Wartenberg wheel

The wheel was designed to test nerve reactions (sensitivity) as it rolled systematically across the skin.

[1] A Wartenberg wheel is generally made of stainless steel with a handle of approximately 18 centimetres (7 in) in length.

The wheel, which has evenly spaced radiating sharp pins, rotates as it is rolled across the flesh.

[3] According to Wartenberg himself, the device was in widespread use in Europe when he lived in Germany.

[3] While he did not invent it, he found it "an indispensable part of the outfit for everyday neurologic practice," and recommended its use to his colleagues in the US.