a diligent driver…
The Case.
A 25 year old registered nurse presents to her GP with a 6 day history of abnormal vision, which she noticed whilst checking her blind-spot when driving. This has been accompanied by painful extraocular movements & the sensation that her right eyelid was drooping. She has had a recent viral URTI & has been quite stressed at work with a pending presentation and upcoming exams….
She has been referred to your ED today (by the Ophthalmologist) with the following visual field examination
** hence the "droopy eyelid" **
On examination, her pupils are equal & reactive directly, but there is a positive Marcus-Gunn reflex on the right side. VA 6/5 on (L) & 6/18 on (R). Normal EOM, but reports pain in the right eye with lateral gaze (“like a tight cord pulling”).
She is holding a letter from the Ophthalmologist which states, “please start treatment!”
[DDET What’s the diagnosis ?]
Optic Neuritis
The most common cause of unilateral painful vision loss in a young adult, typically, in patients ranging from 15-45 years.
It is the initial presentation in ~ 20% of cases of multiple sclerosis (an illness which is much more prevalent at high latitudes).
Clinical Features.
Patients are typically otherwise young & healthy. There may be a history of preceding viral illness. There is a female preponderance (3:1).
Symptoms:
- Painless loss of vision
- hours to days
- subtle vs profound
- Ocular pain (w/ eye movement)
- Reduced visual acuity (ranging from minimal loss to no light perception), colour & contrast vision
- Usually unilateral, though can be bilateral
Signs:
- Relative Afferent Pupillary Defect (RAPD) = Marcus-Gunn pupil
- Decreased colour vision > visual acuity
- ? Patchy visual field defects
- ? Swollen optic discs
[/DDET]
[DDET What are causes ?? What do we need to consider ??]
Aetiologies / Differential Diagnoses.
Corticosteroid-responsive optic neuropathies.
- SLE, Sarcoidosis
- Behcet syndrome (vasculitis w/ oral & genital ulceration + uveitis)
- Autoimmune or chronic-relapsing inflammatory optic neuritis
- Neuromyelitis optica (ON associated with myelitis)
Other inflammatory conditions.
- Post-infectious, post-vaccination
- Acute disseminated encephalomyelitis (ADEM)
Compressive optic neuropathies.
- Primary tumours (gliomas, meningiomas, pituitary, craniopharyngioma)
- Metastases
- Aneurysms
Ischaemic optic neuropathies.
- Anterior / Posterior ischaemic optic neuropathy
- Giant cell arteritis
- Diabetic papillopathy
Infective conditions.
- TB, Syphilis, Bartonella (cat-scratch disease), Lyme disease
- Viral (measles, mumps, zoster, varicella, EBV)
- Cryptococcus, Toxoplasmosis
- Periorbital cellulitis / sinusitis.
Toxic / Nutritional neuropathies.
- B12 deficiency, ethanol/methanol, heavy-metals.
[/DDET]
[DDET Investigations …?]
Investigations.
In a typical case of optic neuritis, without any clinical signs & symptoms of a systemic disease the yield from diagnostic tests is extremely low.
- MRI
- An important prognosticator !!
- Normal @ baseline = 25% risk of MS
- 16% @ 5 years
- 22% @ 10 years
- One or more lesions = 75% risk of MS.
*- CSF
- The presence of oligoclonal bands correlates with later development of MS.
- Those with oligoclonal bands usually have abnormal MRIs (therefore CSF sampling is unnecessary).
- Reserve lumbar puncture for atypical presentations.
The Natural History.
Visual acuity reaches its poorest within 1 week, then will slowly improve over the next several weeks.
Spontaneous visual improvement should occur in >90% of patients within 2-3 weeks.
- 93% have VA of > 6/12 @ 1 year.
- 70% have VA of > 6/6 @ 1 year.
Progression to MS.
- 30% of patients presenting with acute optic neuritis develop multiple sclerosis within 5 years.
- 50% of clinically isolated optic neuritis go on to develop a second MS-defining episode by 15 years.
[/DDET]
[DDET How do we treat this & why ??]
Treatment.
The role of steroids (predominately IV methylprednisolone) remains somewhat controversial.
- Initial studies (following 3 days of IV therapy) showed a reduced rate of MS development over 2 years of follow up.
- Subsequent review of the same cohort at 5 years post-treatment revealed no significant difference in the rate of development of MS.
RCT data on high-dose oral methylprednisolone vs placebo showed improved recovery at 1 & 3 weeks of followup, but no effect at 8 weeks (or in subsequent attack frequency).
- No role in long-term visual outcome.
Treatment with oral prednisone alone increases risk of recurrent optic neuritis.
Meta-analysis data (from 12 RCTs) confirms that whilst high-dose IV methylprednisolone is effective in improving short-term visual recovery, there is no significant benefit in long-term outcome.
There are specific circumstances however, where corticosteroids should be offered:
- Monocular patients
- Severe bilateral visual loss
- Occupations requiring normal visual acuity
THE DOSE = 1 gram IV methylprednisolone for 3 days.
[/DDET]
[DDET What happened next ??]
The Follow-up.
Well, there was concerns that she had features of bilateral optic disc swelling & that her visual field defect was now life altering (unable to drive, unable to work)…..
She is enrolled in ambulatory care for 3 days of IV methylprednisolone and over the next 2-3 weeks her visual acuity and fields improve significantly. Her MRI was normal.
She is now back behind the wheel, working in the ED & able to enjoy reading her partner’s blog @ thebluntdissection !!
Hi Ali !! Thanks for letting me share this.
References.
- Eye Emergency Manual. An Illustrated Guide. NSW Department of Health. www.health.nsw.gov.au
- Rosenʼs Emergency Medicine. Concepts and Clinical Approach. 7th Edition
- Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th Edition.
- Shams PN, Plant GT. Optic Neuritis: A Review. The International MS Journal. 2009; 16:82-89.
- Guercio JR & Balcer LJ. Chapter 9.6 – Inflammatory Optic Neuropathies & Neuroretinitis. Yanoff & Duker: Ophthalmology. 3rd Edition.
[/DDET]
