The nerves to the hand and fingers run from the head through the neck, and then through the shoulders, elbows, wrists and palm.
The cause of the tingling can come from any of those places, but usually from the neck.
Sometimes people will get a taller stem or riser bars in order to put themselves in a more erect position, thinking they have addressed the tingling by taking weight off of their hands; when, in reality, they have straightened out their neck so that they don't pinch the nerves in their neck which go to and from their hands.