A) Head MRI (left panels) demonstrates cortical atrophy in frontal and temporal lobes. Positron emission tomography (PET) with 2-deoxy-2-fluoro- [18F]-D-glucose (FDG) PET (right panels) demonstrates hypometabolism in the same cortical regions. Middle panels show co-registration of MRI and FDG PET studies. B) Thermoregulatory sweating tests in the same patient with PPND. Shaded areas represent sweating over the anterior body surface. Distal anhidrosis is seen.