• Skin wrinkling of the fingers following immersion in warm water depends on intact sympathetic innervation. It is abolished by lesions affecting both central and peripheral sympathetic pathways. It affords a simple and reliable clinical test of sympathetic function.
Jackson Braham, Menachem Sadeh, Ida Sarova-Pinhas. Skin Wrinkling on Immersion of HandsA Test of Sympathetic Function. Arch Neurol. 1979;36(2):113–114. doi:10.1001/archneur.1979.00500380083013