Introduction
Swelling of one or both optic discs can be caused by disease of the:
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eye/s
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optic nerve/s
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orbit/s
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brain
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neck
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chest
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blood
As ophthalmologists we all need to know:
- 1.
What to do for patients with optic disc swelling with normal vision. We recommend urgent (same-day) referral to a neuro-ophthalmologist or neurologist for further assessment. If prompt referral is difficult due to geographic or patient factors, or if you wish to work the patient up yourself, the necessary initial basic investigations are outlined on p. 112.
- 2.
How to make a safe diagnosis of idiopathic intracranial hypertension (IIH), also called primary pseudotumor cerebri syndrome (PTCS). IIH is overdiagnosed and women with life-threatening intracranial disease, such as a brain tumor or dural venous sinus thrombosis, are often initially misdiagnosed by an ophthalmologist as having IIH. In fact, IIH is a diagnosis of exclusion! It should only ever be made after the patient has been fully investigated (including magnetic resonance imaging [MRI] and MR venography [MRV] or computerized tomographic [CT] scan and CT venography [CTV] and lumbar puncture [LP] in all cases) and been found to fit all the diagnostic criteria listed on p. 113.
Examination checklist
Swollen disc/s, normal vision
Have you asked about, and looked for, all the following key features?
History
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ophthalmic symptoms?
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how was the disc swelling discovered – on a routine check or was the patient having visual symptoms or headaches?
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blurred vision?
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transient visual loss?
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double vision?
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headaches?
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if so, are they a new type of headache the patient has never had before?
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are there features suggestive of raised intracranial pressure (ICP) (e.g. headache worst in morning, nausea or vomiting, pulsatile tinnitus)?
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other neurologic symptoms, e.g. numbness, weakness, personality change?
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previous medical and surgical history
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cancer? (possible metastasis)
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deep vein thrombosis, pregnancy, miscarriage, recent dehydration? (possible coagulopathy causing dural venous sinus thrombosis)
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taking any medications that can cause secondary pseudotumor cerebri syndrome? (see p. 141)
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history of diseases that can cause secondary pseudotumor cerebri syndrome? (see p. 141)
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diabetes?
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social history: smoker, alcohol, special diet?
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family history: unexplained visual loss or brain disease?
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if patient over 50: symptoms of giant cell arteritis (GCA)?
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system review questions: any clues to the cause anywhere in the body?
Examination
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visual acuity
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color vision testing
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visual field testing to confrontation
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limitation of eye movements? (possible orbital apex or pituitary tumor)
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pupils
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relative afferent pupillary defect (RAPD)? (unilateral or bilateral asymmetric optic neuropathy or optic tract lesion)
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is there anisocoria? (possible partial third nerve palsy or Horner syndrome from intracranial tumor)
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eyelids: ptosis? (possible partial third nerve palsy or Horner syndrome from intracranial tumor)
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orbits: proptosis, injection, chemosis? (if so, is there a palpable thrill or audible bruit? Suggests carotid-cavernous fistula)
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decreased corneal or facial sensation to light touch? (possible middle cranial fossa tumor)
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if patient over 50: palpate temporal arteries
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disc appearance: are there features of pseudo or true disc swelling?
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measure blood pressure in all cases: malignant hypertension is a rare cause of disc swelling
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full neurologic examination: in all cases of bilateral true disc swelling
Plus: perform perimetry:
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IN ALL CASES
Management flowchart
Swollen disc/s, normal vision
The patient must have ALL of the following:
History
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no blurred vision (except that consistent with visible intraocular disease, e.g. cataract)
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no transient visual loss
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no pulsatile tinnitus (“whooshing” noise in one or both ears in time with the pulse)
Examination
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normal visual acuity unless there is coexistent ocular disease causing blurred vision
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normal color acuity unless there is a history of a congenital color deficit
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the central disc cup is small or absent or the disc is “tilted”
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the nerve fiber layer over the disc is not opacified or swollen and does not obscure the disc vessels
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the disc is not hyperemic (in true swelling, the disc is usually “pinker” than normal due to dilation of disc surface capillaries) or pale
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the disc is elevated but the area of elevation does not extend beyond the disc margin (in true swelling, the swollen nerve fiber layer extends from the disc across the disc margin to the peripapillary retina)
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the circumpapillary light reflex (the circular “ring of reflection” around the disc margin) is bright and regular (it is lost in true disc swelling due to nerve fiber layer swelling)
Perimetry
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normal in both eyes
If equivocal or unsure
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may require fluorescein angiogram (true swelling will show fluorescein leakage), ultrasonography or OCT (may show buried drusen) or urgent referral for neuro-ophthalmic opinion
See p. 119 for details.
For patients with unilateral or bilateral swollen discs who cannot be urgently referred to a neuro-ophthalmologist or neurologist or whom you choose to investigate yourself.
These investigations must be URGENTLY pursued.
1
Review history, examination and perimetry
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make sure it is true disc swelling, not pseudo-swelling
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full systemic history and examination including blood pressure, temperature, urine test and systemic neurologic exam; are there clues to the cause anywhere in the body?
2
Urgent (same-day) MRI optic nerves and brain with contrast, plus MRV brain
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if same-day MRI/MRV is not available, same-day CT brain with contrast combined with CTV can rule out a large tumor or vascular lesion. CT scan alone is not adequate
3
Lumbar puncture if MRI/MRV or CT/CTV normal
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ask for opening pressure to be recorded (should be done in lateral decubitus or prone position; cannot be certain of true opening pressure in sitting position)
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send CSF for biochemistry (protein, glucose, oligoclonal bands), microbiology (microscopy, cell count, culture), cytology
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have blood taken at the time of LP, for glucose and oligoclonal bands
4
Other investigations (if the diagnosis is not made on MRI and LP)
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blood tests
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basic: full blood count, electrolytes, liver function tests, erythrocyte sedimentation rate (ESR), c-reactive protein (CRP)
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inflammatory: angiotensin converting enzyme (ACE), antinuclear antibody (ANA), Aquaporin-4 antibody assay (cell-based)
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infectious: syphilis serology
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others if history or exam suggests
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chest x-ray or CT scan
The patient must have ALL of the following:
History
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no neurologic symptoms other than headache (in most patients) or horizontal diplopia (in some patients)
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on specific questioning, no history of systemic disease, therapeutic drugs, vitamins, foods or toxins that can cause secondary PTCS (see list p. 141), other than obesity
Examination
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visual acuity normal unless macular hemorrhages/exudates/subretinal fluid, tumor compressing optic nerves/chiasm and obstructing third ventricle, or chronic/severe optic nerve damage
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bilateral (or, very rarely, unilateral) optic disc swelling
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no other abnormalities on examination other than (in some cases) unilateral or bilateral sixth nerve palsy
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normal blood pressure, temperature and urine analysis
Perimetry
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any visual field defect, one or both eyes; earliest defect is often an enlarged blind spot or midperipheral scotoma
Investigation results
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normal MRI and MRV or CTV brain (other than dilated optic nerve sheaths or slightly narrowed ventricles in some cases) (CT brain alone is not adequate)
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LP shows raised opening pressure and absolutely normal CSF constituents (normal microbiology, biochemistry and cytology) (IIH should never be diagnosed without an LP)
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normal full blood count, glucose, electrolytes, liver function tests, ESR, CRP, ACE, ANA
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normal chest x-ray or CT scan in appropriate setting
IF THE PATIENT MEETS ALL THESE CRITERIA, SEE P. 146 FOR MANAGEMENT.
Disc pseudo-swelling
(See summary of clinical diagnostic criteria on p. 111.)
Definition
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one or both optic discs appear elevated or have unclear margins, but there is no optic nerve axon swelling (the cause of true disc swelling)
Causes
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small disc ( Fig. 3.1 )
3.1
Congenital optic disc hypoplasia with disc elevation that mimics true disc swelling.
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tilted disc ( Fig. 3.2 )
3.2
Congenital tilted optic disc in patient with myopic astigmatism causing nasal (but not temporal) disc elevation mimicking true disc swelling.
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elevated disc with superficial but unappreciated drusen ( Fig. 3.3 )
3.3
Pseudo-disc swelling from superficial but unappreciated superficial drusen (arrow) .
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elevated disc with deep (buried) drusen ( Fig. 3.4 )
3.4
Pseudo-disc swelling from buried drusen. A Appearance of elevated optic disc. B Ultrasound showing drusen (arrow) .
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elevated disc without drusen ( Fig. 3.5 )
3.5
Pseudo-swelling of optic disc without drusen. The patient had no evidence of drusen on ultrasonography and had normal intracranial pressure by lumbar puncture. The appearance of the optic disc did not change over time.
Characteristics
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no obscuration of large or small vessels as they pass across disc
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disc vessels not dilated
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anomalous branching of retinal vessels
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nerve fiber layer reflexes normal
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no flame-shaped hemorrhages but a subretinal hemorrhage may be present
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cup absent
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this compares with true disc swelling, that shows:
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blurred nerve fiber layer
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flame-shaped hemorrhages
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disc vessels obscured
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cup retained
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dilated retinal veins
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Spontaneous venous pulsations (SVPs)
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the central retinal vein or one of its branches on the disc can be seen to pulsate in about 80% of normal subjects (however, is absent in 20% of normal subjects)
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if SVPs are observed in a patient with possible disc swelling, ICP is probably within the normal range at the time of observation, however:
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ICP can vary markedly during each day or from day to day, so just one observation of SVPs is not reassurance that ICP is not elevated at other times
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therefore, the presence of SVPs should not be relied upon in isolation
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caution: “induced” venous pulsation
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in cases where SVP is not visible, it is possible to induce visible venous pulsations by pressing on the globe through the eyelid while observing the disc
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it is sometimes said that if venous pulsations are easily induced with minimal pressure, this is evidence that ICP is “probably normal” or “almost normal”; however, this is not a reliable sign to differentiate true swelling from pseudo-swelling
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Differentiation from true disc swelling
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consider the setting: pseudo-swelling is often seen:
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on a routine exam
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in an asymptomatic patient
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with marked hypermetropia or myopic astigmatism
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whereas true disc swelling due to papilledema is often seen in a patient who has:
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headaches and sometimes nausea or vomiting
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other neurologic manifestations
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Investigations to help determine if pseudo- or true swelling is present
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ophthalmoscopic appearance
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autofluorescence (discs with pseudo-swelling often autofluoresce)
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fluorescein angiography (true swelling leaks; pseudo-swelling doesn’t) ( Fig. 3.6 )
3.6
Fluorescein angiography in true optic disc swelling versus pseudo-swelling. A Appearance of an optic disc thought to be swollen. B Arteriovenous phase of angiogram shows diffuse leakage of dye. C Late phase of angiogram shows persistent diffuse leakage of dye. These findings are consistent with true optic disc swelling. D Appearance of optic disc thought to be swollen. E Arterial phase of angiogram shows no leakage of dye. F Late phase of angiogram shows staining of disc but no leakage of dye. These findings are consistent with pseudo-swelling of the optic disc.
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ultrasonography
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look for drusen ( Fig. 3.4B )
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perform 30-degree test
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optical coherence tomography ( Fig. 3.7 )
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look for drusen (lumpy, bumpy appearance) vs evidence of subretinal fluid
3.7
Appearance of buried optic disc drusen on optical coherence tomography.
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CT scan
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look for buried drusen (bone windows) ( Fig. 3.8 )
3.8
Appearance of optic disc drusen (arrows) on axial CT scan using bone window setting.
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look for intracranial mass
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MRI for one of the following suggesting true swelling: intracranial mass, flattening of globe, enlarged optic nerve sheaths ( Fig. 3.9 )
3.9
MRI showing changes consistent with papilledema. Note widening of optic nerve sheaths and flattening of back of globes (arrows) .
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LP if bilateral true swelling can’t be excluded by the above
True disc swelling
Suggested investigations for swollen disc/s with normal vision
(See summary box on p. 112.)
There are no clinically diagnosable causes of optic disc swelling with normal vision, so all these patients require thorough investigation. Because there are many possible causes for disc swelling, and many of these are life-threatening, it is ideal if the patient can be referred very urgently (same-day) to a neuro-ophthalmologist or neurologist for urgent investigation.
In some cases, there may be geographic or patient factors which make prompt referral difficult, or you may wish to perform the initial investigations yourself. In such circumstances we recommend the investigations below as an initial basic work-up. However, given that there are many rare causes of disc swelling, if these initial investigations do not reveal a cause we would recommend obtaining specialist neuro-ophthalmic advice.
1
Review history, examination and perimetry
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make sure it is true disc swelling, not pseudo-swelling: see section above for how to tell
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check the blood pressure
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severe hypertension is a rare cause of unilateral or bilateral disc swelling and is usually accompanied by signs of severe hypertensive retinopathy such as hemorrhages, hard exudates and cotton-wool spots
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however, finding elevated blood pressure does not indicate that this is the cause of the disc swelling:
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the patient could have systemic hypertension as a coincidental finding, plus a brain tumor or dural venous sinus thrombosis
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raised ICP can cause secondary raised blood pressure (Cushing’s reflex)
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therefore, all the other investigations still need to be pursued even if severe systemic hypertension is present (don’t just attribute the disc appearance to the blood pressure); however, the relevant specialists should also urgently investigate and (if necessary) treat the systemic hypertension
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check the temperature: patients with infectious optic neuritis, perineuritis or meningitis may have a fever
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urine analysis: glycosuria likely indicates diabetes; hematuria could indicate vasculitis
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are there other clues to the cause anywhere in the body?
2
Urgent (same-day) MRI of optic nerves and brain with contrast, plus MRV brain, or CT brain and CTV
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neuroimaging must be performed urgently: if a patient with disc swelling harbors a large intracranial tumor, brainstem herniation (“coning”) can occur at any time and kill the patient; therefore, imaging should be performed the same day you see the patient
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request “urgent MRI optic nerves and brain with contrast, plus MRV brain” or “CT brain and orbits, with contrast, plus CTV”
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this is the most appropriate initial investigation in all cases of disc swelling and ideally should be the first and only form of neuroimaging
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MRI will show optic nerve abnormalities, space-occupying lesions, hydrocephalus and often abnormal meningeal enhancement in meningitis; subtle abnormalities can be missed if intravenous contrast is not given
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MRV or CTV will demonstrate dural venous sinus thrombosis (not an uncommon cause of papilledema, including in young obese women); it is essential to detect these cases urgently and administer anticoagulation because extension of the thrombus can kill the patient
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CT brain scan
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a normal CT brain scan alone is not adequate reassurance that serious intracranial disease is not present: CT alone will miss many smaller brain tumors and almost all cases of dural venous sinus thrombosis (unless CTV is used)
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hence, if a CT brain is to be performed, a CTV should be done at the same time
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3
Lumbar puncture if MRI and MRV or CT and CTV are normal
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caution: LP must only ever be undertaken after neuroimaging has been performed and the result known
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LP may be contraindicated if the scan reveals a brain tumor or obstructive hydrocephalus (fatal post-LP brainstem herniation can occur)
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serious disease can still be present even if MRI/MRV (or CT/CTV) is normal (e.g. communicating hydrocephalus or chronic meningitis); the only way to diagnose these conditions is to perform an LP
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LP is also essential in the work-up of “suspected IIH” both to rule out abnormalities in the CSF constituents and to document the level of ICP (measured as the LP “opening pressure”)
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ask for opening pressure to be recorded
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the opening pressure is the CSF pressure measured with a manometer tube and provides a measure of the patient’s ICP
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this should be measured with the patient lying on the side with legs bent (lateral decubitus)
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CSF pressure measured with the patient prone gives readings similar to those measured in the lateral decubitus position
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CSF pressure should not be measured with the patient sitting upright as the readings do not reflect true ICP
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normal opening pressure is less than 25 cm of CSF in adults and less than 28 cm of CSF in children but ICP may vary and one pressure reading alone may not be reflective of the “real” ICP
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opening pressure can be falsely elevated if the patient is tense or straining or the LP is “difficult”
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opening pressure can be falsely low if repeated passes have already been made during that attempt, if a previous LP has been performed within the last few weeks or if the patient is already on medical treatment to decrease ICP
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you should also ask for the CSF to be sent urgently to:
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biochemistry: for protein, glucose and oligoclonal bands
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microbiology: for microscopy, cell count and culture
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cytology: looking for malignant cells
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immediately after the LP is performed, blood should also be taken to send to biochemistry for blood glucose and oligoclonal bands (to allow comparison with the CSF results)
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note: an LP may be difficult to perform in an obese patient; consider having it performed under fluoroscopy with the patient in the prone position (CSF pressure in this setting is similar to that with the patient in the lateral decubitus position; the CSF pressure should not be measured with the patient in the sitting position as that may give false readings)
4
Other investigations in ALL patients
Blood tests
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these are necessary both to look for a cause for the disc swelling and as a baseline (before possible medical treatment is commenced)
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basic
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full blood count
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white cell count may be elevated in infections and leukemia
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anemia may contribute to secondary PTCS
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electrolytes and liver function tests
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severe electrolyte disturbance (e.g. that occurring in undiagnosed renal failure) can cause secondary PTCS
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random glucose to check for undiagnosed diabetes
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some potential treatments can cause electrolyte imbalance, so it is important to check that electrolytes are normal before commencing treatment
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ESR and CRP: elevated in infection, cancer, vasculitis
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ACE: elevated in many cases of sarcoidosis (one cause of optic perineuritis and a rare cause of raised ICP)
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ANA: elevated in systemic lupus erythematosus (SLE), an uncommon cause of raised ICP
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infectious serology, for causes of optic perineuritis if MRI/MRV, LP opening pressure and CSF constituents are normal
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syphilis
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less common causes of optic perineuritis are cat scratch disease, toxoplasma and Lyme disease (test only if history is suggestive, e.g. if rash, fever and/or lymphadenopathy)
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other tests if history or exam are suggestive or if results of MRI/MRV (or CTV) or LP are abnormal, e.g. blood tests for specific coagulopathies (such as anticardiolipin antibody syndrome) if dural venous sinus thrombosis is found on MRV or CTV
Chest x-ray and/or chest CT scan
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looking for signs of tuberculosis or sarcoidosis if perineuritis suspected
Eye disease
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many ocular diseases can cause optic disc swelling without optic nerve dysfunction, including:
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hypotony (often post-surgical or post-traumatic)
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central retinal vein occlusion (vision can remain normal if early or mild)
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intraocular inflammation of any cause: anterior, intermediate, posterior or panuveitis can all result in secondary optic disc swelling without signs of optic neuropathy
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in most cases, the diagnosis is obvious from ocular examination, but in cases where there is visible intraocular disease, optic disc swelling and decreased vision, keep an open mind that the same process causing the intraocular disease could also be causing an optic neuropathy in its own right
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for example, a patient with uveitis, disc swelling and reduced vision could have:
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secondary disc swelling with no optic nerve dysfunction (the blurred vision being due to macular edema) or:
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some or all of the blurred vision could actually be due to optic nerve disease caused by the same process that is causing the uveitis (e.g. sarcoidosis)
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in unilateral or bilateral asymmetric cases, the presence of an RAPD (or visual field loss more extensive than that expected from the visible ocular disease) indicates that a true optic neuropathy is present, requiring investigation and treatment in its own right
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Optic nerve disease
In most cases, optic nerve disease causes decreased visual acuity and/or visual field loss. However, optic nerve disease may in rare cases present with unilateral or bilateral optic disc swelling with normal vision, if:
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the optic neuropathy is only early in its evolution or very mild
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inflammation affects only the optic nerve sheath, rather than the nerve itself: optic perineuritis
Early or mild optic neuropathy
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many types of optic neuropathy can result in swollen disc/s with normal vision if mild or early in their course; vision often declines as the disease progresses. Remember that 20/20 vision may not be “normal”. The patient with 20/20 vision who complains of decreased vision may have had 20/15 acuity previously!
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optic nerve compression usually only results in optic disc swelling if the compressive lesion is in the orbit (e.g. an optic nerve sheath meningioma or an orbital tumor) ( Fig. 3.10 ); optic nerve compression from intracranial tumors (such as pituitary tumors) rarely causes disc swelling, unless the lesion also causes raised ICP
