Only one side of body affected (e.g. tremor in one limb), usually with minimal or no functional impairment.
Both sides of the body or the midline is affected, but posture and balance remain normal.
Impaired righting reflexes affecting both sides of the body characterized by a mild to moderate disabling imbalance when standing, turning or walking. The patient remains independent.
Severe disabling disease is present. Yet, the person can still stand and walk unaided. The patient usually requires help with activities of daily living.
The person is often restricted to a bed or a wheelchair unless aided.