Lambert-Eaton syndrome (also called Eaton-Lambert syndrome) is
a very rare condition in which a person's immune system attacks nerve tissues
it mistakenly identifies as invading organisms. As a result, electrical signals
do not travel between nerves and muscles as they should, which typically causes
weakness in the upper arm and thigh muscles.
Other symptoms may
include a dry mouth, muscle pain, vision problems, and droopy eyelids (ptosis).
Men with Lambert-Eaton syndrome may also be unable to achieve or maintain an
erection.
Certain forms of cancer can sometimes trigger the
development of Lambert-Eaton syndrome.