Thank you so much! Very informative. =D I bookmarked this page already!
As ususal, awesome post. Do lesions on these nerves generally show up on a brain MRi?
I have so man of these sx's. I am being checked for disease after disease that causes a lot of the things you explained above. I am seeing that it really could all be from MS.
Thanks for being you
agree, awesome post Quix.
Re; showing up on MRI, I have a large lesion on my brain stem that damaged my 6th cranial nerve and caused constant double vision for about a year. I don't know if they isolated it on MRI to the actual nerve responsible, or, just the brain stem, and concluded damage to that particular cranial nerve based on clinical observation. Since my MRI report said nothing about cranial nerves I assume the latter.
Thanks Quix! for explaining all this and for not making us wait until you could finish it completely. I understand better now how eyelid droop and jaw fatigue with chewing is produced by MS demyelination. They were symptoms that had me wondering about MG a little while back.
I look forward to your second installment on cranial nerves and expect this will become a valuable addition to the Health Page section eventually.
When I learned cranial nerves we were given the mnemonic:
On Old Olympus Thorny Top A Fin And German Viewed Some Hops (it's so stupid, it stuck with me)
Now that I see it again, I do remember the Some Say Money Matters thing. I guess that one stayed in my memory bank just about as long as dollars stay in my piggy bank.
Sure am glad when you can be here.
Once again you've pulled off a great and informative post! Is it going into the health pages?
It might take me a while to connect the dots, brain seems fried today, just not holding on to what i'm reading and understanding today lol. But trying to connect the dots with the sx just to do with my head, not including the brain confusion, and i get...
Eye pain looking up or down. ?? i also go cross eyed
Left eye, occasional opaque blob in middle vision, only lasts a few minutes at a time
Balance, fall backwards looking up
Focus - trouble staying focused, can't hold onto clarity of sight, eyes drift off target
Light sensitive - light = eye pain, pupils no longer go big in dark/low light, sometimes different pupil size but rare.
Blurred sight, not quite double more 1 and a 1/2 eg F11 looks like #111
Tingly static feeling from mid way under right eye traveling up over cheek into scalp,
Hot hot spot on scalp
Nose goes from tingles to numb
Chin tingles or tremors not sure its a new one
Left ear - just the top edge either burns or tingles
Tongue control ??? difficulty with articulation
Facial tremors ????? eye lids (still convinced my eyeballs also bounce) and possibly chin
Balance issues - fall over a lot apart from going over backwards
Vertigo - not all the time but when it hits it lasts for weeks at a time
Hearing - sound seems to switch off like the speaker has blown out but it comes back
Tinnitus - seems to happen prior to hearing switching off though not often
I'm not sure if I've got that right, or where the tremors fit in, i've just been putting it all down to lack of muscle control in the same spots day after day. I also have facial pain that comes and goes but i've had that since I was a child so dont count it because its to do with my jaw being out of align for years before they found the cause. I cant work out where the 'where I am in space' goes lol all I can say is that pain like TN isn't something i have, for that i'm grateful! :-)
Awesome, so much knowledge here I am overwhelmed
I have found this post very detailed thank-you.
I am still in the limboland, I have a couple of things being effected such as cannot taste my food at times, Tongue goes partly numb, eating also can be hard work as, my jaw gets very tired. I have not informed my Neuro of this.
I do now suffer with Tinnitus Which is now effecting my hearing, I now have a app in Oct with the ENT.
Thanks, Quix! The first half of a health page on this. Really good info.
One question. If it's CNII that's responsible for ON, but CNIII that controls pupil dilation, why when I had a suspected case of ON did they keep checking for the afferent pupil effect (my spelling may be off, but they checked the pupil dilation). Is this something that is normally seen in ON?
Thanks again for all your work on this. It's very useful.
This is an AWESOME post. Feel like I am back in school.
Funny, I am so familiar with CN III, CN IV and CN VI from work, that I seemed to have "forgotten" about the rest.
I am thrilled with this post in a selfish way, due to the new neurologist told me that I have 4 of the nerves involved due to my MS and only one is eye related.
I really appreciate this immensely. Looking forward to the next post...the sequel.
Both my MS neuro and now "facial pain" neuro, both said even though they cant see lesions on my cranial nerves with the MRI, they are definitely there. Just too small to see, but not small enough to not cause damage. (I strongly agree with this!).
Well done, again!
Although by the time I finished the post, I forgot what nerve goes where, I know where to find it again (I think)
I sure hope this becomes a HP, then I know I'll be able to locate it in the future.
This is outstanding! Thank you so much!
Say the word, Doc Q and I'll prep it for our HPs!
A-hah! I thought your absence was due to some knitting spree to work on your new CNS. Instead, you were composing yet another masterpiece. Well done and easily understood.
As always, thanks for putting it in terms even I can understand. Now if only I could remember all this. I'll start studying for the exams!
incredible info and great reference!!
ditto what someone else said above about looking forward to ...the sequel! lol!
merci beaucoup and asante sana! (thanks and thanks)
Very very informative!!!!
Love this hope to see more soon.
Steph - The pupils are a complex mix of two different actions. They can activately (meaning under the action of muscles) both constrict to become smaller and they can dilate, becoming larger. Each action is handled by different nerves.
There are two muscles around the pupil in the iris. The first is a circular muscle that surrounds the pupil like a sphincter (purse-string) called the "sphincter pupillae." This is controlled by the parasympathetic nervous system in conjunction (runs alongside) with the third cranial nerve, the Oculomotor Nerve. When extra light hits the light-sensitive cells in the retina a signal goes to the CN III and a signal comes back via the parasympathetic system to constrict the pupil so that too much light is not let in - overwhelming the visual system. That is why your pupils constrict in bright light.
Now, for both muscles the action in one eye also makes the same thing happen in the other eye. So if you shine a bright light into the left eye while shielding the right eye, both pupils will constrict the same. This is important to understand. It happens because each nerve affecting the pupils has crossover fibers to the other eye. When someone is unconscious and the doc checks their pupils, this is the response they are looking for - the pupillary light response which shows that the brainstem is intact. They are checking for proper functioning of the thrid cranial nerve.
The opposite action, widening (or dilation) of the pupils is handled by the "dilator pupillae" which is part of the Sympathetic nervous system. This muscle is the opposite of the first. Instead of going around the pupil, the dialator fibers extend from the edge of the pupil outward to the edge of the iris, so that when they contract they literally "pull" the pupil open. This action originates in a structure in the mid-cervical spinal cord.
Now, you asked about the afferent pupillary response or defect. First you need to know two definitions. There are two words used in nerve signals, "efferent" and "afferent". One follows sensory signals to the brain - the afferent signals. The other causes things out in the body to happen and it originates in the central nervous system. Examples are nerves that make muscles act. I remember which is which by remembering that efferent signals cause EFFort (like muscular effort). Therefore the "other one, the afferent signal" does the opposite - it brings information to the game by Announcing.
In a person with MS or with optic neuritis the doctors look for something called the "Afferent Pupillary Defect." Since the problem uses the word "afferent" we can assume that the problem will be one of sending info upward to the brain and this is exactly what they find.
In a test called the "Swinging Light test" this is what happens. The doctor slowly swings the penlight first into one eye. This should cause both pupils to constrict the same amount. Right? Then, the light is swung to the other eye. As it leaves the first eye and before it arrives at the other eye both pupils will start to dilate again. So when the light arrives at the second eye you will again see constriction. That is the normal response when everything is working correctly.
In optic neuritis the sick eye (one with ON) will not register as much light as a healthy eye. This is because the Optic Nerve (CN II) is damaged and not able to perfectly carry all of the light signal. So, when the light is shown in the good eye, both pupils will constrict, but the good eye will constrict more because it is getting the full effect of the light. When the light is moved to the affected eye (the one with ON) not so much light is signalled and the constriction is less marked and the eye may appear to "paradoxically" dilate. This is called the Marcus-Gunn pupil and is an afferent pupillary problem.
It's not that the pupil in the bad eye actually dilates actively, it's just that it isn't stimulated to constrict as much, so it relaxes to the amount of constriction that fits with the reduced light it is receiving.
So in this case the problem of the pupil which is not constricting enough is due to the lesion on the Optic Nerve, CN II, and not to the Oculomotor Nerve.
So, when you had optic neuritis and had the problem with the pupil, it was all a part of damage to the same cranial nerve, the Optic Nerve (II).
Thanks for great info, Quix. I've got symptoms for numbers 5 and 8 (confirmed with very abnormal AEPs for #8). Bilateral!
Anyway, a question--are those nuclei IN the brainstem, or just beside it? For some reason I always assumed the "nuclei" I've seen mentioned in relation to the vestibular nerve, e.g., are at the intersection of the brainstem and nerve, but then I have not really studied this.
And I did have that very weird crossover thing where left-side BPPV triggered what was almost surely a stapedial spasm in the right ear--which I think had to be a crossed wire in the brainstem itself?
The nuclei are within the brainstem itself.
Thank you, Quix!! That was a perfect explanation. I love understanding these details and having difficulty finding this information. Once again, I'd suggest this be part of a HP on ON. This is really great info and I so appreciate your time in giving such a thorough answer!
Thank you Quix!! This is a wonderful post!
Do you mind if I ask for your 2 cents? My neuro (an neuro-ophthalmologist) is pretty closed lipped during the exam and I find out most my info as he dictates to the PA at the end of the exam.
I had been telling my neuro about 2 eye issues:
1- about 3 weeks ago my husband noticed my pupils were huge, basically fully dilated, while in a well-lit room. This lasted over an hour, and was still there when I went to sleep, but was gone in the morning. I had complained of a headache, maybe from the extra light my pupils were letting in?
Then last Friday afternoon I was outside in the bright sunny day for a few minutes. When I went back inside, where it is much dimmer (we get morning sun in the house), I thought I was going blind! Everything was very blurry where I could only make out shapes. It was very dark and there was a blue tint to everything (I have blue eyes, if that means anything.) It lasted 5 minutes and then suddenly snapped back to normal. When I told my husband he thought it was my pupils not dilating when I went back inside.
And 2) For 3 days last week I would see flashes in my peripheral vision if I looked to the side, like camera flashes going off on either side of me. This went away after 3 days.
My neuro did repeat OCT and VER tests on me. My OCT was unchanged from April, showing slight optic nerve thinning on my left, but still within normal limits. The VEP in April showed an 8 millisecond delay in my left eye. The one on Monday showed a 10 millisecond delay.
He did not do the flashlight test, but he did put his hands up to cover one eye and switched back and forth, is that kind of the same test or something different?
My fundus exam has always been normal. When he was dictating to the PA, the PA mentioned something that sounded like "phototopis". I've tried looking online, and can't find anything. My neuro also said "Acute optic neuritis" and he has never said those words before, though I have seen him for eye issues the last few visits. My eyes just don't seem right, but they also did a regular "read the chart" eye exam on Monday and it was 20/20!
I'm sorry this is so long! I'm wondering, would what I have experienced the last few weeks be why my neuro said optic neuritis? I had gone to see him because the vertigo started back up last thursday, luckily it is mostly a low-level dizziness with the full vertigo flaring up 4-6 times a day & lasting 1-3 hours, so my neuro did not suggest steroids (whew! I'm not looking forward to doing those again!) but he did say he is 80% sure I have MS, up from 70% at my last visit. And he has suggested I start Copaxone, which I will be.
Thank you for your thoughts on these questions! And, thank you for the wonderful post!
I misspoke in the second paragraph about the Swinging Light Test.
"In a test called the "Swinging Light test" this is what happens. The doctor slowly swings the penlight first into one eye. This should cause both pupils to constrict the same amount. Right? Then, the light is swung to the other eye. As it leaves the first eye and before it arrives at the other eye both pupils will start to dilate again. So when the light arrives at the second eye you will again see constriction. That is the normal response when everything is working correctly.
In optic neuritis the sick eye (one with ON) will not register as much light as a healthy eye. This is because the Optic Nerve (CN II) is damaged and not able to perfectly carry all of the light signal. So, when the light is shown in the good eye, both pupils will constrict, "maximally. When the light is moved to the affected eye (the one with ON) not so much light is signalled and the constriction is less marked and the eye may appear to "paradoxically" dilate. This is called the Marcus-Gunn pupil and is an afferent pupillary problem."
Jess - the perception of flashing lights is called photopsis or photopsia. Maybe that is what you heard.
The test where they cover one eye at a time might not use enough light (if they are depending on regular room illumination) to detect a Marcus Gunn pupil. I always used the cover test to detect a lazy eye. So it could be used for that I suppose. Not sure what he was doing.
A weird thing about optic neuritis is that, though it makes things seem blurry, it often does not affect the visual acuity. So, the sight might be normal on the Snellen Chart. Also, if there is blurriness it is not treatable with new glasses.
It sounds like the neuro sees all this as evidence of optic neuritis.
Wish I could say more.
Great Stuff!! I honestly only read a tiny bit because I have eye pain and am waiting for my IV steroids but I know that I am going to be coming back to this when the pain/vision gets better.
Maybe you will have part #2 done by then ? No pressure the first half could last for weeks of reading.
Thanks again Erin :)
Thank you for taking the time to answer my additional questions! I really appreciate it :-)
At this point I guess it's not important what brought him to the point of offering Copaxone...I'm just glad he did!
I hope you are feeling well today!
I have given this Cranial Nerve discussion (via link) prepared by Doc Quixotic to many people over the years as background info, and it's a mainstay educational piece on our forum.
While looking up additional info for a member who had a question about cranial nerves, I gave her this old discussion link, but also found this other "jewel" very useful and complimentary to our initial discussion!
Please check it out - photos during exam as well!
THANK YOU!!!! VERY helpful. I now know that the horrid pain in my ear was trigeminal neuralia! Not an illusion. =^-^=