Can head trauma cause seizures and/or hallucinations?

Yes, it can: Head trauma can cause a host of problems both immediately and long-term. Some injuries are more obvious -- like skull fractures, gunshot wounds, etc. Others, like closed head injuries or concussions, are less obvious but suffering is still present. One needs a good neurologist and neuropsychiatrist to help with such situations. Medications can be tricky, and behavioral management's needed too.