Paroxysmal alternating nystagmus

Paroxysmal reversal of spontaneous nystagmus has rarely been described. Herein, we report recurrent bouts of vertigo and oscillopsia in association with reversed spontaneous nystagmus in a patient with prior surgical resection of the cerebellar vermis due to medulloblastoma and subsequent labyrinthine damage. The symptoms almost completely resolved with carbamazepine. The episodes may be ascribed to paroxysmal reversal of the vestibular asymmetry due to intermittent decompensation by the deficient cerebellum.     

Slowly alternating skew deviation: Description of a pretectal syndrome in three patients

Three patients who had slowly alternating skew deviation are described: each had elements of the Sylvian aqueduct syndrome. This combination of signs supports a pretectal location for lesions associated with alternating skew movements. Postmortem examination of a patient who died of chronic herpes simplex encephalitis showed extensive demyelination and periaqueductal spongiform degeneration; there was preservation of the oculomotor and trochlear nuclei, the medial longitudinal fasciculus, vestibular nuclei, and the interstitial nucleus of Cajal bilaterally. The slowly alternating dysconjugate vertical movements bear a resemblance to both see-saw nystagmus and the ocular tilt response.     

Arnold-Chiari malformation and nystagmus of skew

The Arnold-Chiari malfomation is typically associated with downbeat nystagmus. Eye movement recordings in two patients with Arnold-Chiari malfomation type 1 showed, in addition to downbeat and gaze evoked nystagmus, intermittent nystagmus of skew. To date this finding has not been reported in association with Arnold-Chiari malfomation. Nystagmus of skew should raise the suspicion of Arnold-Chiari malfomation and prompt sagittal head MRI examination.     

Epileptic gaze deviation and nystagmus

We studied a patient with stereotyped focal seizures characterized by leftward conjugate eye- and head-turning followed by nystagmus. Eye deviation was associated with the appearance of seizure activity, recorded over the right temporo-occipital scalp, that did not spread frontally. The initial eye deviation consisted of a staircase of small saccades. The subsequent nystagmus showed rightward decreasing-velocity exponential slow phases and normal leftward quick phases. Saccadic eye movements due to seizures may occur via projections from posterior cortical areas as well as from the frontal eye fields.     

Treatment of periodic alternating nystagmus

Two patients with longstanding acquired periodic alternating nystagmus (PAN) were treated with baclofen, 30 mg/day. Baclofen abolished the PAN and relieved oscillopsia in both patients but was ineffective in another patient with congenital PAN.     

Anti-GAD antibodies and periodic alternating nystagmus

BACKGROUND: Autoantibodies directed against glutamic acid decarboxylase (GAD-Ab) have recently been described in a few patients with progressive cerebellar ataxia, suggesting an autoimmune physiopathologic mechanism. OBJECTIVE: To determine the exact role of GAD-Ab and gamma-aminobutyric acid (GABA)-ergic neurotransmission in the pathogenesis of cerebellar ataxia. DESIGN: Case report. SETTING: University neurological hospital. PATIENT: We report the case of a patient with subacute cerebellar ataxia associated with GAD-Ab showing periodic alternating nystagmus (PAN). INTERVENTION: Baclofen, a GABAergic medication, was given to the patient. MAIN OUTCOME MEASURES: Eye movement recording of spontaneous nystagmus and postrotatory vestibular responses. RESULTS: Baclofen was effective in suppressing PAN and improving postrotatory vestibular responses but not for improving cerebellar ataxia. CONCLUSION: The presence of PAN and the response to baclofen provide a unique opportunity to suggest a direct role of GAD-Ab in cerebellar dysfunction in this patient.     

Different types of skew deviation.

Although all manifest skew deviations appear the same for the clinician, skew deviation can result from different combinations of dysconjugate vertical ocular deviations. Evidence is presented for three different types of skew deviation when it occurs as a feature of an ocular tilt reaction. In type 1 (utricle) there is upward deviation of both eyes with different amplitudes, as described for otolith Tullio phenomenon in humans. In Type 2 (dorsolateral medulla oblongata) hypertropia of one eye occurs while the other eye remains in the primary position, the hypothetical mechanism of skew deviation in Wallenberg's syndrome. In Type 3 (midbrain tegmentum) there is simultaneous hypertropia of one eye and hypotropia of the other eye, as described for electrical stimulation of midbrain tegmentum in monkeys and observed in clinical cases with a paroxysmal ocular tilt reaction.     

Surgical management of skew deviation.

There are no published data on the outcomes of realignment surgery for skew deviation. A retrospective chart review disclosed 10 patients who had undergone surgical correction of skew deviation by three surgeons at a single institution between 1991 and 2002. Nine of 10 patients had satisfactory relief of diplopia with an acceptable field of single binocular vision. Vertical rectus recession or resection was the most common procedure. Four patients required more than one procedure. For nonalternating hypertropias, resection of the inferior rectus muscle or recession of the superior rectus muscle of the hypertropic eye was successful. For alternating hypertropia, resection of both inferior rectus muscles was successful. Oblique muscle surgery was not associated with good outcomes.     

Periodic alternating nystagmus and rebound nystagmus in spinocerebellar ataxia type 6.

We report on a family with ataxia type 6 (SCA6) showing peculiar oculomotor symptoms. The proband presented with periodic alternating nystagmus (PAN), and her 2 brothers had rebound nystagmus and gaze-evoked nystagmus. They carried the identical mutation (the number of expanded CAG repeat, 24) in the CACNA1A gene. The intrafamilial variability of oculomotor symptoms may be ascribed to factors other than CAG repeat expansion size in SCA6.     

Vertical and horizontal epileptic gaze deviation and nystagmus

Periods of epileptic nystagmus consisting of rightward eye deviation and right-beating nystagmus, alternating with upward eye deviation and upbeating nystagmus, occurred in a comatose patient with a left hemisphere subdural hematoma and seizures. The periods of upbeating nystagmus were associated with symmetric, low-voltage 3 to 4 Hz bifrontal spikes. Rightward eye deviation and right-beating nystagmus occurred with diffuse, predominantly left hemispheric 4 to 6 Hz sharp waves. No eye movements occurred in the absence of spike and wave activity. These correlations agree with current concepts of the cortical control of saccadic eye movements in monkeys studied by electrical stimulation.     

Ocular tilt reaction due to an upper brainstem lesion: Paroxysmal skew deviation,torsion, and oscillation of the eyes with head tilt

A patient with a focal brainstem abscess in the region of the zona incerta developed a chronic oculocephalic dyskinesia in which paraoxysmal tonic skew deviation and torsion of the eyes were coupled with ocular oscillations and head tilt.     

Paroxysmal spontaneous nystagmus and vertigo evoked by lateral eye position

Prolonged lateral eye position to the extreme left for 5 to 20 seconds, without vestibular stimulation, induced intense attacks of nystagmus and rotational vertigo lasting 50-90 seconds in a patient. During the attacks the nystagmus beat to the right and counterclockwise, while the patient could look freely around. Clinical data were suggestive of repeated strokes in the vertebrobasilar territory, mainly affecting the right dorsolateral medulla oblongata including the vestibular nuclei. A paroxysmal attack of nystagmus and vertigo evoked by voluntary lateral eye position is an unusual clinical finding. This is discussed in the light of multisensory integration within the vestibular system, which also includes eye position information.     

Periodic alternating nystagmus and vestibulo-spinal system facilitating activity.

OBJECTIVE: Periodic alternating nystagmus has been associated with the instability of the velocity storage mechanism, which is known to play an important role in both the vestibulo-oculomotor and the optokinetic systems. In the present study we looked for a possible spinal equivalent to PAN. METHODS AND RESULTS: In 3 PAN patients, the H-reflex amplitude proved to be slightly but significantly influenced by nystagmus direction, in that it was greater when the nystagmus was beating toward the stimulation side. CONCLUSIONS: This finding suggests that projections from velocity storage may play a role not only in the ocular motor but also in assisting postural stability through the vestibulo-spinal system.     

Analysis of a case of periodic alternating nystagmus.

A patient is described in whom there was periodic deviation of the eyes in darkness associated with alternating nystagmus. An exactly similar situation occurs in normal man subjected to a pendular stimulus. It is proposed that in this patient there was alternating activity of the vestibular nuclei on either side of the brain-stem as a result of a removal of cerebellar inhibition, and that this caused periodic shifts in the null region of Daroff and Dell'Osso.     

Periodic complexes and alternating rotatory nystagmus with cyclic pupillary changes

A 69-year-old male, with a history of a previous subdural hematoma, multistroke dementia and ventricular shunting for hydrocephalus, exhibited while comatose isolated periodic alternating rotatory nystagmus with cyclic pupillary changes and periodic alternating gaze. His simultaneous EEG showed PLEDs and subsequently burst-suppression pattern. The latter abnormality was associated, in addition, to transient eyelid opening, synchronized with the EEG bursts. Complex neuro-ophthalmologic clinical signs, sometimes subtle, may be the sole manifestation of EEG periodic complexes that have potential prognostic and therapeutic implications.