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.
"However, these patients report that stimulation has a deleterious effect on their speech, inducing a severe impact on quality of life and social functioning. And indeed, in the literature stimulation induced dysarthria is reported as being a common side effect affecting between 10% and 75% of patients . Previous studies on VIM-DBS in patients with multiple sclerosis  and essential tremor  have shown a detrimental effect of stimulation on the speech when looking at the subsyllabic level. "
[Show abstract][Hide abstract] ABSTRACT: The present study is the first kinematic study to investigate the speech production of ET patients with VIM-DBS. More specifically, it explores the coordination patterns of articulatory gestures in syllables with simple and complex onsets, CV and CCV, in German. It provides a preliminary analysis of gestural coordination under stimulation for the target words /lima/ and /klima/ in the framework of Articulatory Phonology. The findings reveal a timing deficit in the phonetic realization of competing coupling relations for complex onsets for the patients. The observed perturbation of gestural phase relations can be related to the coupling hypothesis of syllable structure and are taken to be a symptom for dysarthria.
18th International Congress of Phonetik Sciences, Glasgow; 08/2015
"The open-loop strategies may involve the machine-learning of the algorithm parameters or changing the algorithm parameters based on the patient's performance (slow-time scale); however, these strategies do not change stimulation parameters on a pulse-by-pulse basis in response to the evoked activity (fast-time scale), i.e., the level of stimulation does not change in response to any continuous measurement of the level of neural activity that is generated. While many stimulation strategy algorithms in bionic devices have been successful using open-loop techniques   , the outcomes differ from patient to patient     . For example, the benefits of the cochlear implant may vary even among patients with similar otologic pathologies and with the same type of the cochlear implant system . "
[Show abstract][Hide abstract] 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(1):164–174. DOI:10.1016/j.bspc.2014.07.015 · 1.42 Impact Factor
"However, stimulation-induced dysarthria 2 FN2 , p. 142). is a common side effect of thalamic/subthalamic stimulation (Flora et al., 2010; Krack et al., 2002) and, as a result, the extent to which tremor can be suppressed in individuals with essential tremor is limited, as suboptimal parameter settings just below the threshold inducing dysarthria have to be selected by the treating clinician. Recent analyses in controlled essential tremor studies indeed demonstrated that dysarthria is the most significant adverse event, affecting individuals with essential tremor (values reported in the literature range from almost 9% found in Flora et al., 2010, to 75% found in Pahwa et al., 2006) and inducing a severe effect on quality of life and social functioning. "
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Chronic deep brain stimulation of the nucleus ventralis intermedius is an effective treatment for individuals with medication-resistant essential tremor. However, these individuals report that stimulation has a deleterious effect on their speech. The present study investigates one important factor leading to these effects: the coordination of oral and glottal articulation.
Sixteen native-speaking German adults with essential tremor, between 26 and 86 years old, with and without chronic deep brain stimulation of the nucleus ventralis intermedius and 12 healthy, age-matched subjects were recorded performing a fast syllable repetition task (/papapa/, /tatata/, /kakaka/). Syllable duration and voicing-to-syllable ratio as well as parameters related directly to consonant production, voicing during constriction, and frication during constriction were measured.
Voicing during constriction was greater in subjects with essential tremor than in controls, indicating a perseveration of voicing into the voiceless consonant. Stimulation led to fewer voiceless intervals (voicing-to-syllable ratio), indicating a reduced degree of glottal abduction during the entire syllable cycle. Stimulation also induced incomplete oral closures (frication during constriction), indicating imprecise oral articulation.
The detrimental effect of stimulation on the speech motor system can be quantified using acoustic measures at the subsyllabic level.
Journal of Speech Language and Hearing Research 02/2014; 57(4). DOI:10.1044/2014_JSLHR-S-13-0155 · 2.07 Impact Factor
Nathan C. Rowland, Coralie De Hemptinne, Nicole C. Swann, Salman Qasim, Svjetlana Miocinovic, Jill L. Ostrem, Robert T. Knight, Philip A. Starr
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