What are some forms of schizophrenia that don't involve either auditory or visual hallucinations?

All forms. A person may only have delusions and still have schizophrenia. Delusions are fixed, false beliefs. Paranoid schizophrenia is the most common type and it is when a person believes that people he or she doesn't even know is out to get them. One may believe they are being followed, that the tv is trying to provide a special message just for them or that others can hear their thoughts, for example.