Author Topic: "Stupid" Question  (Read 2921 times)

scotts

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"Stupid" Question
« on: October 11, 2009, 12:18:51 pm »
I have been researching and trying to identifying the answer to this question.
I know it should be simple but I can not seem to find it.  This board is a wealth of good information so I figured people on here will know this pretty quickly.
 
Here goes:
What is the difference between what I believe to be a "standard" schwannoma of the 8th cranial nerve (acoustic neuroma) and NF (neurofibromatosis) 1 or NF2 tumors. 

Also, are "standard" acoustic neuromas dependent on PAK1 for their growth the same way that NF1's and NF2's are?

Thanks so much.

Scott

Kaybo

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Re: "Stupid" Question
« Reply #1 on: October 11, 2009, 12:34:56 pm »
No question is ever stupid but i will let someone who knows more about NF2 answer...

;D
Translab 12/95@Houston Methodist(Baylor College of Medicine)for "HUGE" tumor-no size specified
25 yrs then-14 hour surgery-stroke
12/7 Graft 1/97
Gold Weight x 5
SSD
Facial Paralysis-R(no movement or feelings in face,mouth,eye)
T3-3/08
Great life!

Brendalu

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Re: "Stupid" Question
« Reply #2 on: October 11, 2009, 01:56:25 pm »
Scott,
I am an NF2 but I can't answer that question.  I am still freaked out by the diagnosis.  Tony, I believe, is our expert in that area.  I'm sure he will chime in and give the best answer to your question.  There are a couple others out there who have this and have more info than I do.  I hope you find the answers you are looking for.  I will be interested in reading about the growth aspect.
Brenda
Brenda Oberholtzer
AN surgery 7/28/05
Peyman Pakzaban, NS
Chester Strunk, ENT

Jim Scott

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Re: "Stupid" Question
« Reply #3 on: October 11, 2009, 02:22:47 pm »
Scott ~

I'm not an 'expert' on anything - but I'll try to begin to answer your query.  

NF2 tumors grow faster and more aggressively.  NF2 tumors tend to infiltrate the nerves, instead of being adjacent to and pressing on the nerves, as in 'regular' AN patients.  

In lieu of having much useful knowledge to share regarding the gene structure of unilateral ANs and NF2 tumors, I've copied-and pasted this statment from the NIDCD website:

"Scientists believe that both unilateral and bilateral vestibular schwannomas form following the loss of the function of a gene on chromosome 22. Scientists believe that this particular gene on chromosome 22 produces a protein that controls the growth of Schwann cells. When this gene malfunctions, Schwann cell growth is uncontrolled, resulting in a tumor.  Scientists also think that this gene may help control the growth of other types of tumors.  In NF2 patients, the faulty gene on chromosome 22 is inherited. For individuals with unilateral vestibular schwannoma, however, some scientists hypothesize that this gene somehow loses its ability to function properly."

http://www.nidcd.nih.gov/health/hearing/acoustic_neuroma.asp

I regret not being able to supply a more fully-informed response but I trust this information will be adequate, for the time being.

Jim
« Last Edit: October 12, 2009, 03:36:38 pm by Jim Scott »
4.5 cm AN diagnosed 5/06.  Retrosigmoid surgery 6/06.  Follow-up FSR completed 10/06.  Tumor shrinkage & necrosis noted on last MRI.  Life is good. 

Life is not the way it's supposed to be. It's the way it is.  The way we cope with it is what makes the difference.

Cheryl R

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Re: "Stupid" Question
« Reply #4 on: October 11, 2009, 04:37:25 pm »
I am NF2 and know of  Jims mention of  how the tumor infiltrates the nerve and also the chromosone 22  info.   My only info is that an NF2er has no different treatment of their ANs than a unilateral one due to the being NF2.         Drs are more likely to not want a person to have radiation.  But that varies too.        Each case has to be more indvidually analyzed when more than one tumor is present in a person.  The best long term results are harder to know.                 I had to look up the PAK1 as did not remember seeing that but has been awhile since did too much research on tumors. 
                                                                Cheryl R
Right mid fossa 11-01-01
  left tumor found 5-03,so have NF2
  trans lab for right facial nerve tumor
  with nerve graft 3-23-06
   CSF leak revision surgery 4-07-06
   left mid fossa 4-17-08
   near deaf on left before surgery
   with hearing much improved .
    Univ of Iowa for all care

jerseygirl

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Re: "Stupid" Question
« Reply #5 on: October 11, 2009, 05:55:23 pm »
Scott,

You have a very good question and it is not so simple because scientists so far do not know the exact answer to that. The current thinking, as Jim quoted, is that both sporadic ANs and NF2 (bilateral ANs) have NF2 mutations. Nf2's usually now have genetic testing but sporadic ANs are not routinely genetically tested, so it is impossible for scientists to say what the differences are. The idea that both types of ANs arise from the same gene stems from studies of some sporadic ANs which have been genetically analyzed by scientists. The studies showed that sporadic ANs have NF2 mutations.

Nowadays the diagnosis is given based on WHERE these mutations are. If the mutations are found in the blood, it is a full-blown NF2 case because presumably every single cell in the body is mutated. If there is only one AN and no other scwannomas, meningiomas or gliomas anywhere else and no NF2 mutations are found in the blood, then AN is called sporadic, unless the person is very young (below 30) when the case is suspect. In this case only the tumor cells are mutated. More often that not, AN is assumed to be sporadic unless proven otherwise. People who develop one AN, other tumors but have no detectable blood NF2  mutations, are called NF2 somatic mosaics. They have mutations in some cells in the body besides the tumor but not all and it is impossible to say which ones.

The fact that NF2 is inherited is a little bit of a misnomer because about 50% are spontaneous mutations, that is, they have no family history of the disease but have it themselves and can pass it on to the offspring.

NF2s develop ANs at a younger age, within a few years of each other. Their ANs are more aggressive and more difficult to remove. There are plenty exceptions to this "rule", even on this board. There are NF2s who developed their ANs within 20 years of each other, relatively late in life, and so on. Moreover, just because somebody is known to be an NF2 does not in any way predict the course of their disease. Nobody knows how many tumors if any the person will develop during the course of his/her life.

I do not know if it is possible according to the current thinking to have an AN if the person is diagnosed with NF1 because NF1 involves an entirely different gene. NF1 gene has been isolated earlier than NF2 gene and before that nobody distinguished between two types of Neurofibromatosis.  It is possible to have been diagnosed 20 years ago with NF1 only to be reclassified later as NF2 based on the presence of an AN.

I hope I helped and did not confuse you any further.

              Eve 
Right side AN (6x3x3 cm) removed in 1988 by Drs. Benjamin & Cohen at NYU (16 hrs); nerves involved III - XII.
Regrowth at the brainstem 2.5 cm removed by Dr.Shahinian in 4 hrs at SBI (hopefully, this time forever); nerves involved IV - X with VIII missing. No facial or swallowing issues.

scotts

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Re: "Stupid" Question
« Reply #6 on: October 11, 2009, 06:51:04 pm »
Thanks to all for the great information and valuable links you have provided.

You have pointed me in directions that I had not previously known about.

I really appreciate the guidance.


 


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