What is the difference between HGN and other types of nystagmus?

Horizontal Gaze Nystagmus (HGN) is distinctly characterized by its relationship with gaze direction and its prominent association with alcohol impairment. When an individual is under the influence of alcohol or certain other substances, their ability to smoothly track a moving object can be disrupted. This becomes evident as the eyes exhibit involuntary jerking movements when they are directed to the sides. The significance of this nystagmus type lies in its predictive value for determining impairment due to alcohol, making it a useful tool in field sobriety testing.

In contrast, other types of nystagmus may not be specifically tied to gaze direction or intoxication. For example, some forms of nystagmus can occur due to neurological conditions, medications, or even fatigue, and they may not always present the same way during a gaze test. HGN, therefore, stands out for its specific diagnostic implications in identifying alcohol-related impairment, reinforcing why its relation to gaze direction and alcohol makes it a uniquely valuable indicator in the assessment of a person's coordination and cognitive function regarding substance use.