Gaze induced nystagmus occurs or is exacerbated as a result of changing ones gaze toward or away from a particular side which has an affected central apparatus. Peripheral nystagmus occurs as a result of either normal or diseased functional states of the vestibular system and may combine a rotational component with vertical or horizontal eye movements and may be spontaneous, positional, or evoked. Positional nystagmus occurs when a persons head is in a specific position. An example of disease state in which this occurs is Benign paroxysmal positional vertigo (BPPV). Post rotational nystagmus occurs after an imbalance is created between a normal side and a diseased side by stimulation of the vestibular system by rapid shaking or rotation of the head. Spontaneous nystagmus is nystagmus that occurs randomly, regardless of the position of the patients head. Physiological nystagmus
Physiological nystagmus is a form of involuntary eye movement that is part of the vestibulo-ocular reflex (VOR), characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction. Variations
The direction of nystagmus is defined by the direction of its quick phase (e.g. a right-beating nystagmus is characterized by a rightward-moving quick phase, and a left-beating nystagmus by a leftward-moving quick phase). The oscillations may occur in the vertical, horizontal or torsional planes, or in any combination. The resulting nystagmus is often named as a gross description of the movement, e.g. downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus.
Visceroptosis also is known as Glénards disease (after French physician Frantz Glénard [1848–1920]). Glénards theory – the theory that abdominal ptosis is a nutritional disease with atrophy and prolapse of the intestine
Glénards test (also called girdle test) – while standing behind the patient, the examiner places his arms around the patient, so that his hands meet in front of the patients abdomen; he squeezes, raising the viscera, and then allows them to fall suddenly; Glénards theory suggests that if the patient feels relieved by the raising pressure and experiences distress on the release, the condition is probably one of splanchnoptosis
Stillers theory – the theory that gastroptosis is due to universal asthenia characterized by weakness and laxity of the viscera

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This article incorporates text from a publication now in the public domain: Gilman, D. C.; Peck, H. T.; Colby, F. M., eds. (1905). New International Encyclopedia (1st ed.). New York: Dodd, Mead. {{cite encyclopedia}}: Missing or empty |title= (help)