Guest guest Posted May 12, 2000 Report Share Posted May 12, 2000 << The doctor has done blood tests and an EMG.The doctor has sent our blood some place else to see if they can say what type we have. >> Electromyography/Nerve Conduction Study (EMG/NCV) The first study performed is usually EMG/NCV. The results will depend upon the type of CMT. For demyelinating types, the characteristic findings are diffusely and equally decreased conduction velocities. In every nerve tested, both sensory and motor, roughly the same degree of marked slowing is found. The amount of slowing is 60-80%, with absolute values around 20-25 m/s. Such slowing can also be found in asymptomatic individuals, and for this reason family members, even those who do not complain of weakness, are often tested to aid in the diagnosis. Nerve Biopsy Nerve biopsy is usually not necessary for diagnosis, especially since the availability of genetic testing. It is still helpful, however, for diagnostic dillemmas. Findings depend upon the type. Type 1 reveals demyelination and multiple layers of remyelination, called onion bulbing. Type 2 reveals axon loss with wallerian degeneration. Type 3 reveals demyelination with thinning of the myelin sheath. As important as what the biopsy shows, is what the biopsy should not show. There should be no inflammatory infiltrate indicating an autoimmune demyelinating process. Genetic Testing Genetic testing for CMT Type 1A is now commercially available. This allows for definitive diagnosis, even in asymptomatic individuals. Only 50-60% of cases, however, will be positive. The other 40-50% of patients with CMT have another genetic type. http://info.med.yale.edu/neurol/CNeurophysiol/CMT.htm (The 3 paragraphs above are from Yale, but the site is not dated so I don't know how old the information is. It's basically sound, however.) ===== There are at least 20 types that are already identified. Only 4 types of CMT can be diagnosed by DNA blood tests--1A, 1B, 1X, and HNPP. Some medical people do not know how to read the EMG results, so if the outside of the nerve is intact they assume, and report, that there is no CMT. BUT if it is type 2 it is the INSIDE or core of the nerve that is degenerating, NOT the outside. That looks different on an EMG, but the technician needs to know that. Some don't, so they claim there is no CMT. The DNA tests can NOT detect type 2 at this time. Type 2 is found by EMG, reflex tests, family history, and so forth. Type 1 is said to be more common, and it may be, or it could be that it is more often detected. If type 2 manifests itself later it life it may be dismissed as arthritis, aging, laziness, depression, post polio, and so forth. Males have the advantage of wearing pants that cover their AFOs. If his walk is awkward he might find he enjoys being able to walk more naturally with the AFO. I do know the problem, having raised two sons. The teen years are tough on parents (as well as on the teens). Regards, Kat Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 13, 2000 Report Share Posted May 13, 2000 My latest Information about genetic testing is as follows: Type x (as I have) disguises itself so that the genetic test is not definite. Research scientists assume that a lot of people diagnosed with Multiple Sklerosis in reality have cmt type x. Also through nerve biopsy type 2 is diagnosed but genetic testing shows it is type x. That is why genetic testing should be done. I have got these information from my genetic researcher who now is researching cmt (and only cmt) at the university of Zuerich, Switzerland. Bye, KathleenLS@... schrieb: > > > << The doctor has done blood tests and an EMG.The doctor has sent our blood > some place else to see if they can say what type we have. >> > > Electromyography/Nerve Conduction Study (EMG/NCV) > The first study performed is usually EMG/NCV. The results will depend upon > the type of CMT. For demyelinating types, the characteristic findings are > diffusely and equally decreased conduction velocities. In every nerve tested, > both sensory and motor, roughly the same degree of marked slowing is found. > The amount of slowing is 60-80%, with absolute values around 20-25 m/s. Such > slowing can also be found in asymptomatic individuals, and for this reason > family members, even those who do not complain of weakness, are often tested > to aid in the diagnosis. > > Nerve Biopsy > Nerve biopsy is usually not necessary for diagnosis, especially since the > availability of genetic testing. It is still helpful, however, for diagnostic > dillemmas. Findings depend upon the type. Type 1 reveals demyelination and > multiple layers of remyelination, called onion bulbing. Type 2 reveals axon > loss with wallerian degeneration. Type 3 reveals demyelination with thinning > of the myelin sheath. As important as what the biopsy shows, is what the > biopsy should not show. There should be no inflammatory infiltrate indicating > an autoimmune demyelinating process. > > Genetic Testing > Genetic testing for CMT Type 1A is now commercially available. This allows > for definitive diagnosis, even in asymptomatic individuals. Only 50-60% of > cases, however, will be positive. The other 40-50% of patients with CMT have > another genetic type. > http://info.med.yale.edu/neurol/CNeurophysiol/CMT.htm > > (The 3 paragraphs above are from Yale, but the site is not dated so I don't > know how old the information is. It's basically sound, however.) > ===== > There are at least 20 types that are already identified. Only 4 types of CMT > can be diagnosed by DNA blood tests--1A, 1B, 1X, and HNPP. > > Some medical people do not know how to read the EMG results, so if the > outside of the nerve is intact they assume, and report, that there is no CMT. > BUT if it is type 2 it is the INSIDE or core of the nerve that is > degenerating, NOT the outside. That looks different on an EMG, but the > technician needs to know that. Some don't, so they claim there is no CMT. > > The DNA tests can NOT detect type 2 at this time. Type 2 is found by EMG, > reflex tests, family history, and so forth. Type 1 is said to be more common, > and it may be, or it could be that it is more often detected. If type 2 > manifests itself later it life it may be dismissed as arthritis, aging, > laziness, depression, post polio, and so forth. > > Males have the advantage of wearing pants that cover their AFOs. If his walk > is awkward he might find he enjoys being able to walk more naturally with the > AFO. I do know the problem, having raised two sons. The teen years are tough > on parents (as well as on the teens). > > Regards, Kat > > ------------------------------------------------------------------------ > Save up to 54% on Quest & Kelty tents, backpacks, sleeping bags and > outdoor gear. FREE Shipping and a 30 Day Money-Back Guarantee at > screaminghotdeals.com > http://click.egroups.com/1/4012/10/_/616793/_/958146807/ > ------------------------------------------------------------------------ > > Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.