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

LeftEye    RightEye

** 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!”

What’s the diagnosis ?
What are we treating & why ??

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

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.

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.
ADEM03 ADEM04 ADEM02 ADEM01

** an MRI demonstrating plaques from an unrelated patient with ADEM **
    • 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.

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.

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.

  1. Eye Emergency Manual. An Illustrated Guide. NSW Department of Health. www.health.nsw.gov.au
  2. Rosenʼs Emergency Medicine. Concepts and Clinical Approach. 7th Edition
  3. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th Edition.
  4. Shams PN, Plant GT. Optic Neuritis: A Review. The International MS Journal. 2009; 16:82-89.
  5. Guercio JR & Balcer LJ. Chapter 9.6 – Inflammatory Optic Neuropathies & Neuroretinitis. Yanoff & Duker: Ophthalmology. 3rd Edition.

One thought on “a diligent driver…

  1. Hi Chris, you have some great cases on your blog. Are you interested in having your cases ported into our iOS virtual patient simulator Resuscitation!? Happy to chat with you about the details. Thank you.

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