abnormal vestibular system physiology [MP:0004742] is defined as "any functional anomaly of the sensory system responsible for the sense of head position and movement of the body through space; such anomalies may include impaired balance, dizziness, poor regulation of postural muscle tone and inability to detect quick movements of the head." However, we don't have any of the associated motor dysfunctions associated with it.
Consider making parent child relations with:
impaired balance [MP:0001525]
head bobbing [MP:0001410]
These last two terms would need definition revisions since they reference a compulsive behavior. However, head tilting, bobbing and circling are common symptoms of disruption in balance.