“Applying pressure to the skin can activate competing sensory signals, which may temporarily dampen pain perception, a concept sometimes referred to as ‘gate control’ of pain. This is because pain signals travel slower than sensory signals for touch, pressure and vibration,” explained Dr. Jon Stewart Hao Dy, a board-certified neurologist based in Manila, Philippines.
Article source: https://www.huffingtonpost.co.uk/entry/viral-claw-clip-migraines-explained_uk_6abe4fa4e4b02a789b332747