Gertrúd Tamás

Impairment of post-movement beta synchronisation in parkinson's disease is related to laterality of tremor

OBJECTIVE Post-movement beta synchronisation (PMBS) is a physiological indicator of the activity of movement related neural networks. To investigate the pathophysiology of this phenomenon, we examined its characteristics in patients with unilateral tremor-dominant Parkinsons disease (PD). METHODS Movement duration and PMBS was measured after self-paced movement of the thumb at movement-reactive beta frequencies, over the supplementary motor area in 10 PD patients and 8 control subjects. RESULTS Movement duration in PD patients was longer than in controls. In left hand tremor patients, movement of the left hand was significantly longer compared to the right hand. When PD patients moved their non-affected hand, similarly to the controls, PMBS was higher contralateral to the movement. After movement of the tremulous hand, the contralateral PMBS decreased significantly and the contralateral preponderance disappeared. In the same hemisphere, PMBS was higher after contralateral to the non-affected hand movement, than after ipsilateral to the tremulous hand after movement. CONCLUSIONS PMBS in PD is affected by the activity of tremor related neural networks, suggesting that both cortical and subcortical sources are responsible for its generation. Examination of PMBS in various neurological diseases might provide further data on its physiological significance.

Source analysis of beta-synchronisation and cortico-muscular coherence after movement termination based on high resolution electroencephalography.

We hypothesized that post-movement beta synchronization (PMBS) and cortico-muscular coherence (CMC) during movement termination relate to each other and have similar role in sensorimotor integration. We calculated the parameters and estimated the sources of these phenomena. We measured 64-channel EEG simultaneously with surface EMG of the right first dorsal interosseus muscle in 11 healthy volunteers. In Task1, subjects kept a medium-strength contraction continuously; in Task2, superimposed on this movement, they performed repetitive self-paced short contractions. In Task3 short contractions were executed alone. Time-frequency analysis of the EEG and CMC was performed with respect to the offset of brisk movements and averaged in each subject. Sources of PMBS and CMC were also calculated. High beta power in Task1, PMBS in Task2-3, and CMC in Task1-2 could be observed in the same individual frequency bands. While beta synchronization in Task1 and PMBS in Task2-3 appeared bilateral with contralateral predominance, CMC in Task1-2 was strictly a unilateral phenomenon; their main sources did not differ contralateral to the movement in the primary sensorimotor cortex in 7 of 11 subjects in Task1, and in 6 of 9 subjects in Task2. In Task2, CMC and PMBS had the same latency but their amplitudes did not correlate with each other. In Task2, weaker PMBS source was found bilaterally within the secondary sensory cortex, while the second source of CMC was detected in the premotor cortex, contralateral to the movement. In Task3, weaker sources of PMBS could be estimated in bilateral supplementary motor cortex and in the thalamus. PMBS and CMC appear simultaneously at the end of a phasic movement possibly suggesting similar antikinetic effects, but they may be separate processes with different active functions. Whereas PMBS seems to reset the supraspinal sensorimotor network, cortico-muscular coherence may represent the recalibration of cortico-motoneuronal and spinal systems.

Delayed beta synchronization after movement of the more affected hand in essential tremor.

To investigate the pathomechanism of parkinsonian tremor (PT) and essential tremor (ET) by studying the correlation between tremor asymmetry and post-movement beta synchronization (PMBS) of the human EEG. We recorded the EEG of 10 patients with ET, 10 patients with Parkinsons disease and 10 controls. Subjects pressed an on-off switch in a self-paced manner with the thumb of their less (T+) and more (T++) tremulous hand. After digitalization of the EEG from the Cz, C3, C4 electrodes the movement reactive beta frequency, its maximum peak power value and its latency triggered to movement offset were determined. In ET tremor intensity did not influence the power of PMBS, however it was significantly delayed after the movement of the more tremulous hand. In Parkinsons disease after the movement of the more tremulous hand PMBS power was decreased, but it was not delayed. In controls the side of movement had no effect on the power and latency of the PMBS. The neuronal mechanisms underlying PMBS generation are differently affected in essential tremor and Parkinsons disease. The increase of PMBS latency after movement of the more affected hand in ET indicates possible cortical mechanisms in essential tremor generation.

Contralateral voluntary hand movement inhibits human parkinsonian tremor and variably influences essential tremor

While voluntary movement blocks Parkinsonian rest tremor (PT), essential tremor (ET) is enforced by postural and/or kinetic action. We studied the effect of contralateral externally- and internally triggered hand movement on PT and ET to investigate the transhemispheric influences on tremor genesis. We measured the changes of tremor peak frequency power after flash signal (F), flash triggered (FM) and self-paced (SPM) movement of the contralateral hand in nine PT and seven ET patients using accelerometer. PT significantly decreased both during FM and SPM tasks, suggesting that it is generated by a constant subcortico-cortical network, which includes higher order motor areas. Intensity of ET showed a remarkable intra- and interindividual variability both during FM and SPM reflecting a different generator circuitry with variable functional connections.

Quality of Life and Costs in Parkinson's Disease: A Cross Sectional Study in Hungary

Background Patient reported outcomes and costs of illness are useful to capture some of the multiple effects of a disease and its treatments. Our aim was to assess quality of life (QoL) and costs of Parkinsons disease (PD) in Hungary, and to analyze their associations. Methods A cross-sectional questionnaire survey was conducted in one neurology university clinic. Clinical characteristics, PD related resource utilizations and productivity loss in the past 12 months were recorded; the Hoehn&Yahr (HY) scale, PDQ-39 and EQ-5D questionnaires were applied. Cost calculation was performed from the societal perspective. Results 110 patients (34.5% female) were involved with mean age of 63.3 (SD = 11.3) and disease duration of 8.2 (SD = 5.8) years. PDQ-39 summary score was 48.1 (SD = 13.4). The average EQ-5D score was 0.59 (SD = 0.28), and was significantly lower than the population norm in age-groups 45–74. The correlation was significant between EQ-5D and PDQ-39 (−0.47, p = 0.000), the HY scale and EQ-5D (−0.3416, p = 0.0008) and PDQ-39 (0.3419, p = 0.0006) scores. The total mean cost was €6030.2 (SD = 6163.0)/patient/year (direct medical 35.7%, direct non-medical 29.4%, indirect cost 34.9%). A one year increase in disease duration and 0.1 decrease of the EQ-5D utility score increase the yearly costs by 8 to 10%, and 7.8%, respectively. The effect of the PDQ-39 score on total cost was not significant. Conclusions Disease severity and public health importance of PD are clearly demonstrated by the magnitude of QoL loss. PD-related costs are substantial, but are much lower in Hungary than in Western European countries. Disease duration and EQ-5D score are significant proxy of costs.

Management of dystonia in Europe : a survey of the European network for the study of the dystonia syndromes

Dystonia is difficult to recognize due to its large phenomenological complexity. Thus, the use of experts in dystonia is essential for better recognition and management of dystonia syndromes (DS). Our aim was to document managing strategies, facilities and expertise available in various European countries in order to identify which measures should be implemented to improve the management of DS.

Postoperative rehabilitation after deep brain stimulation surgery for movement disorders

Deep brain stimulation (DBS) is a highly efficient, evidence-based therapy for a set of neurological and psychiatric conditions and especially movement disorders such as Parkinsons disease, essential tremor and dystonia. Recent developments have improved the DBS technology. However, no unequivocal algorithms for an optimized postoperative care exist so far. The aim of this review is to provide a synopsis of the current clinical practice and to propose guidelines for postoperative and rehabilitative care of patients who undergo DBS. A standardized work-up in the DBS centers adapted to each patients clinical state and needs is important, including a meticulous evaluation of clinical improvement and residual symptoms with a definition of goals for neurorehabilitation. Efficient and complete information transfer to subsequent caregivers is essential. A coordinated therapy within a multidisciplinary team (trained in movement disorders and DBS) is needed to achieve the long-range maximal efficiency. An optimized postoperative framework might ultimately lead to more effective results of DBS.

Deep brain stimulation or thalamotomy in fragile X-associated tremor/ataxia syndrome? Case report

We present the case of a 66-year-old man who has been treated for essential tremor since the age of 58. He developed mild cerebellar gait ataxia seven years after tremor onset. Moderate, global brain atrophy was identified on MRI scans. At the age of 68, only temporary tremor relief could be achieved by bilateral deep brain stimulation of the ventral intermedius nucleus of the thalamus. Bilateral stimulation of the subthalamic nucleus also resulted only in transient improvement. In the meantime, progressive gait ataxia and tetraataxia developed accompanied by other cerebellar symptoms, such as nystagmus and scanning speech. These correlated with progressive development of bilateral symmetric hyperintensity of the middle cerebellar peduncles on T2 weighted MRI scans. Genetic testing revealed premutation of the FMR1 gene, establishing the diagnosis of fragile X-associated tremor/ataxia syndrome. Although this is a rare disorder, it should be taken into consideration during preoperative evaluation of essential tremor. Postural tremor ceased two years later after thalamotomy on the left side, while kinetic tremor of the right hand also improved.

Primary Sensorimotor Cortex Drives the Common Cortical Network for Gamma Synchronization in Voluntary Hand Movements

Background: Gamma synchronization (GS) may promote the processing between functionally related cortico-subcortical neural populations. Our aim was to identify the sources of GS and to analyze the direction of information flow in cerebral networks at the beginning of phasic movements, and during medium-strength isometric contraction of the hand. Methods: We measured 64-channel electroencephalography in 11 healthy volunteers (age: 25 ± 8 years; four females); surface electromyography detected the movements of the dominant hand. In Task 1, subjects kept a constant medium-strength contraction of the first dorsal interosseus muscle, and performed a superimposed repetitive voluntary self-paced brisk squeeze of an object. In Task 2, brisk, and in Task 3, constant contractions were performed. Time-frequency analysis of the EEG signal was performed with the multitaper method. GS sources were identified in five frequency bands (30–49, 51–75, 76–99, 101–125, and 126–149 Hz) with beamformer inverse solution dynamic imaging of coherent sources. The direction of information flow was estimated by renormalized partial directed coherence for each frequency band. The data-driven surrogate test, and the time reversal technique were performed to identify significant connections. Results: In all tasks, we depicted the first three common sources for the studied frequency bands that were as follows: contralateral primary sensorimotor cortex (S1M1), dorsolateral prefrontal cortex (dPFC) and supplementary motor cortex (SMA). GS was detected in narrower low- (∼30–60 Hz) and high-frequency bands (>51–60 Hz) in the contralateral thalamus and ipsilateral cerebellum in all three tasks. The contralateral posterior parietal cortex was activated only in Task 1. In every task, S1M1 had efferent information flow to the SMA and the dPFC while dPFC had no detected afferent connections to the network in the gamma range. Cortical-subcortical information flow captured by the GS was dynamically variable in the narrower frequency bands for the studied movements. Conclusion: A distinct cortical network was identified for GS in voluntary hand movement tasks. Our study revealed that S1M1 modulated the activity of interconnected cortical areas through GS, while subcortical structures modulated the motor network dynamically, and specifically for the studied movement program.

Ajánlás a Parkinson-kór előrehaladott stádiumának kezeléséhez

The treatment of advanced Parkinsons disease is challenging for both physicians and caregivers. The device-aided therapies need expertise and dedicated hospital centers. In this summary we have concluded the available data and recommendation for the treatment options in advanced Parkinsons disease and adopt them to the daily care in Hungary.