Literatura académica sobre el tema "Oculomotor abnormalities"

AbstractEssential tremor (ET) is the most prevalent movement disorder, characterized mainly by an action tremor of the arms. Only a few studies published as yet have assessed oculomotor abnormalities in ET and their results are unequivocal. The aim of this study was to assess the oculomotor abnormalities in ET patients compared with the control group and to find the relationship between oculomotor abnormalities and clinical features of ET patients. We studied 50 ET patients and 42 matched by age and gender healthy controls. Saccadometer Advanced (Ober Consulting, Poland) was used to investigate reflexive, pace-induced and cued saccades and conventional electrooculography for evaluation of smooth pursuit and fixation. The severity of the tremor was assessed by the Clinical Rating Scale for Tremor. Significant differences between ET patients and controls were found for the incidence of reflexive saccades dysmetria and deficit of smooth pursuit. Reflexive saccades dysmetria was more frequent in patients in the second and third phase of ET compared to the first phase. The reflexive saccades latency increase was correlated with severity of the tremor. In conclusion, oculomotor abnormalities were significantly more common in ET patients than in healthy subjects. The most common oculomotor disturbances in ET were reflexive saccades dysmetria and slowing of smooth pursuit. The frequency of reflexive saccades dysmetria increased with progression of ET. The reflexive saccades latency increase was related to the severity of tremor.

Infantile strabismus is characterized by numerous visual and oculomotor abnormalities. Recently nonhuman primate models of infantile strabismus have been established, with characteristics that closely match those observed in human patients. This has made it possible to study the neural basis for visual and oculomotor symptoms in infantile strabismus. In this review, we consider the available evidence for neural abnormalities in structures related to oculomotor pathways ranging from visual cortex to oculomotor nuclei. These studies provide compelling evidence that a disturbance of binocular vision during a sensitive period early in life, whatever the cause, results in a cascade of abnormalities through numerous brain areas involved in visual functions and eye movements.

Background: Prevailing hypotheses suggest that attention deficit hyperactivity disorder (ADHD) is secondary to dysfunction of motor intentional systems mediated by prefrontal circuitry. Oculomotor paradigms provide a mechanism for examining and localizing dysfunction at the interface between movement and cognition.Objective: Three different saccade tasks (reflexive or prosaccades, antisaccades, and memory-guided saccades) were used to examine functions necessary for the planning and the execution of eye movements, including motor response preparation, response inhibition, and working memory.Methods: The study included 19 children with ADHD, divided into two groups: a group of 8 children on methylphenidate at the time of testing and a group of 11 children not taking any psychoactive medication. Results from the two groups were compared with those from 25 age- and gender-matched normal control children.Results: Both groups of children with ADHD made significantly more directional errors than did controls on the antisaccade task and significantly more anticipatory errors than did controls on the memory-guided saccade task, findings that are consistent with deficits in response inhibition. There were no significant differences in prosaccade latency, although unmedicated children with ADHD showed significantly greater variability in latency on the prosaccade task than did controls. On the memory-guided saccade task there were no significant differences in saccade accuracy; however, unmedicated children with ADHD showed longer saccade latency than did either controls or medicated children with ADHD.Conclusions: Oculomotor findings suggest that deficits in prefrontal functions, in particular response inhibition, contribute to behavioral abnormalities observed in ADHD. Findings also suggest that the administration of methylphenidate is associated with improvements in the consistency of motor response. Although there were no observed improvements in response inhibition with methylphenidate, conclusions await a design in which subjects complete testing both on and off medication.

BackgroundFor certain ocular movement abnormalities, the exact neuroanatomical localization of the causative lesion is still not defined. Oculomotor apraxia, apraxia of eye opening and closing, and motor impersistence are rarely reported in acute stroke, particularly following venous stroke.Case ReportA 34-year-old man presented with headache, vomiting, focal seizures with bilateral tonic-clonic movements, and altered sensorium. Magnetic resonance imaging revealed bilateral frontal and left parietal hemorrhagic infarcts, and contrast venography revealed superior sagittal sinus thrombosis. The patient received anticoagulant treatment with antiepileptics. On re-examination on day 3, the patient had a rare combination of apraxia of eyelid closure, motor impersistence, and oculomotor apraxia. By Day 10 of admission, all oculomotor abnormalities had subsided.ConclusionTo the best of our knowledge, this is the first report of the combination of oculomotor apraxia and apraxia of eyelid closure with motor impersistence in a patient with cerebral venous sinus thrombosis.

OBJECTIVE: To determine if middle-aged and aging men and women with HIV disease (HIV+) should be screened for vestibular and oculomotor dysfunction. METHODS: Age- and sociodemographically matched HIV+ and HIV– men and women were tested on vestibular evoked myogenic potential (VEMP), bi-thermic caloric testing, Dix-Hallpike maneuvers and saccades. RESULTS: HIV+ men had more caloric weakness than HIV– men. HIV+ subjects had more saccade abnormalities than HIV– subjects. A saccade abnormality was positively associated with being HIV+. Among the HIV+ sample, abnormalities were associated with increasing age, being male, ever taking monotherapy, and having an undetectable viral load. Only being male and having an undetectable viral load were statistically significant. Unilateral caloric weakness had a decreased prevalence with age per 10 years, and being HIV+ showed an increased prevalence. In HIV+ subjects only, these abnormalities decreased with age and being male but increased with undetectable viral load and ever taking antiretroviral monotherapy. No statistically significant differences were found. CONCLUSION: Women are at greater risk of vestibular and oculomotor abnormalities than men. HIV+ adults are at greater risk than HIV– adults. Physicians who care for HIV+ men and women should monitor the symptoms of vestibular and oculomotor impairment.

Atypical Parkinsonian Disorders (APD) are a group of neurodegenerative diseases characterized by progressive extrapyramidal symptoms and signs, unresponsive to levo-dopa and associated with a wide range of distinctive clinical features. According to the neuropathological substrate, APD may be classified in two broad categories of pathologies related to the accumulation of abnormal aggregates of proteins: the Alpha-synucleinopathies (Multiple-System Atrophy type C and P – MSA-C and MSA-P) and the Taupathies (Progressive Supranuclear Palsy - PSP and Corticobasal Degeneration - CBD). Due to the presence of overlapping clinical features, their differential diagnosis may often be challenging. Various oculomotor abnormalities, such as saccade dysmetria, increased latency, saccadic intrusions, nystagmus and vertical gaze palsy are often described in APDs with inconstant specificity. My aim was to determine peculiar changes in oculomotor profile that may help in distinguishing these disorders. I examined the eye movements of eleven patients with MSA-C, eight with MSA-P, twelve with PSP and six with CBD. Mean age of MSA-C patients was 58 (mean disease duration 3,7 years); in MSA-P, mean age was 65 (mean disease duration 3,7 years); in PSP group, mean age was 68 (mean disease duration 2 years); in CBD group, mean age was 67 (mean disease duration 2 years). Eye movement recording was obtained through an eye-tracker device (Applied Science Laboratories, Bedford, MA, USA); the visual target was a red dot on a black screen. Horizontal (±10°and 18°) and vertical (up/down 8°) visually-guided saccades, horizontal voluntary saccades (antisaccades) and fixation task were tested and statistically compared with EVAlab’s normative data obtained by healthy controls. As for saccades. standard saccadic parameters (latency, peak velocity, duration, gain and accuracy) were evaluated; moreover, presence of multistep saccades (i.e. saccades constitutes by two or more steps to reach the tardet) was assessed. For antisaccades, number of antisaccade errors with relative corrections, latency and gain of correct antisaccades, latency and gain of prosaccades erroneously directed toward the target and latency of corrective antisaccades were determined. Finally, eventual fixation changes (saccadic intrusions, nystagmus) were evaluated. MSA-C showed slight increased latency in reflexive and voluntary eye movements, with good performance in antisaccade task (low errors rate, high corrections rate). Velocity appeared to be preserved, whereas mild hypometria, with no more than two steps to reach the target, and poor accuracy, defined the saccadic profile. They had a lower number of SWJs in respect to PSP and MSA-P groups, but exhibited diverse forms of central nystagmus. MSA-P patients showed normal latency of reflexive eye movements, and prolonged latency of voluntary, associated to moderate to high range of errors and low percentage of corrections in the antisaccades. Hypometria with high frequency of multistep saccades, characterized by two or more steps to reach the target, and normal velocity defined the dynamic profile. Fixation appeared to be interrupted by SWJs, characterized by small amplitude and high frequency similar to PSP patients, but no nystagmus. Patients with PSP showed saccade slowing both in the horizontal and, more evidently, in the vertical plane, associated with prominent saccadic hypometria with very high range of multistep saccade (usually three of four), analogously defined by slow velocity. Vertical supranuclear palsy was common, so that some patients could not be recorded in the vertical plane. Latency was prolonged in both reflexive and voluntary tasks. Very high number of errors, with equally high number of corrections, characterized the antisaccade performance. Furthermore, PSP showed the highest rate of SWJs, peculiarly characterized by large amplitude and prolonged intersaccadic latency. CBD group made hypometric saccades with high frequency of multistep with two or more steps, and presented a mild saccade slowing. No supranuclear palsy was observable. Furthermore, they showed prominent increased latency in both reflexive and voluntary tasks; they were virtually incapable to perform antisaccade task, and exhibited the highest rate of errors and a very low rate of corrections. Finally, SWJs frequency was the lowest among groups. My findings substantiate peculiar changes of saccade dynamics in APDs, related to specific neuroanatomical substrate. Slowing and fragmentation of all ocular movements is the major finding in PSP patients, due to prominent atrophy of pons and, to a lesser extent, basal ganglia involvement. Saccades are of normal velocity but inaccurate in MSA, particularly MSA-C. MSA-P patients are more hypometric (lower gain and higher number of steps) than MSA-C, suggesting a greater basal ganglia involvement in the former, and a greater cerebellar impairment in the latter, also explaining the MSA-C low accuracy (dispersion of fixation around target) and the presence of central nystagmus. Latency and voluntary saccades performance are more impaired in PSP and particularly in CBD group than both MSA, suggesting a greater cortical impairment (particularly frontal and parietal cortex) in CBD. Saccadic intrusions are mostly typical of MSA-P and PSP, but they differed for the diverse amplitude (greater in PSP than MSA-P) and the intersaccadic latency (the latency between the first and second saccade of the intrusions, greater in PSP than MSA-P). Taken together, these abnormalities may help in configuring a peculiar disease “profile”. Qualitative and quantitative oculomotor profile examination may therefore be considered as a useful tool helping in differentiating ADPs with overlapping clinical features.

Progressive supranuclear palsy (PSP) is a neurodegenerative condition characterized by axial motor features, oculomotor abnormalities, and cognitive dysfunction. PSP is characterized by progressive tau deposition with neuronal loss in cortical and subcortical regions. The underlying etiology of PSP may reflect complex gene-environment interactions, though genetic heterogeneity in the microtubule-associated protein tau (MAPT) gene can confer increased risk. Clinical care of patients with PSP focuses on minimizing motor and non-motor morbidity using available symptomatic therapies.

Hyperbilirubinemia or jaundice refers to excessive levels of bilirubin in the serum of newborn infants. It is of interest to developmentalists, since serum bilirubin can cross the blood–brain barrier and, in high levels, may cause brain damage, particularly in the globus pallidus, substantia nigra reticulata, subthalamic nucleus, brainstem auditory structures (vestibular and cochlear), oculomotor nuclei, the hippocampus, and the cerebellum. Very high levels of bilirubin can cause the classic acute and chronic bilirubin encephalopathies. Controversy exists as to whether lower levels cause minor neurological, cognitive, or behavioral deficits. Hyperbilirubinemia develops in neonates primarily due to their physiologic immaturity, although other conditions and factors may play a role. Bilirubin is a yellow pigment that results from the breakdown of hemoglobin from red blood cells. In routine clinical practice, bilirubin is measured as total serum bilirubin (TSB). Many healthy full-term infants develop a mild degree of jaundice usually termed “physiologic” jaundice or jaundice not attributable to pathologic factors or disease. The number and rate of breakdown of red cells is higher in the newborn and leads to an increased release of bilirubin to the circulation. The newborn’s liver has reduced capacity to take up bilirubin due to immaturity. Additionally, loss of water in combination with reduced intake of fluid prior to establishment of breast feeding may make the infant jaundiced because of dehydration (Stevenson et al. 2004). Although most neonatal jaundice is physiologic, Table 33.2 lists some of the more common ‘‘pathologic’’ mechanisms causing jaundice in newborns (Stevenson et al. 2004). In actuality, all healthy, full-term infants develop some level of neonatal hyperbilirubinemia as a consequence of physiological immaturity in metabolizing bilirubin, mild dehydration, and/or factors in the breast milk (if they are breast-feeding) (Davidson 1941; Maisels et al. 1986). Clinical jaundice is visible at serum bilirubin levels of approximately 5–7 mg/dL, and approximately 50% (Palmer and Mujsce 2001) of all normal newborns appear jaundiced during the first week of life.

Eye movements are used to assess alterations in brain systems involved in cognitive and sensorimotor processes in psychiatric disorders. This chapter summarizes findings comparing saccadic and smooth pursuit eye movement performance across psychotic proband and relative groups, with an emphasis on schizophrenia, schizoaffective disorder, and psychotic bipolar disorder. Inhibitory errors on the antisaccade task represent a robust and graded deficit across probands, with greatest impairment observed in schizophrenia, and among relatives, particularly those with elevated psychosis spectrum traits. Abnormalities in the use of early visual motion information during smooth pursuit is apparent among both probands and relatives, while deficient use of visual feedback for dynamical pursuit appears restricted to probands. Select eye movement measures appear differentially affected by glutamate and dopamine gene variants. Overall, research findings support eye movement measures as promising biomarkers of altered brain systems underlying select cognitive and sensorimotor processes across the psychosis spectrum.

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis that typically involves several organ systems. Approximately 50% of patients have CNS involvement. Symptoms are related to localization of lesions and may include diabetes insipidus or other endocrinopathy due to pituitary involvement, focal neurological symptoms due to parenchymal lesions, compressive symptoms related to pachymeningitis, or general worsening of gait and cognition when lesions are more widespread. Infiltration of the orbits may also occur, resulting in oculomotor abnormalities, retro-orbital pain, exophthalmos, or visual compromise. Osteosclerosis of the long bones seen on imaging is nearly universal. In addition, involvement of the cardiovascular and pulmonary systems, kidneys and retroperitoneum, and skin may occur. The diagnosis is made when pathological findings consistent with ECD are noted in a patient with clinical and imaging findings suggestive of this entity. Interferon-alfa is the most well-studied therapy for ECD; however, suboptimal efficacy and side effects have led to exploration of alternative agents. B-rapidly accelerated fibrosarcoma protein (BRAF) inhibitors seem particularly promising and are currently being studied in clinical trials.

The vestibulocerebellum consists of the flocculus, ventral paraflocculus, nodulus, and uvula. ■ The flocculus receives inputs from the vestibular nucleus and nerve, nucleus prepositus hypoglossi (NPH), inferior olivary nucleus, cell groups of the paramedian tracts (PMT), nucleus reticularis tegmenti pontis (NRTP), and mesencephalic reticular formation. ■ The ventral paraflocculus receives inputs from contralateral pontine nuclei. ■ Project to ipsilateral superior and medial vestibular nuclei, and the y-group ■ Receive input from the medial and inferior vestibular nuclei, vestibular nerve, NPH, and inferior olivary nucleus ■ Project to the vestibular nuclei ■ The oculomotor vermis consists of parts of the declive, folium, tuber, and pyramis. ■ Receives inputs from the inferior olivary nucleus, vestibular nuclei, NPH, paramedian pontine reticular formation (PPRF), NRTP, and dorsolateral and dorsomedial pontine nuclei ■ Projects to the caudal fastigial nucleus ■ Stimulation of the Purkinje cells in the dorsal vermis elicits contralaterally directed saccades and smooth pursuit ■ Receives inputs from the dorsal vermis, inferior olivary nucleus, and NRTP ■ Decussates and projects via the uncinate fasciculus of the brachium conjunctivum to the contralateral PPRF, rostral interstitial nucleus of the medial longitudinal fasciculus, nucleus of the posterior commissure, omnipause neurons in nucleus raphe interpositus, the mesencephalic reticular formation, and superior colliculus ■ Neurons in the fastigial oculomotor region (FOR) fire during both ipsilateral and contralateral saccades. 1. The contralateral FOR neurons burst before the onset of saccade, and the onset of firing is not correlated with any property of the saccade. 2. Conversely, the time of onset for neurons in the ipsilateral FOR varies, with bursts occurring later for larger saccades. 3. Thus, the difference in time of onset between contralateral and ipsilateral FOR activity encodes the amplitude of saccades (i.e., the larger the difference in time of onset, the larger the saccade amplitude). Eye movement abnormalities in uncinate fasciculus lesion include hypometric ipsilesional saccades and hypermetric contralesional saccades (“contrapulsion”). Arnold-Chiari malformation is a malformation of the medullary–spinal junction with herniation of intracranial contents through the foramen magnum. The three types are illustrated in the figure below.

A 44-year-old man sought care for new right-sided tinnitus and sensorineural hearing loss. He was treated with high-dose oral prednisone and acyclovir. Later, mild, intermittent dizziness developed, which progressed to constant, moderate dizziness and was exacerbated by sudden head movements. He participated in vestibular rehabilitation with only mild improvement. Within 5 months of tinnitus onset, horizontal binocular diplopia also developed. Examination showed spontaneous left-beating torsional nystagmus in primary gaze, down-beating nystagmus with leftward gaze, and right-beating torsional nystagmus in rightward gaze. Head impulse testing to the right produced a catch-up saccade. Dix-Hallpike maneuver in both positions led to leftward torsional nystagmus followed by down-beating nystagmus. He had full range of eye motion. There was evidence of asymmetric hearing loss on the right and moderate gait unsteadiness; he was able to complete only a few steps in tandem. Neurologic examination findings were otherwise normal. Oculomotor testing demonstrated abnormalities supportive of a central nervous system disorder. These included excessive square-wave jerks, impaired smooth pursuit, and direction-changing nystagmus. Results of cerebrospinal fluid studies included a normal opening pressure, pleocytosis, and increased protein concentration. Serum and cerebrospinal fluid paraneoplastic evaluations showed a unique immunofluorescence staining pattern on rodent brain tissue by patient immunoglobulin G, which was later confirmed to be immunoglobulin G antibodies to kelch like family member 11. Whole-body positron emission tomography showed a single anterior mediastinal mass, which was then resected. The patient was diagnosed with a paraneoplastic anti-kelch like family member 11 rhombencephalitis with an extratesticular seminoma. After removal of the mediastinal mass, intravenous methylprednisolone was started. The patient had symptom stabilization but no clinical improvement. Cyclophosphamide was added to the weekly pulse-dose intravenous corticosteroids. He had mild improvement in vertigo and gait imbalance. For symptomatic management of the vertigo, he received baclofen, citalopram, and vestibular rehabilitation. He continued to have slow improvement. After approximately 1 year of cyclophosphamide treatment, his gait normalized and nystagmus diminished, although he had persistent neurologic deficits including spontaneous down-beating nystagmus and a few intermittent square-wave jerks. The intravenous methylprednisolone infusions were tapered, with continued examination stability. After stable symptoms and examination findings, cyclophosphamide was discontinued. After discontinuation of cyclophosphamide, new central sensorineural hearing loss developed suddenly in his left ear. This improved with additional intravenous methylprednisolone treatment. Mycophenolate mofetil was also started, and corticosteroids were tapered. Repeated positron emission tomography of the body showed no recurrence of seminoma. Symptoms and audiography findings were stable after 10 months, so the patient elected to discontinue immunosuppression again and has remained stable. Kelch like family member 11 autoimmunity is a distinct paraneoplastic syndrome associated with encephalitis and testicular germ cell tumors (including seminoma).

Amblyopia, an anomaly of human vision defined as substandard visual acuity even though any refractive error has been optically neutralized and there is no ocular disease, develops mainly in children who have significant interocular difference in refractive error (anisometropia) or a manifest oculomotor deviation (strabismus). So much attention has been given to acuity issues in amblyopia, such as the acuity cutoff for diagnosis, appropriate acuity optotypes, and how much of the acuity chart to exposed, that it is common to think that acuity is the main, only, or even the fundamental defect in amblyopia.

Amblyopia is most simply defined as a loss of visual acuity without an identified organic cause. Traditionally, the amblyope is roughly classified as strabismic, anisometropic, refractive or deprivational, according to the accompanying condition thought to be responsible for the acuity loss. Although it is widely recognized that these classes are neither particularly uniform nor discriminative, there is no established means of classifying amblyopes on the basis of visual function alone. Our primary objective is to create a classification system for amblyopia, based on a broad spectrum of clinical, psychophysical and oculomotor abnormalities -- a system that could supplement or supplant the traditional approach leading to better diagnosis and treatment. We here report the results from a pilot study showing that this objective is feasible. Two hundred and fifteen naive subjects, including eighty-two amblyopes, seventy-three recovered amblyopes, forty non-amblyopic strabismic or anisometropic ("at risk") subjects, and twenty normal subjects, participated in the study. The results from numerous psychophysical and oculomotor tests were analyzed statistically to determine if clusters of subjects with similar visual and oculomotor capabilities would emerge from the data base. Cluster analysis identified nine separate clusters. The laboratory measurements were sufficient to predict cluster membership and accounted for between-cluster variation, including whatever variation was due to Snellen acuity and clinical diagnosis.