Sunday, August 30, 2015

Graves ophthalmoplegia case

Hello everyone!

I saw an interesting case in the ward today. And I'll be asking loads of questions for you to answer as you read along!

There was a 75 year old man with proptosis, inability to move his right eye inferiorly or adduct his eye. Any guesses on what it could be?

If you're thinking Graves disease, then you're right!

Why?

Thyroid stimulating immunoglobulins attach to orbital fibroblasts (Because they express TSH receptor like antigen) causing inflammatory infiltration, proliferation of retrobulbar fibroblasts and deposition of glycosaminoglycans (GAG) in the endomysial and perimysial space.
- GAGs that are deposited within the muscle fibres causes enlargement of the muscles.
- Whereas, GAG deposition in retroorbital deposition causes proptosis.

Why?

The GAG have hyaluronic acid as their main substance. This results in increased osmotic pressure which accounts for the profound water binding capacity and interstitial edema of extraocular muscles (EM) and orbital connective tissue (OCT). The GAG have hyaluronic acid as their main substance. This results in increased osmotic pressure which accounts for the profound water binding capacity and interstitial edema of EM and OCT seen in GO.

Which muscle is involved first in Graves?

Inferior rectus. (PS: My professor said that it's the Levator palpebrae superioris muscle but I have no resource backing this fact up.)

Which muscle is involved next?
Inferior rectus is followed by medial rectus and then, anticlockwise all the recti.
So it goes IR, MR, SR and then LR. Obliques are rarely and lastly affected.

Mnemonic: IM SLOw

Involvement of muscles in Graves Ophthalmoplegia mnemonic
Which muscle is the last to recover?
Inferior rectus is the first to go, last to recover.
(It goes opposite of the affected, so first to recover is lateral rectus followed by SR, MR and IR.)

Here's the CT scan from the patient I saw:

CT scan of a patient with Graves ophthalmopathy
CT scan of a patient with Graves ophthalmopathy
Well, what do you see?

Inferior rectus and medial rectus is enlarged
Belly is swollen with sparing of tendons seen in Graves ophthalmopathy
From the study group discussion:

My patient was on carbimazole. I had to get a medicine fitness done to see if we could start him on Methylprednisolone.

What can we expect? What would they be looking for before starting prednisolone?

A focus of infection like tuberculosis. It could become overwhelming due to immunosuppression.

What ocular complications can you expect with prolonged steroids?

- Post sub capsular cataract.
- There is also steroid induced glaucoma due to increase outflow resistance.

In which eye infection, steroids are contraindicated?

Herpes keratitis.

That's all!

It's so much fun learning new cases all by yourself :D

-IkaN

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