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PubMed1983

Electrophysiological investigations of the brainstem in the vertebrobasilar reversible attacks.

A total of 70 selected patients affected by reversible ischemic attacks in the vertebrobasilar system were studied. 50 patients presented transient ischemic attacks (TIA), while the other 20 patients suffered from 1-2 protracted transient ischemic attacks (PTIA). All patients underwent brainstem acoustic evoked potentials (BAEP) and electrooculography (EOG) 7-20 days from the last reversible ischemic attack, when all signs and symptoms completely disappeared. The combination of BAEP and EOG gave objective evidence of brainstem dysfunction in 61 out of 70 patients. BAEP resulted abnormal in 26 patients (16 TIA, 10 PTIA), EOG in 49 (36 TIA, 13 PTIA). Serial controls at 3, 6, and 12 months were conducted in 27 patients. 5 patients showed a normalization for BAEP and 7 for EOG 12 months after the first examination.

Adult↗

PubMed1995

Ocular changes of glycogen storage disease type I.

The glucose-6-phosphatase system comprises at least five different polypeptides and plays a key role in the metabolism of glucose. A defect in these proteins may cause glycogen storage disease type I (GSD I). We examined the ocular changes of two patients with GSD Ia and b. The patient with GSD Ib showed a delayed appearance of the choroidal flush on fluorescein angiography, a subnormal Arden ratio by electrooculography and atrophy of the retinal pigment epithelium and choriocapillaris. The patient with GSD type I a showed a gradual attenuation of the b-wave by electroretinography. These findings appeared similar to those observed with enzyme distribution among ocular tissue reported previously. To our knowledge, the findings described herein represent the first report of ocular changes associated with GSD I.

Adolescent↗

PubMed1990

The influence of increasing ventilatory effort on arousal from sleep.

Arousal from sleep in response to asphyxia can be a lifesaving event. However, the mechanisms responsible for this important arousal response are uncertain. A unifying hypothesis is that arousal results from the increased respiratory effort that occurs as a result of ventilatory stimulation. If this is true, the magnitude of this effort during the breaths immediately preceding arousal from sleep should be similar regardless of the stimulus. Therefore, the negative inspiratory pleural pressure during the breaths preceding arousal would be similar, whether stimulated by added inspiratory resistive load, hypoxia, or hypercapnia. To test this hypothesis, we studied eight young, healthy men during full-night sleep studies. We measured their electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), inspired ventilation (VI), end tidal PCO2 (PETCO2), O2 saturation, and esophageal pressure (esophageal balloon) while inducing arousal from non-REM sleep using (1) a 30-cm H2O/L/s added resistive load, (2) progressive hypoxia, and (3) progressive hyperoxic hypercapnia. All subjects were eventually aroused following the addition of the 30-cm H2O/L/s added load and during progressive hypercapnia. However, only six of the eight men were aroused when the O2 saturation was reduced to a minimum of 70%. For each stimulus, arousal occurred at very different levels of ventilation and arterial chemistry (SaO2 and CO2). However, ventilatory effort for each subject was similar at the point of arousal regardless of the stimulus. The peak-negative esophageal pressure for the single inspiration preceding arousal (for the six subjects arousing with all three stimuli) was 16.8 +/- 1.4 cm H2O for added resistive load, 15.0 +/- 2.4 cm H2O for hypoxia, and 14.7 +/- 2.1 cm H2O for hypercapnia. We conclude that increasing ventilatory effort may be the stimulus to arousal from sleep independent of the source of this rising drive to breathe.

Adult↗

PubMed1991

Low electrooculographic ratios in patients with seasonal affective disorder.

OBJECTIVE: Changes in retinal sensitivity to light have been hypothesized as etiological in seasonal affective disorder. This study was undertaken to investigate sensitivity to light in seasonal affective disorder using electrooculography (EOG), an objective measure of retinal light response. METHOD: In a mood disorders clinic, 19 depressed, drug-free patients with seasonal affective disorder, diagnosed by DSM-III-R criteria, were compared with 19 age- and sex-matched normal comparison subjects. All subjects had identical EOG testing performed during the winter. EOG (Arden) ratios were calculated from the EOG data. RESULTS According to multivariate analysis of variance, the EOG ratios in the patients with seasonal affective disorder were significantly lower than those of the normal comparison subjects, although there was considerable overlap in EOG ratios between patients and comparison subjects. CONCLUSIONS: These results suggest that seasonal affective disorder is associated with subtle retinal abnormalities at the level of the photoreceptor/retinal pigment epithelium complex, consistent with subsensitivity to light. A limitation of this study is that the retinal origins of the EOG response are nonspecific and still not completely elucidated.

Adult↗

PubMed1978

Eye movements in ataxia-telangiectasia.

The spectrum of eye movement disorders in six patients with ataxia-telangiectasia at different stages of progression was assessed quantitatively by electrooculography. All patients demonstrated abnormalities of voluntary and involuntary saccades. The youngest and least involved patient had significantly increased reaction times of voluntary saccades, but normal accuracy and velocity. The other patients demonstrated increased reaction times and marked hypometria of horizontal and vertical voluntary saccades. Saccade velocity remained normal. Vestibular and optokinetic fast components (involuntary saccades) had normal amplitude and velocity but the eyes deviated tonically in the direction of the slow component. We conclude that patients with ataxia-telangiectasia have a defect in the initiation of voluntary and involuntary saccades in the earliest stages. These findings are distinctly different from those in other familial cerebellar atrophy syndromes.

Adolescent↗

PubMed1981

An eye movement disorder in amyotrophic lateral sclerosis.

Defective pursuit eye movements were recorded by electrooculography (EOG) in 11 of 18 patients (61%) with amyotrophic lateral sclerosis. Pursuit defects consisted of a breakdown of smooth tracking into saccadic motions that were grossly in excess (frequencies and amplitudes) of saccadic interruptions of pursuit in normal subjects. In nine patients, defective pursuits cogwheeling) were obvious by visual inspection as well as by EOG; in two, this abnormality was seen only by EOG. In eight patients, the pursuit defect was the only abnormality of oculomotor function; in three, there were also saccadic defects (optokinetic nystagmus or conjugate gaze) discerned by EOG. Autopsy revealed neuronal degeneration in substantia nigra and demyelination in integral capsule in one patient with the pursuit defect but not in another patient without the defect. The pursuit defect may be a sign of extrapyramidal or supratentorial pyramidal involvement in ALS.

Adult↗

PubMed1998

Ocular vergence measurement in projected and collimated simulator displays.

The purpose of this study was to investigate electrooculography (EOG) as a measurement of ocular vergence in both collimated and projected simulator environments. The task required participants to shift their gaze between a central fixation point and a target appearing at one of three eccentricities. EOG was effective in recording ocular vergence. The EOG results were similar between collimated and projected displays, except for differences in vergence changes during lateral movement of the eyes, and ocular excursions downward elicited a greater EOG response than the reverse upward movement. The computer-based technique of recording vergence was found to produce measurable traces from a majority of participants. The technique has potential for further development as a tool for measuring ocular vergence in virtual environments where methods that require the wearing of head-mounted apparatus to track ocular structures (e.g., the pupil), which cannot be worn at the same time as a flight or flight-simulator helmet, are unsuitable.

Computer Simulation↗

PubMedDate not supplied

Modulation of mean eye position during vestibular induced eye movements of the rhesus monkey.

Vestibular induced nystagmus in the dark was measured during sinusoidal rotational stimulation in three male monkeys using electrooculography. A periodic modulation of mean eye position was observed. This periodic modulation was quantified by least squares fitting through the nystagmus a sinusoid whose frequency was the same as that of the stimulus. The magnitude and the phase of the best fitting sinusoid were used to determine gain and phase delay at various combinations of stimulus amplitudes and frequency. Results indicate that the mean eye position in the alert animals is predominantly modulated in the direction of the fast component of nystagmus. The magnitude of this modulation of mean eye position is independent of the amplitude of the stimulus. The phase relationship of this modulation is dependent on the frequency of stimulation. In drowsy animals, the modulation of mean eye position is predominantly in the direction of the slow component of nystagmus. We conclude that the modulation of mean eye position during vestibular induced nystagmus operates as an automatic gain control system which is sensitive to the animal's level of alertness. The quantitative data in this report are useful in refining current models of vestibular nystagmus.

Animals↗

PubMed1991

Tonic cervical stimulation: does it influence eye position and eye movements in man?

In healthy subjects eye movements were analysed during body rotation, during trunk torsion either with the head passively held stationary in space or with the head voluntarily stabilized in space, and during voluntary head movements. Trapezoidal movements around the vertical axis were performed (+/- 40 degrees, plateau 10 s, duration of ramp 1 or 4 s). Moreover the influence of a tonic head deviation up to 40 degrees on optokinetic nystagmus and on vestibulo-ocular reflex during sinusoidal turning was examined. Eye movements were recorded by DC-electrooculography. Saccadic and slow components of eye movements and the shift of eye position during the plateau of the trapezoidal stimulus were analysed. For all modes of stimulation during the plateau no nystagmus occurred. At the end of the dynamic phase of the stimulus relatively frequent eye deviations--mostly in the direction of the head deviation--were observed, not only after turning the trunk with the head stabilized in space (cervical stimulation) but also after turning head and trunk together. The fact that such eye deviations are thus observed even in the absence of any tonic, especially cervical stimulus, supports the assumption that they cannot be attributed to a tonic stimulus but merely to an effect of the preceding phasic stimulus which outlasts them. Also amplitude and direction of eye shifts during the plateau do not depend on a tonic stimulus, but merely on the eye deviation reached at the end of the dynamic phase of stimulation. Optokinetic nystagmus and vestibulo-ocular reflex are not influenced by an additional tonic cervical stimulus.

Adult↗

PubMed2002

Origins of surface potentials evoked by electrical stimulation of oculomotor nerves: are they related to electrooculographic or electromyographic events?

OBJECT: Evoked potentials elicited by electrical stimulation of the oculomotor nerve and recorded from surface electrodes placed on the skin around the eyeball reportedly originate in the eye and are represented on electrooculograms. Because evoked potentials recorded from surface electrodes are extremely similar to those of extraocular muscles, which are represented on electromyograms, the authors investigated the true origin of these potentials. METHODS: Evoked potentials elicited by electrical stimulation of the canine oculomotor nerve were recorded from surface electrodes placed on the skin around the eyeball. A thread sutured to the center of the cornea was pulled and the potentials that were evoked during the resultant eye movement were recorded. These potentials were confirmed to originate in the eye and to be represented on electrooculograms because their waveforms were unaffected by the administration of muscle relaxant. To eliminate the influence of this source, the retina, a main origin of standing potentials of the eyeball, was removed. This resulted in the disappearance of electrooculography (EOG) waves elicited by eye movement. Surface potentials elicited by oculomotor nerve stimulation were the same before and after removal of the retina. Again the oculomotor nerve was electrically stimulated and electromyography (EMG) response of the extraocular muscles was recorded at the same time that potentials were recorded from the surface electrodes. In their peak latencies, amplitudes, and waveforms, the evoked potentials obtained from surface electrodes were almost identical to EMG responses of extraocular muscles. CONCLUSIONS: Evoked potentials elicited by electrical stimulation of the oculomotor nerves and obtained from surface electrodes originated from EMG responses of extraocular muscles. These evoked potentials do not derive from the eye.

Abducens Nerve↗

PubMed2000

[Flexibility in the adaptation of the vestibulo-ocular reflex to modified visual inputs in humans].

The vestibulo-ocular reflex (VOR) serves to stabilize images on the retina. To maintain appropriate performance and minimize image slippage throughout life, the VOR is subject to long-term adaptive regulation in response to visual input. Adaptive changes in VOR gain (eye velocity/head velocity) can be evoked either by fitting subjects with magnifying, miniaturizing, or reversing spectacles during normal behavior or by moving a large visual field in or out of phase relative to the subject's head movement. These changes exhibit frequency-selectivity. Here, we examine the flexibility of VOR gains by causing VOR in similar directions to undergo different behavioral gain changes. Nine healthy adults, ranging in age from 24 to 38 (mean 28.5) with no history of neurotological symptoms participated in the study. All subjects demonstrated clinically normal functioning on a screening battery of tests that included combined neurologic and otologic physical examinations. Horizontal and vertical eye positions were recorded by bitemporal DC coupled electrooculography (EOG). The subject sat in a rotating chair. The axis of rotation of the body was always earth-vertical, the interaural axis crossing the axis of rotation of the chair. The head was positioned at 20 degrees down in all experiments and was stabilized in this position using a chin rest. The chair was 78 cm in diameter and was shielded by a half-cylindrical optokinetic screen positioned in front of the subjects. Random dot patterns were projected onto this screen. During per- and post-adaptation periods, goggles were fitted to ensure that the subject was in complete darkness and the chair was rotated sinusoidally. The amplitude of the rotating chair was 30 degrees and 60 degrees. Frequencies of rotation were 0.1 Hz, 0.2 Hz, 0.3 Hz and 0.4 Hz for amplitudes of 30 degrees and 0.1 Hz, 0.2 Hz, and 0.3 Hz for amplitudes of 60 degrees. To induce VOR adaptation, the retinal slippage velocity caused by the visual input of a large field was changed for short-term; the change was produced by a combination of sinusoidal head rotation and random dot patterns. During each adaptation session, the frequencies of sinusoidal head rotation were either 0.1 Hz or 0.3 Hz and the amplitude was 30 degrees. The random dot patterns were synchronized with the sinusoidal head rotation in the same direction to make the retinal slippage zero (x0 experiment) and in the opposite direction to double the retinal slippage (x2 experiment). Therefore, a total of four adaptation protocols were tested. The subjects were asked to fix their eyes on a single dot by looking straight ahead in the x0 experiment and to follow the dot in the random dot pattern in the x2 experiment. Each adaptation session lasted for 30 minutes. Each subject participated in couple of adaptation experiments everyday. The average VOR gain and phase lag were calculated using a Fourier transformation. Out of all the subjects who participated in the x2 adaptation experiment at 0.3 Hz with an amplitude of 30 degrees, seven subjects showed a steady increase in VOR gain during a couple of the trials. One out of the remaining two subjects showed a decrease in VOR gain in all three trials. Another subject showed an increase in VOR gain during three trials and a decrease in two trials. In the x2 adaptation experiment with a range of 30 degrees at 0.3 Hz (peak velocity: 28 degrees/s), the percent change in gain (post-pre/pre) was 133% at the same stimulation and 100% at 0.4 Hz (peak velocity: 37 degrees/s). The percent change in gain was 65% for amplitudes of 60 degrees at 0.1 Hz (peak velocity: 18 degrees/s) and 64% for amplitudes 60 degrees at 0.2 Hz (peak velocity: 37 degrees/s). In the x1 adaptation experiment (30 degrees at 0.3 Hz), the percent change in gain was -62% for the same conditions and -50% for amplitude of 60 degrees at 0.1 Hz and -30% for amplitudes of 60 degrees at 0.2 Hz. No change, in VOR gain was observed at the other frequencies. The

Adaptation, Physiological↗

PubMedDate not supplied

Atypical vertical retraction syndrome: a case study.

A case of unilateral retraction of the eyeball in downward gaze as well as downshoot with the retraction when an outward horizontal movement of the contralateral eye was attempted has been introduced. The case has an exotropia with inability to adduct involved eye. The face turned to the left to minimize diplopia in the primary position. During the retraction, the lid widened slightly. An analyses by electrooculography and electromyography suggested that there was an abnormal neural connection between the vertical recti of the involved eye and the contralateral lateral rectus muscle. Co-contraction of vertical recti and loss of the reciprocal innervation were seen at the involved eye. Surgical treatment for exotropia, and total transplantation of vertical recti to the insertion of the involved medial rectus resulted in a slight reduction of the exotropia with the face straight, but not in the retraction as well as adduction and elevation of the involved eye. Based on the results, a central mechanism to produce above abnormality was described.

Action Potentials↗

PubMed1999

Multiple evanescent white dot syndrome in older patients.

PURPOSE: To report two patients in their seventh decade who exhibited findings consistent with multiple evanescent white dot syndrome. METHODS: Case reports of two patients referred for evaluation of decreased vision, visual field loss, and retinal white spots. RESULTS: A 60-year-old man and a 67-year-old woman had photopsia, visual field loss, and decreased central visual acuity. Examination disclosed numerous white retinal spots, ranging from 50 to 400 microm, with eventual foveal granularity. Visual field testing showed an enlarged blind spot and peripheral field defects. Fluorescein angiography, electroretinography, and electrooculography results were consistent with multiple evanescent white dot syndrome. Eventually, the retinal lesions resolved in both patients and baseline visual acuity was recovered. CONCLUSION: A diagnosis of multiple evanescent white dot syndrome should be considered in patients with retinal findings typical of multiple evanescent white dot syndrome, regardless of age.

Aged↗

PubMed1976

Pathologic nystagmus: a classification based on electro-oculographic recordings.

The widespread availability of eye movement recording systems has added a new dimension to our ability to accurately describe nystagmus. Electrooculography (EOG) is the simplest and most readily available system. With EOG the effect of loss of fixation (either with eyes closed, or eyes open in darkness) can be accurately assessed and quantitative evaluation of nystagmus speed, frequency and amplitude is easily made. Of equal importance, it provides a permanent record that can be compared with nystagmus recorded in other patients. By comparing clinical observation with paper recordings, both students and experienced clinicians can become more efficient in recognizing different varieties of nystagmus.

Electrooculography↗

PubMed2001

Stability in velocity of otolith-ocular reflex with different stimulus frequencies during step-mode linear acceleration.

Velocity changes in the otolith-ocular reflex (OOR) during a step mode of lateral linear acceleration were examined by electrooculography (EOG) in 4 normal subjects. They were oscillated in darkness at a constant stimulus frequency of 0.175 Hz with 4 different G-levels between 0.2-0.4 G and at a constant G-level of 0.3 G with 4 different stimulus frequencies between 0.115-0.215 Hz. The OOR velocity was increased linearly by elevation of the G-level, though the increase varied considerably among subjects. On the other hand, changes in the stimulus frequency had minimal effect on the OOR velocity. The results indicate that the OOR response property is frequency-independent at a low stimulus-frequency range, even when the head was oscillated rectangularly instead of sinusoidally.

Acceleration↗

PubMed2004

[Sleep apnea in neurological disorders].

The results of the study of sleep apnea (SA) in different forms of neurological disorders (cerebral stroke, diabetic polyneuropathy, neuromuscular diseases and amyotrophic lateral sclerosis--ALS) are presented. Two hundred and two patients, 103 male and 99 female, aged 17-84 years, have been investigated, using questionnaires and polysomnography. Nocturnal recording of EEG, EMG, electrooculography, oronasal air flow, respiratory thorax and abdomen movements, oxyhemoglobin saturation and breathing sounds has been performed. Clinical features of sleep apnea (SA) were most prominent in patients with neuromuscular diseases (58%) and ALS (54%), however the nocturnal study confirmed the presence of SA in patients with diabetic polyneuropathy (53%, mean RDI 15.7 +/- 18.7 epis./h) and cerebral stroke (41%, mean RDI 12.6 +/- 15.6 epis./h). A comparison of the patient's characteristics and sleep breathing indices revealed that factors of neurological damage contribute most significantly to ALS, but in diabetic neuropathy, age and obesity play a greater role.

Adolescent↗

PubMed2004

[Electroretinogram and electrooculogram in a family with Stargardt's disease].

PURPOSE: The aim of this study is to present the earliest functional changes in Stargardt disease in family with three affected and one unaffected children. PATIENTS AND METHODS: Four children: three girls (4, 7, 10, year old) and one boy (13 year old) and their parents (34 rear old mother and 36 year old father) were examined. Visual acuity (Snellen card), color perception (Ishihara's cards), electroretinography (flash full-field ERG--standard and chromatic) and electrooculography (EOG) were done. For ERG and EOG LKC equipment and UTAS E-2000 program was used. RESULTS: 13 year old boy has had visual acuity about 5/50 for about 3 years, nystagmus and no color perception. On his ocular fundus abnormal macular reflex (like beaten metal) was seen. Visual acuity about 5/12 was found in 7 year old girl during routine examination at school, but color perception and ocular fundus were normal. The others examined family members had visual acuity 5/5 without correction and no changes on ocular fundus. Color perception was normal in girls and mother. The father had red-green deficiency. Arden ratio in EOG was below normal (1.4) only in boy but dark trough and light peak amplitudes were lower than normal also in girls 4 and 7 year old and these two girls were also suspected of Stargardt's disease. ERG was nearly abolished in boy and markedly abnormal in his 7 year old sister. In father's ERG small reduction of cone function especially after chromatic stimulations was found. ERG was normal and similar in mother and 10 year old daughter. ERG was not done in the youngest girl. Two years later loss of visual acuity to 4/50 occurred in girl previously 7 and to 5/6 in the youngest sister. CONCLUSION: Detail analysis of EOG and ERG results may lead to diagnose retinal dystrophy in preclinical stadium.

Adolescent↗

PubMed2004

[Acute endophthalmitis of 15-year old boy in the course of acute lymphoblastic leukemia. Part II--Electrophysiological examinations].

PURPOSE: The aim of the study is to present objective estimation of visual function in eyes affected by leukemia. MATERIAL AND METHODS: The boy who was described in the first part of this study was examined. Visual evoked potential (VEP), full-field flash electroretinography (FERG), electrooculography (EOG), were done according to ISCEV standards. RESULTS: The function of retina was decreased proportionally to the areas of infiltration. The amplitude of VEP peaks was lowered when the involvement of the central nervous system occurred. In the eye with retinal infiltration abnormal EOG was present a few months earlier than pigment epithelium destruction was seen in ocular fundus. CONCLUSIONS: Functional deficits may be irreversible.

Acute Disease↗