NEJM -- Sign In Only a patient with a central lesion shows pathologic saccades. To identifypathologic optokinetic nystagmus, move a banded cloth in front of the patient s http://content.nejm.org/cgi/content/full/340/2/151-a
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Vertigo Index Particulate Matter within the Membranous Labyrinth pathologic or Mal. Benign Paroxysmal Positional Vertigo and Rotatory Induced nystagmus. http://www.mumedia.be/vertigo.htm
Extractions: Nouvelles Publications : Dr. R. BONIVER " Nystagmus Paroxystiques bénins: Etat actuel de la question." Anciennes Publications : Procédure de recherche Cliquez ici , puis tapez CTRL-F et indiquez dans la cellule de saisie l'auteur ou le sujet désiré. Horizontal Otolith Ocular Responses to Lateral Translation in Benign Paroxysmal Positional Vertigo. Acta Otolaryng. (Stockh.), 1997, 117, 468-471. The Pathogenesis of Positional Nystagmus. Acta Oto-Laryngol. Stockholm, 1961, 159 : 90-93. Positional Nystagmus in Normals. Adv. Oto-Rhino-Laryngol., 1973, 69 : 276-285. BONIVER R,DEMANEZ J.P.,LENNES G.
OCULAR FIXATION subject to fix his eyes upon a clearly visible target, upon any ongoing nystagmus.The fixation index is the ratio of nystagmus peak slowphase velocity http://www.tchain.com/otoneurology/practice/fixation.html
Extractions: OCULAR FIXATION Impaired Fixation Suppression The diagnosis of impaired fixation suppression is made by observing the effect of asking the subject to fix his eyes upon a clearly visible target, upon any ongoing nystagmus. The fixation index is the ratio of nystagmus peak slow-phase velocity with fixation to nystagmus intensity with fixation removed (e.g. complete darkness or eyes closed). For nystagmus induced by caloric input, Takemori and Cohen (Takemori and Cohen, 1974) found the normal mean fixation index to be 48 10 percent. Similarly, Alpert reported the normal humans had a fixation index between 60 and 70 (Alpert, 1974). However, it is questionable whether these value are appropriate normal values for several reasons. It seems likely that fixation index should increase with age, as the pursuit declines with age, but fixation data according to age are not available. Similarly, fixation suppression is probably affected by the many other variables which affect pursuit. It also seems likely that the efficiency of fixation is related to the intensity of nystagmus that one is attempting to suppress. Peripheral vestibular nystagmus is usually well suppressed by fixation. Congenital nystagmus and many varieties of central nystagmus are unaffected by or even increased by fixation. Nystagmus which is increased by fixation is called "fixation nystagmus".
Extractions: Nystagmus pathologique Définition [MeSH Scope Note ; traduction CISMeF] : Mouvements involontaires de l'oeil divisés en deux types, saccade et pendulaire. Le nystagmus à saccade a une phase lente dans une direction suivie d'une phase rapide corrective dans la direction opposée, et est habituellement provoqué par le dysfonctionnement vestibulaire central ou périphérique. Le nystagmus pendulaire comporte les oscillations qui sont de vitesse égale dans les deux directions et cette condition est souvent associée à la perte visuelle tôt dans la vie. Synonyme(s) MeSH Nystagmus alternant périodique ; Nystagmus associé ; Nystagmus conjugué ; Nystagmus de convergence ; Nystagmus de position fatigable ; Nystagmus de position non fatigable ; Nystagmus dissocié ; Nystagmus en bascule ; Nystagmus en dent de scie ; Nystagmus horizontal ; Nystagmus multidirectionnel ; Nystagmus oculaire spontané ; Nystagmus pendulaire ; Nystagmus permanent ; Nystagmus positionnel fatigable ; Nystagmus positionnel non fatigable ; Nystagmus retractorius ; Nystagmus rotatoire ; Nystagmus symptomatique ; Nystagmus temporaire ; Nystagmus unidirectionnel ; Nystagmus vertical ; Nystagmus à rebond ; Nystagmus à ressort
TRACKING TEST Unidirectional spontaneous nystagmus may be superimposed upon pursuit and cause Spontaneous nystagmus due to peripheral vestibular lesions, when weak, http://www.dizziness-and-balance.com/practice/tracking_test.htm
Extractions: TRACKING TEST (Smooth Pursuit) Timothy C. Hain, MD Please read our Return to Index Search this site Page last modified: March 5, 2005 The screen shot above, from our clinical laboratory in Chicago , shows what a computerized tracking test looks like. The tracking test measures the ability of subjects to match eye movement to visual target movement. The blue line is a target projected by an LCD projector on as screen about 1.5 meters in front of the subject. The green line on the top is the horizontal eye position. Note that sometimes the eye falls behind the target and has to make an abrupt more rapid movement to catch up (this is called a "catch-up saccade). The vertical eye position is shown on the bttom trace. It is rather quiet showing occasional blink artifacts, and a small amount of undulation related an imprecise rotational alignment of the eye-camera with respect to the left eye (this can be easily seen on the right video, which contains the left eye). A example of a processed tracking test (labelled Smooth Pursuit) is shown below. Sinusoidal pursuit is processed with Fourier fits and a Bode plot is produced. This figure shows normal pursuit, where only one eye was recorded. Methods of producing a smooth pursuit target.
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