Optic Neuritis, Emergency Medicine

Basics

Description

Optic nerve dysfunction due to an inflammatory process, commonly associated with myelin destruction
Highly associated with multiple sclerosis (MS); presenting feature in 15 " 20% of MS patients
Grouped by site of inflammation:
- Papillitis: Inflammation of the optic disk
- Retrobulbar neuritis: Inflammation of the optic nerve proximal to the globe
5 yr risk for clinically definite MS following optic neuritis:
- Normal MRI " 16%
- >3 lesions on MRI " 51%
Recurrence is seen in 35% of patients.

Risk Factors

Genetics
High prevalence of A23, B7, and DR2 HLA alleles in patients with optic neuritis:

Especially those that progress to clinically definite MS

Etiology

Idiopathic:
- Most common
- Single isolated events
MS:
- 20 " 50% of patients with optic neuritis
Viral infections:
- Chicken pox
- Measles
- Mononucleosis
- HSV and HZV
- Encephalitis
Postviral optic neuritis:
- Usually occurs 4 " 6 wk after a nonspecific viral illness
Granulomatous inflammation:
- TB
- Syphilis
- Sarcoidosis
- Cryptococcal infection
SLE
HIV:
- Cytomegalovirus
- Toxoplasmosis
- Histoplasmosis
- Cryptococcus
Lyme disease
Contiguous inflammation of meninges, orbit, sinuses, and intraocular inflammation
Drug induced:
- Amiodarone
- Ethambutol
- Tamoxifen

Diagnosis

Signs and Symptoms

Vision loss and pain most common symptoms
Visual loss occurring over days (rarely over hours), peaks in 1 " 2 wk:
- Adults usually unilateral (70%)
- Bilateral visual loss more common in children
Retrobulbar pain: Increased with movement of the affected eye
Light, color vision, and depth perception loss more pronounced than visual acuity loss
Afferent pupillary defect almost always occurs in unilateral cases if other eye is healthy.
Visual field defects:
- Usually characterized by central scotoma
- Deficits resolve by 1 yr in 56% of patients, and 73% resolve by 10 yr
Funduscopic exam usually reveals either swollen (papillitis) or normal disk
Uhthoff sign:
- Visual deficit occurring with exercise or increased body temperature
- Unusual sign seen occasionally

History

Age (typically women 18 " 45 yr)
Pain on eye movement
Speed of onset of symptoms
Associated symptoms
Previous episodes
Family history of optic neuritis, MS

Physical Exam

Check BP.
Complete ophthalmologic and neurologic exam, especially assessment of:
- Pupillary function
- Afferent pupillary defect
- Visual field defect
- Color vision (Ishihara color plates)
- Evaluation of the vitreous body for cells
- Dilated retinal exam (swollen optic disk)

Diagnosis Tests & Interpretation

Lab

CBC
ESR
Rapid plasma reagin, fluorescent treponemal antibody-absorption (FTA-ABS)
Lyme titer
Antinuclear antibody
Purified protein derivative
HIV

Imaging

CXR for TB, sarcoid
CT scan or MRI of brain and orbits:
- Inflammation of the retrobulbar optic nerve during the acute phase may appear as enlargement, thus falsely raising the issue of an optic nerve mass.
- Optic nerve inflammation is seen in 95% of gadolinium-enhanced MRIs.
- Visual field testing (preferably automated testing, such as Octopus or Humphrey)

Differential Diagnosis

Acute papilledema
Ischemic optic neuropathy
Severe systemic hypertension
Intracranial tumor compressing the afferent visual pathway
Orbital mass compressing the optic nerve
Toxic or metabolic neuropathy:
- Heavy metal poisoning
- Anemia
- Malnutrition
- Ethanol/Methanol
- Chloroquine
- Ethambutol
- Isoniazid
Leber hereditary optic atrophy

In children, infectious and postinfectious causes should be considered.
In patients >50 yr, ischemic optic neuropathies (e.g., diabetes and giant cell arteritis) are more common, and appropriate workup should be obtained.

Treatment

Ed Treatment/Procedures

Early ophthalmologic and neurologic consultations
IV steroid pulse followed by oral steroids:
- Recommended for those with ≥2 demyelinating lesions on MRI without a prior history of MS or optic neuritis, or severe vision loss
- Decreases recurrence and progression to MS over 2 yr and shortens duration of visual impairment, but does not affect visual outcome at 1 yr nor rate of progression at 5 yr
- Treatment should be individualized for those with 1 lesion on MRI.
- Oral steroids used alone increases recurrence and should be avoided.

Medication

Methylprednisolone: 250 mg IV q6h for 3 days, followed by oral prednisone (1 mg/kg/d) for 11 days with subsequent 4 day taper

Follow-Up

Disposition

Admission Criteria

Bilateral vision loss
If other sources of acute vision loss cannot be ruled out
IV steroid pulse treatment needed

Discharge Criteria

Unilateral visual impairment
Good home support systems
Neurology and ophthalmology follow-up arranged

Issues for Referral
Referral for interferon ²-1a treatment as outpatient for high-risk patients (those with ≥2 demyelinating lesions on MRI):

Reduces progression to MS

Followup Recommendations

Needs Ophthalmology referral

Pearls and Pitfalls

Rule out space-occupying lesions before making the diagnosis of optic neuritis.
Acute bilateral loss with a severe headache or diplopia should raise concern for pituitary apoplexy.
The true benefit of corticosteroids in the treatment of optic neuritis is unclear, and emergency physicians should consult with appropriate specialists to determine the local standard of practice.
Brain MRI is the most useful predictor of subsequent development of MS.

Additional Reading

Abou Zeid N, Bhatti MT. Acute inflammatory demyelinating optic neuritis: Evidence-based visual and neurological considerations. Neurologist. 2008;14:207 " 223.
Balcer LJ. Clinical practice. Optic neuritis. N Eng J Med. 2006;354:1273 " 1280.
Gal RL, Vedula SS, Beck R. Corticosteroids for treating optic neuritis. Cochrane Database Syst Rev. 2012;4:CD001430.
Germann CA, Baumann MR, Hamzavi S. Ophthalmic diagnoses in the ED: Optic neuritis. Am J Emerg Med. 2007;25(7):834 " 837.
Kale N. Management of optic neuritis as a clinically first event of multiple sclerosis. Curr Opin Ophthalmol. 2012;23:472 " 476.
Kinkel RP, Kollman C, O 'Connor P, et al. IM interferon beta-1a delays definite multiple sclerosis 5 years after a first demyelinating event. Neurology. 2006;66:678 " 684.
Morrow MJ, Wingerchuk D. Neuromyelitis optica. J Neuroophthalmol. 2012;32:154 " 166.

Codes

ICD9

377.30 Optic neuritis, unspecified
377.31 Optic papillitis
377.32 Retrobulbar neuritis (acute)
377.39 Other optic neuritis

ICD10

H46.00 Optic papillitis, unspecified eye
H46.9 Unspecified optic neuritis
H46.10 Retrobulbar neuritis, unspecified eye
H46.8 Other optic neuritis

SNOMED

66760008 Optic neuritis (disorder)
73221001 Optic papillitis (disorder)
230507009 Retrobulbar neuritis (disorder)
432521000124106 Bilateral optic neuritis (disorder)

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