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What causes fourth cranial nerve damage?

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Posted on Sat, 21 May 2016
Question: I have last week being further assesed by eye clinic at a eye hospital
hesses test was carried out
the opinion was 4 th cranial nerve trochlear nerve involvement on the right side, which just so happens to be the opposite side of my fractures in the past.
question ?What do you think would be the cause of my 4 th.nerve sup oblique problem
doctor
Answered by Dr. Olsi Taka (1 hour later)
Brief Answer:
Diabetes most likely.

Detailed Answer:
Hello! I remember we had an exchange in the past regarding your diplopia. I suggested 4th nerve damage to be the issue back then, seems it has been confirmed.

As for the cause I do not think it is due to your trauma. Apart from the opposite side, that is also because if due to acute damage from trauma it would manifest earlier and if due to chronic changes (scarring, bony spurs) it would be visible on MRI. MRI also excludes causes such as aneurysm, stroke, tumor etc.

So with a normal MRI the most probable cause might be damage from diabetes which I remember you suffered from. Diabetes is known to cause damage to the nerves, more classically it causes peripheral neuropathy manifesting in the limbs, but it can also cause isolated cranial nerve palsies, in this case the 4th nerve.

I remain at your disposal for other questions.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Olsi Taka (4 hours later)
i WENT THROUGH MY MEDICAL HISTORY IN DETAIL RECENTLY AND FOUND OUT THAT AFTER A VERY MINOR MVA LAST YEAR AUGUST 31 I COMPLANED OF HEADACHES AND TROUBLE DOWNWARD GAZING USING A PHOTOCOPIER. DIFFICULTY IN FOCUSING
BUT NO CENTRAL DIPLOPIA AT THAT TIME.
THEN 1 MONTH LATER HAVING A FALL DOWN THE STAIRS DUE TO DIPLOPIA I NOW REALIZE BUT AGAIN NO CENTRAL GAZE DIPLOPIA THAT I RECOGNIZED AT THE TIME
WHAT DO YOU THINK
doctor
Answered by Dr. Olsi Taka (15 hours later)
Brief Answer:
Read below

Detailed Answer:
Thank you for the additional information.

It is hard to assess after so much time whether those issues were due to the same cause, whether there was trochlear nerve palsy. That is because after mva at times some headaches and dizziness may be present for several weeks, even months at times. So since your eye movements were not examined at the time it is hard to say, trochlear palsy is the hardest to evidence among the nerves responsible for eye movements, because those movements are in part shared by the 3rd nerve. It is not as in the case of 3rd or 6th nerve palsy where the deficit is much more noticeable.

Given the lack of any lesion on MRI I still wouldn't think it very likely, usually there is more damage present from trauma, not isolated nerve palsy with no accompanying neurological deficit and no damage on imaging.

So while as I said hard to say it with certainty after this many months, I would still put diabetes as a more likely cause.
In terms of management, whether diabetes or trauma, it doesn't change much really. There is no specific treatment, it can only be hoped for natural regeneration of the nerve and compensation from other nerves and muscles. Diabetes control of course is essential, but that applies with or without the palsy.

I hope to have been of help.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Olsi Taka (4 hours later)
The lack of central diplopia may of been due to compensation of body head tilt.
Head tilt to compensate for superior oblique dysfunction.?

Further you suggest downward gazing movement can be oculomotor nerve also involvement ,would that cause steps to split in downward gaze, about one month after MVA Aug 31 2015

Now been examined by two hospital eye clinics including orthoptist whom have suggested diabetes unlikely ?
Regards XXXXX
doctor
Answered by Dr. Olsi Taka (34 minutes later)
Brief Answer:
Read below.

Detailed Answer:
I did not suggest oculomotor nerve damage, I said that it would be evident IF there was oculomotor damage. That is because it commands several muscles, involved in movements in several directions and also eyelid muscles (causing eye closure).

Yes one tries to compensate trochlear damage by head tilt (compensation which should be happening even now though). As I said I can not exclude it since you weren't examined at the time, speaking of probabilities, only saying that I would expect some other findings as well in case of trauma.

As for diabetes, I said that because in our prior exchange you mentioned to have average blood sugar levels of 13 with high values of 21 after meals. I assume that is in mmol/L (it can be expressed in mmol/L or mg/dl, but that can't be mg/dl as it would be impossibly low). So if indeed you have such average levels they are very high, 13 mmol/L are equal to 234 mg/dl, it means you certainly have diabetes.
So if you have diabetes (it is a conclusion which I reached because of the measurement data you provide) I am not really sure how these eye clinics can exclude that really without offering an alternative explanation. There is no specific test for that, it is a diagnosis of exclusion which is made in the situation where there is a diabetic patient with an isolated neuropathy with no other explanation for it by other tests such as MRI in this case. I mean I can understand if they said it is not certain, at times cause may be difficult to elucidate, but can't see how did they exclude it with certainty if you have diabetes, it is a well known cause of isolated neuropathy.

Let me know if I can provide more input.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Olsi Taka

Neurologist

Practicing since :2004

Answered : 3669 Questions

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What causes fourth cranial nerve damage?

Brief Answer: Diabetes most likely. Detailed Answer: Hello! I remember we had an exchange in the past regarding your diplopia. I suggested 4th nerve damage to be the issue back then, seems it has been confirmed. As for the cause I do not think it is due to your trauma. Apart from the opposite side, that is also because if due to acute damage from trauma it would manifest earlier and if due to chronic changes (scarring, bony spurs) it would be visible on MRI. MRI also excludes causes such as aneurysm, stroke, tumor etc. So with a normal MRI the most probable cause might be damage from diabetes which I remember you suffered from. Diabetes is known to cause damage to the nerves, more classically it causes peripheral neuropathy manifesting in the limbs, but it can also cause isolated cranial nerve palsies, in this case the 4th nerve. I remain at your disposal for other questions.