My first test, done by my neurologist didn't use heat. The second one was at Johns Hopkins, the room there was set up with a heat lamp installed, so it couldn't have been unusual. My body temperature is usually in the 96 degree range, and I am always cold from the CMT, the neurologist kept checking and telling the technician I was still too cold. The tests take a long time because they do my arms and legs at the same time since all are affected, also I have extremely long limbs.
The doctor at Hopkins was very pleased with himself because his results were slightly less dire than the ones from my doctor's office. I got the impression he attributed the difference to the heat and his skill, although my doctor is the head of the EMG/NCS department at a major hospital.
I wish someone else would corroborate the heat thing. My husband was with me, I swear I didn't make it up!
As Kitt said, they don't retest for CMT patients because they expect progression, so I won't be having any more.