Pathologic nystagmus and related phenomena. A review

Pathological nystagmus may be spontaneous, positional, or gaze-evoked. Peripheral vestibular nystagmus is usually rotatory, the horizontal component being most prominent. It is - in contrast to a central vestibular nystagmus - strongly inhibited by fixation. Spontaneous congenital nystagmus is also prominent with fixation, but it can usually be distinguished from acquired fixation nystagmus based on its long duration, atypical waveforms and high frequency. Two general types of positional nystagmus can be identified on the basis of nystagmus regularity: static and paroxysmal. The most common variety of positional nystagmus is the so-called benign paroxysmal positional nystagmus, which in the majority of cases occurs as an isolated symptom of unknown cause. Gaze-evoked nystagmus, prominent with fixation, includes dissociated, rebound and gaze-paretic nystagmus forms. Symmetrical gaze-evoked nystagmus is most commonly produced by ingestion of certain drugs. Phenomena related to nystagmus include: amblyopic, voluntary, and convergence-retraction nystagmus, ocular dysmetria, ocular flutter, opsoclonus, ocular bobbing, and ocular myoclonus.     

Failure of fixation suppression of caloric nystagmus and ocular motor abnormalities

Caloric nystagmus is substantially suppressed by visual fixation. The degree of suppression of caloric nystagmus is influenced by the condition of visual fixation. We studied the percent reduction in slow-phase velocity of caloric nystagmus by visual fixation and certain abnormalities in optokinetic nystagmus, smooth pursuit, and maintenance of ocular position of gaze in 38 patients with disorders of the CNS. The inability to suppress caloric nystagmus by visual fixation correlated with reduction in optokinetic nystagmus, deficit in smooth pursuit eye movements, and presence of gaze nystagmus. It seems probable that modulation of the vestibulo-ocular reflex is influenced by the same mechanisms that are concerned with optokinetic nystagmus, maintenance of ocular position of gaze, and smooth pursuit eye movements.     

"Saccadic nystagmus" in cerebellar cortical atrophy.

An ocular dyskinesia designated "saccadic nystagmus" was observed in a patient with cerebellar cortical atrophy. Saccadic nystagmus is a sustained ocular dyskinesia present during visual fixation and abolished by eye closure. It is difficult to distinguish visually from either pendular or jerk nystagmus without eye movement recordings. The oscillations are horizontal and rapid and may be influenced by direction of gaze. Caloric nystagmus (eye closed) and optokinetic nystagmus were normal in our patient. Visual fixation abolished caloric nystagmus, which was replaced by saccadic nystagmus.     

Suppression of congenital nystagmus.

Suppression of congenital nystagmus by eyelid closure was studied by electrooculography in four cases under various conditions in order to elucidate whether the suppression is caused by blocking of fixation or not. The nystagmus persisted in the light as well as in the dark provided that the eyes were kept open. Frenzel's glasses did not suppress the nystagmus except for one case in whom jerky nystagmus was attenuated. In the other cases, only voluntary lid closure suppressed the nystagmus. Passive lid closure while the patient attempted to keep eyes open did not suppress the nystagmus except in one case. Reflex eyelid closure by glabellar tap did not suppress the nystagmus in spite of the occurrence of Bell's phenomenon. Passive eyelid opening while the patient attempted to keep eyes closed, on the other hand, did not reproduce the nystagmus. The suppression of congenital nystagmus by lid closure, at least in some cases, seems to be related to the voluntary effort to keep eyes closed but not specifically to blocking of fixation.     

Impaired suppression of vestibular nystagmus by fixation in cerebellar and noncerebellar patients

Summary The suppression of vestibular nystagmus (VN) by fixation of a small visual target moving with the observer was tested while subjects seated on a rotatable chair were oscillated at 0.1 Hz and peak accelerations of +-10 to 130°/s². Total amplitudes of nystagmus during movement towards one direction occurring despite intended fixation were compared to slow phases of optokinetic nystagmus (OKN) and smooth pursuit (SP) towards the opposite direction.Supported by the Deutsche Forschungsgemeinschaft, SFB 70 (Hirnforschung und Sinnesphysiologie)     

A Variation in FGF14 Is Associated with Downbeat Nystagmus in a Genome-Wide Association Study

The Cerebellum - Downbeat nystagmus (DBN) is a frequent form of acquired persisting central fixation nystagmus, often associated with other cerebellar ocular signs, such as saccadic smooth pursuit...     

Abnormal visual--vestibular interactions in psychosis

Vestibular reactivity and suppression of caloric nystagmus by visual fixation were examined in 40 psychiatric patients (36 schizophrenics and 4 manic-depressives) and 20 normal control subjects. Indices of reactivity commonly considered to reflect vestibular integrity, namely, slow-phase velocity and bilateral symmetry of response, did not discriminate patients from controls. However, response irregularities in the form of dysrhythmia and slower velocity of the nystagmus fast (saccadic) component were present to a significant degree in patients. Visual fixation effectively suppressed caloric nystagmus in normal controls, but not in hospitalized patients. This failure of fixation suppression was most marked in patients showing active symptomatology. These results indicate a central regulatory dysfunction of visual-vestibular interaction in psychiatric patients which varies with intensity of psychotic symptomatology and which does not seem attributable to medication or attentional factors.     

Unilateral pursuit-induced congenital nystagmus

We describe two patients with a lifelong history of oscillopsia only when following objects moving toward their left side. Neurologic examination was normal except for eye movements. The patients showed nystagmus during any tasks that required visual following toward the left (ie, smooth pursuit, optokinetic nystagmus, and vestibulo-ocular-reflex-suppression), but had no nystagmus during fixation of stationary targets or visual following tasks to the right. Eye-movement recordings showed waveforms during pursuit to the left that were typical of congenital nystagmus.     

Multiple system atrophy with macro square wave jerks and pendular nystagmus]

A 51-year-old woman was admitted to our hospital because of gait disturbance and dysuria. Neurological examination revealed limb and truncal ataxia, orthostatic hypotension, cogwheel rigidity in all limbs, generalized hyperreflexia without pathological reflex, and horizontal gaze nystagmus. She became progressively worse and bedridden at age 52. Then she developed abnormal eye movements. Electrooculogram revealed vertical, horizontal or oblique macro square wave jerks and pendular nystagmus. Macro square wave jerks appeared during fixation and disappeared with eye closure or in the dark room. Macro square wave jerks were characterized by a duration of about 200 msec and an amplitude of 10 to 15 degrees. Pendular nystagmus with a duration of several seconds and amplitude of 5 to 15 degrees appeared when she changed her fixation or the point of fixation disappeared. Macro square wave jerks and pendular nystagmus were mildly suppressed after the intramuscular injection of 100 mg of phenobarbital, the oral intake of sodium valproate of 600 mg/day or baclofen of 60 mg/day. They were almost completely depressed after the intravenous injection of 3 mg of diazepam or the oral intake of clonazepam of 1.5 mg/day. We suggested that both macro square wave jerks and pendular nystagmus in this patient might be caused by the dysfunction of GABAergic system in the saccadic eye movement system.     

Bedside Evaluation of Dizzy Patients

In recent decades there has been marked progress in the imaging and laboratory evaluation of dizzy patients. However, detailed history taking and comprehensive bedside neurotological evaluation remain crucial for a diagnosis of dizziness. Bedside neurotological evaluation should include examinations for ocular alignment, spontaneous and gaze-evoked nystagmus, the vestibulo-ocular reflex, saccades, smooth pursuit, and balance. In patients with acute spontaneous vertigo, negative head impulse test, direction-changing nystagmus, and skew deviation mostly indicate central vestibular disorders. In contrast, patients with unilateral peripheral deafferentation invariably have a positive head impulse test and mixed horizontal-torsional nystagmus beating away from the lesion side. Since suppression by visual fixation is the rule in peripheral nystagmus and is frequent even in central nystagmus, removal of visual fixation using Frenzel glasses is required for the proper evaluation of central as well as peripheral nystagmus. Head-shaking, cranial vibration, hyperventilation, pressure to the external auditory canal, and loud sounds may disclose underlying vestibular dysfunction by inducing nystagmus or modulating the spontaneous nystagmus. In patients with positional vertigo, the diagnosis can be made by determining patterns of the nystagmus induced during various positional maneuvers that include straight head hanging, the Dix-Hallpike maneuver, supine head roll, and head turning and bending while sitting. Abnormal smooth pursuit and saccades, and severe imbalance also indicate central pathologies. Physicians should be familiar with bedside neurotological examinations and be aware of the clinical implications of the findings when evaluating dizzy patients.     

Convergence nystagmus associated with Arnold-Chiari malformation

A case of convergence nystagmus associated with an Arnold-Chiari type I malformation is presented. The nystagmus appeared in the absence of fixation, was provoked during Valsalva's maneuver and neck flexion and extension, and attenuated on deep inspiration. Sagittal magnetic resonance images showed that the diameter of the cerebral aqueduct increased with the neck in full flexion and in full extension. Surgical foramen magnum decompression considerably reduced the nystagmus and abolished the postural variation of aqueduct diameter. It is postulated that this nystagmus was due to a combination of mechanical distortion and abnormal transmission of cerebrospinal fluid pressure to the aqueductal region.     

Oculomotor and vestibular findings in autosomal recessive spastic ataxia of Charlevoix-Saguenay.

Electronystagmographic recordings were made of oculomotor and vestibular function in 11 patients with autosomal recessive spastic ataxia of Charlevoix-Saguenay. All had horizontal gaze nystagmus, marked impairment of smooth ocular pursuit and optokinetic nystagmus, and defective fixation suppression of caloric nystagmus. Many had saccadic dysmetria, but saccade velocity was probably unaffected. Abnormalities pointing to brainstem disturbance were sparse. The findings are thought to indicate mainly diffuse cerebellar disease, with particular involvement of vermis and vestibulo-cerebellum.     

Fixation suppression of optokinetic nystagmus modulates cortical visual-vestibular interaction

Water activation positron emission tomography and statistical group analysis were used to evaluate differences in activation-deactivation patterns during small-field visual motion stimulation, eliciting rightward optokinetic nystagmus and its fixation suppression in 12 healthy volunteers. Bilateral patterns of activation in the visual cortex, including the motion-sensitive area MT/V5, and deactivations in an assembly of vestibular areas (posterior insula, thalamus, anterior cingulate gyrus) during optokinetic nystagmus was markedly diminished or totally absent during its fixation suppression. This finding agrees with the concept of a reciprocal inhibitory interaction between the visual-optokinetic and the vestibular systems, which takes place at a lower level during fixation suppression, because the potential mismatch between the two sensory inputs, visual and vestibular, is then reduced.     

Pathologic nystagmus: a classification based on electro-oculographic recordings.

The widespread availability of eye movement recording systems has added a new dimension to our ability to accurately describe nystagmus. Electrooculography (EOG) is the simplest and most readily available system. With EOG the effect of loss of fixation (either with eyes closed, or eyes open in darkness) can be accurately assessed and quantitative evaluation of nystagmus speed, frequency and amplitude is easily made. Of equal importance, it provides a permanent record that can be compared with nystagmus recorded in other patients. By comparing clinical observation with paper recordings, both students and experienced clinicians can become more efficient in recognizing different varieties of nystagmus.     

Acquired convergence-evoked pendular nystagmus in multiple sclerosis.

Nystagmus seen only with convergence is unusual. We describe four cases of acquired convergence-evoked pendular nystagmus in patients with multiple sclerosis. The nystagmus was horizontal and asymmetric in all patients. Eye movement recordings in one subject showed a conjugate rather than a convergent-divergent relationship of the phase of movement between the two eyes. All patients had evidence of optic neuropathy and cerebellar dysfunction. Occlusion of either eye during fixation of near targets led to divergent drift of the covered eye and a decrease in nystagmus. Intravenous scopolamine reduced nystagmus in one patient. Base-in prisms alleviated symptoms of oscillopsia at near and improving reading visual acuity. Convergence-evoked pendular nystagmus may be more common than currently appreciated, particularly among patients with multiple sclerosis.     

Drug therapy for acquired pendular nystagmus in multiple sclerosis

Acquired pendular nystagmus (APN) is regularly accompanied by oscillopsia and impairment of static visual acuity. Therapeutic approaches to APN remain controversial, and there is no generally accepted therapeutic approach. We tested 14 patients who had suffered from APN caused by multiple sclerosis for several years; 12 patients presented with fixational pendular nystagmus (increasing during fixation) and 2 with spontaneous pendular nystagmus. All 11 patients with fixational pendular nystagmus who were given memantine, a glutamate antagonist, experienced complete cessation of the nystagmus. In contrast, scopolamine caused no (6 of 8) or only a minor (10–50%) reduction of the nystagmus (2 of 8). It was concluded that memantine is a safe treatment option for APN. Received: 29 August 1995 Received in revised form: 6 August 1996 Accepted: 19 August 1996     

Periodic alternating nystagmus.

Three patients with periodic alternating nystagmus (PAN) are described in detail. Digital computer methods were used to quantify their disordered eye movement in an attempt to understand the pathophysiology. One of the patients was unusual in showing rebound nystagmus with fixation and PAN without fixation. Each patient had hyperactive vestibular responses and the phase and gain of the PAN cycles were altered in a predictable fashion by vestibular stimuli. It is postulated that PAN represents cyclical firing between reciprocally connected groups of inhibitory neurons within the vestibular and oculomotor nuclei. The cyclical firing is initiated by a critical imbalance of tonic input to either group of normally functioning neurons.     

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).     

Nystagmus and oscillopsia

The ocular motor system consists of several subsystems, including the vestibular ocular nystagmus saccade system, the pursuit system, the fixation and gaze-holding system and the vergence system. All these subsystems aid the stabilization of the images on the retina during eye and head movements and any kind of disturbance of one of the systems can cause instability of the eyes (e.g. nystagmus) or an inadequate eye movement causing a mismatch between head and eye movement (e.g. bilateral vestibular failure). In both situations, the subjects experience a movement of the world (oscillopsia) which is quite disturbing. New insights into the patho-physiology of some of the ocular motor disorders have helped to establish new treatment options, in particular in downbeat nystagmus, upbeat nystagmus, periodic alternating nystagmus, acquired pendular nystagmus and paroxysmal vestibular episodes/attacks. The discussed patho-physiology of these disorders and the current literature on treatment options are discussed and practical treatment recommendations are given in the paper.     

Translocation of cortical migraine phosphenes through eye movements and vestibular stimulation]

Self-observations of migraine-phosphenes demonstrate the influence of gaze and vestibular stimuli upon cortical foci in the human are 17. The scintillating phosphenes appearing in one half-field are seen as moving during voluntary gaze shifts: Saccades and pursuit movements translocate the phosphenes besides the fixation point within a stable outer visual surround. Vestibular stimuli cause a shift and deformation of the phosphene towards the slow phase direction of vestibular nystagmus. In contrast to voluntary eye movements the phosphenes do not transgress the midline during vestibular nystagmus and the translocation is much smaller than the sum nystagmus amplitudes elicited by head acceleration.