The tic movements in themselves cannot harm the brain. However if your neck and neck muscles have taken a toll of strain, you may be prone to getting headaches and/or dizziness and nausea(related to muscle contraction, poor neck posture). The vestibular system (balance)is closely connected to the neck muscles and strain. The vestibular system can result in nausea and dizzyness. This is one possibility (without seeing you I cannot give a formal/complete answer)
Conceivably if you had a violent enough tic you could tear an artery in the neck and cause a stroke - this would be unlikely and you would have other stroke symptoms like focal weakness, clumsiness, difficulty swallowing, sensory loss etc. If that happened, go to the ER. Again this is unlikely to happen and I would not worry about this.
A physical therapist specializing in the neck are the best people to see to get the neck muscles and the vestibular system back on track. Alternatively you could try to get your tics under better control with medication under the supervision of your neurologist.
Good luck
you could be having neck spasms causing your nerves and or muscles to be irritated..