[Impedance plethysmographic evaluation of sympathetic activity to lower extremity].

Impedance plethysmographic analysis was performed in two cases of late cortical cerebellar atrophy (LCCA) and two cases of Shy-Drager syndrome. Blood pressure, heart rate and peripheral hemodynamics (arterial blood flow and vascular resistance of lower extremity) were measured during head-up tilting. In cases of LCCA, there was no decrease of blood pressure by tilting up. Impedance plethysmography showed significant increase in vascular resistance of lower extremity and heart rate was also increased. In cases of Shy-Drager syndrome, however, marked decrease of blood pressure was shown during tilting up, while there was no significant change in heart rate and vascular resistance of lower extremity was decreased. Therefore, in cases of Shy-Drager syndrome, decrease of peripheral sympathetic activity to lower extremity was suggested. Impedance plethysmography of lower extremity is simple, non-invasive and useful method to assess the status of peripheral sympathetic activity.