Nonlinear Terahertz Polarizability of Electrons Solvated in a Polar Liquid.

The nonlinear polaronic response of electrons solvated in liquid 2-propanol is studied by two-dimensional terahertz spectroscopy. Solvated electrons with a concentration of c_{e}≈800  μM are generated by femtosecond photoionization of alcohol molecules. Electron relaxation to a localized ground state impulsively excites coherent polaron oscillations with a frequency of 3.

Spatial distribution of electric-field enhancement across the gap of terahertz bow-tie antennas.

The electric-field enhancement in terahertz (THz) antennas designed for nonlinear THz spectroscopy of soft matter is characterized by spatially resolved electrooptic sampling. To mimic the relevant interaction geometry, metallic, resonant bow-tie antennas are deposited on a thin zinc telluride crystal of 10 µm thickness. The THz electric field transmitted through the antenna gap is recorded by electrooptic sampling.

Verbal fluency in essential tremor patients: the effects of deep brain stimulation.

Objective: To assess the effects of different frequencies of thalamic Deep-Brain-Stimulation (DBS) on cognitive performance of patients suffering from Essential Tremor (ET).

Methods: In 17 ET-patients with thalamic-DBS, Tremor-Rating-Scale (TRS), standardized phonemic and semantic verbal fluency (VF), Stroop-Color-Word-Test and Digit-span-test were investigated in three randomized stimulation-settings: i) high-frequency stimulation (HFS), ii) low-frequency stimulation (LFS) and iii) OFF-stimulation (DBS-OFF). Paired-samples t-test for TRS and one-way repeated measures analysis of variance for cognitive performance were calculated.

Individualized current-shaping reduces DBS-induced dysarthria in patients with essential tremor.

Objective: To investigate in patients with essential tremor (ET) treated with thalamic/subthalamic deep brain stimulation (DBS) whether stimulation-induced dysarthria (SID) can be diminished by individualized current-shaping with interleaving stimulation (cs-ILS) while maintaining tremor suppression (TS).

Methods: Of 26 patients screened, 10 reported SID and were invited for testing. TS was assessed by the Tremor Rating Scale and kinematic analysis of postural and action tremor.

Tractography-guided stimulation of somatosensory fibers for thalamic pain relief.

Background: The spinothalamocortical tract (STC) is seen as a neural tract responsible for or involved in the generation or transmission of thalamic pain. Either the thalamus itself or the posterior limb of the internal capsule (PLIC) are targets for deep brain stimulation (DBS) in patients with thalamic pain, but due to its low contrast, conventional MRI cannot visualize the STC directly.

Objectives: To show the feasibility of integrating diffusion tensor imaging-based tractography into the stereotactic treatment planning for identification of an object-oriented lead trajectory that allows STC-DBS with multiple electrode contacts.

Intracerebral administration of heat-inactivated Staphylococcus epidermidis enhances oncolysis and prolongs survival in a 9L orthotopic gliosarcoma model.

Background/aims: The association between postoperative infection and prolonged survival in high-grade glioma is still a matter of debate. Previously we demonstrated that the intracerebral (i.c.

Intracranial ependymoma: long-term results in a series of 21 patients treated with stereotactic (125)iodine brachytherapy.

Background: We evaluated the long-term outcome in patients harboring intracranial ependymomas treated with interstitial brachytherapy (IBT).

Methods: Twenty-one patients (M/F = 9/12; median age: 29 years; range: 8-70 years), diagnosed with intracranial ependymoma (1 WHO I, 11 WHO II, 9 WHO III) were treated with IBT using stereotactically implanted (125)Iodine seeds between 1987 and 2010, either primarily, as adjuvant therapy following incomplete resection, or as salvage treatment upon tumor recurrence. Sixteen of 21 patients underwent microsurgical resection prior to IBT; in 5 patients, IBT was performed primarily after stereotactic biopsy for histological diagnosis.

Deep brain stimulation of the ventral intermediate nucleus in patients with essential tremor: stimulation below intercommissural line is more efficient but equally effective as stimulation above.

Background: The posterior subthalamic area (PSA), ventral to the intercommissural line (ICL) and the ventral intermediate nucleus (VIM), has been suggested as a promising target for deep brain stimulation (DBS) in patients suffering from essential tremor (ET). In this study the clinical benefit of VIM and PSA DBS on postural tremor suppression was systematically evaluated in a two step approach with a 3D ultrasound kinematic analysis tool.

Methods: We defined the exact position of 40 VIM-DBS-electrodes from 21 ET patients.

Stereotactic 125iodine brachytherapy for the treatment of singular brain metastases: closing a gap?

Background: Brain metastases represent the most common intracranial tumors and are associated with very poor prognosis.

Objective: To investigate the feasibility, survival, and cerebral disease control of patients with singular brain metastases treated with stereotactic 125iodine brachytherapy (SBT), to identify prognostic factors, and to compare results with other local treatment methods.

Methods: Complications, survival (overall and separated by recursive partitioning analysis [RPA] classes), and local and distant disease control were evaluated retrospectively in 90 patients.

Deep brain stimulation in the nucleus ventralis intermedius in patients with essential tremor: habituation of tremor suppression.

In patients with essential tremor (ET) already treated with chronic deep brain stimulation (DBS) of the nucleus ventralis intermedius (VIM) we investigated whether optimization of stimulation parameters could improve clinical tremor suppression, and whether this putative effect could be sustained over time. Twenty-three ET patients with VIM-DBS participated in the prospective study. All electrode contacts were tested systematically and stimulation parameters were optimized over the course of 2 days.

Multimodal localization of electrodes in deep brain stimulation: comparison of stereotactic CT and MRI with teleradiography.

Objective: In cross-sectional imaging, like CT or MRI, electrodes for deep brain stimulation are visualized by an artifact, which can differ from the real physical size of the electrode and even have an asymmetric appearance on MRI. The accuracy of such artifact-based estimation of the real position of the electrode using CT or MRI is investigated here. Stereotactic teleradiography was used as the gold standard.

Linear accelerator radiosurgery for pituitary macroadenomas: a 7-year follow-up study.

Background: A prospective study was conducted to assess the efficacy and side effects of linear accelerator (LINAC)-based radiosurgery (RS) performed with a reduced dose of therapeutic radiation for patients with surgically inaccessible pituitary macroadenomas.

Methods: From August 1990 through January 2004, 175 patients with pituitary macroadenomas were treated with LINAC-RS according to a prospective protocol. To minimize the risk for radiation-induced damage of the pituitary function, the therapeutic dose to be applied was limited to 20 grays.