Pharmacologic treatment for essential tremor and the tremor of Parkinson's disease is often inadequate. Stereotaxic surgery, such as thalamotomy, can effectively reduce tremors. We performed a multicenter trial of unilateral high-frequency stimulation of the ventral intermedius nucleus of the thalamus in 29 patients with essential tremor and 24 patients with Parkinson's disease, using a blinded assessment at 3 months after surgery to compare clinical rating of tremor with stimulation ON with stimulation OFF and baseline and a 1-year follow-up. Six patients were not implanted because of lack of intraoperative tremor suppression (2 patients), hemorrhage (2 patients), withdrawal of consent (1 patient), and persistent microthalamotomy effect (1 patient). A significant reduction in both essential and parkinsonian tremor occurred contralaterally with stimulation. Patients reported a significant reduction in disability. Measures of function were significantly improved in patients with essential tremor. Complications related to surgery in implanted patients were few. Stimulation was commonly associated with transient paresthesias. Other adverse effects were mild and well tolerated. Efficacy was not reduced at 1 year. Chronic high-frequency stimulation is safe and highly effective in ameliorating essential and parkinsonian tremor.

Thalamic stimulation is safe and effective for the long-term management of essential and Parkinsonian tremors. Bilateral stimulation can cause dysarthria and incoordination and should be used cautiously.

Summary: Purpose:We describe an algorithm for rapid realtime detection, quantitation, localization of seizures, and prediction of their clinical onset.Methods: Advanced digital signal processing techniques used in time-frequency localization, image processing, and identification of time-varying stochastic systems were used to develop the algorithm, which operates in generic or adaptable "modes." The "generic mode" was tested on (a) 125 partial seizures (each contained in a 10-min segment) involving the mesial temporal regions and recorded using depth electrodes from 16 subjects, and (b) 205 ten-minute segments of randomly selected interictal (nonseizure) data. The performance of the algorithm was compared with expert visual analysis, the current "gold standard." Results:The generic algorithm achieved perfect sensitivity and specificity (no false-positive and no false-negative detections) over the entire data set. Seizure intensity, a novel measure that seems clinically relevant, ranged between 35.7 and 6129. Detection was sufficiently rapid to allow prediction of clinical onset in 92% of seizures by a mean of 15.5 s.Conclusions: This algorithm, which was implemented with a personal computer, represents a definitive step toward rapid and accurate detection and prediction of seizures. It may also enable development of intelligent devices for automated seizure warning and treatment and stimulate new study of the dynamics of seizures and of the epileptic brain. Key Words: Epilepsy-Seizure-Detection-Prediction-Real time.The membership of the American Epilepsy Society recently ranked ' 'seizure prediction, early recognition, and blockage of seizures" as its primary research priority (1). The importance of accurate, automated, real-time detection, quantitation, and localization of seizures, a singular change in a highly complex, nonstationq time series [the EEG/electrocorticogram, (ECoG)], parallels its elusiveness (2-7). The inability to detect and quantify these changes rapidly, accurately, and automatically and to analyze such long-time series efficiently has limited the understanding of epilepsy and other dynamic diseases (8,9) and possibly the development of more effective and tolerable therapies as well. To be accurate, a solution must distinguish seizure signal changes from those caused by interictal epileptiform discharges,* or activity of extracerebral origin (artifacts) whose spectral domain often overlaps that of seizures. To be in real time, a solution must be highly computationally efficient, allowing on-line prospective rapid identification and quantitation of relevant changes, using short time windows, with limited a priori subject-specific data. We report a method that provides rapid automatic detection, quantitative analysis, and spatiotemporal localization of seizures. This algorithm, in its generic form, achieved sensitivity and specificity equal to that of expert visual analysis, the current ''gold standard," which it surpasses in its ability to quantitate seizure intensity objectively. In addition,...

Serious complications leading to permanent neurologic deficit are rare after STN DBS for advanced PD. However, long-term follow-up demonstrated that hardware complications are relatively common, having occurred in approximately 26% of these patients.

The need for novel, efficacious, antiseizure therapies is widely acknowledged. This study investigates in humans the feasibility, safety, and efficacy of high-frequency electrical stimulation (HFES; 100-500 Hz) triggered by automated seizure detections. Eight patients were enrolled in this study, which consisted of a control and an experimental phase. HFES was delivered directly to the epileptogenic zone (local closed-loop) in four patients and indirectly, through anterior thalami (remote closed-loop), to the other four patients for every other automated seizure detection made by a validated algorithm. Interphase (control vs experimental phase) and intraphase (stimulated vs nonstimulated) comparisons of clinical seizure rate and relative severity (clinical and electrographic) were performed, and differences were assessed using effect size. Patients were deemed "responders" if seizure rate was reduced by at least 50%; the remaining patients were deemed "nonresponders." All patients completed the study; rescue medications were not required. There were 1,491 HFESs (0.2% triggered after-discharges). Mean change in seizure rate in the local closed-loop group was -55.5% (-100 to +36.8%); three of four responders had a mean change of -86% (-100 to -58.8%). In the remote closed-loop, the mean change of seizure rate was -40.8% (-72.9 to +1.4%); two of four responders had a mean change of -74.3% (-75.6 to -72.9%). Mean effect size was zero in the local closed-loop (responders: beneficial and medium to large in magnitude) and negligible in the remote closed-loop group (responders: beneficial and medium to large). HFES effects on epileptogenic tissue were immediate and also outlasted the stimulation period. This study demonstrates the feasibility and short-term safety of automated HFES for seizure blockage, and also raises the possibility that it may be beneficial in pharmaco-resistant epilepsies.