A 31 year-old woman presents with loss of vision in her right eye that has progressed over the last 2 days. She has mild discomfort when her eye moves. On review of systems he mentions that she has had episodes of numbness in her right lower limb and left hand.
Examination confirms that she has reduced visual acuity. A right-sided Marcus-Gunn pupil is also noted.
This appearance is seen on funduscopy of the right eye:
The other eye has a normal optic disc is normal:
Following consultation with an ophthalmologist and a neurologist an MRI of her brain and spine is performed. A total of 4 discretes areas of demyelination are seen.
Q1. What is the likely diagnosis?
Optic neuritis — papillitis is seen on fundoscopy.
The history and MRI findings are suggestive of an underlying diagnosis of new onset multiple sclerosis.
Q2. What features should be sought when taking the history?
The patient is typically female and aged between 18 and 45 years. Check for:
- Painless loss of vision over hours to days, which may be subtle or profound, with a nadir at about 1 week. Determine the rapidity of onset.
- Reduced visual acuity, colour and contrast vision may occur
- Usually it is unilateral, but can be bilateral
- There may have been previous episodes
- There may be orbital pain associated with eye movements
- Other focal neurological symptoms may be present (e.g. paraesthesiase)
- features suggestive of an underlying cause (see Q4), e.g. history of multiple sclerosis
Q3. What are the features on examination?
- Visual acuity — decreased
- Colour vision — decreased
- Visual fields — patchy defects may be present, often arcuate or central
- Pupils — a Marcus-Gunn pupil (a relative afferent pupilary defect or RAPD) may be present.
- Fundoscopy — usually normal (retrobulbar optic neuritis — “neither the patient nor the doctor sees anything!”), papillitis may be present (see below for a comparison with papilloedema).
- Neurological examination — assess for focal neurological defects.
Q4. What are the causes of this condition?
- multiple sclerosis
- viral — e.g. infectious mononucleosis, herpes zoster, viral encephalitis
- childhood infections or vaccinations — e.g. measles, mumps, chickenpox
- Granulomatous inflammations — e.g. tuberculosis, syphilis, sarcoidosis, cryptococcus
- Contiguous inflammation of the meninges, orbit, or sinuses.
The differential includes optic neuropathies such as:
- toxic optic neuropathy — e.g ethambutol, chloroquine, nicotine, alcohol
- metabolic optic neuropathy — vitamin B12 deficiency
- ischemic optic neuropathy — diabetes mellitus, giant cell arteritis, atherosclerosis
- compressive optic neuropathy — e.g. orbital tumour, intracranial mass
Q5. What are the Pulfrich phenomenon and Uhthoff sign?
Both of these are occassionally present in optic neuritis:
- Pulfrich phenomenon — altered perception of moving objects
- Uhthoff sign — worsening of symptoms with exercise or increase in body temperature
Q6. What is the role for oral corticosteroids in the early management of this condition?
There is no role — if you’re going to give steroids, give them IV!
There is an increased risk of optic neuritis recurrences in patients treated with oral prednisone.
Q7. What are the effects of steroids on this condition?
Steroid therapy has been found to:
- reduce the risk of initial progression from optic neuritis to clinically definite multiple sclerosis for 3 years, but had no effect at 5 years.
- increases rate of vision return (at 1 and 3 weeks) but does not improve the final visual outcome (at 8 weeks) or alter the frequency of recurrences.
Q8. What is the investigation and management of this condition?
- Urgent ophthalmology referral.
- consider FBC, ESR, CRP and work up of possible inflammatory/ infectious causes.
- consider MRI — especially if atypical or a first episode, usually in consultation with the ophthalmology or neurology service.
In a first episode of optic neuritis or a patient who has not been diagnosed with multiple sclerosis:
- A 14 day course of steroids starting with methylprednisolone 1 g/day IV for 3 days is given if there is any evidence of demyelination on MRI, and may be given even if the the MRI is negative.
Patients known to have multiple sclerosis or have had previous optic neuritis are not treated with steroids and are observed.
Q9. What percentage of people presenting with this condition develop multiple sclerosis at 5 years?
- Beck RW, Cleary PA, Trobe JD, Kaufman DI, Kupersmith MJ, Paty DW, Brown CH. The effect of corticosteroids for acute optic neuritis on the subsequent development of multiple sclerosis. The Optic Neuritis Study Group. N Engl J Med. 1993 Dec 9;329(24):1764-9. PMID: 8232485.
- Ehlers JP, Shah CP, Fenton GL, and Hoskins EN. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease (5th edition). Lippincott Williams & Wilkins, 2008.
- Jeff Mann’s EM Guidemaps..
- Marx JA, Hockberger R, Walls RM. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edition (2009) Mosby, Inc. [mdconsult.com]
- The 5-year risk of MS after optic neuritis. Experience of the optic neuritis treatment trial. Optic Neuritis Study Group. Neurology. 1997 Nov;49(5):1404-13. PMID: 9371930.
- NSW Statewide Opthalmology Service. Eye Emergency Manual — An illustrated Guide, 2007. [link to free pdf]
- Patel V, Oetting TA. Optic Nerve Drusen: 19 year-old female with blurred vision. EyeRounds.org. August 14, 2007 [fulltext online]
- Sellebjerg F, Nielsen HS, Frederiksen JL, Olesen J. A randomized, controlled trial of oral high-dose methylprednisolone in acute optic neuritis. Neurology. 1999 Apr 22;52(7):1479-84. PMID: 10227638.
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