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Horizontal Gaze Nystagmus (HGN) testing is a common practice used by law enforcement in the United States in the identification of persons who are intoxicated or under the influence of a controlled substance. The key difference between recognizing PAN and horizontal gaze nystagmus is the position of the subject's head in relation to the body.
Nystagmus. Nystagmus is a condition of involuntary (or voluntary, in some cases) [1] eye movement. [2] People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. [3] In normal eyesight, while the head rotates about an axis, distant visual images are sustained by ...
Alexander's law refers to gaze-evoked nystagmus that occurs after an acute unilateral vestibular loss. It was first described in 1912 and has three elements to explain how the vestibulo-ocular reflex responds to an acute vestibular insult. The first element says that spontaneous nystagmus after an acute vestibular impairment has the fast phase ...
Benign paroxysmal positional vertigo ( BPPV) is a disorder arising from a problem in the inner ear. [ 3] Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. [ 1] This can occur with turning in bed or changing position. [ 3]
003429. In medicine, the caloric reflex test (sometimes termed 'vestibular caloric stimulation ') is a test of the vestibulo-ocular reflex that involves irrigating cold or warm water or air into the external auditory canal. This method was developed by Robert Bárány, who won a Nobel prize in 1914 for this discovery.
Horizontal optokinetic nystagmus. The optokinetic reflex ( OKR ), also referred to as the optokinetic response, or optokinetic nystagmus (OKN), is a compensatory reflex that supports visual image stabilization. [ 1] The purpose of OKR is to prevent image blur on the retina that would otherwise occur when an animal moves its head or navigates ...
Dissociated vertical deviation. Dissociated vertical deviation ( DVD) is an eye condition which occurs in association with a squint, typically infantile esotropia. The exact cause is unknown, although it is logical to assume it is from faulty innervation of eye muscles.
Hippus. Pupillary hippus, also known as pupillary athetosis, is spasmodic, rhythmic, but regular dilating and contracting pupillary movements between the sphincter and dilator muscles. [ 1][ 2] Pupillary hippus comes from the Greek hippos meaning horse, perhaps due to the rhythm of the contractions representing a galloping horse. [ 3]