Evaluation of transdermal scopolamine as treatment for acquired nystagmus

Oncologic causes of oculopalatal tremors: neurophysiology and treatment

Oculopalatal tremor (OPT) is an acquired pathology characterized by continuous and rhythmical soft palatal movements combined with pendular nystagmus. Aside from vascular lesions, oncological masses affecting the dentatorubro-olivary pathway can impair brainstem and/or cerebellar pathways, manifesting as dyssynchronous movement. In this review, we delve into the neurophysiology of OPT along with oncological causes and treatment options based on the most recent clinical trial data. This literature review includes medication treatment data from clinical trials enrolling individuals with features of OPT, including acquired pendular nystagmus (APN). Trials were deemed eligible for inclusion in this review if one or more participants had symptoms determined by the trial authors to be caused by OPT. Trials investigating the treatment of APN secondary to a separate cause, such as multiple sclerosis, were excluded from this review. Several early treatments failed to demonstrate a benefit for patients with APN due to OPT. Trials of anticholinergic agents were largely ineffective and poorly tolerated. Botulinum toxin A demonstrated improvement in APN symptoms. Most recently, trials including memantine and gabapentin have demonstrated success with attenuation of APN. Surgical modalities such as DBS have yet to show improvement, though with only a single case report as evidence. Oculopalatal tremor is a unique manifestation of posterior fossa tumors disrupting the Guillain-Mollaret triangle. Symptom control through medication management has had limited success attributed to poor response and medication intolerance. Surgical modalities like DBS may have an emerging role in OPT treatment by targeting dyssynchronous activity in the dentatorubro-olivary pathway.

Otorhinolaryngological adverse effects of urological drugs

PURPOSE

To describe the otorhinolaryngological adverse effects of the main drugs used in urological practice.

MATERIALS AND METHODS

A review of the scientific literature was performed using a combination of specific descriptors (side effect, adverse effect, scopolamine, sildenafil, tadalafil, vardenafil, oxybutynin, tolterodine, spironolactone, furosemide, hydrochlorothiazide, doxazosin, alfuzosin, terazosin, prazosin, tamsulosin, desmopressin) contained in publications until April 2020. Manuscripts written in English, Portuguese, and Spanish were manually selected from the title and abstract. The main drugs used in Urology were divided into five groups to describe their possible adverse effects: alpha-blockers, anticholinergics, diuretics, hormones, and phosphodiesterase inhibitors.

RESULTS

The main drugs used in Urology may cause several otorhinolaryngological adverse effects. Dizziness was most common, but dry mouth, rhinitis, nasal congestion, epistaxis, hearing loss, tinnitus, and rhinorrhea were also reported and varies among drug classes.

CONCLUSIONS

Most of the drugs used in urological practice have otorhinolaryngological adverse effects. Dizziness was most common, but dry mouth, rhinitis, nasal congestion, epistaxis, hearing loss, tinnitus, and rhinorrhea were also reported. Therefore, doctors must be aware of these adverse effects to improve adherence to the treatment and to minimize damage to the health of patients.

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.

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.

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.

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.

EFNS task force - therapy of nystagmus and oscillopsia

An overview of possible treatment options for oculomotor disorders that prevent clear vision is given. Downbeat nystagmus, upbeat nystagmus, seesaw nystagmus, periodic alternating nystagmus, acquired pendular nystagmus, and saccadic oscillations such as opsoclonus/ocular flutter are discussed. In addition, superior oblique myokymia and vestibular paroxysmia are reviewed. All treatment recommendations available in the literature are classified as class C only. In general, only some of the patients benefit from the treatment.

A neurobiological approach to acquired nystagmus

The development of animal and mathematical models for several forms of acquired nystagmus has led to more comprehensive knowledge of these disorders. In the best understood forms, such as periodic alternating nystagmus, our range of knowledge includes an animal model, the neurotransmitters involved, and effective treatment. For some other forms, such as downbeat nystagmus, we have an animal model, but reliable treatment is lacking. In other cases, exemplified by acquired pendular nystagmus, we have only a provisional hypothesis for pathogenesis to account for the oscillations, without an animal model, but effective treatment is possible in some patients. The present trend of studying all aspects of the neurobiology of nystagmus, from molecules to behavior, seems to be the best approach to extend our knowledge and to identify new treatments, but much remains to be done.

Peripheral and central eye movement disorders

Continuing advances have rendered the neural control of eye movements one of the best understood motor systems, from molecules to complex behaviors. Nevertheless, new discoveries have required re-evaluation of established concepts, from the genetics of disorders that affect extraocular muscles to the way in which the cerebral cortex governs behaviors that encompass several functional classes of eye movements.