Re: Peripheral Nervous System - Defined

[Guest guest]

Larry and ,

IMHO I think you are both right Ain't life grand? I have always thought of it

in 3 components: the CNS (brain and spinal chord); the PNS (all the nerves that

origniate from the chord and go out to the rest of the body) and the Cranial

nerves which have some characteristics of both as they orginate as CNS and end

as PNS. I have always categorized them as " special " peripheral nerves in my own

brain.

I am one with an affected cranial nerve, Left facial branch, also have

balance/dizziness problems and have a strong family history of menieres and

deafness in the family members with CMT (CN VII). Coincidence? That's a stretch.

First rule in medicine, try to find a cause that encompasses all the symptoms

instead of many causes of many symptoms.

Maybe the fact that cranial nerves are " special " peripheral nerves accounts for

the fact that not as many folks are impacted with CN problems as with peripheral

nerve problems. But, due to my own experience, I have no doubt that they can be

affected by CMT.

My 2 cents,

Holli

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[Guest guest]

Hi Holli,

Thanks for clearing that up!    J/k.

 

I was hoping that you would chime in.  Thank you.

 

Discussing the nerves themselves seems to be the easy part.  It's the " why "

that's the hard part for me to understand. 

 

Why are some peripheral nerves symptomatic and others not.  I appreciated your

opinion about the cranial nerves being " special " .  That makes sense.

 

What really confuses me is why some PN nerves are symptomatic and others

aren't.  Larry pointed out that distance doesn't always explain it and I

agree.  But then what causes the variation?

 

I recall reading more than one study of the phrenic nerve in CMT1A patients,

where 100% the patients showed slowed responses and evidence of demyelination,

but just a small percentage were symptomatic.  Why the variation in impact on

patients within the same subtype?

 

The research, especially over the last decade, is phenomenal and has

really helped to confirm the wide variety of symptoms that are attributable

to the disease, but exactly why some nerves are impacted and others aren't

still isn't clear...at least not to me.

 

So I appreciate your opinion and perspective.  Thanks again.

 

From: hmm_md <hmm_md@...>

Subject: Re: Peripheral Nervous System - Defined

Date: Thursday, November 5, 2009, 11:30 AM

 

Larry and ,

IMHO I think you are both right Ain't life grand? I have always thought of it

in 3 components: the CNS (brain and spinal chord); the PNS (all the nerves that

origniate from the chord and go out to the rest of the body) and the Cranial

nerves which have some characteristics of both as they orginate as CNS and end

as PNS. I have always categorized them as " special " peripheral nerves in my own

brain.

I am one with an affected cranial nerve, Left facial branch, also have

balance/dizziness problems and have a strong family history of menieres and

deafness in the family members with CMT (CN VII). Coincidence? That's a stretch.

First rule in medicine, try to find a cause that encompasses all the symptoms

instead of many causes of many symptoms.

Maybe the fact that cranial nerves are " special " peripheral nerves accounts for

the fact that not as many folks are impacted with CN problems as with peripheral

nerve problems. But, due to my own experience, I have no doubt that they can be

affected by CMT.

My 2 cents,

Holli

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[Guest guest]

said what I was mulling over in trying to answer the differences in mi

and other posts.

I think is is a matter of frame of reference or context. The neurological

context could see all nerves that leave the CSF (Cerebral Spinal Fluid) and the

BBB (Blood-Brain Barrier) as peripheral. From that frame or reference, are

distal from the origins within the CSF/BBB.

From the anatomical frame of reference, peripheral nerves would be those that

enervate muscles and structures at extreme distances from CSF/BBB. From this

frame if reference, cranial nerve VIII -- the Audiovestibular -- might be

classed as a peripheral nerve as the auditory canal is as distal from the brain

and within the skull as possible.

If anyone wants to read a fascinating book on frame of reference, I recommend

" Flatland " by Edwin Abbot. The book may be downloaded free and legal at

http://www.gutenberg.org/etext/201.

The frame of reference for all my posts has always been slanted toward finding

ways to overcome the deficits that CMT visits on us (CMT -- the gift that never

stops taking), and methods that may increase quality of life.

That context focuses on how to stay on my feet and out of a chair, and

medications I have found effective in meeting that goal. I have given up

consulting with neurologists and now only consult with a physiatrist. I trust

she will tell me in need to see those more interested in nerve conduction speed

than making sure I won't trip over a blade of grass and break my hip.

Finally 12 vs 13 cranial nerves. When I studied neuroanatomy back in the dark

ages -- 1965 -- there were 12 cranial nerves, but then there were also 48

chromosomes, and not 46 as we know(?) now. Over time number change and change

again. Today there is a dispute if there are 12 cranial nerves or 13. Some are

saying that the XI Accessory nerves can be seen as 2 separate nerves.

I guess I chose 13 to reflect the fact I am not suffering with and excess of

tristadecaphobia.

Regards.

--Larry

P.S. Please let it end here!

[Guest guest]

,

I wish I knew the answer to your questions! It would solve a lot and we could

just forget about all the other doctors! I keep reading and looking and

thinking, just like you and Larry. With enough of us devoting much of our CNS's

to it, our PNS's may benefit!

Holli