/v2/v2c005.html

11. Mendrinos E et al. Ocular ischemic syndrome. Surv Ophthalmol. 2010 Jan-Feb;55(1):2-34.

12. Hayreh SS. Ischemic optic neuropathy. Prog Retin Eye Res. 2009 Jan;28(1):34-62.

13. Savino, PJ et al. Neuroimaging and acute ocular motor mononeuropathies: a prospective study. Arch Ophthalmol. 2011 Mar;129(3):301-5.

14. Kaufman D; Ischemic Optic Neuropathy Decompression Trial Study Group; Optic nerve decompression surgery for nonarteritic ischemic optic neuropathy (NAION is not effective and could be harmful: Results of the Ischemic Optic Neuropathy Decompression Trial (IONDT)., Invest Ophthalmol Vis Sci 1995;36:S196

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