See-saw Nystagmus Research Articles

Update on central oculomotor disorders and nystagmus

The diagnosis of ocular motor disorders and the different forms of a nystagmus is based on a systematic clinical examination of all types of eye movements: eye position, spontaneous nystagmus, range of eye movements, smooth pursuit, saccades, gaze-holding function, vergence, optokinetic nystagmus, as well as testing of the function of the vestibulo-ocular reflex (VOR) and visual fixation suppression of the VOR. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum, and cortex. There is a simple clinical rule: vertical and torsional eye movements are generated in the midbrain, horizontal in the pons. The cerebellum is relevant for almost all types of eye movements; typical pathological findings are saccadic smooth pursuit, gaze-evoked nystagmus or dysmetric saccades.Nystagmus is defined as a rhythmic, most often involuntary eye movement. It normally consists of a slow (pathological) drift of the eyes and a fast central compensatory movement of the eyes back to the primary position (re-fixation saccade). There are three major categories: first, spontaneous nystagmus, i. e. nystagmus which occurs in the gaze straight ahead position as upbeat or downbeat nystagmus; second, nystagmus that becomes visible at eccentric gaze only and third, nystagmus which can be elicited by certain maneuvers, e. g. head-shaking, head positioning, air pressure or hyperventilation, most of which are of peripheral vestibular origin. The most frequent central types of spontaneous nystagmus are downbeat and upbeat, infantile, pure torsional, pendular fixation, periodic alternating, and seesaw nystagmus. Many types of central nystagmus allow a precise neuroanatomical localization: for instance, downbeat nystagmus, which is most often caused by a bilateral floccular lesion or dysfunction, or upbeat nystagmus, which is caused by a lesion in the mesencephalon or medulla oblongata. Examples of pharmacotherapy are the use of 4-aminopyridine for downbeat and upbeat nystagmus, memantine or gabapentin for fixation pendular nystagmus or baclofen for periodic alternating nystagmus.

Clinical features and imaging characteristics in achiasmia.

Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity.

See-saw nystagmus associated with retinitis pigmentosa.

See-saw nystagmus is an uncommon form of nystagmus, and its pathophysiology remains poorly understood since the first case reported by Maddox in 1913. 1 Furthermore, see-saw nystagmus associated with retinitis pigmentosa is very rare. To the best of our knowledge, only 2 cases of see-saw nystagmus associated with retinitis pigmentosa have been reported since 1986. 2 Here, I report a case of seesaw nystagmus associated with retinitis pigmentosa. There were no clinical cranial nerve deficits and no cerebellar signs. Magnetic resonance imaging of the brain showed no lesions of the brainstem, cerebellum or evidence of demyelination. This case shows a rare association between see-saw nystagmus and retinitis pigmentosa. It is therefore important to recognise this, and future studies are needed to provide clarity on the underlying mechanism of this clinical entity.

Visual Fixation-Induced Hemi-Seesaw Nystagmus

Seesaw nystagmus (SSN) is characterized by conjugate torsional nystagmus with opposite vertical components in the two eyes. The waveform may be pendular or jerk (hemi-seesaw nystagmus, HSSN), in which the slow phase corresponds to one half-cycle and the quick phase to the other. Pendular SSN and HSSN have distinct clinical presentations and underlying causes. The pathophysiology of pendular SSN may be instability of visuovestibular interactions, while the underlying mechanism for HSSN may be related to the ocular tilt reaction or an imbalance in vestibular pathways. We report a patient with HSSN due to unilateral mesodiencephalic infarction that becomes apparent during visual fixation only.

Nystagmus in Children - a Survey

Nystagmus describes an involuntary, periodic movement of one or both eyes. About 1/600 children and adolescents have nystagmus, most of them idiopathic infantile nystagmus (IIN), also called "congenital nystagmus", which can be caused by mutations in the FRMD7 gene. Other frequent forms of nystagmus are latent nystagmus, which is usually associated with infantile strabismus, and nystagmus associated with albinism. Sometimes difficult to distinguish in young infants is a sensory nystagmus, where a defect in the visual system reduces vision and causes nystagmus. Causes include retinal dystrophies, congenital stationary night blindness and structural ocular defects including optic nerve hypoplasia or dense bilateral congenital cataracts. Unilateral nystagmus can be the sign of an anterior visual pathway lesion. Seesaw nystagmus may be associated with suprasellar and mesodiencephalic lesions and - rarely - with retinal dystrophies.The ophthalmology plays a key role in identifying the form of nystagmus. Children with new onset nystagmus, with spasmus nutans, with vertical or unilateral nystagmus and those with seesaw nystagmus require neurologic evaluation including imaging of the brain.The treatment of nystagmus depends on the underlying cause. Even minor refractive errors should be corrected, contact lenses offer advantages over glasses.Gabapentin and memantine, possibly also carbonic anhydrase inhibitors, are effective in treating IIN, nystagmus in albinism and sensory nystagmus. Nevertheless, pharmacologic treatment of nystagmus is rarely used in children; the reasons are the limited effects on vision, the need for lifelong therapy, and potential side effects. Eye muscle surgery (Anderson procedure, Kestenbaum procedure) can correct a nystagmus-related anomalous head posture. The concept of "artifical divergence" of Cüppers may help to decrease nystagmus intensity in patients whose nystagmus dampens with convergence. The four-muscle-tenotomy, which involves disinsertion and reinsertion of the horizontal muscles at the original insertion of both eyes, has a proven but limited positive effect on visual acuity.

Pendular Seesaw Nystagmus: Disappearance With Monocular Occlusion

We report a case of pendular seesaw nystagmus caused by bitemporal hemianopia; the nystagmus disappeared while in darkness as previously described, but it also disappeared with monocular occlusion, which indicates the pivotal role of binocular vision in the pathogenesis.

Nystagmus: Diagnosis, Topographic Anatomical Localization and Therapy.

Nystagmus is defined as rhythmic, most often involuntary eye movements. It normally consists of a slow (pathological) drift of the eyes, followed by a fast central compensatory movement back to the primary position (refixation saccade). The direction, however, is reported according to the fast phase. The cardinal symptoms are, on the one hand, blurred vision, jumping images (oscillopsia), reduced visual acuity and, sometimes, double vision; many of these symptoms depend on the eye position. On the other hand, depending on the etiology, patients may suffer from the following symptoms: 1. permanent dizziness, postural imbalance, and gait disorder (typical of downbeat and upbeat nystagmus); 2. if the onset of symptoms is acute, the patient may experience spinning vertigo with a tendency to fall to one side (due to ischemia in the area of the brainstem or cerebellum with central fixation nystagmus or as acute unilateral vestibulopathy with spontaneous peripheral vestibular nystagmus); or 3.positional vertigo. There are two major categories: the first is spontaneous nystagmus, i.e., nystagmus which occurs in the primary position as upbeat or downbeat nystagmus; and the second includes various types of nystagmus which are induced or modified by certain factors. Examples are gaze-evoked nystagmus, head-shaking nystagmus, positional nystagmus, and hyperventilation-induced nystagmus. In addition, there are disorders similar to nystagmus, such as ocular flutter or opsoclonus. The most common central types of spontaneous nystagmus are downbeat and upbeat, infantile, pure torsional, pendular fixation, periodic alternating, and seesaw nystagmus. Many types of nystagmus allow a precise neuroanatomical localization: for instance, downbeat nystagmus, which is most often caused by a bilateral floccular lesion or dysfunction, or upbeat nystagmus, which is caused by a lesion in the midbrain or medulla. Examples of drug treatment are the use of 4-aminopyridine for downbeat and upbeat nystagmus, memantine or gabapentin for pendular fixation nystagmus, or baclofen for periodic alternating nystagmus. In this article we are focusing on nystagmus. In a second article we will focus on central ocular motor disorders, such as saccade or gaze palsy, internuclear ophthalmoplegia, and gaze-holding deficits. Therefore, these types of eye movements will not be described here in detail.

Delayed-onset seesaw nystagmus following brain irradiation

Seesaw nystagmus (SSN) is a rare, debilitating neurologic syndrome with few known etiologies. Typically, patients present with oscillopsia subsequent to a recent neurologic insult, with only a handful of patients showing delayed onset after trauma. We report a case of seesaw nystagmus in a patient with a large meso-diencephalic mass treated with external beam radiation therapy (XRT), who developed asymptomatic SSN nearly 8 years after treatment.

Surgical Treatment of a Patient with See-Saw Nystagmus (SSN): Case Report

Background: Acquired See-saw Nystagmus (SSN) is a rare form of nystagmus characterized by elevation and intorsion of one eye with synchronous depression and intorsion of the contralateral eye in the first half cycle, followed by a reversal in the direction of the movements during the next half cycle. We herein report a case of a 47-year-old woman with a 3-year history of constant diplopia as a consequence of multiple neurosurgical interventions due to hemorrhage from a cavernous angioma located in the subthalamic region. She also had a history of major depressive disorder and ulcerative colitis. The patient underwent a surgical intervention with a 5 mm bilateral recession of the superior and inferior rectus muscles. Five years after surgery, the patient reported less recurrent and prominent episodes of transient horizontal deviation with horizontal diplopia, with a prevalence of well-being and comfort.

Seesaw nystagmus with internuclear ophthalmoplegia from bilateral dorsomedial pons and left thalamus infarction: a case report

BackgroundWe describe for the first time the clinical features and mechanisms of a bilateral dorsomedial pons and left thalamus infarction with seesaw nystagmus and internuclear ophthalmoplegia.Case presentationA 62-year-old Chinese man was hospitalized for sudden-onset dizziness, diplopia, and gait disturbance. A neurological examination revealed seesaw nystagmus and internuclear ophthalmoplegia. Magnetic resonance imaging disclosed an acute infarction confined to the bilateral dorsomedial pons and left thalamus. Subsequently, 2 weeks of antithrombotic therapy led to an improvement in his symptoms.ConclusionsThis case illustrates that the acute onset of seesaw nystagmus and internuclear ophthalmoplegia accompanied by risk factors for cerebrovascular diseases are highly suggestive of brainstem infarction.

Don’t Miss This! Red Flags in the Pediatric Eye Examination: Acquired Nystagmus

ABSTRACTWhen a new patient presents with a chief complaint of nystagmus, the clinician must know what further action is necessary in order to identify vision or life-threatening diseases. Some types of acquired nystagmus include upbeat nystagmus, downbeat nystagmus, see-saw nystagmus, and period alternating nystagmus. By identifying the characteristics and causes, acquired nystagmus can be recognized as a “red flag.” In contrast, children diagnosed with infantile or physiological nystagmus generally will not need neurological testing. As crucial as it is to recognize acquired nystagmus, it is equally important to differentiate among the specific subtypes and to be familiar with the key features of infantile nystagmus.

Paraneoplastic seesaw nystagmus and opsoclonus provides evidence for hyperexcitable reciprocally innervating mesencephalic network

Seesaw nystagmus is characterized by the rhythmic combination of vertical and torsional dysconjugate oscillations where one eye moves up and inward while the other moves down and outward. Common association of seesaw nystagmus with accessory optic track lesions lead to traditional hypothesis that it is due to the mismatch in the vision and vestibular systems. Here we propose a novel mechanism for seesaw nystagmus. We hypothesize that reverberations due to abnormal increases in the excitability of the reciprocally innervating circuit of excitatory burst neuron in the midbrain interstitial nucleus of Cajal causes the seesaw nystagmus. Analogous oscillations of the brainstem burst generators may be responsible for generation of saccadic oscillations or opsoclonus. The key difference is that the interstitial nucleus of Cajal lacks inhibitory burst neurons, hence the lack of post-inhibitory rebound, and relatively lower frequency of the oscillatory cycles causing pendular seesaw nystagmus. In contrast the brainstem burst generator, with reciprocally innervating excitatory and inhibitory burst neurons, and further inhibitory influence of the omnipause neurons results in the post-inhibitory rebound at the burst neurons, hence high oscillation frequency. This novel concept is supported by a unique observation in a patient with antineuronal nuclear autoantibody type 2 due to breast cancer who had combined seesaw nystagmus and superimposed saccadic oscillations. The patient neither had cerebellar deficits typically thought to cause paraneoplastic opsoclonus nor visual deficits that are known cause of seesaw nystagmus. We propose that hyperexcitability of the burst neurons in the interstitial nucleus of Cajal due to paraneoplastic antibody caused pendular seesaw nystagmus. On the other hand, increased excitability of brainstem burst generators and reduced efficacy of the omnipause neurons caused saccadic oscillations.

Congenital achiasma and see-saw nystagmus in VATER syndrome association with hydrocephalus

Congenital achiasma and see-saw nystagmus in VATER syndrome association with hydrocephalus

The Red Flag: When Pediatric Nystagmus is a Harbinger of Life-Threatening Disease

ABSTRACTPediatric nystagmus may be the harbinger of systemic or neurologic disease with significant morbidity and potential mortality. This paper reviews pediatriconset nystagmus, which may be associated with systemic diseases such as spasmus nutans, opsoclonus/ocular flutter, downbeat nystagmus, convergence retraction nystagmus, and see-saw nystagmus. These unique forms of nystagmus may be indicative of life- or vision-threatening diseases; thus, their recognition will facilitate earlier diagnosis and treatment, resulting in better outcomes.

Teaching Video Neuro Images : See-saw nystagmus

A 43-year-old woman experienced a worsening of her usual headache. As a right hemifacial hypoesthesia had appeared, the patient underwent a brain MRI that revealed a giant cavernoma localized at the left meso-diencephalic region (figure, A and B). After the operation, an involuntary ocular oscillation known as see-saw nystagmus developed (video on the Neurology® Web site at www.neurology.org). See-saw nystagmus consists of alternating phases of intorsion of the elevating eye and extorsion of the descending eye.(1) The patient displayed a right head tilt with left hypertropia referred to as "ocular tilt reaction" (figure, C)-a phenomenon related to the imbalance in the graviceptive pathways between vestibular nuclei and the interstitial nucleus of Cajal (figure, D).(2.)

Pharmacotherapy of Vestibular Disorders and Nystagmus

Vertigo and dizziness are with a life-time prevalence of ~30% among the most common symptoms and are often associated with nystagmus or other oculomotor disorders. The prerequisite for a successful treatment is a precise diagnosis of the underlying disorder. In this overview, the current pharmacological treatment options for peripheral and central vestibular, cerebellar, and oculomotor disorders including nystagmus are described. There are basically seven groups of drugs that can be used (the "7 As"): antiemetics; anti-inflammatory, anti-Menière's, and antimigraine medications; antidepressants, anticonvulsants, and aminopyridines. In acute vestibular neuritis, recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Menière's disease, a long-term high-dose treatment with betahistine-dihydrochloride (at least 48 mg three times daily) had a significant effect on the frequency of the attacks; the underlying mode of action is evidently an increase in inner-ear blood flow. The use of aminopyridines is a well-established therapeutic principle in the treatment of downbeat and upbeat nystagmus as well as episodic ataxia type 2 and cerebellar gait disorders. As was shown in animal experiments, these potassium channel blockers increase the activity and excitability and normalize irregular firing of cerebellar Purkinje cells. They evidently augment the inhibitory influence of these cells on vestibular and deep cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus; gabapentin and memantine improve pendular and infantile nystagmus. However, many other eye-movement disorders such as ocular flutter, opsoclonus, central positioning, and see-saw nystagmus are still difficult to treat. Although substantial progress has been made, further state-of-the-art trials must still be performed on many vestibular and oculomotor disorders, namely Menière's disease, vestibular paroxysmia, vestibular migraine, and many forms of central eye-movement disorders.

Functional organisation of visual pathways in a patient with no optic chiasm

Congenital achiasma offers a rare opportunity to study reorganization and inter-hemispheric communication in the face of anomalous inputs to striate cortex. We report neuroimaging studies of a patient with seesaw nystagmus, achiasma, and full visual fields. The subject underwent structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI) studies, and functional MRI (fMRI) using monocular stimulation with checkerboards, motion, objects and faces, as well as retinotopic quadrantic mapping. Structural MRI confirmed the absence of an optic chiasm, which was corroborated by DTI tractography. Lack of a functioning decussation was confirmed by fMRI that showed activation of only ipsilateral medial occipital cortex by monocular stimulation. The corpus callosum was normal in size and anterior and posterior commissures were identifiable. In terms of the hierarchy of visual areas, V5 was the lowest level region to be activated binocularly, as were regions in the fusiform gyri responding to faces and objects. The retinotopic organization of striate cortex was studied with quadrantic stimulation. This showed that, in support of recent findings, rather than projecting to an ectopic location contiguous with the normal retinotopic map of the ipsilateral temporal hemi-retina, the nasal hemi-retina's representation overlapped that of the temporal hemi-retina. These findings show that congenital achiasma can be an isolated midline crossing defect, that information transfer does not occur in early occipital cortex but at intermediate and higher levels of the visual hierarchy, and that the functional reorganisation of striate cortex in this condition is consistent with normal axon guidance by a chemoaffinity gradient.

Hemi-seesaw nystagmus in lateral medullary syndrome

Seesaw and hemi-seesaw nystagmus are rare in lateral medullary syndrome. We describe a patient with lateral medullary syndrome who, in addition to other more typical ocular manifestations, demonstrated hemi-seesaw nystagmus (HSSN).

Oxcarbazepine-induced jerky see–saw nystagmus

A 43-year-old female presented to the emergency department because of dizziness, drowsiness and generalized urticaria that occurred the previous day. Patient’s history revealed protracted delivery with neonate asphyxia, following which she had been diagnosed with epilepsy at age 7 when she experienced her first generalized tonic–clonic seizure. Her MRI showed ulegyria and hypoxic–ischaemic changes characteristic for perinatal damage. Her last visit to an epilepsy clinic was 18 days before. At that time a change in her therapy was made with gradual initiation of oxcarbazepine (start dose of 300 mg QD in the evening for 5 days, than 300 mg BID for 5 days, than 300 mg in the morning and 600 mg in the evening for 5 days) and tapering of levetiracetame. Her therapy, at the time of her presentation to the emergency department, was (in total daily doses): oxcarbazepine 900 mg, sodium valproate 1,000 mg, levetiracetame 750 mg, clonazepam 4.5 mg, lamotrigine 100 mg. Neurologic examination revealed a jerky see–saw nystagmus (SSN) more pronounced on the right eye (Video 1). Brain CT scan was normal. Oxcarbazepine and lamotrigine were discontinued and carbamazepine was gradually introduced. The carbamazepine was chosen because this drug controlled her seizures very well in the past, however, pediatric neurologist chose to switch from carbamazepine to levetiracetame at one point. On follow-up, a week later, she did not have nystagmus and did not experience dizziness and drowsiness any more but still had residual urticaria on her face and neck. SSN is a torsional–vertical nystagmus in which one eye elevates and intorts, while the other depresses and extorts. Jerky SSN is reportedly caused by lesions in the chiasmal or parasellar area thus resulting from disruption of the visual pathway [1]. However, SSN was described in association with vascular and inflammatory lesions of the rostral midbrain, pons and cerebellum [1, 2]. Based on these reports, SSN can result from dysfunction of the medial longitudinal fasciculus (MLF) that coordinates input to the oculomotor and trochlear nuclei from the vestibular nuclei [2]. One of the most common side–effects of oxcarbazepine therapy is nystagmus and it is related to its mono-hydroxyderivative levels in serum [3]. The therapeutic effect of oxcarbazepine results from its effect of blocking neural ion channels. We hypothesize that the same effect caused SSN in our patient blocking neurons that are part of the MLF. As nystagmus is a well-described side–effect of antiepileptic therapy and given the fact that nystagmus in our patient commenced on initiation and disappeared on discontinuation of oxcarbazepine, we report on a yet undescribed case of jerky SSN caused by oxcarbazepine.

Plasticity and Stability of the Visual System in Human Achiasma

The absence of the optic chiasm is an extraordinary and extreme abnormality in the nervous system. The abnormality produces highly atypical functional responses in the cortex, including overlapping hemifield representations and bilateral population receptive fields in both striate and extrastriate visual cortex. Even in the presence of these large functional abnormalities, the effect on visual perception and daily life is not easily detected. Here, we demonstrate that in two achiasmic humans the gross topography of the geniculostriate and occipital callosal connections remains largely unaltered. We conclude that visual function is preserved by reorganization of intracortical connections instead of large-scale reorganizations of the visual cortex. Thus, developmental mechanisms of local wiring within cortical maps compensate for the improper gross wiring to preserve function in human achiasma.