Although Multiple Sclerosis is the most common central nervous system (CNS) inflammatory demyelinating disorder, other CNS inflammatory disorders should be included in the differential diagnosis. Neuromyelitis Optica Spectrum Disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease are less common but share some clinical characteristics, such as optic neuritis and myelitis, which can make a specific diagnosis challenging. However, these disorders have distinctive and generally different clinical phenotypes, prognosis and management. It is imperative to distinguish each from one another, especially since the treatment(s) can be different.

Ocular signs:

Optic neuritis (ON) is a condition in which the nerve in the eye becomes inflamed or irritated. ON is a condition that can happen because of a disease or without any specific known cause. A person who has optic neuritis might go on to develop multiple sclerosis.

The most common cause for ON is inflammatory demyelination of the optic nerve. Demyelination is a process in which the myelin is stripped off by disease. It is believed that ON is an autoimmune process, where for some unknown reason the immune system attacks tissues of the body causing injury. While this may occasionally occur after an infection, there is often no clear reason why the immune attack occurs.

Symptoms:

• Optic neuritis usually occurs in one eye, though occasionally both eyes are affected (1 in 10 ).
• Vision loss is common and typically occurs over a few days and stops progressing by one to two weeks.
• Symptoms include blurring of vision, a loss of part or all of central vision, reduced color vision, and dimness of vision.
• It may also be night time difficulty with contrast and glare.
• Most patients with ON have eye pain which is characteristically worse with movement of the eye.
• Sometimes people see flickering or flashing lights when they have optic neuritis (1 in 3 ).
• Some people notice that when they exercise or exert themselves, or while taking a hot shower, their vision becomes blurrier   
• Testing: MRI study of the brain and orbits with gadolinium contrast may confirm the diagnosis of acute demyelinating optic neuritis. Blood Test(s) may differentiate between MS(There are no specific tests for MS. Instead, a diagnosis of multiple sclerosis often relies on ruling out other conditions that may produce similar signs and symptoms, known as DiffDx), MOG(MOG IgG1) and NMSOD(aquaporin-4 receptor (AQP4) IgG).

   

  
  
  

Author

Paddy Kalish OD, JD and B.Arch