Tests

March 15, 2000

<< I have also heard you guys talk about some tests that are painful, are any

of these

them? >>

The EMG is painful for some people. I felt virtually nothing.

Electromyography (EMG) and nerve conduction velocity tests help confirm

neuropathy, and document specific nerve involvement and the predominant type

of fiber involved (sensory, motor). Demyelinating lesions slow nerve

conductions, and focal demyelinating blocks may be documented. An axonal

process causes spontaneous activity on EMG along with low amplitude evoked

responses, and relatively preserved conduction velocities on nerve conduction

studies. In carpal tunnel syndrome, conduction slows across the carpal

ligament, prolonging the latency to the abductor pollicis brevis or blocking

it altogether. The distal sensory latency is similarly lengthened. Ulnar

motor and sensory distal latencies must be normal in the same arm. Muscle

biopsy may sometimes provide specific diagnoses (trichinosis, sarcoidosis,

polyarteritis). Sural nerve biopsies rarely are indicated.

From the Merck manual.

Kat in Seattle

Why is she having all these tests? Wasn't Chance diagnosed with CMT? When a

person has family history of CMT it makes the diagnosis rather simple.

April 14, 2000

There are three DNA blood tests available for CMT and a fourth in the

advanced experimental stages.

The tests are called:

-- DNA genetic screen for CMT Type 1A

-- DNA genetic screen for CMT Type 1 X-Linked

-- DNA genetic screen for HNPP --

and the one that is in the experimental stages is for CMT Type 1B and is

available at some of the University Medical Centres that are doing research.

These blood tests will NOT identify the other 20 or more types of CMT.

http://www.geneclinics.org/profiles/index.html

DESCRIPTION: Charcot-Marie-Tooth disorder (CMT) is an inherited neurological

disease characterized by a slowly progressive degeneration of the muscles in

the foot, lower leg, hand, and forearm, and a mild loss of sensation in the

limbs, fingers, and toes. The first sign of CMT is generally a high arched

foot or gait disturbances. Other symptoms of the disorder may include foot

bone abnormalities such as high arches and hammer toes, problems with hand

function and balance, occasional lower leg and forearm muscle cramping, loss

of some normal reflexes, occasional partial sight and/or hearing loss, and,

in some patients, scoliosis (curvature of the spine).

CMT is a disorder of genetic heterogeneity, in which mutations in different

genes can produce the same clinical symptoms. In CMT, there are not only

different genes but different patterns of inheritance. The most common type,

CMT1A, is inherited in an autosomal dominant pattern. This means that if one

parent has CMT there is a 50 percent chance of passing the disease on to each

child. Other types are autosomal recessive or sex-linked CMT. Each type is

characterized by symptoms ranging from severe weakness and wasting of leg and

hand muscles to very mild symptoms or no symptoms at all. Full expression of

CMT's clinical symptoms generally occurs by age 30. The more severe symptoms

are related to an earlier age of onset.

http://www.lvhealth.com/lv/mental/encyc/charcott.htm

April 14, 2000