Validating computationally predicted TMS stimulation areas using direct electrical stimulation in patients with brain tumors near precentral regions.

The spatial extent of transcranial magnetic stimulation (TMS) is of paramount interest for all studies employing this method. It is generally assumed that the induced electric field is the crucial parameter to determine which cortical regions are excited. While it is difficult to directly measure the electric field, one usually relies on computational models to estimate the electric field distribution.

Intraosseous ultrasonography to determine the accuracy of drill hole positioning prior to the placement of pedicle screws: an experimental study.

Object: Dorsal fixation with rods and pedicle screws (PSs) is the most frequently used surgery to correct traumatic and degenerative instabilities of the human spine. Prior to screw placement, screw holes are drilled along the vertebral pedicles. Despite the use of a variety of techniques, misplacement of screw holes, and consequently of the PSs, is a common problem.

Robot-assisted image-guided transcranial magnetic stimulation for somatotopic mapping of the motor cortex: a clinical pilot study.

Purpose: Shape and exact location of motor cortical areas varies among individuals. The exact knowledge of these locations is crucial for planning of neurosurgical procedures. In this study, we have used robot-assisted image-guided transcranial magnetic stimulation (Ri-TMS) to elicit MEP response recorded for individual muscles and reconstruct functional motor maps of the primary motor cortex.

Intra-osseous ultrasound for pedicle screw positioning in the subaxial cervical spine: an experimental study.

Background: In contrast to other regions of the human spine, dorsal fixation with rods and pedicle screws is comparatively rarely performed in the cervical spine. Although this technique provides a higher mechanical strength than the more frequently used lateral mass screws, many surgeons fear the relatively high rate of misplacements. This higher incidence is mainly due to the complex vertebral anatomy in this spinal segment.

Intraosseous ultrasound in the placement of pedicle screws in the lumbar spine.

Study Design: Experimental and intraoperative evaluation of the efficiency of a novel technique.

Objective: To determine the accuracy of pedicle screw hole placements before screw implantation in the lumbar spine.

Summary Of Background Data: Deviations from planned trajectories occur in a significant number of screw placements in posterior lumbar fixation.

Improved visibility of the subthalamic nucleus on high-resolution stereotactic MR imaging by added susceptibility (T2*) contrast using multiple gradient echoes.

Reliable identification of the subthalamic nucleus (STN) is a critical step in deep brain stimulation for Parkinson disease but difficult on T1-weighted stereotactic MR imaging. By simultaneous imaging of multiple gradient echoes, susceptibility contrast is added to conventional T1-weighted high-resolution MR image. Thus, the visibility of the STN is enhanced on a second co-localized dataset by exploiting the sensitivity of the T2*-relaxation to local iron deposits.

A pair of clamps for a safe removing and repositioning of beta and gamma angular settings of Brown-Roberts-Wells stereotactic system during operation.

The Brown-Roberts-Wells arc system is a non-target-centered design, i.e., without an independent approach angle.

Expression of focal adhesion kinase (p125 FAK) and proline-rich tyrosine kinase 2 (PYK2/CAKb) in cerebral metastases, correlation with VEGF-R-, ecNOS III-labelling and morphometric data.

Background: Cerebral metastasis occurs in about 20% of all neurosurgical patients. Cerebral metastases have a typical spherical morphology with a common central necrosis and perifocal oedema. It has been proposed that oedema extension, tumour volumes and infiltrative behaviour are partially mediated by vascular endothelial growth factor (VEGF) and nitric oxide (NO).

Oedema extension in cerebral metastasis and correlation with the expression of nitric oxide synthase isozymes (NOS I-III).

Background: The development of a peritumoral oedema is a common radiological sign in preoperative CT- and MRI scans of patients with cerebral metastasis. Large tumours can be accompanied by a marginally extended oedema and vice versa. Several cytokines (VEGF) have been identified as mediators of vascular induction and permeability.

Expression of nitric oxide synthase isozymes (NOS I-III) by immunohistochemistry and DNA in situ hybridization. Correlation with macrophage presence, vascular endothelial growth factor (VEGF) and oedema volumetric data in 220 glioblastomas.

Background: Nitric oxide (NO) is synthesized from arginine by three different isozymes of nitric oxide synthase (NOS I-III). NO has been identified as a powerful metabolite of vascular smooth muscle cell function, cerebral blood circulation and oedema induction. NOS induction by different cytokines has been shown previously in glioblastoma cell cultures and NOS III expression due to astrocytoma grading has been shown in several tumors recently.

A new forceps for the safe and easier insertion of subdural catheter: technical note.

A new forceps suitable for the safe and easier insertion of a silicon catheter into the subdural space is described. The use of this new tool has two advantages: Firstly, the insertion of the silicon subdural catheter is parallel to the brain surface and secondly, the movement of the catheter's end in the subdural space is controlled with greater accuracy. Thus, the surgeon has the opportunity to direct the catheter to the right position avoiding penetration or injury of the brain.

MiniMATCH: a simple method for local data transfer between MRI and CT scan sets.

A comparison of the spatial position of distinct locations within cranial MRI and CT scan sets can easily be done with a simple algorithm designed as a computer program. After determination of a basic system formed by the coordinates of anatomical landmarks in CT and MRI, arbitrary points can be identified on one scan set and transferred quantitatively to the other. Pros and cons of the method are discussed and opposed to the properties of specifically designed image processing systems.

Determination of the burr hole-site using the Brown-Roberts-Wells stereotactic system. A simple marking technique: technical note.

The authors describe a new tool-set with which the determination of the burr hole-site using the BRW-stereotactic system can be done on a non-sterile-washed head. The described attainment permits an increased security, not only reducing exposure of the operative field to a minimum but also shortening the operative length. The use of this tool-set for marking smaller superficial cortical processes is also possible.

Atypical and malignant meningiomas: evaluation of different radiological criteria based on CT and MRI.

The following are our results of a retrospective analysis of 214 patients, operated on meningiomas, in order to investigate radiological criteria of malignancy. Among these cases there were 31 patients with a histologically confirmed diagnosis of malignant subtypes. As uncertain signs of malignancy of ensuing radiological features are an irregular enhancement of contrast-media and the size of cerebral edema.

[Implantation of a phrenic stimulator in central respiratory paralysis].

Neoplastic or traumatic lesions of the brain stem or the upper spinal cord frequently cause respiratory insufficiency necessitating permanent mechanical ventilation. If the integrity of the diaphragm and its nerves is not affected, adequate ventilation can be achieved by electric stimulation of the phrenic nerves. Diaphragm pacing systems mean the patients can be independent of ventilator treatment.

[Experience with retrogasserian glycerol rhizotomy in the treatment of trigeminal neuralgia.].

From August 1981 to May 1993 a total of 1263 percutaneous retrogasserian glycerol rhizotomies after Hakanson were performed. The intervention was performed with X-ray monitoring under local anaesthesia and rarely lasted longer than 20 min. It achieved good results in the treatment of idiopathic trigeminal neuralgia (TN) and symptomatic trigeminal neuralgia due to multiple sclerosis (TNMS).

[Microsurgical resection of small brain tumor processes with stereotactic control].

From 1986 we have operated upon 13 patients with small neoplasms localised deep intracerebrally or subcortically in the central region with stereotactic guidance. Exact localisation of the tumour was one aim, whereas another one was to avoid damaging functionally important structures. In the first two patients we performed stereotactic marking of the tumour after craniotomy.

[Application of digital image processing techniques in cephalometry].

Digital image processing methods were applied to cephalometric analysis. Conventionally taken x-rays were captured by the aid of a video-camera. Digital processing was done using the IPS-System (Kontron).

[An applicator for the implantation of I125 seeds for interstitial therapy of brain tumors].

A compact magazine has been developed allowing a quick and easy implantation of I-125 seeds in interstitial therapy of intracranial tumors. The magazine is made of steel and has the shape of a right parallelepiped. One seed can be put each time into a movable insert.

Impulse cytophotometric DNA analysis in pituitary adenomas.

Flow cytometric DNA analysis was carried out on 32 microsurgically removed pituitary adenomas. Additionally, the histograms of tumor cell nuclei of 7 patients were compared with those of the cultured cells from the same tumor samples. The tumors were classified into 3 groups according to the proliferation index (PI) of the flow cytometric results: 1) tumors with DNA patterns of slow proliferation (PI under 10), to which the majority of the examined pituitary adenomas belonged; 2) pituitary adenomas with diploid karyograms and PI values from 10 to 15; 3) diploid or aneuploid karyograms with PI values above 15.

Five-and-a-half years' experience with percutaneous retrogasserian glycerol rhizotomy in treatment of trigeminal neuralgia.

The results of treating trigeminal neuralgia with percutaneous retroganglionic glycerol rhizotomy in 319 patients from an overall series of 394 patients with 459 operations carried out over a period of 5 1/2 years are reported. Idiopathic trigeminal neuralgia was the diagnosis in 252 patients. 34 patients had trigeminal neuralgia associated with multiple sclerosis.