Session
8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI
Detection and Standardized Field Sobriety Testing
• Rotational
• Post
Rotational
• Caloric
Vestibular Nystagmus
8-20
Vestibular
Nystagmus is caused by movement or action to the vestibular system.
Types
of vestibular nystagmus:
•
Rotational Nystagmus occurs when the person is spun around or rotated rapidly,
causing
the fluid in the inner ear to be disturbed. If it were possible to observe the
eyes
of a rotating person, they would be seen to jerk noticeably.
•
Post Rotational Nystagmus is closely related to rotational nystagmus: when the
person
stops spinning, the fluid in the inner ear remains disturbed for a period of
time,
and
the eyes continue to jerk.
Neither
Rotational nor Post Rotational Nystagmus will interfere with the Horizontal
Gaze
Nystagmus
test because of the conditions under which they occur.
•
Caloric Nystagmus occurs when fluid motion in the canals of the vestibular
system is
stimulated
by temperature as by putting warm water in one ear and cold in the other.
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HS
178 R5/13 13 of 62
Standardized Field
Sobriety Testing
March 2013 Edition
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