Deep brain stimulation for essential tremor: a systematic review.
ABSTRACT Deep brain stimulation (DBS) is a neurosurgical treatment, which has proven useful in treating Parkinson's disease. This systematic review assessed the safety and effectiveness of DBS for another movement disorder, essential tremor. All studies concerning the use of DBS in patients with essential tremor were identified through searching of electronic databases and hand searching of reference lists. Studies were categorized as before/after DBS or DBS stimulation on/off to allow the effect of the stimulation to be analyzed separately to that of the surgery itself. A total of 430 patients who had received DBS for essential tremor were identified. Most of the reported adverse events were mild and could be treated through changing the stimulation settings. Generally, in all studies, there was a significant improvement in outcomes after DBS compared with baseline scores. In addition, DBS was significantly better in testing when the stimulation was turned on, compared with stimulation turned off or baseline. Based on Level IV evidence, DBS is possibly a safe and effective therapy for essential tremor.
Conference Paper: Spectrally efficient multiuser space-time modulation[Show abstract] [Hide abstract]
ABSTRACT: To achieve full transmit diversity for a single user with NT antennas the coherence time of the channel has to be at least NT time-slots long. The same minimum number of slots (or dimensions) guarantees full transmit diversity for every user in a "narrowband" multiuser system in which all users communicate simultaneously and occupy the same bandwidth. However, with an increase in the number of users, an increasing signal-to-noise ratio (SNR) is required of each user to achieve the same error probability as in the single-user case. We showed earlier that this SNR penalty can be alleviated, and even eliminated for sufficiently high SNR, with only a marginal increase of the bandwidth and a judicious design of "spreading matrices" that spread a single-user space-time constellation or (block-) code. In other words, such signaling exploits multiuser diversity and ensures that each user enjoys single-user like performance for sufficiently high SNR. For instance, for NT-transmit antennas per user and a single-user space-time constellation that requires only the minimum time-slots NT, no more than NT+1 slots are required for the common signal space of any number of users. We present here simplified design criteria to obtain the spreading sequences/matrices. We also show that the optimum multiuser receiver can be implemented by the (generalized) sphere decoder of Damen et al. (see IEE Electronics Letters, vol.36, no.2, p.166-167, 2000).Information Theory, 2002. Proceedings. 2002 IEEE International Symposium on; 01/2002
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ABSTRACT: Currently, open-loop stimulation strategies are prevalent in medical bionic devices. These strategies involve setting electrical stimulation that does not change in response to neural activity. We investigate through simulation the advantages of using a closed-loop strategy that sets stimulation level based on continuous measurement of the level of neural activity. We propose a model-based controller design to control activation of retinal neurons. To deal with the lack of controllability and observability of the whole system, we use Kalman decomposition and control only the controllable and observable part. We show that the closed-loop controller performs better than the open-loop controller when perturbations are introduced into the system. We envisage that our work will give rise to more investigations of the closed-loop techniques in basic neuroscience research and in clinical applications of medical bionics.Biomedical Signal Processing and Control 11/2014; 14:164–174. · 1.07 Impact Factor
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ABSTRACT: Background Essential tremor is regarded to be a disease of the central nervous system. Neuroimaging is a rapidly growing field with potential benefits to both diagnostics and research. The exact role of imaging techniques with respect to essential tremor in research and clinical practice is not clear and a systematic review into the different imaging techniques in essential tremor is lacking the literature. Methods We performed a systematic literature search combining the terms essential tremor and familial tremor with the keywords: imaging, MRI, VBM, DWI, fMRI, PET and SPECT, both in abbreviated as well as in full form. We summarize and discuss the quality and the external validity of each study and place the results in the context of existing knowledge regarding the pathophysiology of essential tremor. Results A total of 48 neuroimaging studies met our search criteria, roughly divided in 19 structural and 29 functional and metabolic studies. The quality of the studies varied, especially concerning inclusion criteria. Functional imaging studies indicated cerebellar hyperactivity during rest and during tremor. The studies also pointed to involvement of the thalamus, the inferior olive and the red nucleus. Structural studies showed less consistent results. Discussion and conclusion Neuroimaging techniques in essential tremor give insight in the pathophysiology of essential tremor indicating involvement of the cerebellum as most consistent finding. GABAergic dysfunction might be a major premise in the pathophysiological hypotheses. Inconsistencies between studies can be partly explained by the inclusion of heterogeneous patient groups. Improvement of scientific research requires more stringent inclusion criteria and application of advanced analysis techniques. Also, the use of multimodal neuroimaging techniques is a promising development in movement disorders research. Currently, the role of imaging techniques in essential tremor in daily clinical practice is limited.NeuroImage: Clinical. 01/2014;