Polyneuropathy occurs with a combination of multiple symptoms, signs, and abnormal electrodiagnostic studies so electrophysiological examination should always be done to avoid underestimating peripheral neuropathy.Autonomic disturbance can be assessed by recording PASP even in subclinical conditions. Also it gives a quantitative data about the degree of damage of descending sympathetic fibers, so that it will be very helpful for early diagnosis of autonomic dysfunction