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To investigate the frequency and pattern of failure of the fixation suppression (FFS) of spontaneous nystagmus (SN) in unilateral cerebellar infarction, and to identify the structure responsible for FFS, 29 patients with acute, mainly unilateral, isolated cerebellar infarction who had SN with a predominantly horizontal component were enrolled in this study. The ocular fixation index (OFI) was defined as the mean slow phase velocity (SPV) of the horizontal component of SN with fixation divided by the mean SPV of the horizontal component of SN without fixation. The OFI from age- and sex-matched patients with vestibular neuritis was calculated and used as the control data. The FFS of SN was only found in less than half (41 %, 12/29) of the patients. Approximately 65 % ( n = 7) of the patients with isolated anterior inferior cerebellar artery territory cerebellar infarction showed FFS, whereas only a quarter ( n = 3) of the patients with isolated posterior inferior cerebellar artery (PICA) territory cerebellar infarction showed FFS. The proportion of gaze-evoked nystagmus (6/12 [50 %] vs. 2/17 [12 %], p = 0.04) and deficient gain of ipsilesional pursuit (10/12 [83 %] vs. 6/17 [35 %], p = 0.05) was more frequent in the FFS group than in the group without FFS. Lesion subtraction analysis in isolated PICA territory cerebellar infarction revealed that the nodulus was commonly damaged in patients with FFS, compared to that of patients without FFS. Our study shows that FFS of SN due to acute cerebellar infarction is less common than previously thought and the nodulus may be an important structure for the suppression of SN in humans. [ABSTRACT FROM AUTHOR]

Background: It was the aim of this study to investigate the pattern of evolution of hyperventilation-induced nystagmus (HIN) in vestibular neuritis (VN) and to determine whether HIN influences the dizziness outcome at the last follow-up visit. Methods: Fifty-three consecutive patients with VN underwent a quantitative vestibular function test including hyperventilation and the Korean version of the Dizziness Handicap Inventory during the acute period and the follow-up visit. Results: The incidence of HIN was higher in the acute (62%, 33/53) than in the chronic (17%, 9/53) stages of VN. Approximately 70% (6/9) of patients who continued to have persistent HIN at the last follow-up reported dizziness compared to only 27% (12/44) of patients who had no HIN. Patients who complained of persistent dizziness were significantly more likely to have persistent HIN and high Korean Dizziness Handicap Inventory scores at the last follow-up compared with patients who did not suffer from dizziness. In terms of the degree of recovery of dizziness, patients with HIN initially beating toward the contralesional side exhibited significantly more improvement than patients with HIN initially beating toward the ipsilesional side. Conclusions: The presence of either HIN beating toward the ipsilesional side at the acute stage of VN or persistent HIN at the follow-up visit is associated with persistent dizziness. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Impairment of gaze holding mechanism and gaze-evoked nystagmus (GEN) in the vertical plane due to a focal brain lesion is usually caused by a failure of the vertical neural integrator, which is known to be localized in the interstitial nucleus of the Cajal in the upper midbrain. We report a patient with hemorrhagic stroke involving the paramedian pontine tegmentum who presented with vertical GEN due to a failure of vertical gaze holding mechanism and unilateral internuclear ophthalmoplegia. The possible structure taking a role as a vertical neural integrator in this patient might be the paramedian tract (PMT) neuron. [Copyright &y& Elsevier]

Rotational vertebral artery syndrome (RVAS) is characterized by recurrent attacks of paroxysmal vertigo, nystagmus, and ataxia induced by head rotation. Although recent report has described the RVAS as an important but unrecognized cause of isolated vascular vertigo, the locus of injury site responsible for isolated vertigo in RVAS is still unclear. We report here two patients with RVAS who had a stereotypic clinical presentation characterized by recurrent attacks of isolated vertigo induced by head rotation. The pattern of nystagmus observed in our patients with RVAS can be best explained by the stimulation of the vestibular labyrinth bilaterally or unilaterally. In RVAS, the isolated vertigo may occur due to transient ischemia of the superior vestibular labyrinth. RAVS should be considered in the differential diagnosis of positional vertigo, especially when vertigo is developed while sitting or standing position. [ABSTRACT FROM AUTHOR]

Positional vertigo and nystagmus without associated neurological symptoms and signs are characteristic features of benign paroxysmal positional vertigo (BPPV). Although positional nystagmus may occur with caudal cerebellar infarction including the nodulus, positional nystagmus is usually associated with other neurological signs such as spontaneous or gaze-evoked nystagmus, perverted head-shaking nystagmus, cerebellar dysmetria, or severe gait ataxia with falling. We present a patient with nodular infarction who had positional vertigo with nystagmus as a sole manifestation. Video-oculography showed apogeotropic positional horizontal nystagmus during head turning while supine, which was consistent with apogeotropic BPPV involving the horizontal canal. MRI disclosed acute infarct in the nodulus. Nodulus infarction should be considered in a patient with positional nystagmus, especially when the presenting symptoms and signs are consistent with BPPV involving the horizontal canal. [ABSTRACT FROM AUTHOR]

The caloric test is probably the most widely used clinical test of vestibular function. A unilateral decrease in response to cold and warm water reliably indicates a unilateral peripheral vestibular lesion. Central signs on caloric testing are less common but important to recognize because they are often associated with lesions of the brainstem. We describe a patient with a tumor originating in the floor of the fourth ventricle who presented with premature reversal after cold stimulation on one side and perverted nystagmus after cold stimulation of the other side. [ABSTRACT FROM AUTHOR]

Abstract: Upbeat nystagmus (UBN) is typically increased with upward gaze and decreased with downward gaze. We describe a patient with acute multiple sclerosis who developed primary position UBN with a linear slow phase waveform, in which the velocity of nystagmus was intensified in downward gaze and decreased during upward gaze. Brain MRI showed high signal lesions in the paramedian dorsal area of the caudal medulla encompassing the most caudal part of the perihypoglossal nuclei. Clinicians should be aware of possibility of a caudal medullary lesion in a patient with UBN, especially when the velocity of the UBN is increased in downward gaze. [Copyright &y& Elsevier]