NANOSNET

Yesterday, a 38-year-old female (a medical doctor herself) presented for a ptosis of the left eye that started two days before (01 February).

With regards to her personal medical history, we retain coeliac disease.

Although questionable, I thought the left pupil might be a bit smaller upon examination. The ptosis measured 2 mm and it improved after instilling  a drop of apraclonidine.

She also mentioned diplopia in upgaze (orthoptics exam still awaiting). Other than the ptosis and the diplopia in upgaze there were no further complaints.

Since the clinical picture was not completely congruent with a Horner syndrome, I asked for an orbital MRI scan, which revealed a thickened left CN III: Diffuse thickening with T2/STIR hyperintensity of the left oculomotor nerve along its cavernous sinus, superior orbital fissure, and intra-orbital course, without abnormal contrast enhancement.

I suppose the DD would involve inflammatory causes, sarcoidosis / IgG4, and schwannoma, as already suggested by our neuroradiologist, but we would be interested in hearing your opinion.

The radiologist arranged for a link that will direct you to the photo's. The patient's name will not be revealed and is displayed as "Anonymous"

The link will work best by identifying yourself as a patient:

https://radiologie.uzbrussel.be

Reference number: POW679887

Date of Birth: 10/06/1987

Kind regards,

Michel

Edit to add: After apraclonidine, the ptosis resolved. The difference in pupil size was questionable from the start, but there was no obvious reversal.
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Hi Michel,

I have two patients like this whom we have called presumed schwannoma and have intermittent painful partial CN3 palsies that self resolve. Most of the items on the differential would be more enhancing. The other diagnosis to consider would be a solitary neurofibroma. Biopsy seems overly invasive if it is self resolving but I think serial imaging for growth is reasonable. It is unclear if steroids benefit recovery but may help the pain.

The MRI is interesting, in the cav sinus it definitely looks like CN3, in the orbit, it involves the branch to the medial rectus and there is an inferior branch that appears to follow a course more typical for V2 in the inferior orbit extending past the inferior rectus. This is very similar to one of my two cases. I think it is difficult to track the cisternal component, the link does not include a coronal CISS sequence.

Best,

Drew

------------------------------
Andrew Carey
Associate Professor
Wilmer Eye Institute, Johns Hopkins Medicine
Baltimore MD
------------------------------

Original Message:
Sent: 2/4/2026 8:54:00 AM
From: Andrew Carey
Subject: RE: Unilateral thickened CN III with "discrete" clinical findings

Hi Michel,

I have two patients like this whom we have called presumed schwannoma and have intermittent painful partial CN3 palsies that self resolve. Most of the items on the differential would be more enhancing. The other diagnosis to consider would be a solitary neurofibroma. Biopsy seems overly invasive if it is self resolving but I think serial imaging for growth is reasonable. It is unclear if steroids benefit recovery but may help the pain.

The MRI is interesting, in the cav sinus it definitely looks like CN3, in the orbit, it involves the branch to the medial rectus and there is an inferior branch that appears to follow a course more typical for V2 in the inferior orbit extending past the inferior rectus. This is very similar to one of my two cases. I think it is difficult to track the cisternal component, the link does not include a coronal CISS sequence.

Best,

Drew

------------------------------
Andrew Carey
Associate Professor
Wilmer Eye Institute, Johns Hopkins Medicine
Baltimore MD
------------------------------

Dear Sherif,

Thank you, there is no headache or history of migraine

Michel

-------------------------------------------

Original Message:
Sent: 02-04-2026 09:01
From: Sherif Ahmed Kamel Abdelbar
Subject: Unilateral thickened CN III with "discrete" clinical findings

Is there any headache or doubts about ophthalmoplegic migraine ??

Sherif 

Sent from Yahoo Mail for iPhone

Original Message:
Sent: 2/4/2026 8:54:00 AM
From: Andrew Carey
Subject: RE: Unilateral thickened CN III with "discrete" clinical findings

Hi Michel,

I have two patients like this whom we have called presumed schwannoma and have intermittent painful partial CN3 palsies that self resolve. Most of the items on the differential would be more enhancing. The other diagnosis to consider would be a solitary neurofibroma. Biopsy seems overly invasive if it is self resolving but I think serial imaging for growth is reasonable. It is unclear if steroids benefit recovery but may help the pain.

The MRI is interesting, in the cav sinus it definitely looks like CN3, in the orbit, it involves the branch to the medial rectus and there is an inferior branch that appears to follow a course more typical for V2 in the inferior orbit extending past the inferior rectus. This is very similar to one of my two cases. I think it is difficult to track the cisternal component, the link does not include a coronal CISS sequence.

Best,

Drew

------------------------------
Andrew Carey
Associate Professor
Wilmer Eye Institute, Johns Hopkins Medicine
Baltimore MD
------------------------------

Dear Andrew, 

Many thanks for your kind response. There hasn't been any pain involved so far. It does appear we will be limited to observation other than perhaps a trial with steroids / LP for work-up. 

Michel

-------------------------------------------

Original Message:
Sent: 02-04-2026 08:53
From: Andrew Carey
Subject: Unilateral thickened CN III with "discrete" clinical findings

Hi Michel,

I have two patients like this whom we have called presumed schwannoma and have intermittent painful partial CN3 palsies that self resolve. Most of the items on the differential would be more enhancing. The other diagnosis to consider would be a solitary neurofibroma. Biopsy seems overly invasive if it is self resolving but I think serial imaging for growth is reasonable. It is unclear if steroids benefit recovery but may help the pain.

The MRI is interesting, in the cav sinus it definitely looks like CN3, in the orbit, it involves the branch to the medial rectus and there is an inferior branch that appears to follow a course more typical for V2 in the inferior orbit extending past the inferior rectus. This is very similar to one of my two cases. I think it is difficult to track the cisternal component, the link does not include a coronal CISS sequence.

Best,

Drew

------------------------------
Andrew Carey
Associate Professor
Wilmer Eye Institute, Johns Hopkins Medicine
Baltimore MD
------------------------------

Dreaming about a world where angiography of the cranial nerve vasa nervorum exists; I imagine quite a few of the 'idiopathic' cases (especially relapsing-remitting) represent arteriovenous pathologies that are difficult to prove with current imaging modalities.

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KemarGreenAssistant Professor of NeurologyCompanyName]kgreen66@jhmi.edu
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Original Message:
Sent: 02-04-2026 10:18
From: Michel Van Lint
Subject: Unilateral thickened CN III with "discrete" clinical findings

Dear Andrew, 

Many thanks for your kind response. There hasn't been any pain involved so far. It does appear we will be limited to observation other than perhaps a trial with steroids. 

Michel