Tics are a movement disorder that produce involuntary contractions of muscle, and are commonly presented as eye blinks, shrugs, grunts, or sniffs. Tics usually develop in childhood; adult onset is very rare.
In a recent case study, a young adult who suffered a severe traumatic brain injury developed tics a year after his injury. When comparing his MRI scan from two weeks after his injury to an MRI scan done after the tics developed, his doctors found several small, new lesions to the basal ganglia of his brain.
Abnormalities of the basal ganglia are known to be related to tics. In the case of this young man, damage in the frontal lobe may have cut off neuronal pathways to the basal ganglia, therefore creating a new problem long after the original injury.