Optic Neuritis Uğur Kaan Kalem Dönem V

Introduction Optic neuritis is an inflammatory, demyelinating condition that causes acute visual loss. It is known as optic papillitis (when the head of the optic nerve is involved) and retrobulbar neuritis (when the rest of the nerve is involved) It is highly associated with multiple sclerosis (MS). Optic neuritis is the presenting feature of MS in 15 to 20 percent of patients and occurs in 50 percent at some time during the course of their illness. In some people, signs and symptoms of optic neuritis may be the first indication of multiple sclerosis.

Etiology The optic nerve comprises axons that emerge from the retina and carry visual information to the primary visual nucleus, most of which are transferred to the occipital cortex of the brain to be processed into vision.  Inflammation of the optic nerve causes loss of vision, usually because of the swelling and destruction of the myelin sheath.

Etiology The most common etiology is multiple sclerosis or ischemic optic neuropathy. Some other common causes of optic neuritis include infection (Tooth Abscess in upper jaw, syphilis, Lyme disease) autoimmune disorders (e.g. lupus, neuromyelitis optica), Methanol poisoning, B12 deficiency and Diabetes .

Epidemiology Optic neuritis typically affects young adults ranging from 18–45 years of age, with a mean age of 30–35 years. There is a strong female predominance. The annual incidence is approximately 5/100.000

Signs and Symptoms Optic Neuritis Treatment Trial (ONTT), which included 457 patients, aged btw 18-46 years, with acute unilateral optic neuritis. The two most common symptoms of optic neuritis are vision loss and eye pain.

Signs and Symptoms Optic neuritis is usually monocular in its clinical presentation. Bilateral optic neuritis is more common in children younger than 12 to 15 years old. Because bilateral symptoms are relatively uncommon, they should suggest an alternative cause of optic neuropathy.

Signs and Symptoms Vision loss typically develops over a period of hours to days, peaking within one to two weeks. Greater than 90% of patients in the ONTT had a significant decrease in central visual acuity. Eye pain occurred in 92% of patients in the ONTT and often worsened with eye movement. The onset of pain generally coincided with the visual acuity loss and improved along with it.

Signs and Symptoms - others An afferent pupillary defect always occurs in optic neuritis if the other eye is uninvolved and otherwise healthy. The visual field defect in optic neuritis is typically characterized as a central scotoma Papillitis with hyperemia and swelling of the disk, blurring of disk margins, and distended veins is seen in one-third of patients with optic neuritis (pic 2). Two-thirds of these patients have retrobulbar neuritis with a normal funduscopic examination (pic 1). Papillitis is more common in children less than 14 years old. Peripapillary hemorrhages are rare in optic neuritis, but are a common accompaniment to papillitis due to anterior ischemic optic neuropathy (AION).

Signs and Symptoms - others Photopsias Loss of color of vision out of proportion to the loss of visual acuity is specific to optic nerve pathology. Color desaturation refers to a qualitative inter-eye difference in color perception that can be tested by comparing vision of a red object with each eye. A patient with monocular "red desaturation" may report that the red color appears "washed out," pink, or orange when viewed with the affected eye. Temporary exacerbations of visual problems in patients can occur with increased body temperature (Uhthoff's phenomenon). Hot showers and exercise are classic precipitants.

Differential Diagnosis In children, infectious and postinfectious causes of optic nerve impairment should be considered as alternatives to optic neuritis, while in an older patient (>50 years), ischemic optic neuropathy (due to diabetes mellitus or giant cell arteritis) is a more likely diagnosis than optic neuritis. In cases of recurrent optic neuritis that are not due to neuromyelitis optica or MS, other causes of recurrent optic neuritis should be investigated (such as sarcoidosis, lupus, chronic relapsing inflammatory optic neuropathy (CRION))

CRION Chronic Relapsing Inflammatory Optic Neuritis, is a form of recurrent optic neuritis that is steroid responsive.  Patients typically present with pain associated with visual loss. CRION is a diagnosis of exclusion, and other demyelinating, autoimmune, and systemic causes should be ruled out.  Early recognition is crucial because it is treatable with immunosuppressive treatment, as steroids. As a characteristic feature, relapse occurs after reducing or halting steroids.

Evaluation and Diagnosis In general, optic neuritis is a clinical diagnosis based upon the history and examination findings. Because important findings on funduscopic examination help differentiate typical from atypical cases of optic neuritis, an ophthalmologic examination should be considered an essential feature of the clinical evaluation. Magnetic resonance imaging study of the brain and orbits with contrast provides confirmation of the diagnosis in most cases and also provides and assessment of the risk of subsequent multiple sclerosis.

Evaluation and Diagnosis Lumbar puncture — It is not an essential diagnostic test but it is beneficial in atypical cases (those with bilateral presentation, <15 years in age, or symptoms suggesting infection). Approximately 60 to 80 percent of patients with acute optic neuritis have nonspecific abnormalities in the cerebrospinal fluid (CSF), including lymphocytes (10 to 100) and elevated protein.

Evaluation and Diagnosis Optical coherence tomography — OCT measures the thickness in the retinal nerve fiber layer and detects thinning in most (85 percent) of patients with optic neuritis. These abnormalities are also common in MS patients, who do not have a clinical history of optic neuritis.

Prognosis Recovery of vision — Without treatment, vision begins to improve after a few weeks. Improvement can continue over many months; 90% have 20/40 or better vision in one year. Some patients may have a better or worse prognosis. Patients with MS may have somewhat less favorable prognosis than those without.

Prognosis Recurrence — In the ONTT, there was a 35% recurrence of optic neuritis in 10 years: 14 percent in the original eye, 12 percent in the other eye, and 9 percent in both eyes. Risk of multiple sclerosis — In the ONTT, the five-year incidence of clinically definite MS was 30% following the first episode of idiopathic demyelinating optic neuritis. The cumulative incidence increased to 40% in 12 years and 50% in 15 years.

Treatment Treatments for patients with optic neuritis are focused on improving vision and preventing or ameliorating the development of multiple sclerosis (MS). Corticosteroids — Intravenous corticosteroids are used in selected patients with optic neuritis as there is some evidence that this treatment may delay onset of MS and hasten visual recovery. Oral prednisone is generally not used.

Treatment I.V methylprednisolone accelerated the recovery of visual function; however one-year visual outcomes were similar to placebo. A meta-analysis that compared treatment with I.V methylprednisolone to placebo found no benefit of treatment on visual outcomes at six months and at one year. I.V methylprednisolone also reduced the risk of conversion to MS within the first two years in comparison with either placebo or oral  prednisone.

Treatment Other acute immunomodulatory therapy — Alternative treatments used for acute neuroimmunologic disease include intravenous immunoglobulin (IVIG) and plasma exchange. These do not have established improvement in treatment of optic neuritis.

Sources http://www.uptodate.com.lproxy.yeditepe.edu.tr/contents/optic-neuritis-pathophysiology-clinical-features-and-diagnosis?source=search_result&search=optic+neuritis&selectedTitle=1~150 http://www.mayoclinic.org/diseases-conditions/optic-neuritis/basics/symptoms/con-20029723 http://www.ncbi.nlm.nih.gov/pubmed/26273799