Absence of nystagmus during REM sleep in a patient with waking nystagmus and oscillopsia

Polygraphic recording is presented of the sleep pattern in a young male who developed nystagmus and oscillopsia associated with a remittent CNS demyelinating disease. The vestibular nystagmus observed during wakefulness disappeared during all stages of sleep, including rapid eye movement sleep (REM). Since vestibular nystagmus experimentally induced in wakefulness is also absent during all phases of sleep, these findings suggest that during sleep similar suppressive mechanisms are operative.     

Hyperventilation-induced nystagmus in patients with vestibular schwannoma

OBJECTIVE: To analyze the nystagmus evoked by hyperventilation in patients with unilateral vestibular schwannoma and to use this information to predict the effects of hyperventilation on individual ampullary nerves. METHODS: Three-dimensional scleral search coil eye movement recording techniques were used to record the magnitude and time course of eye movements in six patients with unilateral vestibular schwannoma and hyperventilation-induced nystagmus. The presenting complaints in five of these patients were vertigo or dysequilibrium. RESULTS: The eye movement response to hyperventilation was a "recovery" nystagmus with slow-phase components corresponding to excitation of the affected vestibular nerve. Projection of the eye velocity vector into the plane of the semicircular canals revealed that fibers arising from the ampulla of the horizontal canal were most affected by hyperventilation with lesser activation of fibers to the superior canal and smaller, more variable responses from posterior canal fibers. CONCLUSIONS: The three-dimensional characteristics of the nystagmus evoked by hyperventilation in patients with vestibular schwannoma provide insight into the vestibular end organs affected by the tumor and the mechanism responsible for the nystagmus. This finding indicates that hyperventilation resulted in a transient increase in activity from these partially demyelinated axons.     

Absence of REM and altered NREM sleep in patients with spinocerebellar degeneration and slow saccades

The pontine tegmentum contains the neurons responsible for generation of saccadic eye movements and certain phases of sleep. We studied two genetically unrelated patients with spinocerebellar degeneration and slow saccadic eye movements. Multiple all-night sleep studies in both patients disclosed absence of REM and stage 4 sleep with an extremly short stage 3 and long stage 2. Both patients had a sleep stage (X) not previously reported. These are the first awake and ambulatory humans in whom consistent abscence of REM sleep has been demonstrated. Both behaved appropriately during wakefulness and showed no overt psychological abnormalities.     

Respiratory muscle activity during REM sleep in patients with diaphragm paralysis

The diaphragm is the main inspiratory muscle during REM sleep. It was hypothesized that patients with isolated bilateral diaphragm paralysis (BDP) might not be able to sustain REM sleep. Polysomnography with EMG recordings was undertaken from accessory respiratory muscles in patients with BDP and normal subjects. Patients with BDP had a normal quantity of REM sleep (mean +/- SD, 18.6 +/- 7.5% of total sleep time) achieved by inspiratory recruitment of extradiaphragmatic muscles in both tonic and phasic REM, suggesting brainstem reorganization.     

Optic nystagmus and vestibular nuclei: Unitary activity of vestibular neurons during nystagmus

The behavior of 102 vestibular neurons during optic nystagmus was investigated in 25 guinea pigs with extracellular microelectrodes. The recorded vestibular neurons were electrophysiologically identified by their orthodromic response to ipsilateral labyrinthine stimulation and by antidromic activation from the medial longitudinal fascicle. Of the 102 recorded units, 92 were modulated by the electrical stimulation of at least one optic nerve. The presence of vestibular neurons sensitive to the direction of nystagmus induced by labyrinthine or optic stimulation was also analyzed.     

The relation between abnormal behaviors and REM sleep microstructure in patients with REM sleep behavior disorder

ObjectiveTo investigate the temporal relation between rapid eye movement (REM) sleep microstructure (REMs, EMG activity) and motor events in REM sleep behavior disorder (RBD).MethodsPolysomnographic records of eight patients with RBD were analyzed and compared with those of eight sex- and age-matched controls. We examined sleep microstructure for REM sleep with and without REMs and phasic chin EMG activity and their temporal relation to motor events on video.ResultsAll types of motor events were either more frequent in RBD patients than in controls (P ? 0.007) or present solely in RBD patients. In RBD, major motor events were significantly more frequent during REM sleep with REMs than during REM sleep without REMs (violent, 84.0% vs. 16.0%, P < 0.001; complex/scenic behavior, 78.1% vs. 23.2%, P < 0.001; major jerks, 77.5% vs. 20.3%, P < 0.001), whereas minor motor activity was evenly distributed (54.1% vs. 45.9%, P = 0.889). Controls showed predominantly minor motor activity with rare myoclonic body jerks. The distribution of motor events did not differ between REM sleep with and without REMs (40.9% vs. 59.1%, P = 0.262).ConclusionsIn RBD, major motor activity is closely associated with REM sleep with REMs, whereas minor jerks occur throughout REM sleep. This finding further supports the concept of a dual nature of REM sleep with REMs and REM sleep without REMs and implies a potential gate control mechanism of REM sleep with REMs for the manifestation of elaborate or violent behaviors in RBD.     

Capturing nystagmus in the emergency room: posterior circulation stroke versus acute vestibular neuritis

Journal of Neurology - To compare acute nystagmus characteristics of posterior circulation stroke (PCS) and acute vestibular neuritis (AVN) in the emergency room (ER) within 24&nbsp;h of...     

Dream experience during REM and NREM sleep of patients with complex partial seizures

This study examined the effectiveness of the cognitive processes underlying dreaming in patients with complex partial seizures (CPS), by assessing the frequency of recall and the structural organization of dreams reported after awakenings provoked alternately during REM and stage 2 NREM sleep on 12 cognitively unimpaired CPS-patients (six with epileptic focus in the right hemisphere and six in the left one). Each patient was recorded for three consecutive nights, respectively, for adaptation to the sleep laboratory context, for polysomnography and for dream collection. The frequency of dream recall was lower after stage 2 NREM sleep than REM sleep, regardless of the side of epileptic focus, while the length and structural organization of dreams did not significantly differ in REM and NREM sleep. However, the length of story-like dreams was influenced by global cognitive functioning during REM sleep. These findings indicate that in CPSs-patients the elaboration of dream experience is maintained in both REM and NREM sleep, while the access to information for conversion into dream contents and the consolidation of dream contents is much less effective during NREM rather than during REM sleep. Further studies may distinguish between these two possibilities and enlighten us as to whether the impaired memory functioning during NREM sleep is a side effect of anticonvulsant treatment.     

REM sleep and prolactin in patients with non-affective psychoses

Reduced REM latency is a common polysomnographic finding in patients with schizophrenia. This has been attributed to cholinergic hyperactivity secondary to increased dopaminergic tone. We studied polysomnographic sleep recordings, and morning serum prolactin levels as a measure of dopaminergic tone in 17 drug-free patients suffering from non-affective psychoses, hypothesizing that REM-latency and prolactin would correlate. A clear-cut positive correlation between prolactin and REM latency was found, as well as a negative correlation between prolactin and REM sleep. The findings may be explained by dopaminergic and secondary hypercholinergic and/or serotonergic mechanisms responsible for the regulation of REM sleep and the secretion of prolactin.     

REM sleep latency during nocturnal sleep in mentally retarded infants

REM sleep latency observed in 61 mentally retarded infants (4-13 months of age) was studied throughout nocturnal sleep. Mentally retarded infants revealed a J distribution of short (less than 8 min) and long (more than 8 min) REM sleep latencies. This feature of distribution was similar to that obtained by other authors from normal infants under 3 months of age. REM sleep latency did not depend on the duration of prior wakefulness. Long REM sleep latencies were no more often preceded by long episodes of wakefulness than were short REM sleep latencies. No correlation was found between REM sleep latency and age, developmental quotient or daytime clinical EEG abnormalities.     

Sawtooth wave density analysis during REM sleep in temporal lobe epilepsy patients

BACKGROUND AND PURPOSE: This study analyzes sawtooth waves (STW), a characteristic feature of rapid eye movement (REM) sleep, in temporal lobe epilepsy patients in order to test the hypothesis of STW dysfunction in this population. METHODS: Polysomnographic records from 16 patients with temporal lobe epilepsy and 11 controls were scored for density (STW/h of REM sleep), duration (STW duration in s), and frequency of STW (waves/second within each STW complex). These measures were compared between both groups. RESULTS: STW measures were significantly different in control vs. epilepsy patients; respectively, density was 60.8 vs. 20.9 waves/h (P<0.005), average duration was 6.5 vs. 5.4 s (P<0.005 cycles 1-4), and frequency was 2.75 vs. 2.61 Hz (P<0.0005 across all cycles). CONCLUSIONS: Our measurements show a change in the density, duration and frequency of STW in patients with temporal lobe epilepsy compared to controls. Other parameters of REM sleep appear to be similar in both groups. These findings suggest a cortical influence on REM sleep either directly or through limbic-hypothalamic-brainstem connections.     

ACTH activates rapid eye movement-related phasic inhibition during REM sleep in patients with infantile spasms

OBJECTIVES: Phasic inhibition index (PII) is the rate of the simultaneous occurrence of phasic chin muscle activity (PCMA) and rapid eye movement bursts during rapid-eye-movement sleep (REMS). In naive patients with infantile spasms (IS), the PII value was found to reflect their prognosis. We studied the effects of adrenocorticotropic hormone (ACTH) on REMS components including PII in IS. METHODS: REMS parameters were examined in 18 IS patients before and after ACTH treatment. The effects of corticosteroids (CSs) were examined in 3 patients with congenital adrenal hyperplasia (CAH) and 3 with nephrotic syndrome (NS). RESULTS: ACTH decreased PII and PCMA in IS patients. In CAH patients, physiological doses of CSs corrected the increased intrinsic ACTH level and increased PII. In NS patients, therapeutic doses of CSs suppressed PCMA without affecting PII. CONCLUSION: ACTH suppressed PCMA through CSs, and reduced PII directly. ACTH was hypothesized to eliminate IS through these dual modes of action.     

Suppression of vestibular nystagmus

A beside test to evaluate suppression of vestibular nystagmus by fixation on an object that rotates with the patient's head is described.     

Spontaneous sleep interruptions during extended nights. Relationships with NREM and REM sleep phases and effects on REM sleep regulation.

OBJECTIVES: There is no agreement in the literature as to whether sleep interruption causes rapid eye movement (REM) pressure to increase, and if so, whether this increase is expressed as shortened REM latency, increased REM density, or increased duration of REM sleep. The purpose of the present study was to examine the effect of different durations of spontaneous sleep interruptions on the regulation of REM sleep that occurs after return to sleep. METHODS: The occurrence of spontaneous periods of wakefulness and their effects on subsequent REM sleep periods were analysed in a total sample of 1189 sleep interruptions which occurred across 364 extended nights in 13 normal subjects. RESULTS: Compared with sleep interruptions that last less than 10 min, sleep interruptions that last longer than 10 min occur preferentially out of REM sleep. In both the short and long types of sleep interruptions, the duration of REM periods that ended in wakefulness were shorter than the duration of those that were not interrupted by wakefulness. REM densities of the REM periods that terminated in periods of wakefulness were higher than those of uninterrupted REM periods. The proportion of episodes of wakefulness following REM sleep that were long-lasting progressively increased over the course of the extended night period. The sleep episodes that followed the periods of wakefulness were characterised by a short REM latency. REM duration was increased in episodes that followed long sleep interruptions compared to those that followed short sleep interruptions. REM density did not appear to change significantly in the episodes that followed sleep interruption. CONCLUSIONS: REM sleep mechanisms appear to be the main force controlling sleep after a spontaneous sleep interruption, presumably because during the second half of the night, where more sleep interruptions occur, the pressure for non-rapid eye movement sleep is reduced and the circadian rhythm in REM sleep propensity reaches its peak. Processes promoting REM sleep at the end of the night are consistent with the Pittendrigh and Daan dual oscillator model of the circadian pacemaker.     

Subtle gait changes in patients with REM sleep behavior disorder

Many people with rapid eye movement (REM) sleep behavior disorder (RBD) have an underlying synucleinopathy, the most common of which is Lewy body disease. Identifying additional abnormal clinical features may help in identifying those at greater risk of evolving to a more severe syndrome. Because gait disorders are common in the synucleinopathies, early abnormalities in gait in those with RBD could help in identifying those at increased risk of developing overt parkinsonism and/or cognitive impairment. We identified 42 probable RBD subjects and 492 controls using the Mayo Sleep Questionnaire and assessed gait velocity, cadence, and stride dynamics with an automated gait analysis system. Cases and controls were similar in age (79.9 ± 4.7 and 80.1 ± 4.7, P = 0.74), Unified Parkinson's Disease Rating Scale Part III (UPDRS) score (3.3 ± 5.5 and 1.9 ± 4.1, P = 0.21) and Mini–Mental State Examination scores (27.2 ± 1.9 and 27.7 ± 1.6, P = 0.10). A diagnosis of probable RBD was associated with decreased velocity (?7.9 cm/s; 95% confidence interval [CI], ?13.8 to ?2.0; P < 0.01), cadence (?4.4 steps/min; 95% CI, ?7.6 to ?1.3; P < 0.01), significantly increased double limb support variability (30%; 95% CI, 6–60; P = 0.01), and greater stride time variability (29%; 95% CI, 2–63; P = 0.03) and swing time variability (46%; 95% CI, 15–84; P < 0.01). Probable RBD is associated with subtle gait changes prior to overt clinical parkinsonism. Diagnosis of probable RBD supplemented by gait analysis may help as a screening tool for disorders of α‐synuclein. © 2013 International Parkinson and Movement Disorder Society     

REM sleep EEG spectral analysis in patients with first-episode schizophrenia

The pathophysiology of schizophrenia includes abnormalities in subcortical-cortical transfer of information that can be studied using REM sleep EEG spectral analysis, a measure that reflects spontaneous and endogenous thalamocortical activity. We recorded 10 patients with first-episode schizophrenia and 30 healthy controls for two consecutive nights in a sleep laboratory, using a 10-electrode EEG montage. Sixty seconds of REM sleep EEG without artifact were analyzed using FFT spectral analysis. Absolute and relative spectral amplitudes of five frequency bands (delta, theta, alpha, beta1 and beta2) were extracted and compared between the two groups. Frequency bands with significant differences were correlated with BPRS positive and negative symptoms scores. Patients with schizophrenia showed lower relative alpha and higher relative beta2 spectral amplitudes compared to healthy controls over the averaged total scalp. Analysis using cortical regions showed lower relative alpha over frontal, central and temporal regions and higher relative beta2 over the occipital region. Absolute spectral amplitude was not different between groups for any given EEG band. However, absolute alpha activity correlated negatively with BPRS positive symptoms scores and correlated positively with negative symptoms scores. Since similar results have been reported following EEG spectral analysis during the waking state, we conclude that abnormalities of subcortical-cortical transfer of information in schizophrenia could be generated by mechanisms common to REM sleep and waking.