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PubMed1996

Electroencephalographic and polygraphic features of 24-hour recordings in sleeping sickness and healthy African subjects.

Electroencephalographic (EEG) and polygraphic features were analysed in six healthy control subjects and eight patients suffering from sleeping sickness meningoencephalitis in order to determine possible functional relationships. One patient was disqualified because of intermittent metabolic disease. Twenty-four h polygraphic recordings-EEG, electrooculography (EOG), electromyography (EMG), nasal and buccal air flow, chest respiratory movements-were performed continuously both on paper and on cassette tapes. Tapes were played back on paper (paper speed: 15 mm/s). Traces were analyzed for normal and pathologic features, and transient activation phases and paroxysmal hypnopompic hypersynchrony events were counted. During wakefulness, slow theta and delta waves occurred in four patients, but alpha reactivity was present. During sleep, normal features were seen. However, transient activation phases were decreased in the patients. During slow-wave sleep, four patients presented predominantly monophasic frontal delta bursts along with paroxysmal hypnopompic hypersynchrony events. In conclusion, in sleeping sickness patients, although dampened, the waking process remains responsive and slows down only during the late stage of meningoencephalitis.

Adolescent↗

PubMed1979

The effect of oxazepam on ocular readaptation time.

The readaptation time (RAT) is the interval during which a person exposed to a bright intense light flash cannot perceive a given target. In this study the target used was an optokinetic pattern and the elicited nystagmus (OKN) was registered with electrooculography (EOG), thus giving an objective registration of RAT. Oxazepam in therapeutic doses was given to five healthy subjects and the RAT and serum concentrations of the drug were registered simultaneously at different time intervals. An almost parallel increase of RAT and serum concentration of oxazepam was recorded. This suggests that RAT reflects the depressant effect on the CNS of this drug and it may be used as an objective method of following the clinical effect of a depressant drug as a function of time after intake.

Adaptation, Ocular↗

PubMed1984

Saccadic eye movements--use in ergophthalmology.

Saccadic eye movements are the fast "catching movements" we use to bring a new object to the foveal region. They can be measured and analysed quantitatively e.g. with electrooculography. Saccades are sensitive to drugs, alcohol and fatigue and thus their measurement seems to be a promising method for research in toxicology and ergonomics.

Ergonomics↗

PubMed1992

Stabilization of gaze during circular locomotion in light. I. Compensatory head and eye nystagmus in the running monkey.

1. A rhesus and cynomolgus monkey were trained to run around the perimeter of a circular platform in light. We call this "circular locomotion" because forward motion had an angular component. Head and body velocity in space were recorded with angular rate sensors and eye movements with electrooculography (EOG). From these measurements we derived signals related to the angular velocity of the eyes in the head (Eh), of the head on the body (Hb), of gaze on the body (Gb), of the body in space (Bs), of gaze in space (Gs), and of the gain of gaze (Gb/Bs). 2. The monkeys had continuous compensatory nystagmus of the head and eyes while running, which stabilized Gs during the slow phases. The eyes established and maintained compensatory gaze velocities at the beginning and end of the slow phases. The head contributed to gaze velocity during the middle of the slow phases. Slow phase Gb was as high as 250 degrees/s, and targets were fixed for gaze angles as large as 90-140 degrees. 3. Properties of the visual surround affected both the gain and strategy of gaze compensation in the one monkey tested. Gains of Eh ranged from 0.3 to 1.1 during compensatory gaze nystagmus. Gains of Hb varied around 0.3 (0.2-0.7), building to a maximum as Eh dropped while running past sectors of interest. Consistent with predictions, gaze gains varied from below to above unity, when translational and angular body movements with regard to the target were in opposite or the same directions, respectively. 4. Gaze moved in saccadic shifts in the direction of running during quick phases. Most head quick phases were small, and at times the head only paused during an eye quick phase. Eye quick phases were larger, ranging up to 60 degrees. This is larger than quick phases during passive rotation or saccades made with the head fixed. 5. These data indicate that head and eye nystagmus are natural phenomena that support gaze compensation during locomotion. Despite differential utilization of the head and eyes in various conditions, Gb compensated for Bs. There are various frames of reference in which an estimate of angular velocity that drives the head and eyes could be based. We infer that body in space velocity (Bs) is likely to be represented centrally to provide this signal.

Adaptation, Physiological↗

PubMed1996

Central mesencephalic reticular formation (cMRF) neurons discharging before and during eye movements.

1. One hundred twenty neurons were recorded in the central mesencephalic reticular formation (cMRF) of four rhesus monkeys, trained to make visually guided and targeted saccadic eye movements. Eye movements were recorded with the head fixed, using electrooculography (EOG) or subconjunctival scleral search coils. Seventy-six percent (92/120) of cells discharged before and during contraversive visually guided or targeted rapid eye movements, and 76% of these (70/92) responded during contraversive spontaneous saccades in the dark. cMRF neurons had large contraversive movement fields and either a high (> 10 spikes/s) or low background level of spontaneous activity in the dark. The optimal movement vectors (i.e., saccades with greatest response) were predominantly horizontal, although many had a vertical component. Cells with optimal movement vectors within +/- 25 degrees of pure vertical were more rostral in the MRF and were excluded from the analysis. 2. A subgroup of cMRF neurons (31 of 92) that discharged before and during visually guided saccades were examined for visual sensitivity. Slightly less than one-half of these cells (42%, 13/31) were visuomotor units, i.e., they responded to visual targets in the absence of eye movement. The other 58% (n = 18) did not discharge during the visual probe trial; they were movement-related cells. 3. Microstimulation (threshold 40-60 microA at 333 Hz) at the sites of many of these cMRF neurons produced contraversive saccadic eye movements at short latency (< 40 ms). The amplitude and direction of the elicited saccades were similar to the optimal movement vector determined from single-unit recording. This suggested that cMRF cells recorded at the same locus of electrical microstimulation participated in the network responsible for the production and control of rapid eye movements. 4. The 92 saccade-related neurons were divided into two groups on the basis of their background discharge rate. Firing rates for both low background (28%, n = 26) and high background (72%, n = 66) cells increased approximately 30 ms before contraversive saccades and reached a peak discharge just before saccade onset. The low background neurons had either no activity or generated a few spikes just before the end of ipsiversive saccades. The steady rate of discharge (> 10 spikes/s) of high background neurons was inhibited from approximately 20 ms before ipsiversive saccades until just before saccade end. 5. Cells were also subdivided on the basis of how their discharge rates fell at the end of saccades. Clipped cells (38%, n = 35) had activity that fell sharply with saccade offset. Partially clipped cells (62%, n = 57) had persistent firing in the 100 ms following the saccade that was > 20% higher than the firing during the 100 ms before the saccade. 6. Latencies between the 90% point on the rising edge of the peak discharge and the start of the saccade were < or = 5.3 ms for eye movement-related cells in two monkeys. Longer latencies (11-19 ms) were found when measured between the 10% point on the rising edge of the peak discharge and saccade onset. These latencies were equal to or shorter than those obtained for eye movement-related burst neurons in the intermediate and deep layers of the superior colliculus analyzed similarly. Delays between the peak discharge and peak eye velocity were 13.6-15.1 ms for the same group of cMRF eye movement-related cells. These were significantly shorter than the delays measured for eye movement neurons in the superior colliculus (SC) of one of the monkeys. These findings suggest that the buildup discharge of cMRF neurons occurs early enough before saccades to contribute to saccade triggering. The peak discharge, however, occurs with or after the burst in the SC, suggesting that this portion of the discharge serves a function other than saccade triggering. 7. The number of spikes in bursts associated with eye movement was correlated with saccade parameters.

Animals↗

PubMed1992

A modified method of electronystagmography for recording eye movement during the galvanic vestibular test.

This study demonstrates a new technique for recording galvanic nystagmus using conventional electrooculography: a first pair of electrodes is placed at the nasal and lateral orbital margin of the left eye. An additional pair of electrodes is placed near the left angle of the mouth. This latter pair of electrodes picks up voltage variations induced by heart beat but only a minimal part of voltage variations caused by eye movements during bipolar, binaural electric stimulation. Electronic subtraction of the voltage variations near the angle of the mouth from the voltage variations at the equilateral eye cancels the cardiac interference and allows a pure recording of horizontal eye movements. 35 of 40 subjects could be examined successfully.

Adult↗

PubMed1981

Progressive supranuclear palsy: functional analysis of the response to methysergide and antiparkinsonian agents.

Twelve patients with progressive supranuclear palsy were treated with methysergide; the response was monitored with videotaped examination, electrooculography, and psychometric assessment. Used alone and with antiparkinsonian agents, methysergide improved the quality of life in eight patients for 6 months to 2 years. Benefits were especially dramatic in four patients with severe dysphagia. The disorder of visually guided behavior included abnormal orienting responses, visuosocial expression and regard, and visual search. Mesencephalic visuomotor centers appear to be important not only in control of ocular motility but also in the elaboration of visually guided behavior and the orienting of spatial attention.

Aged↗

PubMed1981

Downbeat nystagmus: a type of central vestibular nystagmus.

We used electrooculography to study horizontal and vertical eye movements in 17 patients with downbeat nystagmus (Chiari malformation, 9; multiple sclerosis, 2; olivopontocerebellar atrophy, 2; brainstem infarction, 2; and idiopathic nystagmus, 2). In all patients the velocity of slow components of the spontaneous nystagmus increased on lateral gaze, remained relatively unchanged with loss of fixation, and increased markedly after rapid positional changes in the sagittal plane. Horizontal and vertical smooth pursuit was impaired in all patients. Vertical pursuit recordings at multiple ramp velocities suggested superimposition of the spontaneous nystagmus on attempted pursuit rather than selective impairment of downward pursuit. Finally, all patients had impaired fixation suppression of vestibular nystagmus when they were rotated with a fixation point moving with their head. We conclude that downbeat nystagmus is a type of central vestibular nystagmus resulting from an imbalance in the central vertical vestibuloocular pathways.

Adolescent↗

PubMed2004

Normal polysomnographic respiratory values in children and adolescents.

STUDY OBJECTIVES: Polysomnography is important in the evaluation of children and adolescents with sleep-disordered breathing. Adult criteria for obstructive sleep apnea have been shown to be inapplicable to children. Nevertheless, very little data are available regarding normal respiratory parameters during sleep in healthy children and adolescents. The purpose of the study was to characterize normal polysomnography values in healthy children and adolescents and to establish respiratory reference values for pediatric polysomnography. DESIGN, SETTING AND PARTICIPANTS: Seventy healthy, normal children and adolescents were studied. Age ranged from 1 to 15 years (mean +/- SD, 8.02 +/- 4.57 years). All children underwent overnight polysomnography including EEG, electromyography, electrooculography, ECG, pulse oximetry arterial oxygen saturation (SpO(2)), chest wall and abdomen motion, oral and nasal airflow, and end-tidal PCO(2) (PETCO(2)). RESULTS: Three children (4%) had a mean of 0.37 obstructive apneas (OAs) per hour of sleep (1 to 5 OAs per child per study), with mean apnea duration of 10.3 +/- 2.1 s. This was not accompanied with oxygen desaturation. Twenty-six children had one to seven central apneas (CAs) per child, resulting in a mean of 0.4 CAs per hour of sleep (median, 0.33; 97.5 percentile, 0.9). Eleven of the 58 events of CA in six children coincided with oxygen desaturation to a minimum of 88% (nadir apnea desaturation range, 88 to 93%). The mean SpO(2) was 97.2 +/- 0.8% with SpO(2) nadir of 94.6 +/- 2.2%. PETCO(2) > 45 mm Hg occurred for 1.6 +/- 3.8% of total sleep time (TST) in 21 of 70 children (30%), with a distribution of 1.3 +/- 3.03% in the range of 46 to 47 mm Hg; < 0.7% were within the range of 48 to 50 mm Hg; and in 0.29 +/- 0.24% of TST, PETCO(2) values were > 50 mm Hg. CONCLUSIONS: Based on these data, the recommended limits for normal values are as follows: OA index, 1; CA index, 0.9; oxygen desaturation, 89%; baseline saturation, 92%; and PETCO(2) > 45 mm Hg for < 10% of TST.

Adolescent↗

PubMed1985

Respiration during sleep in children with COPD.

Seventeen children (mean age, nine years) with chronic obstructive pulmonary disease (COPD) were studied during sleep. Electroencephalography, electrooculography, and electromyography were all recorded. Airflow was measured by nasal and oral thermistors, and abdominal and thoracic anteroposterior diameters by magnetometers. Transcutaneous partial pressure of O2 (tcPO2) and of CO2 (tcPCO2) were monitored. The average total sleep time was 283 min +/- 36 (1 SD). Breathing pauses (BP) five seconds or longer were measured. The mean time of BP expressed as a percentage of TST was 1.3 percent +/- 0.8 (1 SD). The BP occurred most frequently during REM sleep. Forty-six percent of BP were obstructive (OBP). The percentage of OBP was significantly related to the degree of lung resistance during wakefulness. Periodic breathing was observed with a mean frequency of 2.2 times per night (range: 0 to 7). Episodes with paradoxic inward rib cage motion were seen one to 29 times (mean 6.6). Drops in tcPCO2 greater than 5 mm Hg occurred one to eight times and 67 percent were observed during REM sleep. Compared to tcPCO2 during W the mean maximal decrease in tcPCO2 was 14 mm Hg (range 8 to 29). tcPCO2 rose with a mean maximal of 9.1 mm Hg (range 6 to 13). It was concluded that children with COPD had worsened gas exchange during sleep.

Child, Preschool↗

PubMedDate not supplied

Cervico-vestibular and visuo-vestibular interaction. Self-motion perception, nystagmus, and gaze shift.

In 8 healthy subjects we studied self-motion perception and nystagmus due to sinusoidal stimulation (amplitude 90 degrees peak to peak, frequency 0.05 Hz) of the horizontal semicircular canals, the cervical proprioceptors, and the retina. We used an electrically driven rotatory chair and optokinetic drum combination. For cervical stimulation the subject's head was placed in a clamp, attached to the drum. Eye movements were recorded by means of electrooculography, d.c. amplification. Subjects signalled the estimated head position by means of a 'joystick'. In the present series of experiments the vestibular and cervical informations were played off against each other in combined stimulation conditions with an interstimulus phase lag of 0 to 315 degrees, in steps of 45 degrees. Similarly, the vestibular and visual informations were played off against each other. Concerning estimated head position, our main finding is that both the visually and the cervically induced illusion of head rotation overrule the vestibular sensation of head motion. The ocular response to combined vestibular plus cervical stimulation shows that both nystagmus slow phases and saccades of the cervical and the vestibular responses add up by vectorial summation.

Adult↗

PubMed1995

Continuous brainstem auditory evoked potential monitoring during nocturnal sleep.

Continuous monitoring of brainstem auditory evoked potentials (BAEPs) was performed simultaneously with polysomnographic recordings during nocturnal sleep in 9 normal males (mean age 25.3 +/- 2.7 years). Four-channel electroencephalography, respiration (abdominal and thoracic), rectal temperature, electrocardiography, electrooculography, chin electromyography, non-invasive blood pressure (Finapres), oxygen saturation and two channels of BAEPs were recorded by a multivariable computer system. All data except BAEPs were preprocessed, integrated over 30 s and printed on a single sheet. Sleep stages were classified visually. Latencies, interpeak latencies, amplitudes and the I/V amplitude ratio of the BAEPs were analysed in the awake state and different sleep stages. The results confirm that, as previously reported, the slight BAEP latency modifications observed during sleep are correlated to body temperature variations. The analysis of the absolute amplitudes of BAEPs showed insignificant (ANOVA) variations with sleep (e.g., mean amplitude of peak V +/- SD: wakefulness = .36 microV +/- .11, REM = .22 microV +/- .05, stage 2 = .27 microV +/- .14, stage 3 = .25 microV +/- .14, stage 4 = .26 microV +/- .11). A significant change between wakefulness and deep sleep could be found in the latencies of wave IV and V and in the amplitude ratio I/V (P < .05, ANOVA, Student-Newman-Keuls method).

Adult↗

PubMed2000

[Influence of vestibular input on visually guided saccades].

A common pathway in the brainstem is thought to exist for the induction of visually guided saccades and rapid phase nystagmus (Ref. Ohki et al. 1988). This common pathway is often referred to as "the saccade generator" or "the burst generator." The presence of this pathway suggests that vestibular function can be examined by applying "visual stimuli" and "vestibular stimuli" at the same time. We therefore investigated whether caloric stimulation affects the latency, amplitude and velocity of saccadic eye movements and if so, how. Nine normal volunteers participated in the experiment. Eye movements were recorded using DC electrooculography. Caloric stimulation was applied to the right ear using an air caloric stimulator (10 degrees C) during saccades. Two experiments involving visually guided saccades were performed. Task 1: The subject was asked to fixate on a central fixation point. Another spot of light then randomly appeared at one of two different locations (20 degrees to the right or left). The subject was then asked to scan towards the second light as quickly as possible. Task 2: The procedure was the same as in Task 1, except that the target appeared only briefly and then later reappeared at the same location. The saccade latency was unaffected by caloric stimulation in Task 1, while the latency of the rightward saccades increased significantly in Task 2. The saccade amplitude and velocity increased significantly in both directions in Task 1, while the amplitude and velocity of the leftward saccades increased significantly in Task 2. These results can be explained by the synergistic activation of Burster-Driving Neurons by the saccade signal and the vestibular signals. The combinations of these saccade tasks and caloric stimulation, especially Task 2, may be useful in clinically examining vestibulo-oculomotor functions.

Adult↗

PubMed2006

[Flexibility of adaptation of vestibule-ocular reflex in human beings].

Vestibulo-ocular reflex (VOR) makes images remain relatively stable on the retina. To keep appropriate performance and minimize image slip throughout life, VOR is subject to long-term adaptive regulation by visual input. It has been reported that adaptive changes in VOR gain (eye velocity/head velocity) are 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 feature frequency-selectivity. We studied the flexibility of adaptive gain change in VOR required by a horizontal visual-vestibular mismatch in earth vertical axis rotation (EVAR), including adaptive gain change from EVA to off-vertical axis rotation (OVAR) and other velocities. The visual-vestibular mismatch was made by oscillating subjects in EVAR for 30 minutes at 0.3 Hz with the peak velocity of 30 deg/s and 60 deg/s, synchronized with both in-phase (gain decrease: x 0 experiment) and out-of-phase (gain increase: x 2 experiment) sinusoidal rotation of white-black stripe patterns. Subjects were 19 healthy adult volunteers with no history of neurological symptoms. Horizontal and vertical eye positions were recorded by bitemporal DC-coupled electrooculography. In the x 2 adaptation experiment with 0.3 Hz at the peak velocity of 30 deg/s, the percent change in gain (post-pre/ pre) was 110% at the same stimulation and 100% at 40 deg/s in EVA. In the x 0 adaptation experiment with 0.3 Hz at the peak velocity of 30 deg/s, the percent change in gain was -50% at the same stimulation in EVA. In the x 2 adaptation experiment with 0.3 Hz at the peak velocity of 60 deg/s, the percent change in gain was 66% at the same stimulation in EVA, 30% at the same stimulation in nose-up position, and 74% at the same stimulation in nose-down position. In the x 0 adaptation experiment with 0.3 Hz at the peak velocity of 60 deg/s, the percent change in gain was -34% at the same stimulation in EVA. No change in VOR gain was observed at other peak velocities. These results suggest that VOR adaptation depends frequency and maximum angular head velocity, and this characteristic is observed in OVAR.

Adaptation, Ocular↗

PubMed1999

Isolated cranial nerve palsies due to brainstem lesions.

Isolated cranial nerve palsies are often attributed to lesions of the respective nerves along their extraaxial courses. There are a significant number of reports of individual patients with cranial nerve palsies, mostly of the 3rd and 6th nerves, as the sole manifestation of brainstem lesions proven by magnetic resonance imaging (MRI) or computer-assisted tomography (CT). An intraaxial basis may still be underestimated if based on MRI only, as electrophysiological abnormalities indicating brainstem lesions (masseter reflex, blink reflex, DC electrooculography) may be independent from MRI-documented morphological lesions. This article reviews the evidence that ischemic and demyelinating brainstem lesions are an important and underestimated cause of clinically isolated cranial nerve palsies. Especially in middle-aged and elderly people with 3rd and 6th nerve palsies, small pontine and mesencephalic infarctions seem to be more frequent than small-vessel ischemic infarctions of the extraaxial nerves.

Aged↗

PubMed1999

[Acquired pendular nystagmus after pontine hemorrhage].

A 60-year-old hypertensive woman had a pontine hemorrhage that caused slight right hemiplegia, deep sensory disturbance on her right side and dysarthria. Three months after the stroke, she was transferred to our hospital for rehabilitation. Approximately 6 months later, she gradually began to complain of the visual oscillation. Continual, unceasing conjugate vertical/rotatory eye movements were observed. Fixation was momentary at best because of an inability to dampen the spontaneous eye movements. Electrooculography (EOG) showed bilateral vertical/rotatory sinusoidal eye movements of 2.5 Hz frequency and 10- to 35-degree amplitude. Both vertical and horizontal optokinetic nystagmus were absent. Caloric stimulation did not evoke any responses bilaterally. There were no rhythmical movements at similar frequencies in other parts of the body such as palatal myoclonus. MRI revealed not only hematoma mainly at the dorsal pontine tegmentum but also hypertrophy of the inferior olive nucleus, suggesting disruption of the central tegmental tract. Lesions of this tract may be one cause of pendular nystagmus. Several drug therapies were investigated for the nystagmus. There was no response to baclofen 15 mg. Trihexyphenidyl 4 mg was discontinued because of drug-induced hallucinations. Tiapride 600 mg and phenobarbital 90 mg were each slightly effective in reducing both frequency and amplitude of nystagmus. Treatment with clonazepam 1 mg resulted in the striking disappearance of nystagmus. She was aware of this and no longer experienced oscillopsia. Despite the visual benefit, however, the patient did not wish to continue this drug because of drowsiness and muscle relaxation. The potential long-term therapeutic application of clonazepam should be further investigated. To our knowledge, there have been no reports of successful treatment in acquired pendular nystagmus with clonazepam. Therefore, based on this favorable experience, it is suggested that clonazepam should be added to the list of potential therapies for pendular nystagmus.

Anticonvulsants↗

PubMed1998

Temperature Order Effects in the Caloric Reaction.

Does it matter in what order the four irrigations are conducted in the caloric test? It has been suggested that warm water (44 degrees C) elicits stronger reactions than does cold water (30 degrees C), which might be explained simply by slight differences in water temperatures. However, if it can be shown that starting with cold water diminishes the difference between the warm and cold irrigations, it might be worthwhile to apply the cold irrigations first. Binaural, bithermal caloric irrigation was conducted in darkness using electrooculography. Maximum slow-phase velocity was measured. One hundred and eighteen consecutive patients from our laboratory were tested with warm water first and then with cold irrigations. In a second run, 108 subjects were irrigated with cold water before the warm. Employing cold irrigations first produces a smaller difference between the warm and the cold irrigations than does the opposite order. However, the lateral and directional preponderances, according to the formulas of Jongkees, are not affected by this change of irrigation order. The fact that initial warm-water irrigations cause the temperature effect differences to be larger than do initial cold-water irrigations is a phenomenon having only marginal clinical implications.

Journal Article↗

PubMedDate not supplied

[Dynamics of motor components of optokinetic nystagmus during exposure of the vestibular apparatus to angular accelerations].

The effect of angular accelerations on the optokinetic nystagmus was studied on 25 test subjects using a special vestibulo-optokinetic trainer rotated according to five programs and electrooculography. Angular accelerations were found to induce indirectly changes in the amplitude and time of the optokinetic nystagmus via the vestibular apparatus. Optimization of parameters of the optokinetic nystagmus was reflected in the criterion of positive difference + delta between angular velocities of the slow component of the nystagmus and optokinetic stimuli. It is postulated that the criterion + delta is a necessary factor in the organization of optimal time relations between optokinetic stimuli and central processes that are responsible for the final result--sensory image of movement.

Acceleration↗