Superior oblique myokymia

Superior oblique myokymia is an unusual eye movement phenomenon generally considered to be a uniocular rotary microtremor easily treated with carbamazepine. Eleven new cases are presented, one with a unique combination of motility problems, emphasizing that the disorder may have varying clinical manifestations. Long-term follow-up of the patients revealed a natural history of recurrent spontaneous remissions and relapses. Treatment with carbamazepine was of short-term benefit in most patients but failed to affect the long-term course of the disease. No patient developed other evidence of neurological disease. The condition seems to be a benign, permanent condition limited in its manifestations to the superior oblique muscle.     

Superior oblique myokymia

Superior oblique myokymia (SOM) is an uncommon, monocular movement disorder involving rapid torsional, low-amplitude contractions of the superior oblique muscle that causes monocular oscillopsia and diplopia. Ocular and neurologic examination in these patients is usually normal, and the clinical course is characterized by exacerbation remissions with good response to medical treatment. In this review, we present recent advances in the pathogenesis of SOM and provide an algorithm for the investigation and management of these patients.     

Superior oblique myokymia caused by vascular compression.

A 49-year-old man had left superior oblique myokymia for eight years. Magnetic resonance images with enhanced spoiled gradient recalled acquisition in the steady state (SPGR) and flow imaging using steady acquisition (FIESTA) disclosed a branch of the superior cerebellar artery lying on the root exit zone of the left trochlear nerve. Posterior fossa craniotomy confirmed the imaging findings. A Teflon pad was placed between the compressing artery and the trochlear nerve. The patient's superior oblique myokymia has completely resolved with a one-year follow-up. Only one such case has been previously reported. This is the first report to display the imaging findings.     

Superior oblique myokymia associated with a posterior fossa tumor: oculographic correlation with an idiopathic case

Superior oblique myokymia (SOM) was the only neurologic sign in a patient with an astrocytoma involving the midbrain tectum. Oculography showed monocular bursts of tonic and phasic intorsion and depression and miniature oscillations identical to those of idiopathic SOM. SOM stopped after tumor resection.     

A case of superior oblique myokymia observed by an image-analysis system.

Superior oblique myokymia is a microtremor of the eye that causes monocular torsional oscillopsia. A modified Harada-Ito procedure was used to treat a case of the disease in a 20-year-old woman. The authors used video-image analysis pre- and postoperatively to evaluate the effect of the surgery on abnormal torsional eye movements. This analysis revealed that before surgery, the abnormal torsional movement had a very regular cycle (duration of attack, 8.0 +/- 0.5 s; time interval between attacks, 18.7 +/- 3.2 s; n = 9). After the surgery, amplitude of the abnormal torsional eye movement was reduced, and the oscillopsia had subjectively improved, although the movement cycle remained unchanged. The authors' video-image analysis, which used iris striation, proved to be a useful method for clinical measurement of torsional eye movements.     

A clinically oriented approach to smooth pursuit eye movement quantitative evaluation

The electrooculographic technique was used to record smooth pursuit eye movements in 71 healthy subjects homogeneously distributed within an age range between the 2nd and the 6th decades. The target moved at constant velocity (triangular ramps) and 9 different target velocities (V), from 10 deg/s to 50 deg/s were considered and presented according to pseudorandom sequence. Ad hoc software suppressed catch-up saccades so that a pursuit index (PI) value was computed for each ramp taking into account only the smooth pursuit tracking modality. It was demonstrated that the relationship between V and PI could be described by the linear model PI = a + b * V. Pursuit index was proved to be influenced by the age of subject (decade factor in the analysis of variance), since an almost linear increase in b values yields a reduction of pursuit index values. The method was tested in 22 multiple sclerosis patients and an association was found between the occurrence of cerebellar signs and the reduction of a value.     

Cognitive mechanisms and motor control during a saccadic eye movement task: evidence from quantitative electroencephalography

The saccadic movement is an important behavioral measure used to investigate several cognitive processes, including attention and sensorimotor integration. The present study aimed at investigating changes in beta coherence over frontal, motor, occipital, and parietal cortices during the performance of two different conditions of a prosacadic paradigm. The conditions involved a different pattern of stimulus presentation: a fixed and random stimulus presentation. Twelve healthy volunteers (three male, mean age of 26.25 (SD=4.13) performed the task, while their brain activity pattern was recorded using quantitative electroencephalography. The results showed an interaction between factors condition and moment for the pair of electrode C3/C4. We observed a main effect for moment to CZ/C4, FZ/F3, and P3/PZ. We also found a main effect for condition to FZ/F4, P3/P4, and O1/O2. Our results demonstrated an important role of the inter-connection of the two hemispheres in visual search and movement preparation. The study demonstrates an automation of action and reduction of the focus of attention during the task. We also found that the inter-hemispheric beta coherence plays an important role in the differentiation of the two conditions, and that beta in the right frontal cortex is able to differentiate the conditions, demonstrating a greater involvement of procedural memory in fixed condition. Our results suggest a neuronal specialization in the execution of prosacadic paradigm involving motor task sequence.     

Concurrent and quantitative evaluation of neuronal activity and eye movement signals in behavioral experiments

Using inexpensive integration circuits, a device was developed that can transform extracellularly recorded neuronal impulses into signals readily visible on polygraph charts. The device included also a frequency divider. The characteristics of the circuit are quantitatively evaluated. The problems related to the limitation of such analog circuits are discussed.     

Perspectives on the rapid eye movement sleep switch in rapid eye movement sleep behavior disorder

Rapid eye movement (REM) sleep in mammals is associated with wakelike cortical and hippocampal activation and concurrent postural muscle atonia. Research during the past 5 decades has revealed the details of the neural circuitry regulating REM sleep and muscle atonia during this state. REM-active glutamatergic neurons in the sublaterodorsal nucleus (SLD) of the dorsal pons are critical for generation for REM sleep atonia. Descending projections from SLD glutamatergic neurons activate inhibitory premotor neurons in the ventromedial medulla (VMM) and in the spinal cord to antagonize the glutamatergic supraspinal inputs on the motor neurons during REM sleep. REM sleep behavior disorder (RBD) consists of simple behaviors (i.e., twitching, jerking) and complex behaviors (i.e., defensive behavior, talking). Animal research has lead to the hypothesis that complex behaviors in RBD are due to SLD pathology, while simple behaviors of RBD may be due to less severe SLD pathology or dysfunction of the VMM, ventral pons, or spinal cord.     

Attention and eye movement control: An overview

Summary A review of recent experimental and theoretical findings is presented which relates the results of neurophysiological and psychological research on attention and eye movement to cognitive theorizing. With respect to the relation between shifts of attention and saccadic eye movements, several experiments have demonstrated that it is possible to dissociate the line of attention from the gaze direction. On the other hand, there is some indirect (although not yet conclusive) evidence that saccadic eye movements always produce a concomitant shift of attention. Another question is whether there is a moment-to-moment control of each consecutive saccade and latency or whether indirect control models (i.e. planning several saccades in advance) are more appropriate. The function of attentional processes which have to coordinate stimulus driven (bottom-up) and concept driven (top-down) mechanisms are discussed and related to some studies investigating local and global scanpaths.This article was presented in part at the Symposium on Eye Movements and Psychopathology, Berlin, 23–24 June 1988Supported by the Swiss National Science Foundation, grants 1.187.85 and 3.940.84     

快速动眼睡眠型和非快速动眼睡眠型阻塞性睡眠呼吸暂停综合征患者的临床特征分析

目的 比较快速动眼睡眠(REM)型和非REM(NREM)型阻塞性睡眠呼吸暂停综合征(OSA)患者的临床特征、多导睡眠监测(PSG)参数和血清学指标间的差异.方法 收集2018年1月至2019年6月住院且PSG提示总呼吸暂停低通气指数(AHI)≥5的OSA患者129例.统计REM期AHI值(AHIREM)和NREM期AH...     

First rapid eye movement sleep periods and sleep-onset rapid eye movement periods in sleep-stage sequencing of hypersomnias

ObjectivesDiscrimination between narcolepsy, idiopathic hypersomnia, and behavior-induced inadequate sleep syndrome (BIISS) is based on clinical features and on specific nocturnal polysomnography (NPSG) and multiple sleep latency test (MSLT) results. However, previous studies have cast doubt on the specificity and sensitivity of these diagnostic tools.MethodsEleven variables of the NPSG were analyzed in 101 patients who were retrospectively diagnosed with narcolepsy with cataplexy (N + C) (n = 24), narcolepsy without cataplexy (N−C) (n = 38), idiopathic hypersomnia with long sleep period (IHL) (n = 21), and BIISS (n = 18).ResultsFifteen out of 24 N + C and 8 out of 38 N−C entered the first rapid eye movement (REM) sleep period (FREMP) from sleep stage 1 (N1) or wake (W), though this sleep-stage sequence did not arise in the other patient groups. FREMP stage sequence was a function of REM sleep latency (REML) for both N + C and N−C groups. FREMP stage sequence was not associated with mean sleep latency (MSL) in N + C but was associated in N−C, which implies heterogeneity within the N−C group. REML also was a useful discriminator. Depending on the cutoff period, REML had a sensitivity and specificity of up to 85.5% and 97.4%, respectively.ConclusionsThe FREMP stage sequence may be a useful tool in the diagnosis of narcolepsy, particularly in conjunction with sleep-stage sequence analysis of sleep-onset REM periods (SOREMPs) in the MSLT; it also may provide a helpful intermediate phenotype in the clarification of heterogeneity in the N−C diagnostic group. However, larger prospective studies are necessary to confirm these findings.     

Defining muscle activities for assessment of rapid eye movement sleep behavior disorder: From a qualitative to a quantitative diagnostic level

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by dream enacting behavior. Its polysomnographic hallmark is loss of physiological REM muscle atonia. Current diagnostic criteria require both a typical history of RBD or videographic documentation of abnormal REM-sleep related behaviors and the polysomnographic demonstration of REM sleep without atonia with “the electromyographic (EMG) finding of excessive amounts of sustained or intermittent elevation of submental EMG tone or excessive phasic submental or limb EMG twitching”.Until now, there has not been a generally accepted consensus on how muscle activity during REM sleep should be scored. Moreover, current diagnostic criteria do not specify which muscle or muscle combinations are the most suitable for differentiating between RBD and non-RBD. The term “excessive” refers to the scorer’s subjective impression and not to objective quantitative cutoff values.This article reviews published manual and computer-assisted scoring methods of EMG activity that are applied in RBD research. It includes the existing studies on EMG activity assessment in different muscles, available data on night-to-night variability, as well as recently established quantitative EMG cutoff values. The research that has been undertaken in the last years has greatly improved RBD diagnosis, taking it from a qualitative to a quantitative level. This development is of upmost importance, since RBD is often the first non-motor symptom of a neurodegenerative disease.     

探索性眼球活动和精神分裂症的诊断

目的:用DEM-2000型眼动监测仪再次验证探索性眼球活动检查在精神分裂症诊断中的价值。方法:给231例精神分裂症(患者组)和274名正常对照者(对照组)进行探索性眼球活动检查。测定凝视点数(NEF)和反应性探索分(RSS),计算敏感度和特异度,进行判别分析,利用判别公式计算判别D值。结果:患者组较对照组的NEF、RSS和D值均显著为低(P均<0.001)。判别公式能区分精神分裂症患者和正常对照者。结论:探索性眼球活动可以作为精神分裂症的辅助诊断指标。