Jochen Wirths

Directional DBS increases side‐effect thresholds—A prospective, double‐blind trial

The objective of this study was to investigate whether directional deep brain stimulation (DBS) of the subthalamic nucleus in Parkinsons disease (PD) offers increased therapeutic windows, side‐effect thresholds, and clinical benefit.

Malignant deep brain stimulation‐withdrawal syndrome in a patient with Parkinson's disease

Deep brain stimulation (DBS) is a well established therapeutic option for patients with advanced Parkinson’s disease (PD). Recent publications report promising long-term results concerning the efficacy and safety of DBS after 5 years. Furthermore, a sustainable stimulation-induced improvement of motor functions and an enduring reduction of dopaminergic medication were reported in a single-center, 10-year follow-up study. However, complications, such as hardware infection, psychiatric side effects, technical problems, or battery depletion, may occur in a considerable number of patients. Here, we report a previously undescribed “malignant DBS-withdrawal syndrome” after battery depletion as a possible complication of DBS therapy in a patient with PD.

Determining the orientation angle of directional leads for deep brain stimulation using computed tomography and digital x‐ray imaging: A phantom study

Purpose Orientating the angle of directional leads for deep brain stimulation (DBS) in an axial plane introduces a new degree of freedom that is indicated by embedded anisotropic directional markers. Our aim was to develop algorithms to determine lead orientation angles from computed tomography (CT) and stereotactic x‐ray imaging using standard clinical protocols, and subsequently assess the accuracy of both methods. Methods In CT the anisotropic marker artifact was taken as a signature of the lead orientation angle and analyzed using discrete Fourier transform of circular intensity profiles. The orientation angle was determined from phase angles at a frequency 2/360° and corrected for aberrations at oblique leads. In x‐ray imaging, frontal and lateral images were registered to stereotactic space and sub‐images containing directional markers were extracted. These images were compared with projection images of an identically located virtual marker at different orientation angles. A similarity index was calculated and used to determine the lead orientation angle. Both methods were tested using epoxy phantoms containing directional leads (Cartesia™ Boston Scientific, Marlborough, USA) with known orientation. Anthropomorphic phantoms were used to compare both methods for DBS cases. Results Mean deviation between CT and x‐ray was 1.5° ± 3.6° (range: −2.3° to 7.9°) for epoxy phantoms and 3.6° ± 7.1° (range: −5.6° to 14.6°) for anthropomorphic phantoms. After correction for imperfections in the epoxy phantoms, the mean deviation from ground truth was 0.0° ± 5.0° (range: −12° to 14°) for x‐ray. For CT the results depended on the polar angle of the lead in the scanner. Mean deviation was −0.3° ± 1.9° (range: −4.6° to 6.6°) or 1.6° ± 8.9° (range: −23° to 34°) for polar angles ≤ 40° or > 40° Conclusions The results show that both imaging modalities can be used to determine lead orientation angles with high accuracy. CT is superior to x‐ray imaging, but oblique leads (polar angle > 40°) show limited precision due to the current design of the directional marker.

Deep brain stimulation of the posterior subthalamic area and the thalamus in patients with essential tremor: study protocol for a randomized controlled pilot trial

BackgroundDeep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus is effective in medication refractory essential tremor (ET). In recent years, evidence has accumulated that the region ventral to the VIM, the posterior subthalamic area (PSA), might be an equally or even more effective target for electrode implantation. However, this evidence is primarily based on case series, cross-sectional observations, and retrospective data.Methods/designA prospective crossover pilot study investigating the effects of PSA stimulation in medication refractory ET patients was designed. In this study, bilateral electrodes are implanted such that at least one of the electrode contacts is located in the PSA and VIM, respectively. This implantation approach allows (1) a prospective double-blind investigation of the effects of PSA stimulation compared to baseline, as well as (2) a crossover comparison between VIM and PSA stimulation with respect to tremor suppression and side effect profiles.DiscussionThe results of this double-blinded, prospective study will allow a better understanding of the effects and side effects of PSA compared to VIM-DBS in patients with ET.Trial registrationGerman Clinical Trials Register: DRKS00004235. Registered on 4 July 2012.

The Effect of Uni- and Bilateral Thalamic Deep Brain Stimulation on Speech in Patients With Essential Tremor: Acoustics and Intelligibility.

Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) is performed to suppress medically‐resistant essential tremor (ET). However, stimulation induced dysarthria (SID) is a common side effect, limiting the extent to which tremor can be suppressed. To date, the exact pathogenesis of SID in VIM‐DBS treated ET patients is unknown.

DBS of the PSA and the VIM in essential tremor: A randomized, double-blind, crossover trial

Objective To evaluate deep brain stimulation (DBS) of the posterior subthalamic area (PSA) in essential tremor (ET) and compare it to the ventral intermediate nucleus of the thalamus (VIM) in terms of stimulation efficacy, efficiency, and side effects. Methods DBS leads were implanted such that contacts were placed in the VIM, on the intercommissural line, and in the PSA. Thirteen patients with ET entered a randomized, double-blind crossover phase and completed a 1-year follow-up. Results PSA-DBS significantly reduced tremor severity and improved quality of life. There were no relevant differences in quality and frequency of stimulation side effects between VIM and PSA, with a tendency toward greater tremor improvement with PSA stimulation. Clinical benefit was achieved at significantly lower stimulation amplitudes in the PSA. The majority of patients remained with PSA-DBS after 1 year. Conclusion In accordance with previous retrospective investigations, our prospective data suggest that PSA-DBS is at least equally effective as but possibly more efficient than VIM-DBS. Classification of evidence This study provides Class I evidence that for patients with essential tremor, PSA-DBS is not significantly different from VIM-DBS in suppressing tremor, but clinical benefit from PSA-DBS is attained at lower stimulation amplitudes.

A functional micro-electrode mapping of ventral thalamus in essential tremor

Using microelectrode recordings in patients with essential tremor undergoing DBS surgery, Pedrosa et al. demonstrate that the ventrolateral thalamus shows maximum tremor-related activity and the highest coherence with electromyographic activity in the contralateral arm. Efferent pockets of activity outnumber afferent, and the phase relationship between these components modulates tremor amplitude.

Authors’ reply to “Dosimetric of intracranial stereotactic radiosurgery: only ‘an exercise of style’”

We thank Dr. Fiorentino and colleagues for their interest in our article comparing dosimetric treatment plan quality in intracranial stereotactic radiosurgery (SRS) [12]. The purpose of our study was to test whether robotic radiosurgery can create at least equivalent treatment plans when compared to classical SRS with a linear accelerator (linac-SRS). Linac-SRS with conical collimators or a micro-multileaf collimator is widely used and a well-established clinical standard for the treatment of small intracranial target volumes [7, 10]. Treatment plan comparisons allow, if they are carried out properly, reliable statements to be made about the clinical utility of a new irradiation method or new radiation device [9]. Since plan comparisons can generally be carried out using a matched pair analysis, the required number of cases investigated can be kept low. Usually about 10 cases (range 1–15) are used in the literature [1, 3, 5, 6, 8, 9]. Vice versa, methodological requirements for meaningful plan