The effects of baclofen and cholinergic drugs on upbeat and downbeat nystagmus

Effects of Baclofen on Central Paroxysmal Positional Downbeat Nystagmus

Paroxysmal positional nystagmus frequently occurs in lesions involving the cerebellum, and has been ascribed to disinhibition and enhanced canal signals during positioning due to cerebellar dysfunction. This study aims to elucidate the mechanism of central positional nystagmus (CPN) by determining the effects of baclofen on the intensity of paroxysmal positional downbeat nystagmus due to central lesions. Fifteen patients with paroxysmal downbeat CPN were subjected to manual straight head-hanging before administration of baclofen, while taking baclofen 30 mg per day for at least one week, and two weeks after discontinuation of baclofen. The maximum slow phase velocity (SPV) and time constant (TC) of the induced paroxysmal downbeat CPN were analyzed. The positional vertigo was evaluated using an 11-point numerical rating scale (0 to 10) in 9 patients. After treatment with baclofen, the median of the maximum SPV of paroxysmal downbeat CPN decreased from 30.1°/s [interquartile range (IQR) = 19.6-39.0°/s] to 15.2°/s (IQR = 11.2-22.0°/s, Wilcoxon signed rank test, p < 0.001) with the median decrement ratio at 40.2% (IQR = 28.2-50.6%). After discontinuation of baclofen, the maximum SPV re-increased to 24.6°/s (IQR = 13.1-34.4°/s, Wilcoxon signed rank test, p = 0.001) with the median increment ratio at 23.5% (IQR = 5.2-87.9%). In contrast, the TCs of paroxysmal downbeat CPN remained unchanged at approximately 3.0 s throughout the evaluation. The positional vertigo also decreased with the medication (Wilcoxon signed rank test, p = 0.020), and remained unchanged even after discontinuation of medication (Wilcoxon signed rank test, p = 0.737). The results of this study support the prior presumption that paroxysmal CPN is caused by enhanced responses of the semicircular canals during positioning due to cerebellar disinhibition. Baclofen may be tried in symptomatic patients with paroxysmal CPN.

Current and Emerging Medical Therapies for Dizziness

Medical therapies for dizziness are aimed at vertigo reduction, secondary symptom management, or the root cause of the pathologic process. Acute peripheral vertigo pharmacotherapies include antihistamines, calcium channel blockers, and benzodiazepines. Prophylactic pharmacotherapies vary between causes. For Meniere disease, betahistine and diuretics remain initial first-line oral options, whereas intratympanic steroids and intratympanic gentamicin are reserved for uncontrolled symptoms. For cerebellar dizziness and oculomotor disorders, 4-aminopyridine may provide benefit. For vestibular migraine, persistent postural perceptual dizziness and mal de débarquement, treatment options overlap and include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants and calcium channel blockers.

[Vertical nystagmus]

The review article provides a definition and classification of different nystagmus types, a comparative description of the central and peripheral vestibular nystagmus. The pathogenetic patterns of up-beating and down-beating nystagmus are accurately described. The features of nystagmus formation in various diseases are discussed, such as Wernicke encephalopathy, Arnold-Chiari anomaly, spinocerebellar ataxia and vestibular migraine. The authors provide their own data on oculomotor disorders in 100 patients with vestibular migraine and migraine with a brain stem aura. This article considers approaches to treatment: surgical and conservative. In conclusion, was noted the possibility of differentiating the central and peripheral vestibular nystagmus by means of clinical study. As well, the differences between vertical nystagmus associated with organic lesions of the brain stem or cerebellum and transient nystagmus with vestibular migraine are highlighted. The authors note the need for in-depth studies of nystagmus in vestibular migraine patients and methods of dealing with it.

A Case of Infratentorial Meningioma Causing Spontaneous Downbeat Nystagmus: Case Report and Review of the Literature

BACKGROUND

Spontaneous downbeat nystagmus is a finding that raises suspicions of a central nervous system disorder. Vermis and lower brainstem lesions are considered to be responsible, but the exact mechanism is still controversial. We observed a rare case of spontaneous downbeat nystagmus caused by an infratentorial meningioma.

CASE DESCRIPTION

A 50-year-old woman was incidentally diagnosed with infratentorial tumor. Later, she suffered from oscillopsia and the symptom disturbed her daily life especially while driving. Magnetic resonance imaging showed a tumor of approximately 30 mm in diameter at the dorsal midline of the posterior fossa. The tumor was compressing the cerebellar vermis and was apparently responsible for the symptoms that affected her daily life; therefore, we decided to perform tumor removal. The postoperative course was uneventful, and the spontaneous downbeat nystagmus completely disappeared.

CONCLUSIONS

Vertical nystagmus is a finding that raises suspicion of a central nervous system disorder, and requires detailed examination. In addition, in case of vertical nystagmus because of tumor compression of the vermis, removal of the tumor can be an effective treatment.

Advances in pharmacotherapy of vestibular and ocular motor disorders

INTRODUCTION

Vertigo and dizziness are common chief complaints of vestibular and ocular motor disorders (lifetime prevalence 30%). Treatment relies on physical, pharmacological, psychological and rarely surgical approaches. Eight groups of drugs are currently used in vestibular and ocular motor disorders, namely anti-vertiginous, anti-inflammatory, anti-menière's, anti-migrainous medications, anti-depressants, anti-convulsants, aminopyridines and agents that enhance vestibular plasticity.

AREAS COVERED

The purpose of this review is to summarize the pharmacological characteristics and clinical applications of medications that are used for peripheral, central and functional vestibular and ocular motor disorders. The level of evidence for the respective drugs is described alongside the pathophysiological premises supporting their use. The authors place particular focus on translation and back-translation in vestibular pharmacological research and the repurposing of known drugs for new indications and rare disorders.

EXPERT OPINION

The use of drugs in vestibular and ocular motor disorders is often based on open-label, non-controlled studies and expert opinion. In the future, strong evidence derived from RCTs is needed to support the effectiveness and tolerability of these therapies in well-defined vestibular and ocular motor disorders. Vestibular pharmacological research must be guided by a better understanding of the molecular targets relevant in the pathophysiology of vestibular and ocular motor disorders.

The Comprehensive Management of Cerebellar Ataxia in Adults

PURPOSE OF REVIEW

In this review, we present the multidisciplinary approach to the management of the many neurological, medical, social, and emotional issues facing patients with cerebellar ataxia.

RECENT FINDINGS

Our holistic approach to treatment, developed over the past 25 years in the Massachusetts General Hospital Ataxia Unit, is centered on the compassionate care of the patient and their family, empowering them through engagement, and including the families as partners in the healing process. We present the management of ataxia in adults, beginning with establishing an accurate diagnosis, followed by treatment of the multiple symptoms seen in cerebellar disorders, with a view to maximizing quality of life and effectively living with the consequences of ataxia. We discuss the importance of a multidisciplinary approach to the management of ataxia, including medical and non-medical management and the evidence base that supports these interventions. We address the pharmacological treatment of ataxia, tremor, and other associated movement disorders; ophthalmological symptoms; bowel, bladder, and sexual symptoms; orthostatic hypotension; psychiatric and cognitive symptoms; neuromodulation, including deep brain stimulation; rehabilitation including physical therapy, occupational therapy and speech and language pathology and, as necessary, involving urology, psychiatry, and pain medicine. We discuss the role of palliative care in late-stage disease. The management of adults with ataxia is complex and a team-based approach is essential.

Regulatory roles of perineuronal nets and semaphorin 3A in the postnatal maturation of the central vestibular circuitry for graviceptive reflex

Perineuronal nets (PN) restrict neuronal plasticity in the adult brain. We hypothesize that activity-dependent consolidation of PN is required for functional maturation of behavioral circuits. Using the postnatal maturation of brainstem vestibular nucleus (VN) circuits as a model system, we report a neonatal period in which consolidation of central vestibular circuitry for graviception is accompanied by activity-dependent consolidation of chondroitin sulfate (CS)-rich PN around GABAergic neurons in the VN. Postnatal onset of negative geotaxis was used as an indicator for functional maturation of vestibular circuits. Rats display negative geotaxis from postnatal day (P) 9, coinciding with the condensation of CS-rich PN around GABAergic interneurons in the VN. Delaying PN formation, by removal of primordial CS moieties on VN with chondroitinase ABC (ChABC) treatment at P6, postponed emergence of negative geotaxis to P13. Similar postponement was observed following inhibition of GABAergic transmission with bicuculline, in line with the reported role of PN in increasing excitability of parvalbumin neurons. We further reasoned that PN-CS restricts bioavailability of plasticity-inducing factors such as semaphorin 3A (Sema3A) to bring about circuit maturation. Treatment of VN explants with ChABC to liberate PN-bound Sema3A resulted in dendritic growth and arborization, implicating structural plasticity that delays synapse formation. Evidence is thus provided for the role of PN-CS-Sema3A in regulating structural and circuit plasticity at VN interneurons with impacts on the development of graviceptive postural control.

[New aspects of symptomatic MS treatment: Part 4-sexual dysfunction and eye movement disorders]

The symptomatic treatment of multiple sclerosis (MS) is nowadays of similar importance as immunotherapy within a comprehensive treatment concept of this chronic disease. It makes a considerable contribution to the reduction of disabilities in activities of daily living as well as social and occupational life. Moreover, symptomatic treatment is of great importance for amelioration of the quality of life. Since our last survey of symptomatic MS treatment in 2004 and publication of the guidelines of the German Neurological Society and the Clinical Competence Network Multiple Sclerosis (Klinisches Kompetenznetz Multiple Sklerose, KKNMS) in 2014, several developments within the topics of mobility, bladder and sexual function, vision, fatigue, cognition and rehabilitation have taken place. These new findings together with further aspects of disease measurement methods and overall treatment strategies of the respective symptoms as well as treatment goals are introduced in several individual contributions. In this article the symptoms of sexual dysfunction and eye movement disorders are discussed.

Update on the pharmacotherapy of cerebellar and central vestibular disorders

An overview of the current pharmacotherapy of central vestibular syndromes and the most common forms of central nystagmus as well as cerebellar disorders is given. 4-aminopyridine (4-AP) is recommended for the treatment of downbeat nystagmus, a frequent form of acquired persisting fixation nystagmus, and upbeat nystagmus. Animal studies showed that this non-selective blocker of voltage-gated potassium channels increases Purkinje cell excitability and normalizes the irregular firing rate, so that the inhibitory influence of the cerebellar cortex on vestibular and deep cerebellar nuclei is restored. The efficacy of 4-AP in episodic ataxia type 2, which is most often caused by mutations of the PQ-calcium channel, was demonstrated in a randomized controlled trial. It was also shown in an animal model (the tottering mouse) of episodic ataxia type 2. In a case series, chlorzoxazone, a non-selective activator of small-conductance calcium-activated potassium channels, was shown to reduce the DBN. The efficacy of acetyl-DL-leucine as a potential new symptomatic treatment for cerebellar diseases has been demonstrated in three case series. The ongoing randomized controlled trials on episodic ataxia type 2 (sustained-release form of 4-aminopyridine vs. acetazolamide vs. placebo; EAT2TREAT), vestibular migraine with metoprolol (PROVEMIG-trial), cerebellar gait disorders (sustained-release form of 4-aminopyridine vs. placebo; FACEG) and cerebellar ataxia (acetyl-DL-leucine vs. placebo; ALCAT) will provide new insights into the pharmacotherapy of cerebellar and central vestibular disorders.

Neuro-ophthalmology of type 1 Chiari malformation

Chiari malformation is a congenital deformity leading to herniation of cerebellar tonsils. Headache is a typical symptom of this condition, but patients with Chiari malformation often present with double vision and vertigo. Examination of eye movements in such patients often reveals nystagmus and strabismus. Eye movement deficits in the context of typical symptomatic presentation are critical clinical markers for the diagnosis of Chiari malformation. We will review eye movement deficits that seen in patients with type 1 Chiari malformation. We will then discuss the underlying pathophysiology and therapeutic options for such deficits.

Central ocular motor disorders, including gaze palsy and nystagmus

An impairment of eye movements, or nystagmus, is seen in many diseases of the central nervous system, in particular those affecting the brainstem and cerebellum, as well as in those of the vestibular system. The key to diagnosis is a systematic clinical examination of the different types of eye movements, including: eye position, range of eye movements, smooth pursuit, saccades, gaze-holding function and optokinetic nystagmus, as well as testing for the different types of nystagmus (e.g., central fixation nystagmus or peripheral vestibular nystagmus). Depending on the time course of the signs and symptoms, eye movements often indicate a specific underlying cause (e.g., stroke or neurodegenerative or metabolic disorders). A detailed knowledge of the anatomy and physiology of eye movements enables the physician to localize the disturbance to a specific area in the brainstem (midbrain, pons or medulla) or cerebellum (in particular the flocculus). For example, isolated dysfunction of vertical eye movements is due to a midbrain lesion affecting the rostral interstitial nucleus of the medial longitudinal fascicle, with impaired vertical saccades only, the interstitial nucleus of Cajal or the posterior commissure; common causes with an acute onset are an infarction or bleeding in the upper midbrain or in patients with chronic progressive supranuclear palsy (PSP) and Niemann-Pick type C (NP-C). Isolated dysfunction of horizontal saccades is due to a pontine lesion affecting the paramedian pontine reticular formation due, for instance, to brainstem bleeding, glioma or Gaucher disease type 3; an impairment of horizontal and vertical saccades is found in later stages of PSP, NP-C and Gaucher disease type 3. Gaze-evoked nystagmus (GEN) in all directions indicates a cerebellar dysfunction and can have multiple causes such as drugs, in particular antiepileptics, chronic alcohol abuse, neurodegenerative cerebellar disorders or cerebellar ataxias; purely vertical GEN is due to a midbrain lesion, while purely horizontal GEN is due to a pontomedullary lesion. The pathognomonic clinical sign of internuclear ophthalmoplegia is an impaired adduction while testing horizontal saccades on the side of the lesion in the ipsilateral medial longitudinal fascicule. The most common pathological types of central nystagmus are downbeat nystagmus (DBN) and upbeat nystagmus (UBN). DBN is generally due to cerebellar dysfunction affecting the flocculus bilaterally (e.g., due to a neurodegenerative disease). Treatment options exist for a few disorders: miglustat for NP-C and aminopyridines for DBN and UBN. It is therefore particularly important to identify treatable cases with these conditions.

Diagnostic approach to abnormal spontaneous eye movements

PURPOSE OF REVIEW

Abnormal spontaneous eye movements, including nystagmus and saccadic intrusions, are often encountered in neurologic practice and can cause disabling visual symptoms, such as oscillopsia and blurred vision. This article reviews the spectrum of abnormal spontaneous eye movements and describes their characteristics, etiology, and management.

RECENT FINDINGS

The number of prospective, controlled, and masked clinical trials evaluating candidate treatments for abnormal spontaneous eye movements has increased significantly over the past decade. The findings of recent clinical trials are highlighted, and the dosing and potential side effects of proposed medical treatments are summarized.

SUMMARY

Abnormal spontaneous eye movements are often encountered in neurologic practice. Recent clinical trials provide an evidence base to guide treatment decisions for these disorders.

Symptomatic treatment and management of multiple sclerosis

The range of symptoms which occur in multiple sclerosis (MS) can have disabling functional consequences for patients and lead to significant reductions in their quality of life. MS symptoms can also interact with each other, making their management challenging. Clinical trials aimed at identifying symptomatic therapies have generally been poorly designed and have tended to be underpowered. Therefore, the evidence base for the management of MS symptoms with pharmacologic therapies is not strong and tends to rely upon open-label studies, case reports, and clinical trials with small numbers of patients and poorly validated clinical outcome measures. Recently, there has been a growing interest in the management of MS symptoms with pharmacologic treatments, and better-designed, randomized, double-blind, controlled trials have been reported. This chapter will describe the evidence base predominantly behind the various pharmacologic approaches to the management of MS symptoms, which in most, if not all, cases, requires multidisciplinary input. Drugs routinely recommended for individual symptoms and new therapies, which are currently in the development pipeline, will be reviewed. More interventional therapies related to symptoms that are refractory to pharmacotherapy will also be discussed, where relevant.

Natural course of positional down-beating nystagmus of peripheral origin

The aim of this study was to assess the natural course of positional down-beating nystagmus (pDBN) and vertigo in patients with no evidence of central nervous system involvement and of presumed peripheral origin. Fifty-three patients with pDBN had a complete otoneurological examination. All subjects, apart from three (excluded from the study), showed no additional neurological signs and normal brain imaging. Patients were randomly assigned to two groups: with or without treatment with exercise. Patients were seen again after 24 h, and then weekly for up to 6 months. Forty-seven patients (94%) showed pDBN in the straight head-hanging position and in a Dix-Hallpike position. A torsional component was detected in 17 patients (34%). The mean latency and duration of pDBN was 4.7 ± 5 s and 40.1 ± 22 s, respectively. After 2 weeks, only 12 patients (24%) still had pDBN and all but one patient had recovered by 1 month. Twenty patients (40%) were diagnosed with a typical posterior canal benign paroxysmal positional vertigo (PC BPPV) before or after pDBN. This study assessed for the first time the natural course of presumed peripheral pDBN, which was characterized by a spontaneous remission in 24 patients in the first week and in 49 patients within 4 weeks. pDBN is much more common than previously suggested, with about the same frequency as lateral canal BPPV. Furthermore, the clinical characteristics of pDBN have been highlighted, as well as its possible relationship to PC BPPV.

Treatment of nystagmus

OPINION STATEMENT

Patients with congenital and acquired forms of nystagmus are commonly encountered in clinical practice. Many report visual symptoms, such as oscillopsia and blurred vision, which can be alleviated if the nystagmus can be suppressed. Pharmacologic, optical, and surgical treatments are available, with the choice of treatment depending on the characteristics of the nystagmus and the severity of the associated visual symptoms. Downbeat nystagmus can be treated with 4-aminopyridine, 3,4-diaminopyridine, or clonazepam. Upbeat nystagmus can be reduced with memantine, 4-aminopyridine, or baclofen. Torsional nystagmus may respond to gabapentin. Acquired pendular nystagmus in patients with multiple sclerosis is often partially suppressed by gabapentin or memantine. Acquired pendular nystagmus in patients with oculopalatal tremor can respond to gabapentin, memantine, or trihexyphenidyl. Although acquired periodic alternating nystagmus is often completely suppressed by baclofen, memantine can be effective in refractory cases. Seesaw nystagmus can be reduced with alcohol, clonazepam, or memantine. Infantile nystagmus may not cause significant visual symptoms if "foveation periods" are well developed, but the nystagmus can be treated in symptomatic patients with gabapentin, memantine, acetazolamide, topical brinzolamide, contact lenses, or base-out prisms to induce convergence. Several surgical therapies have also been reported to improve infantile nystagmus syndrome (INS), but selection of the appropriate therapy requires preoperative evaluation of visual acuity and nystagmus intensity in different gaze positions. Other treatment options for nystagmus include botulinum toxin injections into the extraocular muscles or retrobulbar space. Electro-optical devices are currently being developed, in order to noninvasively negate the visual consequences of nystagmus.

P6 acupressure effectiveness on acute vertiginous patients: a double blind randomized study

OBJECTIVES

The purpose of this study was to evaluate the effectiveness of P6 acupressure on vertigo and neurovegetative symptoms, its possible interference with vestibular-ocular reflex (VOR), and its clinical usefulness during acute vertigo.

MATERIALS AND METHODS

Two hundred and four patients, either affected by acute vertigo (n=124) or undergoing labyrinth stimulation (n=80), were randomly divided in two homogeneous groups: an experimental group A and a placebo group B. Each patient rated severity of vertigo and neurovegetative symptoms on a visuo-analogue scale ranging from 0 to 10, before and after bilateral placement of a P6 device. The latter was placed on the P6 acupressure point (appropriate placement) in Group A patients or on the dorsal part of the carpus (inappropriate placement) in the Group B patients. Furthermore, qualitative and quantitative nystagmus parameters were collected via recorded video-oculoscopy and electronystagmography.

RESULTS

Eighty-five percent of Group A patients reported improvement of symptoms, which was significant for neurovegetative symptoms, but not for vertigo. In contrast, only 11% of the Group B patients reported improvement. VOR analysis did not show any significant variation of qualitative and quantitative nystagmus variables.

CONCLUSIONS

This study demonstrated that the P6 device is effective in improving neurovegetative symptoms in patients affected by spontaneous and provoked vertigo, without any interference with VOR. Given the low cost and lack of side-effects of the P6 device, its routine application is suggested for acute vertigo and during labyrinth stimulation.

Comparison of 10-mg doses of 4-aminopyridine and 3,4-diaminopyridine for the treatment of downbeat nystagmus

OBJECTIVE

Animal experiments have demonstrated that aminopyridines increase Purkinje cell excitability, and in clinical studies, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP) improved downbeat nystagmus. In this double-blind, prospective, crossover study, the effects of equivalent doses of 4-AP and 3,4-DAP on the slow-phase velocity (SPV) of downbeat nystagmus were compared.

METHODS

Eight patients with downbeat nystagmus due to different etiologies (cerebellar degeneration [n = 1], bilateral vestibulopathy [n = 1], bilateral vestibulopathy and cerebellar degeneration [n = 1], Arnold-Chiari I malformation and cerebellar ataxia [n = 1], cryptogenic cerebellar ataxia [n = 4]) were included. They were randomly assigned to receiving a single capsule of 10 mg of 3,4-DAP or 4-AP followed by 6 days with no medication. One week later, the treatment was switched, that is, 1 single capsule (10 mg) of the other agent. Recordings with 3-dimensional video-oculography were performed before and 45 and 90 minutes after drug administration.

RESULTS

Both medications had a significant effect throughout time (pre vs post 45 vs post 90) (F() = 8.876; P < 0.01). Following the administration of 3,4-DAP, mean slow velocity decreased from -5.68°/s (pre) to -3.29°/s (post 45) to -2.96°/s (post 90) (pre vs post 45/post 90 P < 0.01). In 4-AP, the mean SPV decreased from -6.04°/s (pre) to -1.58°/s (post 45) to -1.21°/s (post 90) (pre vs post 45/post 90 P < 0.00001). Both after 45 and after 90, the mean SPVs were significantly lower for 4-AP than for 3,4-DAP (P < 0.05). None of the patients reported serious side effects.

CONCLUSION

Based on these results, 10-mg doses of 4-AP lead to a more pronounced decrease of the SPV of downbeat nystagmus than do equivalent doses of 3,4-DAP.

No effects of anti-motion sickness drugs on vestibular evoked myogenic potentials outcome parameters

OBJECTIVE

To investigate the effects of meclizine (50 mg), baclofen (10 mg), cinnarizine (20 mg) + dimenhydrinate (40 mg), and promethazine (25 mg) + dextro-amphetamine (5 mg) on the parameters of the vestibular evoked myogenic potential (VEMP) test.

STUDY DESIGN

Double-blind placebo-controlled prospective randomized trial.

SETTING

University hospital.

SUBJECTS

Twenty-four (first block: baclofen versus placebo) and 20 healthy male subjects (second block: meclizine, cinnarizine + dimenhydrinate and promethazine + dextro-amphetamine versus placebo).

INTERVENTIONS

VEMP test.

MAIN OUTCOME MEASURES

Threshold, p13 and n23 latencies, p13-n23 latency difference, p13-n23 peak-to-peak amplitude, mean rectified voltage of the sternocleidomastoid muscle contraction and the corrected amplitude.

RESULTS

There were no clinically significant pharmacologic effects on the VEMP outcome parameters. However, there was a statistically significant left-right asymmetry after intake of the combination promethazine + d-amphetamine for the parameters p13 and latency difference.

CONCLUSION

The absence of clinically significant effects can be explained by the predominant presence of the target receptors for the applied drugs in the medial vestibular nucleus, which receives the lowest grade of saccular projections. It also can be hypothesized that the VEMP methodology and techniques in general do not allow determining pharmacologic effects in a healthy group of subjects because of a too small discriminative power. The left-right asymmetry can be explained by a depressive action of the drugs on the central compensation mechanisms. Because there were no significant differences between the VEMP parameters obtained after intake of the placebos of both blocks, we concluded that there were no training effects.

Therapy for nystagmus

Pathological forms of nystagmus and their visual consequences can be treated using pharmacological, optical, and surgical approaches. Acquired periodic alternating nystagmus improves following treatment with baclofen, and downbeat nystagmus may improve following treatment with aminopyridines. Gabapentin and memantine are helpful in reducing acquired pendular nystagmus due to multiple sclerosis. Ocular oscillations in oculopalatal tremor may also improve following treatment with memantine or gabapentin. The infantile nystagmus syndrome (INS) may have only a minor impact on vision if "foveation periods" are well developed, but symptomatic patients may benefit from treatment with gabapentin, memantine, or base-out prisms to induce convergence. Several surgical therapies are also reported to improve INS, but selection of the optimal treatment depends on careful evaluation of visual acuity and nystagmus intensity in various gaze positions. Electro-optical devices are a promising and novel approach for treating the visual consequences of acquired forms of nystagmus.

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.

Current treatment of vestibular, ocular motor disorders and nystagmus

Vertigo and dizziness are among the most common complaints with a lifetime prevalence of about 30%. The various forms of vestibular disorders can be treated with pharmacological therapy, physical therapy, psychotherapeutic measures or, rarely, surgery. In this review, the current pharmacological treatment options for peripheral and central vestibular, cerebellar and ocular motor disorders will be described. They are as follows for peripheral vestibular disorders. In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Menière's disease a recent study showed long-term high-dose treatment with betahistine has a significant effect on the frequency of the attacks. The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA 2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. However, many other eye movement disorders such as ocular flutter opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat. Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA 2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Menière's disease, bilateral vestibular failure, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.

Pharmacotherapy of vestibular and ocular motor disorders, including nystagmus

We review current pharmacological treatments for peripheral and central vestibular disorders, and ocular motor disorders that impair vision, especially pathological nystagmus. The prerequisites for successful pharmacotherapy of vertigo, dizziness, and abnormal eye movements are the “4 D’s”: correct diagnosis, correct drug, appropriate dosage, and sufficient duration. There are seven groups of drugs (the “7 A’s”) that can be used: antiemetics; anti-inflammatory, anti-Ménière’s, and anti-migrainous medications; anti-depressants, anti-convulsants, and aminopyridines. A recovery from acute vestibular neuritis can be promoted by treatment with oral corticosteroids. Betahistine may reduce the frequency of attacks of Ménière’s disease. The aminopyridines constitute a novel treatment approach for downbeat and upbeat nystagmus, as well as episodic ataxia type 2 (EA 2); these drugs may restore normal “pacemaker” activity to the Purkinje cells that govern vestibular and cerebellar nuclei. A limited number of trials indicate that baclofen improves periodic alternating nystagmus, and that gabapentin and memantine improve acquired pendular and infantile (congenital) nystagmus. Preliminary reports suggest suppression of square-wave saccadic intrusions by memantine, and ocular flutter by beta-blockers. Thus, although progress has been made in the treatment of vestibular neuritis, some forms of pathological nystagmus, and EA 2, controlled, masked trials are still needed to evaluate treatments for many vestibular and ocular motor disorders, including betahistine for Ménière’s disease, oxcarbazepine for vestibular paroxysmia, or metoprolol for vestibular migraine.

Central oculomotor disturbances and nystagmus: a window into the brainstem and cerebellum

BACKGROUND

Oculomotor disturbances and nystagmus are seen in many diseases of the nervous system, the vestibular apparatus, and the eyes, as well as in toxic and metabolic disorders. They often indicate a specific underlying cause. The key to diagnosis is systematic clinical examination of the patient's eye movements. This review deals mainly with central oculomotor disturbances, i.e., those involving smooth pursuit, saccades, gaze-holding, and central types of nystagmus.

METHODS

We searched the current literature for relevant publications on the diagnosis and treatment of oculomotor disturbances and nystagmus, and discuss them selectively in this review along with the German Neurological Society's guidelines on the topic.

RESULTS

A detailed knowledge of the anatomy and physiology of eye movements usually enables the physician to localize the disturbance to a specific area in the brainstem or cerebellum. The examination of eye movements is an even more sensitive method than magnetic resonance imaging for the diagnosis of acute vestibular syndromes and for the differentiation of peripheral from central lesions. For example, isolated dysfunction of horizontal saccades is due to a pontine lesion, while isolated dysfunction of vertical saccades is due to a midbrain lesion. Generalized gaze-evoked nystagmus (GEN) has multiple causes; purely vertical GEN is due to a midbrain lesion, while purely horizontal GEN is due to a pontomedullary lesion. Internuclear ophthalmoplegia involves a constellation of findings, the most prominent of which is impaired adduction to the side of the causative lesion in the ipsilateral medial longitudinal fasciculus. The most common pathological types of central nystagmus are downbeat and upbeat nystagmus (DBN, UBN). DBN is generally due to cerebellar dysfunction, e.g., because of a neurodegenerative disease.

CONCLUSION

This short review focuses on the clinical characteristics, pathophysiology and current treatment of oculomotor disorders and nystagmus.

Which medication do I need to manage dizzy patients?

Vertigo and dizziness are not independent disease entities, but instead symptoms of various diseases. Accordingly, a variety of treatment approaches are required. Here we review the most relevant drugs for managing dizziness, vertigo, and nystagmus syndromes. It is important to differentiate symptomatic treatment of nausea and vomiting with, for example, dimenhydrinate and benzodiazepines, and prophylactic treatment of motion sickness with scopolamine from a causal therapy of the underlying disorders. Examples of such causal therapy include aminopyridines for downbeat nystagmus and episodic ataxia type 2; carbamazepine for vestibular paroxysmia, paroxsymal dysarthria and ataxia in multiple sclerosis, and superior oblique myokymia; betahistine, dexamethasone, and gentamicin for Menière's disease; gabapentin and memantine for different forms of acquired and congenital nystagmus; corticosteroids for acute vestibular neuritis and Cogan's syndrome; metoprolol and topiramate for vestibular migraine; and selective serotonin reuptake inhibitors such as paroxetine for phobic postural vertigo. The clinical entities are briefly described, the various medications are discussed in alphabetical order, and dosage, major side effects, contraindications, and alternative medications of each drug are displayed in boxes for easy reference.

[Pharmacological treatment of nystagmus]

Nystagmus can be associated with strong discomfort due to oscillopsia, blurry vision and dizziness. Since generally no curative treatment methods exist, studies focus on potential pharmaceuticals to dampen the nystagmus. An overview is given on which forms of nystagmus can be treated with what kind of pharmacological substances and their possible mechanism of nystagmus dampening. Controlled studies found gabapentin and memantine to be effective in acquired pendular nystagmus and early-onset idiopathic nystagmus, and an efficacy of 4-aminopyridine in downbeat nystagmus.

Treatments for neuro-ophthalmologic conditions

Neuro-ophthalmology covers disorders that fall between the cracks of Neurology and Ophthalmology. Neurologists see patients with neuro-ophthalmic disorders. Recognition of the diagnosis is difficult enough, but treatment can be challenging. This article reviews several common neuro-ophthalmic disorders, outlining their features and treatments, from retinal vascular disorders to eye movements and blepharospasm.

Nystagmus and saccadic intrusions

We review current concepts of nystagmus and saccadic oscillations, applying a pathophysiological approach. We begin by discussing how nystagmus may arise when the mechanisms that normally hold gaze steady are impaired. We then describe the clinical and laboratory evaluation of patients with ocular oscillations. Next, we systematically review the features of nystagmus arising from peripheral and central vestibular disorders, nystagmus due to an abnormal gaze-holding mechanism (neural integrator), and nystagmus occurring when vision is compromised. We then discuss forms of nystagmus for which the pathogenesis is not well understood, including acquired pendular nystagmus and congenital forms of nystagmus. We then summarize the spectrum of saccadic disorders that disrupt steady gaze, from intrusions to flutter and opsoclonus. Finally, we review current treatment options for nystagmus and saccadic oscillations, including drugs, surgery, and optical methods. Examples of each type of nystagmus are provided in the form of figures.

Eye disorders in patients with multiple sclerosis: natural history and management

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system and leading cause of disability in young adults. Vision impairment is a common component of disability for this population of patients. Injury to the optic nerve, brainstem, and cerebellum leads to characteristic syndromes affecting both the afferent and efferent visual pathways. The objective of this review is to summarize the spectrum of eye disorders in patients with MS, their natural history, and current strategies for diagnosis and management. We emphasize the most common disorders including optic neuritis and internuclear ophthalmoparesis and include new techniques, such as optical coherence tomography, which promise to better our understanding of MS and its effects on the visual system.

Crossover trial of gabapentin and memantine as treatment for acquired nystagmus

We conducted a masked, crossover, therapeutic trial of gabapentin (1,200mg/day) versus memantine (40 mg/day) for acquired nystagmus in 10 patients (aged 28-61 years; 7 female; 3 multiple sclerosis [MS]; 6 post-stroke; 1 post-traumatic). Nystagmus was pendular in 6 patients (4 oculopalatal tremor; 2 MS) and jerk upbeat, hemi-seesaw, torsional, or upbeat-diagonal in each of the others. For the group, both drugs reduced median eye speed (p < 0.001), gabapentin by 32.8% and memantine by 27.8%, and improved visual acuity (p < 0.05). Each patient improved with 1 or both drugs. Side effects included unsteadiness with gabapentin and lethargy with memantine. Both drugs should be considered as treatment for acquired forms of nystagmus.

Medical treatment of vestibular disorders

BACKGROUND

The lifelong prevalence of rotatory vertigo is 30%. Despite this high figure, patients with vertigo generally receive either inappropriate or inadequate treatment. However, the majority of vestibular disorders have a benign cause, take a favorable natural course, and respond positively to therapy.

OBJECTIVE

This review puts special emphasis on the medical rather than the physical, operative, or psychotherapeutic treatments available.

METHODS

A selected review of recent reports and studies on the medical treatment of peripheral and central vestibular disorders.

RESULTS/CONCLUSIONS

In vestibular neuritis, recovery of the peripheral vestibular function can be improved by oral corticosteroids; in Menière's disease, there is first evidence that high-dose, long-term administration of betahistine reduces attack frequency; carbamazepine or oxcarbamazepine is the treatment of first choice in vestibular paroxysmia, a disorder mainly caused by neurovascular cross-compression; the potassium channel blocker aminopyridine provides a new therapeutic principle for treatment of downbeat nystagmus, upbeat nystagmus, and episodic ataxia type 2.

Failure of gamma-aminobutyrate acid-beta agonist baclofen to improve balance, gait, and postural control after vestibular schwannoma resection

INTRODUCTION

Incomplete postural control often occurs after vestibular schwannoma (VS) surgery. Customized vestibular rehabilitation in man improves and speeds up this process. Animal experiments have shown an improved and faster vestibular compensation after administration of the gamma-aminobutyrate acid (GABA)-beta agonist baclofen.

OBJECTIVE

To examine whether medical treatment with baclofen provides an improvement of the compensation process after VS surgery.

DESIGN

A time-series study with historical control.

SETTING

Tertiary referral center.

METHODS

Thirteen patients who underwent VS resection were included and compared with a matched group of patients. In addition to an individualized vestibular rehabilitation protocol, the study group received medical treatment with 30 mg baclofen (a GABA-beta agonist) daily during the first 6 weeks after surgery.

MAIN OUTCOME MEASURES

Clinical gait and balance tests (Romberg maneuver, standing on foam, tandem Romberg, single-leg stance, Timed Up & Go test, tandem gait, Dynamic Gait Index) and Dizziness Handicap Inventory. Follow-up until 24 weeks after surgery.

RESULTS

When examining the postoperative test results, the group treated with baclofen did not perform better when compared with the matched (historical control) group. Repeated-measures analysis of variance revealed no significant group effect, but a significant time effect for almost all balance tests during the acute recovery period was found. An interaction effect between time and intervention was seen concerning single-leg stance and Dizziness Handicap Inventory scores for the acute recovery period.

CONCLUSION

Medical therapy with baclofen did not seem to be beneficial in the process of central vestibular compensation.

[Pharmacotherapy of central oculomotor disorders]

Nystagmus causes blurred vision due to oscillopsia, as well as impaired balance. Depending on etiology, additional cerebellar and brain stem signs may occur. We present the current pharmacotherapy of the most common forms of central nystagmus: downbeat nystagmus (DBN), upbeat nystagmus (UBN), acquired pendular nystagmus (APN), and congenital nystagmus (CGN). Recommended medical therapies are aminopyridines (4-AP) for DBN and UBN, gabapentin and memantine for CGN and APN, and baclofen for periodic alternating nystagmus (PAN).

Central vestibular disorders

Dizziness or vertigo is an erroneous perception of selfmotion or object-motion as well as an unpleasant distortion of static gravitational orientation. It is caused by a mismatch between the vestibular, visual, and somatosensory systems. Thanks to their functional overlap, the three systems are able to compensate, in part, for each other's deficiencies. Thus, vertigo is not a well-defined disease entity, but rather a multisensory syndrome that results when there is a pathological dysfunction of any of the stabilizing sensory systems (e.g., central vestibular disorders, peripheral vestibular diseases with asymmetric input into the vestibular nuclei). This article provides an overview of the most important and frequent forms of central vestibular vertigo syndromes, including basilar/vestibular migraine, which are characterized by ocular motor, postural, and perceptual signs. In a simple clinical classification they can be separated according to the three major planes of action of the vestibulo-ocular reflex: yaw, roll, and pitch. A tonic imbalance in yaw is characterized by horizontal nystagmus, lateropulsion of the eyes, past-pointing, rotational and lateral body falls, and lateral deviation of the perceived straight-ahead. A tonic imbalance in roll is defined by torsional nystagmus, skew deviation, ocular torsion, tilts of head, body, and the perceived vertical. Finally, a tonic imbalance in pitch can be characterized by some forms of upbeat or downbeat nystagmus, fore-aft tilts and falls, and vertical deviation of the perceived straight ahead. The thus defined syndromes allow for a precise topographic diagnosis as regards their level and side.

Oscillopsies : approches physiopathologique et thérapeutique

Oscillopsia is an illusion of an unstable visual world. It is associated with poor visual acuity and is a disabling and stressful symptom reported by numerous patients with neurological disorders. The goal of this paper is to review the physiology of the systems subserving stable vision, the various pathophysiological mechanisms of oscillopsia and the different treatments available. Visual stability is conditioned by two factors. First, images of the seen world projected onto the retina have to be stable, a sine qua non condition for foveal discriminative function. Vestibulo-ocular and optokinetic reflexes act to stabilize the retinal images during head displacements; ocular fixation tends to limit the occurrence of micro ocular movements during gazing; a specific system also acts to maintain the eyes stable during eccentric gaze. Second, although we voluntary move our gaze (body, head and eye displacements), the visual world is normally perceived as stable, a phenomenon known as space constancy. Indeed, complex cognitive processes compensate for the two sensory consequences of gaze displacement, namely an oppositely-directed retinal drift and a change in the relationship between retinal and spatial (or subject-centered) coordinates of the visual scene. In patients, oscillopsia most often results from abnormal eye movements which cause excessive motion of images on the retina, such as nystagmus or saccadic intrusions or from an impaired vestibulo-ocular reflex. Understanding the exact mechanisms of impaired eye stability may lead to the different treatment options that have been documented in recent years. Oscillopsia could also result from an impairment of spatial constancy mechanisms that in normal condition compensate for gaze displacements, but clinical data in this case are scarce. However, we suggest that some visuo-perceptive deficits consecutive to temporo-parietal lesions resemble oscillopsia and could result from a deficit in elaborating spatial constancy.

Optic neuritis and the neuro-ophthalmology of multiple sclerosis

Multiple sclerosis (MS) is the most common cause of neurological disability in young adults. Since approximately 40% of the brain is devoted to vision, demyelination commonly affects visual function, resulting in a myriad of neuro-ophthalmic symptoms. In this chapter, we examine the seminal afferent and efferent neuro-ophthalmological manifestations of MS, highlighting those history and examination findings critical for the diagnosis and treatment of various visual and ocular motor disorders. Among the topics, a special emphasis will be placed on optic neuritis, the most common clinically isolated demyelinating syndrome. This chapter focuses on the evaluation and treatment of visual sensory and oculomotor disorders in MS. The objective is to provide the reader with a working model for enhancing their care of patients with demyelinating disease.