The term chronic subjective dizziness (CSD) is used to describe a commonly encountered type of dizziness that is not easily categorized into one of several other types, and for which the physical examination is typically normal. Patients with CSD frequently initially suffer a sudden injury of some sort to their vestibular system, the neurologic network that preserves our sense of balance. Even after this initial injury has healed, people with CSD usually describe a vague sense of unsteadiness worsened by triggers in their environment such as high places, standing on moving objects, or standing in motion-rich environments like busy streets or crowds.
Chronic subjective dizziness (CSD) is characterized by persistent (>3 months) dizziness, lightheadedness, or unsteadiness, without vertigo or ataxia. Symptoms often are worse in highly stimulating visual environments (eg, busy malls or grocery stores) or settings with indistinct visual orientation cues (eg, large open areas, heavy fog). Neuro-otologic examination and laboratory testing reveal no active vestibular deficits.
CSD is not a psychiatric illness, but exists at the interface of psychiatry and neuro-otology. For example, anxiety and depressive disorders often accompany CSD, but are not an integral part of it. Treatment outcomes are good and prognosis for full function is high.
Source(s): About.com: Neurology, Current Psychiatry