1/10. optic flow induced nystagmus.A new form of nystagmus is described in this paper: optic flow induced nystagmus (OFN). Optic field flow, for example when driving or viewing films on a large screen, triggered non-fatiguable upbeat nystagmus. This type of nystagmus could not be induced by vestibular stimuli, positioning, or self motion. The aetiology and anatomical correlate of OFN remains unknown. Treatment with gabapentin suppressed OFN.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
2/10. The neck-eye reflex in patients with reduced vestibular and optokinetic function.It is accepted that the neck-eye loop (cervico-ocular reflex, COR) is enhanced following loss of vestibular function and that this helps to restore gaze stability during head movements. In this paper we address the question of which structures and/or mechanisms may participate in such plastic enhancement by investigating the COR in 2 patients with absent vestibular function and reduced smooth pursuit-optokinetic eye movements (SP-OKN). The patients had multisystem atrophy involving the vestibular system and the cerebellum. The COR (elicited by angular motion of the trunk relative to the fixed head and angular motion of the head relative to the fixed trunk) was not enhanced in these 2 patients when compared with normal subjects, in contrast to previous findings in a group of patients with absent vestibular function alone. Measurements of slow phase eye movement velocity during SP-OKN stimuli and during combined COR-OKN stimulation (head oscillation relative to the stationary trunk in the light) showed identical values in these two conditions, which indicates that the neck-eye loop did not contribute to gaze stability during head movements. The absence of plastic enhancement of the COR in these patients may be secondary to interruption of SP-OKN pathways at various possible sites and/or to involvement of the vestibulocerebellum, which is known to mediate adaptive plasticity in the vestibulo-ocular reflex.- - - - - - - - - - ranking = 2keywords = motion (Clic here for more details about this article) |
3/10. Impairment of vertical motion detection and downgaze palsy due to rostral midbrain infarction.We present two cases with acute onset of vertical gaze palsy, mainly consisting of impaired downgaze and apraxia of downward head movements, together with neuropsychological deficits (hypersomnia, impaired attention and disorders of memory and affective control). CT and MRI revealed bilateral post-ischaemic lesions in the dorsomedial thalamus and the mesodiencephalic junction, dorsomedial to the red nucleus, thus being restricted to the territory of the posterior thalamosubthalamic paramedian artery, which includes the region of the rostral interstitial nucleus of the medial longitudinal fascicle as the main premotor nucleus for the generation of vertical saccades. In our patients, oculographic examination with electro-oculography and magnetic search coil recording showed severe impairment of downward more than upward saccades and only minor deficits of vertical pursuit and the vestibulo-ocular reflex. Visual functions were normal, with one exception: a psychophysical test of motion perception revealed a significant deficit in the detection of vertical movements. This could be due to a central adaptive mechanism which, in order to minimize oscillopsia, might elevate thresholds for vertical motion perception in cases of vertical gaze palsy. As an alternative explanation, lesions within the midbrain tegmentum could have damaged subcortical visual pathways involved in motion perception.- - - - - - - - - - ranking = 7keywords = motion (Clic here for more details about this article) |
4/10. Familial vestibulocerebellar dysfunction: a new syndrome?Three members of a single family with the symptom of "motion sickness" showed rebound nystagmus, saccadic pursuit eye movements, defective optokinetic slow phase velocity and lack of fixation suppression of vestibularly induced nystagmus. One of them showed vestibular hyperreactivity and a gradual build-up of the optokinetic response. In absence of other abnormalities, these findings can be localized to the vestibulocerebellum (flocculo-nodular lobe).- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
5/10. Periodic alternating nystagmus clearing after cataract surgery.A 60-year-old man developed periodic alternating nystagmus in association with decreased vision due to cataracts. Prior to surgery, vision was limited to hand motion only in both eyes. An extracapsular cataract extraction with insertion of a posterior chamber intraocular lens was performed in the patient's left eye. On the first postoperative day, vision was 20/60 in the left eye and the nystagmus was absent with both eyes open. Periodic alternating nystagmus that occurs with poor vision is related to a loss of fixation. Surgery aimed at improving the visual status may be effective in extinguishing the nystagmus.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
6/10. Migraine equivalent as a cause of episodic vertigo.There are many transient neurologic disturbances associated with various types of migraine. Visual symptoms, such as scintillating scotomata are most common, but somatosensory, motor, cranial nerve, and brain stem symptoms also occur. Among the brain stem symptoms, vestibular manifestations are quite common and include nonspecific dizziness, disequilibrium, vertigo, and motion intolerance. Auditory symptoms are less common. These transient neurologic symptoms can precede the headache as an aura, can occur during the headache, or, uncommonly, can immediately follow the headache. It is also well documented that the neurologic symptoms can occur in the period between headaches, a situation termed "migraine equivalent." Migraine equivalents usually occur in patients who have experienced typical migraine headaches earlier in life or who have migraine headaches at times other than when they experience equivalent symptoms. Rarely, typical migraine equivalent symptoms precede the development of the headaches by months or years, or occur in individuals who never develop headaches. Five patients with migraine equivalent symptoms that include vertigo are presented. The vertigo was the dominant symptom in some cases and was accompanied by nausea and vomiting. Differentiation from peripheral labyrinthine disorders is difficult, but a personal or family history of migraine, the temporal association of the neuro-otologic symptoms with other migraine equivalent symptoms, a characteristic pattern of occurrence of the symptoms, and a positive response to antimigrainous therapy are features that strengthen the diagnosis of a migraine equivalent phenomenon.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
7/10. Jerk nystagmus: some new findings.eye movements in a subject with jerk nystagmus were recorded during a variety of tracking tasks using a photoelectric method. New findings included ability to reduce nystagmus amplitude and frequency when instructed "to hold the eye steady" rather than "to fixate" in the presence of a visible target, changes in nystagmus characteristics and visual acuity as a function of head position which related to overall retinal-image motion, marked variability of nystagmus especially during reading, and necessity of a prolonged period of visual feedback for generation of nystagmus to approach a "steady-state" level. Clinical implications of these findings are discussed, including use of the "hold" command during ophthalmoscopy in patients with nystagmus.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
8/10. arnold-chiari malformation: improvement in eye movements after surgical treatment.We studied abnormalities of eye movement in five patients with arnold-chiari malformation before and after suboccipital decompression. Before operation all patients complained of oscillopsia at rest and visual blurring of fixated targets during and immediately after their heads were in motion. Three patients had downbeat nystagmus, one patient had horizontal nystagmus in the primary position and on eccentric gaze and one patient had rotatory nystagmus on lateral gaze only. Smooth pursuit, optokinetic nystagmus and fixation suppression of vestibular nystagmus were markedly impaired. Within two months after operation nystagmus in the primary position had resolved in three patients, and four had complete to near-complete resolution of nystagmus in all gaze positions over subsequent months. Oscillopsia decreased concurrently. affording significant functional visual improvement. One patient had only slight functional improvement and continued to have prominent nystagmus seven years after operation. Smooth pursuit, optokinetic nystagmus and fixation suppression of vestibular nystagmus improved in all patients, but none had complete recovery at the higher velocities of stimulation. They still complained of visual blurring associated with head motion, probably due to the poor fixation suppression of vestibular nystagmus. Our findings suggest that abnormalities of eye movement in arnold-chiari malformation are due to compression of the herniating cerebellum against the caudal brain-stem and not a congenital aberrancy of oculomotor pathways. Nystagmus resolved more readily than pursuit or fixation suppression abnormalities, but most patients showed gradual improvement in all abnormalities four months after operation.- - - - - - - - - - ranking = 2keywords = motion (Clic here for more details about this article) |
9/10. Torsional nystagmus during vertical pursuit.We examined three patients with cavernous angioma within the middle cerebellar peduncle. Each patient had an unusual ocular motor finding: the appearance of a strong torsional nystagmus during vertical pursuit. The uncalled-for torsion changed direction when vertical pursuit changed direction. In one patient, we recorded eye movements with the magnetic field technique using a combined direction and torsion eye coil. The slow-phase velocity of the inappropriate torsional nystagmus was linearly related to the slow-phase velocity of vertical smooth pursuit, and changed direction when vertical pursuit changed direction. This torsional nystagmus also appeared during fixation suppression of the vertical vestibulo-ocular reflex (VOR), but was minimal during vertical head rotation when fixing a stationary target in the light. We suggest that inappropriately directed eye movements during pursuit might be another ocular motor sign of cerebellar dysfunction. Furthermore, we speculate that the signals used for vertical smooth pursuit are, at some stage, encoded in a semicircular canal VOR coordinate framework. To illustrate, for the vertical semicircular canals, vertical and torsional motion are combined on the same cells, with the anterior semicircular canals mediating upward movements and the posterior semicircular canals mediating downward movements. For the right labyrinth, however, both vertical semicircular canals produce clockwise slow phases (ipsilateral eye intorts, contralateral eye extorts). The opposite is true for the vertical semicircular canals in the left labyrinth; counterclockwise slow phases are produced. Hence, to generate a pure vertical VOR, the anterior or posterior semicircular canals on both sides of the head must be excited so that opposite-directed torsional components cancel. Thus, if pursuit were organized in a way similar to the VOR, pure vertical pursuit would require that oppositely-directed torsional components cancel in normals. If this did not happen, a residual torsional nystagmus could appear during attempted vertical pursuit.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
10/10. The ocular tilt reaction. A paroxysmal dyskinesia associated with elliptical nystagmus.The ocular tilt reaction, a synkinesis of ocular torsion, skew deviation, and head tilting, was a paroxysmal disorder in a patient with multiple sclerosis. In this distinctive pattern of eye and head motion, the 12 o'clock corneal meridians of both eyes are rotated conjugately in the direction of the lower skewed eye and the head is inclined laterally in the same direction. Paroxysmal activation of brain stem otolithic vestibular projections is proposed responsible for the dyskinesia. Coincident attacks of vertical and horizontal low amplitude pendular oscillation of the eyes produced elliptical nystagmus. This ocular motor disorder was treated effectively with carbamazepine.- - - - - - - - - - ranking = 1keywords = motion (Clic here for more details about this article) |
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