EFNS task force - therapy of nystagmus and oscillopsia

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.

Eye Movement Compensation and Spatial Updating in Visual Prosthetics: Mechanisms, Limitations and Future Directions

Despite appearing automatic and effortless, perceiving the visual world is a highly complex process that depends on intact visual and oculomotor function. Understanding the mechanisms underlying spatial updating (i.e., gaze contingency) represents an important, yet unresolved issue in the fields of visual perception and cognitive neuroscience. Many questions regarding the processes involved in updating visual information as a function of the movements of the eyes are still open for research. Beyond its importance for basic research, gaze contingency represents a challenge for visual prosthetics as well. While most artificial vision studies acknowledge its importance in providing accurate visual percepts to the blind implanted patients, the majority of the current devices do not compensate for gaze position. To-date, artificial percepts to the blind population have been provided either by intraocular light-sensing circuitry or by using external cameras. While the former commonly accounts for gaze shifts, the latter requires the use of eye-tracking or similar technology in order to deliver percepts based on gaze position. Inspired by the need to overcome the hurdle of gaze contingency in artificial vision, we aim to provide a thorough overview of the research addressing the neural underpinnings of eye compensation, as well as its relevance in visual prosthetics. The present review outlines what is currently known about the mechanisms underlying spatial updating and reviews the attempts of current visual prosthetic devices to overcome the hurdle of gaze contingency. We discuss the limitations of the current devices and highlight the need to use eye-tracking methodology in order to introduce gaze-contingent information to visual prosthetics.

The role of optical coherence tomography and infrared oculography in assessing the visual pathway and CNS in multiple sclerosis

In this review, a current overview is provided of how optical coherence tomography and infrared oculography can aid in assessing the visual system and CNS in multiple sclerosis (MS). Both afferent and efferent visual disorders are common in MS and visual complaints can have a tremendous impact on daily functioning. Optical coherence tomography and infrared oculography can detect and quantify visual disorders with high accuracy, but could also serve as quantitative markers for inflammation, neurodegeneration and network changes including cognitive decline in MS patients. The assessment of the efferent and afferent visual pathways is relevant for monitoring and predicting the disease course, but is also potentially valuable as an outcome measure in therapeutic trials.

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.

Principles of vestibular pharmacotherapy

Ideally, vestibular pharmacotherapy is intended, through specific and targeted molecular actions, to significantly alleviate vertigo symptoms, to protect or repair the vestibular sensory network under pathologic conditions, and to promote vestibular compensation, with the eventual aim of improving the patient's quality of life. In fact, in order to achieve this aim, considerable progress still needs to be made. The lack of information on the etiology of vestibular disorders and the pharmacologic targets to modulate, as well as the technical challenge of targeting a drug to its effective site are some of the main issues yet to be overcome. In this review, my intention is to provide an account of the therapeutic principles that have shaped current vestibular pharmacotherapy and to further explore crucial questions that must be taken into consideration in order to develop targeted and specific pharmacologic therapies for each type and stage of 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.

Nystagmus in childhood

Nystagmus is an involuntary rhythmic oscillation of the eyes, which leads to reduced visual acuity due to the excessive motion of images on the retina. Nystagmus can be grouped into infantile nystagmus (IN), which usually appears in the first 3-6 months of life, and acquired nystagmus (AN), which appears later. IN can be idiopathic or associated to albinism, retinal disease, low vision, or visual deprivation in early life, for example due to congenital cataracts, optic nerve hypoplasia, and retinal dystrophies, or it can be part of neurological syndromes and neurologic diseases. It is important to differentiate between infantile and acquired nystagmus. This can be achieved by considering not only the time of onset of the nystagmus, but also the waveform characteristics of the nystagmus. Neurological disease should be suspected when the nystagmus is asymmetrical or unilateral. Electrophysiology, laboratory tests, neurological, and imaging work-up may be necessary, in order to exclude any underlying ocular or systemic pathology in a child with nystagmus. Furthermore, the recent introduction of hand-held spectral domain optical coherence tomography (HH SD-OCT) provides detailed assessment of foveal structure in several pediatric eye conditions associated with nystagmus and it can been used to determine the underlying cause of infantile nystagmus. Additionally, the development of novel methods to record eye movements can help to obtain more detailed information and assist the diagnosis. Recent advances in the field of genetics have identified the FRMD7 gene as the major cause of hereditary X-linked nystagmus, which will possibly guide research towards gene therapy in the future. Treatment options for nystagmus involve pharmacological and surgical interventions. Clinically proven pharmacological treatments for nystagmus, such as gabapentin and memantine, are now beginning to emerge. In cases of obvious head posture, eye muscle surgery can be performed to shift the null zone of the nystagmus into the primary position, and also to alleviate neck problems that can arise due to an abnormal head posture.

'Dancing eyes, dancing feet syndrome' in small cell lung carcinoma

A 60-year-old man presented with a 25-day history of acute onset instability of gait, tremulousness of limbs and involuntary eye movements. Examination revealed presence of opsoclonus, myoclonus and ataxia, without any loss of motor power in the limbs. Prompt investigations were directed towards identifying an underlying malignancy which is often associated with this type of clinical scenario. CT of the brain was normal and cerebrospinal fluid examination showed lymphocytic pleocytosis. A cavitatory lesion was found in the right lung base on the high-resolution CT of the chest and histopathological examination of this lung mass showed small cell lung carcinoma. The patient was managed symptomatically with levetiracetam and baclofen and referred to oncology department for resection of the lung mass.

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.

Balance

This chapter addresses the important and undertreated problem of balance disorders. The chapter has a simplified summary of the physiology of balance problems in order to set the scene. The issue of assessment is next addressed with discussion of important tests including the Berg Balance Scale and the Get Up and Go Test, and others. Posturography is discussed as well as assessment of the gravitional vertical. The assessment of vestibular function is of key importance and discussed in some detail. The focus of the chapter is on balance rehabilitation. Re-training of postural alignment and of sensory strategies are key but adaptation of the environment and re-training of cognitive strategies are also helpful in individual cases. Vestibular exercises can also be used. The chapter then critically analyses the efficacy of these treatments in specific balance disorders such as in stroke, Parkinson disease, polyneuropathies, multiple sclerosis, and vestibular disorders. Overall, there is a growing body of evidence that balance rehabilitation improves symptoms, function, and quality of life for those troubled by these disabling problems.

Wernicke's encephalopathy: expanding the diagnostic toolbox

Wernicke's encephalopathy (WE) is a life threatening neurological disorder that results from thiamine (Vitamin B1) deficiency. Clinical signs include mental status changes, ataxia, occulomotor changes and nutritional deficiency. The conundrum is that the clinical presentation is highly variable. WE clinical signs, brain imaging, and thiamine blood levels, are reviewed in 53 published case reports from 2001 to 2011; 81 % (43/53) were non-alcohol related. Korsakoff Syndrome or long-term cognitive neurological changes occurred in 28 % (15/53). Seven WE cases (13 %) had a normal magnetic resonance image (MRI). Four WE cases (8 %) had normal or high thiamine blood levels. Neither diagnostic tool can be relied upon exclusively to confirm a diagnosis of WE.

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.

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.

The evidence base for the evaluation and management of dizziness

OBJECTIVES

Dizziness presentations pose many clinical challenges. The objective of this study is to broadly summarize the evidence base that supports clinical decisions in dizziness presentations.

METHODS

MEDLINE (1966 to September 2007), Web of Science and The Cochrane Library were searched for articles with clinical relevance on topics concerning dizziness. Additional sources were also searched for clinical practice guidelines. The following information was abstracted from each article: year of publication, journal type, type of article and the topics of the article.

RESULTS

Of nearly 3000 articles identified, 1244 articles met the inclusion criteria. The most common article type was a case report or case series, followed by expert opinion or review articles, studies of medical tests and clinical trials. Meta-analyses and systematic reviews were found on benign paroxysmal positional vertigo and Meniere's disease, but only a few other topics. No clinical practice guidelines were found that focus specifically on dizziness.

CONCLUSIONS

The evidence base for the evaluation and management of dizziness seems to be weak. Future work to establish or summarize evidence in clinically meaningful ways could contribute to efforts to optimize patient care and health care utilization for one of the most common presenting symptoms.

Paraneoplastic movement disorders

Neurologic paraneoplastic syndromes (NPSs) result from damage to the nervous system due to the remote effects of cancer not related to metastasis, infection, or metabolic derangements. NPSs are rare, affecting 1 in 10,000 patients with cancer. Pathogenesis is likely related to the immune mechanisms: normal neural tissue is mistakenly attacked due to the similarity in the onconeural antigens expressed by the tumor cells. Among the various "classic" and other NPSs, this review focuses on paraneoplastic movement disorders, including ataxia due to cerebellar degeneration, stiff-person syndrome, opsoclonus-myoclonus syndrome, chorea, parkinsonism, and tremor. The recently described syndrome of paraneoplastic anti-N-methyl-D-aspartate receptor encephalitis is also included, given that these patients have complex movements such as stereotypies and dyskinesias in addition to psychiatric symptoms, altered sensorium, and other neurologic signs. Although variable, treatment and prognosis of NPSs rely heavily on treatment of the underlying malignancy and immunotherapy.

[Ocular motor disorders in multiple sclerosis]

Multiple sclerosis is the most common disabling neurological disease in young people. Many neuro-ophthalmological manifestations can occur during the course of the illness, and optic neuritis is both the most frequent and the best known. However, some ocular motility disorders can also occur, but since there may be no symptoms, they often remain underdiagnosed. These eye movement disorders are mostly related to brain-stem and cerebellum lesions. They can be acute, indicating a spatial dissemination of the demyelinating disease, and consequently may indicate the need for systemic treatment of multiple sclerosis. More often, they evolve slowly, progressing with the multiple sclerosis. In this case, they could provide a clue to the prognosis of the disease. In this survey, we discuss the two major symptoms of ocular motor disorders likely to occur during multiple sclerosis: oscillopsia and diplopia.

An update on acquired nystagmus

Proper evaluation and treatment of acquired nystagmus requires accurate characterization of nystagmus type and visual effects. This review addresses important historical and examination features of nystagmus and current concepts of pathogenesis and treatment of gaze-evoked nystagmus, nystagmus due to vision loss, acquired pendular nystagmus, peripheral and central vestibular nystagmus, and periodic alternating nystagmus.

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.

An update on opsoclonus

PURPOSE OF REVIEW

The aim of this article is to review opsoclonus, with particular emphasis on its immunopathogenesis and pathophysiology.

RECENT FINDINGS

Infections (West Nile virus, Lyme disease), neoplasms (non-Hodgkin's lymphoma, renal adenocarcinoma), celiac disease, and allogeneic hematopoietic stem cell transplantation can cause opsoclonus. Newly identified autoantibodies include antineuroleukin, antigliadin, antiendomysial, and anti-CV2. Evidence suggests that the autoantigens of opsoclonus reside in postsynaptic density, or on the cell surface of neurons or neuroblastoma cells (where they exert antiproliferative and proapoptotic effects). Most patients, however, are seronegative for autoantibodies. Cell-mediated immunity may also play a role, with B and T-cell recruitment in the cerebrospinal fluid linked to neurological signs. Rituximab, an anti-CD20 monoclonal antibody, seems efficacious as an adjunctive therapy. Although changes in synaptic weighting of saccadic burst neuron circuits in the brainstem have been implicated, disinhibition of the fastigial nucleus in the cerebellum, or damage to afferent projections to the fastigial nucleus, is a more plausible pathophysiologic mechanism which is supported by functional magnetic resonance imaging findings in patients.

SUMMARY

There is increasing recognition that both humoral and cell mediated immune mechanisms are involved in the pathogenesis of opsoclonus. Further studies are needed to further elucidate its immunopathogenesis and pathophysiology in order to develop novel and efficacious therapy.

Management of paraneoplastic neurological syndromes: report of an EFNS Task Force

Paraneoplastic neurological syndromes (PNS) are remote effects of cancer on the nervous system. An overview of the management of classical PNS, i.e. paraneoplastic limbic encephalitis, subacute sensory neuronopathy, paraneoplastic cerebellar degeneration, paraneoplastic opsoclonus-myoclonus, Lambert-Eaton myasthenic syndrome and paraneoplastic peripheral nerve hyperexcitability is given. Myasthenia gravis and paraproteinemic neuropathies are not included in this report. No evidence-based recommendations were possible, but good practice points were agreed by consensus. Urgent investigation is indicated, especially in central nervous system (CNS) syndromes, to allow tumour therapy to be started early and prevent progressive neuronal death and irreversible disability. Onconeural antibodies are of great importance in the investigation of PNS and can be used to focus tumour search. PDG-PET is useful if the initial radiological tumour screen is negative. Early detection and treatment of the tumour is the approach that seems to offer the greatest chance for PNS stabilization. Immune therapy usually has no or modest effect on the CNS syndromes, whereas such therapy is beneficial for PNS affecting the neuromuscular junction. Symptomatic therapy should be offered to all patients with PNS.

Pharmacological advances in the treatment of neuro-otological and eye movement disorders

PURPOSE OF REVIEW

First, to describe the current pharmacological treatment options for peripheral and central vestibular, cerebellar, and ocular motor disorders. Second, to identify vestibular and ocular motor disorders in which treatment trials are warranted.

RECENT FINDINGS

Peripheral vestibular disorders: In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Ménière's disease treatment strategies range from low-salt diet, diuretics, and betahistine, to intratympanic injection of corticosteroids or gentamicin. Unfortunately most of the trials on Ménière's disease do not have an up-to-date design. In bilateral vestibulopathy steroids do not seem to improve vestibular function.Central vestibular, cerebellar, and ocular motor disorders: The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA2). 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. Many other eye movement disorders, however, such as ocular flutter, opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat.

SUMMARY

Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Ménière's disease, bilateral vestibulopathy, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.

Localizing forms of nystagmus: Symptoms, diagnosis, and treatment

Nystagmus is a rhythmic oscillation of the eyes that may be acquired or congenital. The symptoms of acquired nystagmus include blurred vision and oscillopsia. Most patients with congenital nystagmus do not have oscillopsia symptoms. Several forms of nystagmus have localizing value and any neuroimaging should be directed to the topographic localization suggested by the morphology of the nystagmus and any accompanying localizing signs. Several optical, medical, and surgical treatments have been used with some success in specific forms of nystagmus.

Pharmacology of vertigo/nystagmus/oscillopsia

PURPOSE OF REVIEW

To describe recent developments in the pharmacological treatment of vertigo and nystagmus while focusing on vestibular neuritis, Meniere's disease, downbeat nystagmus, periodic alternating nystagmus, acquired pendular nystagmus, and superior oblique myokymia.

RECENT FINDINGS

In the last 2 years several studies have been published on possible pharmacological treatment options for nystagmus and oscillopsia. In the treatment of vestibular neuritis two studies showed that cortisone treatment was effective for restoring labyrinthine function. This benefit seems more likely if treatment is started within the first 2 days of onset. For recurrent vertigo attacks due to Meniere's disease, the titration technique with daily or weekly doses of intratympanic gentamicin until onset of vestibular symptoms, change in vertigo or hearing loss rated best for complete vertigo control. A new pharmacological treatment option for downbeat nystagmus is the administration of potassium channel blockers (e.g. 4-aminopyridine). They are thought to reinforce the inhibitory action of cerebellar Purkinje cells. Several case reports have proven the beneficial effect of baclofen on periodic alternating nystagmus, of gabapentin and memantine on acquired pendular nystagmus, and of carbamazepine and gabapentin on superior oblique myokymia.

SUMMARY

There have been several new developments in the treatment of nystagmus and vertigo over the last 2 years. These include potassium channel blockers for the treatment of downbeat nystagmus, early cortisone treatment to improve recovery of the labyrinth function in vestibular neuritis, and intratympanic gentamicin treatment for Meniere's disease. Other pharmacological treatment options are baclofen for periodic alternating nystagmus, gabapentin and memantine for acquired pendular nystagmus, and carbamazepine for superior oblique myokymia.

Current treatment of nystagmus

Acquired and congenital nystagmus often causes decreased visual acuity as a direct result of the inability to maintain stable foveal vision. In addition, acquired nystagmus causes a disabling subjective sensation of movement of the visual world called oscillopsia. The eye movements themselves do not require treatment if the patient is asymptomatic. However, therapy is necessary if visual disability is present. Treatments based in pharmacologic mechanisms are preferred. There are few controlled treatment trials and therapeutic efficacy generally is sought in a trial and error approach, depending on the type of nystagmus present. Treatment with 3,4-diaminopyridine and 4-aminopyridine recently have been shown to be effective for downbeat nystagmus. Gabapentin, baclofen, and clonazepam also are useful in some patients with downbeat nystagmus. Baclofen is the therapy of choice for periodic alternating nystagmus. Gabapentin often is effective for acquired pendular nystagmus. Clonazepam and valproate also may be effective for acquired pendular nystagmus. Memantine now is available in the United States and is promising in the treatment of pendular nystagmus. Optical devices that negate the negative effects of nystagmus continue to undergo development research. These and other medical, surgical, and optical devices are potentially useful alone or in combination with other therapies.