Quantification of sensory trick impact on tremor amplitude and frequency in 60 patients with head tremor.

Head tremor with an obvious head deviation is the typical clinical picture of tremulous cervical dystonia (TCD), whereas head tremor without any significant head deviation allows for the differential diagnosis of dystonic head tremor (DHT) as well as essential head tremor (EHT). Clinical and polyelectromyographic (poly-EMG) studies have shown a suppression of dystonic muscle activity in patients with TCD performing a maneuver called geste antagonistique. The effect of these trick maneuvers on head tremor has not been investigated in patients with DHT and EHT. We studied the impact of sensory trick maneuvers on head tremor amplitude and frequency clinically by using the tremor subscore of the Tsui scale and by means of computer-based accelerometry in 60 patients with head tremor as their major disorder. Based on clinical data (modified Tsui scale: rating of spontaneous head deviation [rotation + lateroflexion + ante-/retroflexion]), pharmacologic response of tremor (propranolol, primidone, or alcohol), family history (postural hand tremor in first-degree relatives), and poly-EMG findings (reciprocal inhibition in neck muscles during voluntary head rotation), 34 patients were diagnosed as having TCD, 14 were classified as having DHT, and 12 patients were diagnosed as having EHT. Using a clinical rating scale, head tremor amplitudes showed a significant decrease compared with baseline during the performance of sensory trick maneuvers in patients with TCD and DHT, but not in patients with EHT. This clinically observed effect was accompanied by a significant reduction in the mean peak power of the dominant frequency in patients with TCD (decrease by 83%, p = 0.0001) and DHT (decrease by 90%, p = 0.01), but not in patients with EHT (decrease by 6%, p = 0.6). Head tremor frequencies showed no significant changes in relation to the trick maneuvers. We conclude that a significant reduction of head tremor amplitude during a sensory trick maneuver is a useful quantitative criterion to distinguish TCD and DHT from EHT.     

“Visual sensory trick” in patient with cervical dystonia

Sensory tricks are clinical maneuvers that may partially relieve dystonic contractions. Any clinical maneuver that modulates afferent sensory and efferent motor pathways could be used as a sensory trick in patients with cervical dystonia. Although various sensory tricks have been described to reduce cervical dystonia, little is known about the exact mechanisms by which they operate. We report a case of cervical dystonia that was alleviated through the use of a visual-sensory trick. Our findings suggest that visual stimulation might be an effective sensory trick in cervical dystonia by compensating for a defective sensory system, or because visual pathways might be also affected by sensory interactions in cervical dystonia.     

Sensory tricks in cervical dystonia: perceptual dysbalance of parietal cortex modulates frontal motor programming

Cervical dystonia is a disabling basal ganglia disorder characterized by an involuntary head deviation to one side. A typical but also mysterious feature is the impressive improvement of muscle spasms and involuntary head posture by application of a sensory facial stimulus (sensory trick). Here, we report the effect of a sensory trick on cortical activation patterns in 7 patients with cervical dystonia by using H2(15)O positron emission tomography. The application of the sensory trick stimulus, resulting in a near-neutral head position, led to an increased activation mainly of the superior and inferior parietal lobule (ipsilateral to the original head turn) and bilateral occipital cortex and to a decreased activity of the supplementary motor area and the primary sensorimotor cortex (contralateral to the head turn). We propose that a perceptual dysbalance induced by a sensory trick maneuver leads to a relative displacement of the egocentric midvertical reference to the opposite side and a decrease in motor cortex activity. This modulation of motor programming gives novel insights into the mechanisms involved in sensorimotor integration in movement disorders.     

"Trick" movements in facial dystonia

Two patients with facial dystonia (blepharospasm and/or oromandibular dystonia) presented with an unusual "trick" movement. Both patients were able to inhibit blepharospasm and oromandibular dystonia by vocalizations including singing, reading, and speaking spontaneously. The significance of "trick" movements in facial dystonia is discussed.     

Complex mechanisms of sensory tricks in cervical dystonia.

Muscle activities in 26 patients with predominantly rotational torticollis were quantified using surface electromyography. In the subgroup of 19 patients with an effective sensory trick, different modes and bilateral locations of trick application led to significant (P < 0.002) reduction of electromyographic (EMG) activity. A strong correlation was found between the efficacy of trick manoeuvres and the starting head position. Trick application in a neutral or even contralateral position was most effective while no reduction of muscle activity during trick application at the maximum dystonic head position was found (P < 0.001). We propose a two-phase model: First, normalisation of head posture is obtained by counterpressure or volitional antagonistic muscle activity. In a second step, this position can be stabilised using sensory tricks challenging central adaption of distorted sensorimotor integration.     

Abnormal surface EMG during clinically normal wrist movement in cervical dystonia

We investigated whether patients with cervical dystonia (CD) have abnormal muscle activation in non-dystonic body parts. Eight healthy controls and eight CD patients performed a flexion-extension movement of the right wrist. Movement execution was recorded by surface electromyography (EMG) from forearm muscles. Although patients had no complaints concerning wrist movement and had no apparent difficulty in executing the task, they demonstrated lower mean EMG amplitude (flexor: 0.32 mV and extensor: 0.61 mV) than controls (flexor: 0.67 mV; P  = 0.021 and extensor: 1.18 mV; P  = 0.068; borderline significant). Mean extensor muscle contraction was prolonged in patients (1860 ms) compared with controls (1334 ms; P  = 0.026). Variation in mean EMG amplitude over movements tended to be higher in patients (flexor: 43% and extensor: 35%) than controls (flexor: 34%; P  = 0.072 and extensor: 26%; P  = 0.073). These results suggest that CD patients also have abnormal muscle activation in non-dystonic body parts at a subclinical level. This would support the concept that in dystonia, non-dystonic limbs are in a 'pre-dystonic state'.     

Patterned electromyographic activity in the sit-to-stand movement.

OBJECTIVES: Postural activity is an essential part of any voluntary movement. In movements involving all body parts such as in the sit-to-stand maneuver (STS), postural activity becomes intermingled with the activity required to perform the actual movement, and is usually difficult to recognize. METHODS: In this paper, we have analyzed the electromyographic activity of muscles of the leg, thigh, trunk and neck in 20 healthy volunteers who performed the STS maneuver. In order to identify the postural and the executional EMG activity, subjects were requested to perform the movement according to 6 predefined experimental conditions. Our hypothesis was that changing the conditions or the strategies of the movement would modify the postural activity, without significantly altering the EMG pattern required for performing the movement itself. RESULTS: Tibialis anterior (TA), abdominal (ABD) and sternocleidomastoid (SCM) were the muscles activated first in the most natural condition for the movement (reference), but their activity and that of the trapezius (TRA) was suppressed or greatly diminished in other conditions. Conversely, lumbar paraspinal (LPS), quadriceps (QUA), and hamstrings (HMS) were activated in a patterned sequence that was invariable in all conditions, and time locked to the moment of take-off from the seat. The soleus (SOL) was the last muscle activated and, together with QUA and HMS, remained active during standing. CONCLUSIONS: We conclude that TA, SOL, ABD, SCM and TRA are involved in preparatory and accompanying postural movements, while LPS, QUA, and HMS are activated in a consistent patterned sequence and can be considered the executional muscles for the STS movement. Recognition of the role of each muscle in the STS movement can contribute to a better understanding of the movement deficits of certain patients, and help to devise adaptive motor strategies in neurorehabilitation.     

The effects of self-involvement on attention, arousal, and facial expression during social interaction with virtual others: a psychophysiological study

Social neuroscience has shed light on the underpinnings of understanding other minds. The current study investigated the effect of self-involvement during social interaction on attention, arousal, and facial expression. Specifically, we sought to disentangle the effect of being personally addressed from the effect of decoding the meaning of another person's facial expression. To this end, eye movements, pupil size, and facial electromyographic (EMG) activity were recorded while participants observed virtual characters gazing at them or looking at someone else. In dynamic animations, the virtual characters then displayed either socially relevant facial expressions (similar to those used in everyday life situations to establish interpersonal contact) or arbitrary facial movements. The results show that attention allocation, as assessed by eye-tracking measurements, was specifically related to self-involvement regardless of the social meaning being conveyed. Arousal, as measured by pupil size, was primarily related to perceiving the virtual character's gender. In contrast, facial EMG activity was determined by the perception of socially relevant facial expressions irrespective of whom these were directed towards.     

Auditory startle response in cervical dystonia.

The excitability of brainstem neurons is abnormally enhanced in patients with cervical dystonia (CD), but the extend of such abnormality is not known. We examined whether patients with CD showed abnormalities in the auditory startle response (ASR), a brainstem reflex elicited by an unexpected loud stimulus. Thirteen patients with CD were investigated 3 months after botulinum toxin treatment. Thirteen healthy volunteers served as controls. ASRs were elicited by binaural high-intensity auditory stimuli. Reflex electromyographic (EMG) activity was recorded simultaneously with surface electrodes bilaterally from masseter, orbicularis oculi, sternocleidomastoid, and biceps brachii muscles. We found that ASR onset latencies were similar for patients and controls. CD patients had significantly lower ASR probabilities than controls (P = 0.007). ASR area under the curve was significantly smaller in CD patients (P = 0.017). Similar to controls, patients showed a significant habituation of ASR (P < 0.001, each); however, CD patients showed a prolonged tonic or phasic EMG activity after the initial ASR that was not observed in controls. Normal latencies and recruitment pattern indicate a preserved organization of intrinsic neural pathways mediating ASR in CD. Reduced ASR probability and magnitude as well as prolonged EMG activity after the proper startle response corroborate and extend previous findings on brainstem dysfunction in CD.     

Sensory trick phenomenon in cervical dystonia: a functional MRI study

Journal of Neurology - Sensory trick may relieve dystonic symptoms in patients with idiopathic cervical dystonia (CD). We investigated the patterns of brain functional MRI (fMRI) during resting...     

Descending control of muscles in patients with cervical dystonia.

It was reported recently that specific features in the frequency analysis of electromyographic (EMG) activity in the sternocleidomastoid (SCM) and splenius (SPL) muscles were able to distinguish between rotational idiopathic cervical dystonia (CD) and voluntary torticollis in individual subjects. Those with CD showed an abnormal drive to muscles at 5 to 7 Hz and an absence of the normal 10 to 12 Hz peak in the autospectrum of SPL. We sought to determine whether the same abnormalities in the frequency domain are found in complex CD, in which the head is displaced in more than two planes. EMG activity was recorded in the SCM, SPL, trapezius, and levator scapulae muscles bilaterally in 10 patients with complex CD. Frequency analysis of EMG was compared with conventional clinical and polymyographic assessment. The autospectrum of SPL during free dystonic contraction showed an absence of a significant peak at 10 to 12 Hz in 8 of the 10 patients. The presence of a 5 to 7 Hz frequency drive showed a significant association with muscle pairs determined as dystonic by means of polymyography (P < 0.005). The neck posture predicted blindly, based on the low-frequency drive, correlated significantly with the clinical assessment of posture (P < 0.01). Conventional assessment and the results of frequency analysis correlated, suggesting that a low-frequency drive to neck muscle may be a general feature of simple rotational and more complex cervical dystonia. The pattern of coherence between the EMG in different neck muscles may provide a means of identifying leading dystonic muscles, especially in patients with complex cervical dystonia.     

Effects of lung volume and chemoreceptor activity on blood pressure and R-R interval during the Valsalva maneuver

Study objectives The purpose of the present investigation was to examine the effect of lung volume and inspiration of 100 % oxygen on blood pressure and R-R interval responses during the Valsalva maneuver. Design and Participants Fourteen healthy subjects completed eight Valsalva maneuvers. Four of the maneuvers were completed after inspiring to total lung capacity while the remaining maneuvers were completed at end-expiratory lung volume. Two maneuvers completed at a given lung volume were performed under hyperoxic conditions while the remaining maneuvers were completed under normoxic conditions. Results Overall, a significant increase in blood pressure and decrease in R-R interval occurred throughout phases I–IV of the Valsalva maneuvers that were initiated from end-expiratory lung volume as compared to total lung capacity. These changes were accompanied by a concomitant increase in baroreflex sensitivity during phase IV. Furthermore, independent of lung volume the baroreflex response was attenuated under hyperoxic conditions. Conclusions We conclude that the lung volume that exists prior to the onset of the maneuver alters the blood pressure and R-R interval response during phases I–IV of the Valsalva maneuver. Furthermore, we suggest that these responses are mediated in part by changes in chemoreceptor activity since the baroreflex was reset and the sensitivity was reduced under hyperoxic conditions. Given these findings, we recommend that lung volume be controlled when patients are completing a Valsalva maneuver to obtain reliable and reproducible measures of blood pressure, R-R interval duration and baroreflex sensitivity. Received: 25 July 2000, Accepted: 20 November 2001     

平山病患者的临床、肌电图和磁共振研究

目的探讨平山病(HD)患者的临床表现、肌电图和磁共振(MRI)特点。方法收集2009-05-2012-02收治的HD患者的人口学资料、临床表现、电生理和颈椎MRI表现,并进行分析。另设年龄、性别匹配的健康对照组进行电生理检查。结果 (1)HD患者共25例,均为男性,年龄15～24岁,平均年龄(17.64±2.20)岁。临床表现局限于单侧者22例,其中右侧15例、左侧7例;双侧者3例。手或/和前臂肌肉萎缩25例,冷麻痹13例,手指震颤5例。(2)有临床表现侧小指展肌和拇短展肌肌肉电位波幅均减低,且二者波幅比值减小。(3)异常自发活动出现率在第一骨间肌和小指展肌100%、拇短伸肌89.3%、拇短展肌85.7%;在单侧有临床表现的22例中,11例(50%)患者的无症状侧显示异常自发活动。(4)完成MRI扫描的14例中,自然位均显示第2～7颈椎体后方下缘连线与椎体相交、下段颈髓萎缩变扁平;屈曲位时硬膜腔后壁前移7例。结论 HD多见于男性,以右侧多发。结合临床、肌电图以及影像学表现,有助于临床更全面认识HD。     

Nonspecific facilitation of responses to transcranial magnetic stimulation.

We examined the effect of facial muscle contraction and eye movements on motor evoked potentials (MEPs) from the abductor pollicis brevis muscle (APB) evoked by transcranial magnetic stimulation (TMS). The hypothesis was that activity of large cortical regions (face) influences the excitability of spinal motoneurons via cortical or subcortical pathways. MEPs were recorded in 12 healthy subjects during the following conditions: (1) rest; (2) facial muscle contraction; (3) eye movements; (4) 10% precontraction of the target muscle; and (5) simultaneous target muscle precontraction and facial muscle contraction. In 9 subjects, spinal motoneuron excitability was assessed by measurements of F waves during the same facilitation maneuvers. Activation of eye and facial muscles clearly facilitated MEPs from the APB. The facilitation of MEP size during nonspecific maneuvers was almost similar to that obtained by target muscle precontraction, whereas shortening of latencies was significantly smaller. The occurrence and amplitude of F waves increased in parallel with MEP size during specific and nonspecific facilitation, pointing to spinal motoneuronal threshold changes as a potential facilitatory mechanism by facial and eye muscle activation. The different MEP latencies during specific and nonspecific facilitation were not explained by different spinal motoneuron excitability, but raise the possibility that supraspinal mechanisms contributed to nonspecific facilitation.     

神经肌电图对特发性面瘫治疗及预后评估的研究

目的探讨神经肌电图(神经电图electroneurography,ENG和肌电图electromyography,EMG)在特发性面瘫治疗及预后评估中的价值。方法采用丹麦生产的keypointⅣ肌电图仪对96例确诊为特发性面瘫的患者进行患侧与健侧ENG、EMG检测,分别记录患侧面神经颞支、颧支、颊支的运动传导潜伏期、波幅以及所支配的额肌、眼轮匝肌、口轮匝肌的肌电图情况,并与自身健侧作对比。结果特发性面瘫患者患侧面神经运动传导潜伏期延长、M波波幅降低,与自身健侧相比,差异有统计学意义(P<0.05)。波幅下降<70%、NCV(神经传导速度)减慢<20%、EMG大致正常的轻度患者,3个月内面肌完全恢复,治愈率100%;波幅下降70%～90%、NCV减慢20%～50%、EMG呈部分神经源性损害的中度患者,3个月内大部分可完全恢复,治愈率87.8%;波幅下降>90%、NCV减慢>50%、EMG呈部分或完全神经源性损害的中重度患者,3个月内面肌完全恢复者为50%;诱发电位消失、NCV引不出、EMG呈完全神经源性损害的重度患者,3个月内面肌完全恢复者为25%。结论 ENG和EMG检测对特发性面瘫的神经损伤、面肌恢复等预后评估有重要价值,能对临床治疗提供客观依据。     

The association between premature plantarflexor muscle activity,muscle strength,and equinus gait in patients with various pathologies

This study provides an overview on the association between premature plantarflexor muscle activity (PPF), muscle strength, and equinus gait in patients with various pathologies. The purpose was to evaluate whether muscular weakness and biomechanical alterations are aetiological factors for PPF during walking, independent of the underlying pathology. In a retrospective design, 716 patients from our clinical database with 46 different pathologies (orthopaedic and neurologic) were evaluated. Gait analysis data of the patients included kinematics, kinetics, electromyographic activity (EMG) data, and manual muscle strength testing. All patients were clustered three times. First, patients were grouped according to their primary pathology. Second, all patients were again clustered, this time according to their impaired joints. Third, groups of patients with normal EMG or PPF, and equinus or normal foot contact were formed to evaluate the association between PPF and equinus gait. The patient groups derived by the first two cluster methods were further subdivided into patients with normal or reduced muscle strength. Additionally, the phi correlation coefficient was calculated between PPF and equinus gait. Independent of the clustering, PPF was present in all patient groups. Weak patients revealed PPF more frequently. The correlations of PPF and equinus gait were lower than expected, due to patients with normal EMG during loading response and equinus. These patients, however, showed higher gastrocnemius activity prior to foot strike together with lower peak tibialis anterior muscle activity in loading response. Patients with PPF and a normal foot contact possibly apply the plantarflexion–knee extension couple during loading response. While increased gastrocnemius activity around foot strike seems essential for equinus gait, premature gastrocnemius activity does not necessarily produce an equinus gait. We conclude that premature gastrocnemius activity is strongly associated with muscle weakness. It helps to control the knee joint under load independent from the underlying disease, and it is therefore a secondary deviation. If treated as primary target, caution should be exercised.     

Suprasegmentally induced motor unit activity in paralyzed muscles of patients with established spinal cord injury

In an attempt to demonstrate the presence of functional descending fibers in patients with clinically apparent functional spinal cord transection, we examined electromyographically recorded paralyzed leg muscle responses to the Jendrassik and other reinforcement maneuvers. Two patterns were observed: a low-amplitude, short onset time reinforcement maneuver response (RMR) restricted to one to three muscle groups (RMR1), and a larger-amplitude response with a longer onset time that occurred bilaterally in essentially all of the recorded muscles (RMR2). The responses imply preserved descending facilitory influence on isolated populations of motor units (RMR1) or on segmental interneuron pools (RMR2). Such findings indicate the presence of functioning fibers traversing the injured portion of the spinal cord in patients diagnosed as having a complete lesion. In such cases, it is possible for patients to initiate subclinical motor unit activity or suprasegmentally induced gross movement through reinforcement maneuvers, but not to control the amplitude or duration of the response.     

A computer-assisted method for averaging movement-related cortical potentials with respect to EMG onset

The recording of movement-related cortical potentials (MRCP) relies on the use of EMG activity or some other index of movement as a trigger for averaging. EMG activity can vary considerably from one movement to the next, particularly in patients with movement disorders. This results in an MRCP formed from individual sweeps which are averaged with respect to differing periods during the EMG activity. We describe a computer-assisted method for identifying EMG onset associated with each movement made by the subject. The method allows the experimenter to reject trials associated with artefacts or with spurious trigger pulses produced by resting EMG activity. It is also possible to average the MRCP into categories associated with differing EMG characteristics such as EMG duration, peak EMG amplitude and the duration from EMG onset to peak. Using this method we have been able to record reliable MRCP from patients with movement disorders in whom this would otherwise have been technically impossible.     

Activity of peri-oral facial muscles and its coordination with jaw muscles during ingestive behavior in awake rabbits

To study peri-oral facial muscle activity patterns and coordination with jaw muscles during ingestive behavior, electromyographic (EMG) activities in the peri-oral facial (buccinator: BUC, orbicularis oris: ORB) and jaw (masseter, digastric) muscles along with jaw movement trajectories were recorded in awake rabbits. A standardized amount of apple in a cylindrical shape was used as the test food. The period from food intake to just before swallowing (the masticatory sequence) was divided into three masticatory periods (preparatory period, rhythmic chewing period and preswallow period) based on the activity pattern of jaw muscles and jaw movement trajectories, and jaw movements and EMG activities in both the jaw and facial muscles during each masticatory period were assessed. Both the jaw and facial muscles were active throughout the masticatory sequence, and the activity patterns of facial muscles and the pattern of coordination between the facial and jaw muscles varied for each masticatory period. No consistent pattern was noted for the BUC activity during the preparatory period, whereas the ORB showed tonic activity throughout this period. During the rhythmic chewing and preswallow periods, both the ORB and BUC showed jaw-movement-related rhythmic bursts. However, significant differences were noted in the burst properties in both facial muscles and their temporal correlations with the jaw muscle activities between these two periods. Results suggest that the neural mechanisms regulating facial muscle activities may differ between the masticatory periods, and such mechanisms may contribute to the well-coordinated orofacial movements required for smooth masticatory sequence.     

Treatment of apogeotropic benign positional vertigo: comparison of therapeutic head-shaking and modified Semont maneuver

Several methods of physiotherapy have been advanced for apogeotropic type benign positional vertigo involving the horizontal semicircular canal (HC-BPV). The aim of this study was to determine the therapeutic efficacies of the proposed maneuvers in apogeotropic HC-BPV. Using a prospective randomized trial involving seven nationwide dizziness clinics in Korea, we compared the immediate efficacies of head-shaking and modified Semont maneuvers in 103 consecutive patients with apogeotropic HC-BPV. We also determined an additional therapeutic benefit of mastoid oscillation while the patients without response to both maneuvers were performing the Brandt–Daroff exercise. Successful treatment was defined as resolution of positional vertigo and nystagmus, or as transition into geotropic HC-BPV. Results showed that head shaking was more effective than the modified Semont maneuver (37.3 vs. 17.3%, P = 0.02). However, therapeutic efficacy did not differ between the maneuvers after the initial non-responders switched over to the other maneuver (23.3 vs. 25.0%, P = 0.861). Mastoid oscillation provided no additional benefit while the patients without response to both maneuvers were performing the Brandt–Daroff exercise. Most positional vertigos resolved within a week (89.4%) irrespective of the treatment modalities applied and all showed resolution within 28 days. The head-shaking maneuver described here proved more effective than the modified Semont maneuver in treating apogeotropic HC-BPV. Mastoid vibration conferred no additional benefit during the Brandt–Daroff exercise. S.-Y. Oh (Department of Neurology, School of Medicine, Chonbuk National University) conducted the statistical analyses.