The effect of trigeminal neuralgia on the body depends on what is causing the condition. While the cause cannot always be determined, it is commonly the result of pressure on the trigeminal nerve. When something like a vein or artery presses against the nerve, which can cause pain impulses or block impulses; the result is pain or slight numbness. The same result can also happen if you develop a tumor near the trigeminal nerve, but this is much less common. A condition like multiple sclerosis can also result in trigeminal neuralgia, by causing damage to the myelin sheath that protects the nerve.