Paresthesias - Another Try

After all the questions I realized I had not done a good job of explaing paresthesias.  Thank you to everyone who helped with this.

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Yesterday upon the stair
I met the man that wasn't there.
He wasn't there again today.
Oh, I wish he'd go away!

Paresthesias are among the most common problems in MS.  A paresthesia is simply an abnormal sensation without an apparent cause.  But, understanding what they really are as applied to ourselves are can be a little tricky.  To really understand what can be happening, one needs a basic understanding of how a nerve works.


A Little Bit About Nerves and How They Work

Nerves can carry a signal in only "one" direction.  Ever.  All nerves are this way.  The main nerves that we deal with in MS are the motor nerves and the sensory nerves.  The motor nerves carry the signal from the brain to the muscles.  We want to move and the brain sends the signals to cause the muscle to contract.  The sensory nerves carry signals of sensation or feeling in the opposite direction, from out in our body to our brain.  This is how we experience the world.

Sensory nerves come in many flavors depending on the type of nerve ending.  There are special nerve endings for pain, soft touch, pressure, heat, vibration and many others.  When a nerve ending is stimulated the nerve carries the information to the brain and we percieve or feel it.  If a pain nerve is stimulated by injury, whether a pinpr*ck or a broken bone we feel pain.  The difference in how much pain we feel depends on how many nerves are stimulated and how fast they fire.  The faster they fire the more painful something is.

When a nerve is damaged it can do several things. The effect can be Negative.  It can have no signal arrive at all or the signal may be reduced in strength. If it is totally interrupted on it's way to the brain no signal at all will get through. This causes numbness. Even if the interruption is high up in the spinal cord or the brain, if it doesn't arrive at its destination in the final area of the brain there is no sensation from it.  So, if the foot is injured, there may be a normal pain signal in the nerve almost all the way up, but if it is completely interrupted before reaching the final spot in the brain, there is no pain felt.  The area is numb.  Numbness is the final result when any of the sensory nerves are completely cut off.  So when an area is really totally numb we can't feel touch, pain, hot, cold - anything.  

Also, a damaged nerve may have a reduced signal arriving at the brain.  In this case we will feel pretty much the correct sensation, but not enough of it. This is also a negative (reduced) effect.  If the nerves carrying the sensation of heat are affected by MS, then we may think that very hot bath water is just warm and we may burn ourselves.  The sensation of warmth is not an abnormal sensation, it is just not enough of the normal sensation.  This is not technically a paresthesia.

The opposite of a Negative signal is a Positive error signal.  The signal is there, but it is too much or it brings wrong information.   These positive error signals are called "paresthesias."


PARESTHESIAS

When a sensory nerve is damaged, like in MS, if it can send a bad signal to the brain.  We feel this as a paresthesia.  It sends signals that are inappropriate to what is happening.  Our feet or face may tingle, but there is nothing causing the tingling.  We may feel a band-like sensation around our chest or around a limb. but there is nothing wrapping around us to cause it.  The tongue might feel burned, but there have been no hot foods.  When we flex our neck, a lightening sensation may zap in various areas (L'Hermitte's), but no one is behind us with a cattle prod.  A common problem is the sensation of a hot or cold patch (which we sometimes interpret as wet).  A paresthesia may be constant or it may be intermittent.  It can be triggered wihen something does stimulate the area as when simple soft touch is felt as unbareably painful.  This is a condition of paresthesia known as allodynia.  

The special senses of sight, smell, hearing and taste may also be affected in MS and cause paresthesias.  In Optic Neuritis, a person may see flashing lights, halos, wavy lines, things that appear to scurry round in the peripheal vision.  These are paresthesias.  If the visual signal is reduced there my be shadows, visual field defects, or diminished color saturation (intensity).  The sense of smell may disappear.  Or we may have paresthesias of smells that are not there.  For some reason these smells are always odd and usually very unpleasant.  (why can't we smell cinnamon or lilics? lol).  Loss of hearing is also not uncommon in MS.  Paresthesias of hearing and taste occur but not often.


The Special Case of Pain

In truth, pain can be a paresthesia.  If there is no injury to the body part, but it hurts anyway, it is a painful paresthesia.  However, pain is just usually called "pain."   In medicine we tend to call it nerve pain or neuropathic pain.  Just like other paresthesias it can be constant or intermittent.  It can be stimulated by touching the painful part or it can also occur spontaneously (all by itself).  People tend to think all paresthesias have to do with the skin, but pain especially can occur in any area that has sensation, including deep in the muscles or bones or even in the abdomen.


Other Examples of Paresthesias

Itching without cause.  this can be constant or intermittent and it has been described in paroxyms.  Often the application of heat will result in itching.

Burning of any area.

A feeling of vibration or buzzing is a very common sensation.  I have heard it described in every conceivable part of the body, in patches and in huge areas.  In the head , within the abdomen  Many describe it as like a cell phone on silent buzz.

The feeling of walking on rocks when the floor is smooth.  Or the sense of a rock in your shoe.

Feeling that the toes or fingers are crossed, but they are not.

Feeling like there are insects or something crawling on you

Feeling like you are urinating down your leg.

Paresthesias are not harmless.  Though the sensations themselves do no harm, their very presence can destroy the quality of life.  Many just cannot be ignored.  They also can cause secondary problems by giving us bad information about our world.  We can be burned or injured if we don't feel/perceive the threatening object.  Visual paresthesias may obscure something we need to see to get around effectively or to drive.  We may drop something because we didn't have good information about whether we have it securely.

I hope this is moving toward a better explanation of paresthesias and how varied they can be.

The floor is open to questions.

Quix

[tonyad]

Thank you for more info on paresthesias.
I can and do relate to many escpecially when you mentioned the itching.
I get this "phantom itch" at the end of my nose.......it drives me up the wall!
I read somewhere that people who take some pain meds will have an itchy nose....I do not take pain meds though.
Have a great night and a better tomorrow
Chow,
~Tonya

[Sarahsmom46]

What about tinnitus (sp?)?  Would tinnitus be a type of parethesia?  If so, do people with MS get it?  

Julie

[cat1203]

I itch so much sometimes i wake up with blood on my sheets or pillowcase.  My nose drives me nuts.  The numbness and tingling and the pain seem to melt into one another.  Anyone have that?

[Want to feel well!!!]

VERY GOOD explanation!!!!

Wanna :o)

[georgejackson]

cheers, that is so well explained.

[jensequitur]

I sometimes have the reverse problem - thinking of something as a paresthesia, when it actually exists!  I'm so used to hot droplets on my legs that when I dripped coffee on myself this morning, I thought it was my nerves firing.  Nope, it was actually coffee.  

And yesterday I got a little splinter in my finger, that at first I thought was another paresthesia - no, actually it was a splinter!  I guess I blew it off because it felt weird - the site of the splinter felt tingly as well as painful.

[sllowe]

bump!

[zafira91]

i juz want to know why do people who got paresthesia tend to use warm water or winding their hand for sometime to relief the numbness and tingling..?

[jensequitur]

Sometimes all it takes is to distract the brain from the paresthesia - putting a wrap on the hand, or running it under warm water, gives the nerves something else to think about.

[michelleislay]

question:

where, if at all, would evidence or cause of paraesthesia show up on an mri?

if it is a negative signal not quite reaching the brain...is there a lesion somewhere causing the interruption along the nerve?

for a postive signal, is there a lesion somewhere on the brain or spine, misinterpretting what could potentially be a fine signal coming in?

how does it work quix? you have totally peaked my interest!!

michelle

[jensequitur]

Paresthesia are caused by damage to the nerves, or by damage to the connections that those nerves make to the brain and spinal cord.  It's very difficult to find where that damage is.  Almost always you're better off treating the symptom than trying to find where the damage is.

I have lesions in my spine; one is in the dorsal column of the spine, and causes my paresthesia and leg weakness, as well as the lack of reflex.  There's others in the upper cord, which cause cramping and pain around my torso.

[Pablo_Morphy]

Ah, paresthesias!  After my diagnosis several things started making sense (I'm sure so many of you have thought the same thing!!!!).  E.g. cold, cold, cold feet that feel cold and... aren't really cold at all.  Or my current companion, the crawling insects inside my skin here and there, accompanied by a pain on the center of my back.  

I know they aren't harmful as such, but I would love them to go AWAY!

[mamiJ]

so, when I see things moving around in the room from the corner of my eyes, it can be a paresthesia?  I'm not just losing it?

[RedFlame]

I read, read, read and re-read------I even took notes!!   Now I get it!!

As always, thanks so much Qux!