Brachial neuralgia
In my early days in practice I had a patient with right lower cervical pain. After using a "cervical break" technique ON THE SAME SIDE he immediately had severe tingling and stinging pain radiating down his arm.
A break technique of course closes down the foramen on the same side, so ever since I try to avoid a cervical break on the side of pain. I either use a rotatory technique on the same side, or a break on the opposite side.
The patient recovered, but I clearly I injured the nerve.