Eye twitching is often caused by fatigue and stress and can cease by its own. It can last for some days, weeks or even months. You have to avoid coffee and stressful or tiring situations and activities. You can use lorazepam for some days, also. Rarely it can be a sign of some disease such as Bell s palsy and Tourette syndrome, or eye infection but other symptoms and signs occur. According to your concern about the relation of vertebral artery and facial nerve: if the facial nerve has any abnormality and if it presents with spasms , someone should have hemifacial (half of the face) spasms. You can see a neurologist to undergo the objective examination.