Opsoclonus, body tremulousness, and benign encephalitis

Modeling gaze position-dependent opsoclonus

Opsoclonus/flutter (O/F) is a rare disorder of the saccadic system. Previously, we modeled O/F that developed in a patient following abuse of anabolic steroids. That model, as in all models of the saccadic system, generates commands to make a change in eye position. Recently, we saw a patient who developed a unique form of opsoclonus following a concussion. The patient had postsaccadic ocular flutter in both directions of gaze, and opsoclonus during fixation and pursuit in the left hemifield. A new model of the saccadic system is needed to account for this gaze-position dependent O/F. We started with our prior model, which contains two key elements, mutual inhibition between inhibitory burst neurons on both sides and a prolonged reactivation time of the omnipause neurons (OPNs). We included new inputs to the OPNs from the nucleus prepositus hypoglossi and the frontal eye fields, which contain position-dependent neurons. This provides a mechanism for delaying OPN reactivation, and creating a gaze-position dependence. A simplified pursuit system was also added, the output of which inhibits the OPNs, providing a mechanism for gaze-dependence during pursuit. The rest of the model continues to generate a command to change eye position.

A GABAergic Dysfunction in the Olivary-Cerebellar-Brainstem Network May Cause Eye Oscillations and Body Tremor. II. Model Simulations of Saccadic Eye Oscillations

Eye and body oscillations are shared features of several neurological diseases, yet their pathophysiology remains unclear. Recently, we published a report on two tennis players with a novel presentation of eye and body oscillations following self-administration of performance-enhancing substances. Opsoclonus/flutter and limb tremor were diagnosed in both patients. Common causes of opsoclonus/flutter were excluded. High-resolution eye movement recordings from one patient showed novel spindle-shaped, asymmetric saccadic oscillations (at ~3.6 Hz) and ocular tremor (~40-60 Hz). Based on these findings, we proposed that the oscillations are the result of increased GABAA receptor sensitivity in a circuit involving the cerebellum (vermis and fastigial nuclei), the inferior olives, and the brainstem saccade premotor neurons (excitatory and inhibitory burst neurons, and omnipause neurons). We present a mathematical model of the saccadic system, showing that the proposed dysfunction in the network can reproduce the types of saccadic oscillations seen in these patients.

Parainfectious Ocular Flutter and Truncal Ataxia in Association with Dengue Fever

Ocular flutter is an eye movement disorder characterized by purely horizontal rapid saccadic oscillations lasting for a few minutes which stops spontaneously. Postinfectious ocular flutter and truncal ataxia are a rare entity. There are reported cases of opsoclonus myoclonus ataxia in association with dengue virus infection. However, there are no reported cases of parainfectious ocular flutter and truncal ataxia in association with dengue virus infection. Hereby, we report a child with dengue fever who had ocular flutter and truncal ataxia.

Paraneoplastic neurological complications of breast cancer

Breast cancer is the most frequent cause of cancer of women in much of the world. In countries with screening programs, breast cancer is often detected before clinical symptoms are apparent, but occasionally the occurrence of a paraneoplastic syndrome precedes the identification of cancer. In breast cancer, there are known to be paraneoplastic endocrine syndromes and neurologic syndromes. The neurologic syndromes are often hard to identify and treat. The neurologic syndromes associated with breast cancer include cerebellar degeneration, sensorimotor neuropathy, retinopathy, stiff-persons syndrome, encephalitis, and opsoclonus-myoclonus. Most of these are mediated by antibodies against known neural antigens, although some cases appear to be mediated by non-humoral mechanisms. Treatments differ depending upon the syndrome type and etiology. Outcomes also vary depending upon duration of disease, the treatments used and the responsiveness of the underlying cancer. A thorough review of the published literature is provided along with recommendations for management and future research.

Craniofacial dysmorphism and opsoclonus

Report of a case with craniofacial dysmorphism and opsoclonus. The opsoclonus commenced in the perinatal period and abated at 18 months. Previous cases of opsoclonus associated with cranial and facial anomalies are reviewed, and it is suggested that opsoclonus in the authors' case was related to the delayed maturation of inhibitory cells in the brainstem.

Tremor in childhood

Tremor in childhood is not commonly described in the literature; but it is also likely underappreciated. The etiology of childhood tremor encompasses a wide variety of pathologic processes. Tremor may occur in isolation, or in association with other neurologic findings or systemic disorders. This article aims to provide an overview of tremorogenic mechanisms with respect to neuroanatomy and neurophysiology, particularly as they relate to children. Classification of tremors, diagnostic entities in childhood, and treatment will also be discussed. With improved recognition and characterization of childhood tremors, we may gain a better understanding of the pathophysiology of the disease and determine more age-appropriate treatment strategies.

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.

Benign opsoclonus in preterm infants

Opsoclonus is a rare childhood ocular motility disorder characterized by irregular, chaotic, involuntary bursts of high amplitude, back-and-forth oscillations of the eyes,without pause intervals. Although this disorder is associated with neuroblastoma and other neural crest tumors, as well as with other neurologic abnormalities, it was also reported in healthy infants. The purpose of this study was to prospectively investigate the prevalence of opsoclonus in preterm infants, and to find any conditions associated with this disorder. Between August 2000 and April 2003, 528 consecutive preterm infants with gestation of less than 33 weeks or birth weight of less than 1500 gm were examined in accordance with our medical centers' retinopathy of prematurity screening policy. Opsoclonus was identified in three patients (0.6%), who were all otherwise physically and neurologically intact. One patient developed threshold retinopathy of prematurity that resolved after laser treatment. On follow-up examinations, the opsoclonus gradually disappeared by the age of 6 months in all infants,with no other complications. This study suggests that opsoclonus can be a benign, self-limiting phenomenon in preterm infants as was previously reported in term infants. However, because of the risk of severe associated illnesses, it is prudent to perform several diagnostic procedures and to continue careful follow-up until this phenomenon spontaneously resolves.

Opsoclonus in three dimensions: oculographic, neuropathologic and modelling correlates

Opsoclonus is a dyskinesia consisting of involuntary, arrhythmic, chaotic, multidirectional saccades, without intersaccadic intervals. We used a magnetic scleral search coil technique to study opsoclonus in two patients with paraneoplastic complications of lung carcinoma. Eye movement recordings provided evidence that opsoclonus is a three-dimensional oscillation, consisting of torsional, horizontal, and vertical components. Torsional nystagmus was also present in one patient. Antineuronal antibody study revealed the presence of anti-Ta (Ma2 onco-neuronal antigen) antibodies in one patient, which had previously been associated only with paraneoplastic limbic encephalitis and brainstem dysfunction, but not opsoclonus, and only in patients with testicular or breast cancer. Neuropathologic examination revealed mild paraneoplastic encephalitis. Normal neurons identified in the nucleus raphe interpositus (rip) do not support postulated dysfunction of omnipause cells in the pathogenesis of opsoclonus. Computer simulation of a model of the saccadic system indicated that disinhibition of the oculomotor region of the fastigial nucleus (FOR) in the cerebellum can generate opsoclonus. Histopathological examination revealed inflammation and gliosis in the fastigial nucleus. This morphological finding is consistent with, but not necessary to confirm, damage to afferent projections to the FOR, as determined by the model. Malfunction of Purkinje cells in the dorsal vermis, which inhibit the FOR, may cause opsoclonus by disinhibiting it.

The legacy of David G. Cogan, MD

The professional life of David G. Cogan was characterized by both personal accomplishments and the nurture of his students and colleagues.

Neurological sequelae of the dancing eye syndrome

Fifty-four patients with dancing eye syndrome (DES), presenting over a 25-year period, were reviewed retrospectively. One third of them were on active follow up at the time of the study. Malignancy was uncommon, diagnosed in only 4 patients, neuroblastoma in 3 cases and acute lymphoblastic leukaemia (ALL) in 1. An intercurrent illness preceded onset of DES in 51% of the children and was of equivocal significance. There was no clear temporal relationship to immunization. The acute phase of the illness was severe and caused total immobilization in 88% of patients. A favourable initial response to treatment with prednisolone or corticotrophin gel was observed in all patients. Although corticotrophin seemed to produce a more rapid response, overall improvement was similar with both treatments. Long-term neurological morbidity was a major problem with 91% of children suffering either persisting symptoms or repeated relapses. A persisting disability was found in 88% and was considered severe in 61% of patients. No features prognostic of neurological severity or outcome were identified.

CONCLUSION

Demonstrable malignancy is uncommon in the dancing eye syndrome. The neurological legacy of DES is often evident well into adult life.

Opsoclonus myoclonus syndrome secondary to Epstein-Barr virus infection

We report the first two children to have the "opsoclonus myoclonus syndrome" after a serologically confirmed acute Epstein-Barr virus infection. Although opsoclonus was absent in one patient, both patients had all other features typical of this syndrome. Patients without opsoclonus have been described as having an isolated postinfectious myoclonus syndrome but probably lie within the spectrum of opsoclonus myoclonus syndrome. The prognosis for the opsoclonus myoclonus syndrome in children with Epstein-Barr virus infection and without evidence for a neuroblastoma appears to be better than in those patients where a cause cannot be identified.

Eye movement tics

An 8-year-old girl presented with opsoclonus-like eye movement and an 18 month history of intermittent facial tics. Investigations were all normal. Electro-oculography showed the eye movements to be of variable amplitude (10-40 degrees), with no intersaccadic interval, and with a frequency of 3-4 Hz. Saccades, smooth pursuit, optokinetic, and vestibular reflexes were all normal. These abnormal eye movements eventually disappeared. It is thought that they were a form of ocular tics.

Opsoclonus-myoclonus syndrome: correlation of radiographic and pathological observations

We report a case of a child with opsoclonus-myoclonus syndrome. Neuroradiological studies indicated a lesion in the cerebellar vermis. A cerebellar biopsy revealed changes consisting of Purkinje and granular cell loss with gliosis. This case report documents the correlation of radiologic and pathological findings in a patient with opsoclonus-myoclonus syndrome.

Supranuclear disorders of eye movement

Eye movements are the result of activity in discrete systems. Saccades and smooth pursuit movements respond to target position and target velocity respectively. Compensatory responses to movements that alter the position of the eyes in space depend upon the vestibular and optokinetic systems. Vergence movements allow fusion and binocular vision. Eye movement abnormalities of supranuclear origin may be divided into nystagmus, other ocular oscillations, saccadic dysfunction, smooth pursuit dysfunction, gaze palsy, tonic deviation, and vergence disability. An algorithm for the analysis of supranuclear eye movement disorders is presented.

Pontine lesion in opsoclonus-myoclonus syndrome shown by MRI

Two patients with opsoclonus-myoclonus syndrome are reported whose magnetic resonance imaging (MRI) showed brain stem lesions. Both patients developed the opsoclonus-myoclonus syndrome after an upper respiratory illness. One case had visual hallucinations during the course of illness and MRI revealed a focal lesion in the pons involving the junction of basis and tegmentum. MRI of the second case showed a focal lesion at the upper pontine tegmentum.

Saccade abnormalities in patients with ocular flutter

In a group of 8 patients with opsoclonus or ocular flutter, the eye movements were recorded by electro-oculography (EOG). The spontaneous eye movement pattern and the amplitude and peak velocity of the refixation saccade were analysed. The EOG recording demonstrated frequent bursts of horizontally and vertically directed saccades elicited without any intersaccadic interval. Three patients also demonstrated an increased frequency of square waves. In 6 of the 8 patients the peak velocity of the voluntary saccades was increased; in 5 patients this condition was found for saccades in both directions. Over-shooting oscillations or slightly hypermetric voluntary saccades occurred in 5 patients. It is proposed that the ocular flutter and the increased saccadic velocities found in the present series of patients is caused by a disorder of the burst cells in the brain stem saccadic control system.

Saccadic intrusions and oscillations

There are a number of different types of involuntary saccadic eye movements which differ from normal saccades in that they take the fovea away from its target. This article presents a classification and description of these abnormal eye movements and indicates how they may be used to increase the precision of neurologic diagnosis.

Pediatric neuro-ophthalmology

The author discusses an extended list of the ophthalmic signs and symptoms of neurologic disease (some of which were once considered to be benign or isolated eye problems) under the general categories of vision problems, pupil signs, eye movement disorders, fundus abnormalities, and eyelid abnormalities.

Syndrome of opsoclonus-myoclonus caused by Coxsackie B3 infection

Coxsackie B3 was cultured from 2 children who presented within two weeks of each other from the Cape Cod, Massachusetts, area showing opsoclonus and myoclonus. The organism was recovered from the cerebrospinal fluid of 1 patient and from the stools of both. Both children had cerebrospinal fluid pleocytosis and gradual, spontaneous resolution of their symptoms.

Transient supranuclear disturbances of gaze in healthy neonates

We examined 242 healthy neonates. Five developed transient tonic downward deviation of the eyes and eight showed any resultant visual, systemic, or neurologic abnormality. However, five of the 22 children with neonatal skew deviation developed a subsequent comitant horizontal stabismus. Although transient supranuclear disturbances of gaze are common in healthy neonates, skew deviation is a risk factor for development of horizontal stabismus.

Benign encephalitis: electro-oculographic analysis of opsoclonus

Two cases of benign encephalitis are described, which showed opsoclonus associated with myoclonic jerks of the body and face, and with cerebellar dystaxia in one case. EOG and EEG analysis during the course of these cases showed: 1. opsoclonic eye movements were triggered by saccadic and non-saccadic eye movements, 2. decrease of luminancy and loss of fixation were releasing, but not triggering opsoclonic bursts during the initial stages, 3. eye closure had the strongest trigger effect, which lasted very long and allowed an objective description of the (benign) course of the illness, 4. besides conjugate, mostly horizontal, spontaneous eye movements oblique and vertical ones were also obtained. Monocular and disconjugate eye movements were seen only during the initial stages, 5. statistical analysis of the frequency of single eye movements during periods of opsoclonic bursts showed that, in the course of the disease the variability of frequencies decreased and the degree of fast frequencies increased, particularly with open eyes, 6. the frequent coincidence of opsoclonus and lesions of the cerebellum or of the cerebellar pathways is striking, but the initially distinct EEG changes, the very different trigger modes and certain pathoanatomically described cases without any cerebellar lesion indicate the more general character of the disturbance. 7. the entity of opsoclonus, body tremulousness, and benign encephalitis has to be differentiated from other syndromes including the sign opsoclonus by recording the EEG and EOG during the course of the disease; this might lead to very useful diagnostic and prognostic information.

A hypothetical explanation of saccadic oscillations

Eye movements in a patient with saccadic oscillations (ocular flutter) were recorded and analyzed. Findings were related to recent microelectrode studies in the monkey pontine reticular formation which have identified three types of premotor neurons related to saccadic eye movements: burst, tonic, and pause cells. We incorporated these cell types into a hypothetical circuit that generates saccades by rapidly driving the eye to a designated orbital position rather than preprogramming a distance for movement. Physiological measurements suggest that this neural network is unstable and that the burst neurons must be tonically inhibited to prevent saccadic oscillations during periods of fixation. Pause cells, which discharge tonically except during saccades, when they pause, appear to inhibit burst cells and prevent such saccadic oscillations. Analysis of our patient's behavior indicates that many types of saccadic oscillations can be explained and classified by assuming an abnormality of pause cell control over saccadic burst neurons.

Infantile polymyoclonus: Its occurrence in second cousins

Two second cousins with infantile polymyoclonus are described. All other published cases in the literature are sporadic,and the occurrence of two cases of this exceedingly rare disorder in one family raises the possibility of genetic transmission. Careful examination of the family pedigree is indicated in this disorder.

Ocular bobbing and opsoclonus: two abnormal spontaneous eye movements occurring in the same patient: case report

A case in which two rare abnormal spontaneous eye movements, ocular bobbing and opsoclonus, were observed, is reported. Their pathophysiology and distinction from other abnormal spontaneous eye movements are discussed.