Sub-clinical seizures are not typically associated with the characteristic behaviors of conventional seizures, but they are characterized by abnormal EEG patterns. Head-banging or ear hitting may be caused by a middle ear infection. Self-injury acts as a release, and thus, lowers arousal. That is, they are repetitive, ritualistic behaviors which provide the individual with some form of sensory stimulation or arousal.
Some individuals exhibit self-injury to escape or avoid a task.
Although it has not been discussed in the research literature, there is also the possibility that these behaviors could be related to hypersensitivity to certain sounds in the environment. Basically, there are many reasons why people engage in self-injurious behavior. The best way to determine the reason for the behavior in an individual is to conduct a functional analysis. This involves analyzing what occurs prior to the behavior as well as what happens immediately after the behavior. If one can rule out possible social influences on the behavior, then physiological causes should be investigated.