A method and a device for establishing the presence of nerve damage (polyneuropathy) in a subject or the extent of nerve damage is distinguished by having the following features: the skin temperature on an extremity of the subject is increased, the perfusion value of this extremity is simultaneously measured and the time from onset of the increase in skin temperature to the onset of an increase in perfusion due to the increased skin temperature is evaluated as a measure of the presence or the extent of nerve damage.
