Ocular myasthenia gravis can occur as an isolated autoimmune disorder although most people with ocular symptoms go on to develop generalized MG within the first two years
Ocular myasthenia gravis is an autoimmune eye disorder that can occur alone or as a feature of generalized myasthenia gravis. In fact, eye changes related to weakened eye muscles or eyelid muscles are one of the first symptoms to occur in more than two-thirds of all patients with myasthenia gravis (MG). From 70 to 80 percent of patients with isolated ocular myasthenia gravis go on to develop generalized myasthenia gravis within the first two years.
Who is Affected?
Although three times as many women as men develop myasthenia gravis, slightly more men than women develop ocular myasthenia gravis. And while the mean age for generalized MG is 33 years, the mean age for ocular myasthenia is 38 years. The highest incidence of ocular myasthenia gravis occurs among the Chinese. Patients with ocular myasthenia gravis often have thyroid antibodies or autoimmune thyroid disease. Patients with generalized myasthenia gravis, in contrast, are more likely to be Italian and rarely develop autoimmune thyroid disease.
Symptoms of Ocular MG
Symptoms of ocular MG are very similar to those seen in thyroid eye disease, a disorder that is often confused with ocular MG. Common symptoms include diplopia (double vision), ptosis (drooping eyelids), light sensitivity, weakness of lid closure, nystagmus (constant involuntary movements of the eyeball in any direction) visual disturbances, and eyelid retraction, which causes an incomplete eye closure.
Disease Course
Similar to other autoimmune diseases, ocular MG is characterized by periods of variable symptoms alternating with periods of remission. When ocular symptoms alone persist for 3 years, patients are unlikely to develop generalized myasthenia gravis. Symptoms are often mild after periods of rest and intensify with activity. Symptoms of ocular MG also are unlikely to worsen after the first three years of the disease. Spontaneous remissions are also known to occur and can persist for years.
Environmental Factors
Symptoms of ocular MG tend to worsen with exposure to bright sunlight and during periods of emotional stress, viral illness, surgery, menstruation, pregnancy, and following immunizations.
Diagnosis
Test to confirm the diagnosis of ocular MG include repetitive nerve stimulation, and single-fiber electromyography (EMG) of the frontalis muscle. In addition, the eye muscles are examined for fatigue and weakness and the Tensilon test is usually performed. In the Tensilon test, a small amount of edrophonium is injected intravenously. If myasthenia gravis is present, the eye muscles will show a positive response and symptoms of muscle weakness and ptosis will improve dramatically. Eye muscle function may also be assessed before and after a 30-minute eye rest. In MG, improvement is seen after the period of rest.
Blood tests for blocking acetylcholine receptor antibodies are also used to help diagnose ocular MG although patients with ocular MG alone are less likely to have acetylcholine receptor antibodies than patients with generalized MG. About 70 percent of patients with ocular MG have these antibodies compared to 90 percent of patients with generalized MG.
An MRI or CT scan can be used to rule out other causes of eye symptoms such as tumors, and thyroid function tests are used to differentiate ocular MG from thyroid eye disease.
Treatment
Treatment for ocular MG is similar to treatment for generalized MG. Treatments include cholinesterase inhibitors such as pyridostigmine (Mestinon), prednisone and azathioprine. In severe cases, plasmapheresis or intravenous immunoglobulin (IVIG) therapy may be used.
For eyelid drooping, eyelid tape and wire eyelid crutches are often used. Eye patches and prisms are used to reduce symptoms of double vision.
The copyright of the article Ocular Myasthenia Gravis in Autoimmune Disease is owned by Elaine Moore. Permission to republish Ocular Myasthenia Gravis in print or online must be granted by the author in writing.
I am frustrated by the lack of support and information on the validation of
depression in MG patients that have relapes. Yes I am thankful my MG has
remained mostly occular for the past 14 years, however when I get a relapse
I go into this depressed mode and I am generally angry at the world and it
takes me two weeks or more to convince myself I am luckier than most. Why
are there not more articles to support this and at least validate this so
we don't think we are loosing our marbles every time we get a relapse?
Apr 22, 2009 11:40 PM
Elaine Moore :
Hi, Here's a link to PubMed, which is a great research site with both old
and vry new journal article abstraacts; http://www.ncbi.nlm.nih.gov/pubmed/
a simple search led me to
this abstract Lambert-Eaton Myasthenic Syndrome.
In the followin abstract researcers how a search for
tumors is important in helping diagnose this condition. I've also heard of
immunologocial changes, for instance acetylcholine receptor antibodies that
are used in diagnosis.
Weimer MB, Wong J. Maria B. Weimer,
MD Louisiana State University Health Sciences Center, Department of
Neurology, 200 Henry Clay Suite 3314, New Orleans, LA 70118, USA.
mweime@lsuhsc.edu.
Lambert Eaton myasthenic syndrome (LEMS) is a
rare neuromuscular junction disease. Often, the signs and symptoms of LEMS
are mistaken for myasthenia gravis and therefore the workup is misdirected.
A physician must look for an occult malignancy when the diagnosis is made
and then continue to search for a malignancy for at least 5 years after
diagnosis. The diagnosis of LEMS can be confirmed with electrophysiologic
studies or with serum calcium channel antibodies. In most patients with
LEMS, 3,4-diaminopyridine will improve strength. In patients without
malignancy, immunosuppressants do have a role in the treatment of LEMS.
Patients and physicians must be aware that certain situations and drugs may
exacerbate weakness.
There are some immunological changes that
can help with diagnosis. Our son gets married saturday so i have little
time to look this week. but if you comment again and remind me i should be
able to help you. best, elaien
May 2, 2009 7:55 PM
Elaine Moore :
Hi, I'm sorry to hear that your mother is having problems with wound
healing. Dr. Ian Zagon at Pennsylvania State University has done a lot of
work with topical naltrexone for wound healing in diabetes. This should
also apply to your mother's condition. He has several studies on the
subject and you should be able to find more information on the Penn State
website, which has links to Dr. Zagon's article abstracts. Best, Elaine
Oct 16, 2009 6:40 AM
Guest :
My daughter is 2 and a half years old. She was diagnosed with ocular
myasthenia gravis when she was 17 months old. She has had a MRI, a CT, and
an EMG. The results of these tests were normal. Now she is taking 2ml of
Mestinon every four hours. Some days the medicine works and some days the
medicine does not work. The nuerologist said that the next possible step is
a medicine with steriods but i am a little skeptical of giving her that
because she is so young. So what i am asking is, what is left for me to do
seeing that my daughter is only 2?
Oct 16, 2009 11:56 AM
Elaine Moore :
Hi, I'm sorry to hear about your daughter. You have a right to ask for
a second opinion. Another doctor might agree that steroids are needed or
perhaps choose an entirely different therapy such as IVIG. Best, Elaine
Oct 18, 2009 10:45 AM
Guest :
I have had this in my eyes since I was a young teen. I am now 50. It is
mostly in my left eye although If I cover my right eye and then remove the
cover after focusing with the left, then the right eye will be the one that
is moved. I had left it untreated most of my life because the doctor only
really prescribed mestinon wich for one did not really help much but left
me with intense stomach pains. I recently have been taking prednisone and
mestinon with a pill called belladonna which has really helped with the
stomach pains. I am worried this is going to take over my whole body and
kill me someday. My eyeball itself moves, not the eyelid. Is that still
myasthenia?
Oct 19, 2009 11:09 AM
Elaine Moore :
Hi, Your eyeball movement and diagnosis indicate that you do have
ocular MG. Best, Elaine
