Braham J, Sadeh M, Sarova-Pinhas I
Arch Neurol. 1979 Feb;36(2):113-4. doi: 10.1001/archneur.1979.00500380083013.
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.