Biomedical subjects

V M Tronnier

Publications and source records attributed to V M Tronnier.

At least 19 recordsLinked to original sources

PubMed2006

[Deep brain stimulation in the posterior hypothalamus for chronic cluster headache. Case report and review of the literature].

Primary chronic cluster headache (CCH) is a rare but severe pain syndrome and pathophysiological explanations are still missing. PET studies revealed activation in the hypothalamus and therefore it became a target for therapeutic deep brain stimulation (DBS). A case of a 39-year-old woman and a literature review are presented. The patient suffered from left-sided primary CCH for 14 months. The headache was resistant to any pharmacological therapy or treatment was limited by major drug side effects. Using a stereotactic approach a quadripolar lead was inserted in the left posterior hypothalamus. A test trial was performed and attack frequency, intensity, and adverse events were noted. Intraoperative test stimulation evoked typical side effects like tachycardia, diplopia and panic attacks. During the trial test a marked reduction in frequency and intensity of CCH was recorded. After 7 days the stimulation device was implanted subcutaneously. DBS with implantation of a lead in the ipsilateral inferior posterior hypothalamus is an experimental treatment option and should be offered to selected patients in a prospective controlled clinical trial. Data concerning the long-term follow-up need to be collected.

Adult↗

PubMed2005

Behr syndrome variant with tremor treated by VIM stimulation.

Behr syndrome was first described in 1909 as a syndrome of heredofamilial optic atrophy, visual disturbances, nystagmus, and variable pyramidal tract signs. The syndrome has been reported in both sexes. So far, tremor has not been reported to be part of Behr Syndrome. We present the case of a 51-year-old man with a rare complicated dominant inherited cerebellar ataxia with accompanying visual loss and tremor (CICALVT) resembling a Behr Syndrome variant who suffered from advanced visual deterioration since childhood and progressive spastic paraparesis for 15 years. Furthermore, the patient presented increasing tremor of both hands for 5 years. The successful treatment of the tremor using deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus (VIM) is reported. Our case indicates that deep brain stimulation of the ventral intermediate nucleus is an adequate operative intervention that can help to reduce tremor even in patients with complicated movement disorders.

Deep Brain Stimulation↗

PubMed2005

[Spinal cord stimulation in Failed-Back-Surgery-Syndrome. Preliminary study for the evaluation of therapy by functional magnetic resonance imaging (fMRI)].

BACKGROUND: Spinal cord stimulation (SCS) is an effective alternative treatment in patients with chronic neuropathic pain and mainly radicular distribution. The aim of this prospective study was to investigate changes in BOLD signal with fMRI during active SCS and to correlate the results with the clinical pain intensity, measured with a visual analogue scale (VAS). PATIENTS AND METHODS: Three patients with failed back surgery syndrome were tested during the clinical trial of SCS. A first fMRI was performed with marked pain and a high VAS score. Before the second fMRI a therapeutic stimulation phase with pain reduction was carried out. RESULTS: With high pain levels SCS activated the cingulate gyrus, thalamus, prefrontal cortex, supplementary motor area and postcentral gyrus. After pain reduction, SCS did not elicit these activations in the second fMRI, using the same stimulation parameters. CONCLUSIONS: In patients with chronic neuropathic pain and high VAS levels, SCS elicited BOLD activation in the cingulate gyrus, thalamus, prefrontal cortex, and primary and secondary somatosensory area. Pain reduction by SCS resulted in a reduction of functional activity in these areas as revealed by follow-up fMRI.

Electric Stimulation Therapy↗

PubMed2004

Treatment of trigeminal neuralgia associated with multiple sclerosis: case report.

The incidence of trigeminal neuralgia (TN) in patients with multiple sclerosis is higher than in the general population. If pharmacologic therapy fails, invasive procedures in the gasserian ganglion are usually offered. Microvascular decompression is not routinely performed. The authors report a patient with persistent TN after repetitive trigeminal radiofrequency rhizotomy and finally successful microvascular decompression after demonstration of neurovascular compression with high-resolution MRI.

Decompression, Surgical↗

PubMed2004

Active deep brain stimulation during MRI: a feasibility study.

The goal of this study was to evaluate the feasibility of active deep brain stimulation (DBS) during the application of standard clinical sequences for functional MRI (fMRI) in phantom measurements. During active DBS, we investigated induced voltage, temperature at the electrode tips and lead, forces on the electrode and lead, consequences of defective leads and loose connections, proper operation of the neurostimulator, and image quality. Sequences for diffusion- and perfusion-weighted imaging, fMRI, and morphologic MRI were used. The DBS electrode and lead were placed in a NaCl solution-filled phantom. The results indicate that there are severe potential hazards for patients. Strong heating, high induced voltage, and even sparking at defects in the connecting cable could be observed. However, it was demonstrated that under certain conditions, safe MR examinations during active DBS are feasible. Certain safety precautions are recommended in this report.

Body Temperature↗

PubMed2004

Facial expression recognition and subthalamic nucleus stimulation.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor signs in Parkinson's disease. However, clinical studies suggest that DBS of the STN may also affect cognitive and emotional functions. OBJECTIVE: To study the impact of STN stimulation in Parkinson's disease on perception of facial expressions. RESULTS: There was a selective reduction in recognition of angry faces, but not other expressions, during STN stimulation. CONCLUSIONS: The findings may have important implications for social adjustment in these patients.

Adult↗

PubMed2003

Differential modulation of subcortical target and cortex during deep brain stimulation.

The combination of electrical deep brain stimulation (DBS) with functional imaging offers a unique model for tracing brain circuitry and for testing the modulatory potential of electrical stimulation on a neuronal network in vivo. We therefore applied parametric positron emission tomography (PET) analyses that allow characterization of rCBF responses as linear and nonlinear functions of the experimentally modulated stimulus (variable stimulator setting). In patients with electrodes in the thalamic ventrointermediate nucleus (VIM) for the treatment of essential tremor (ET) here we show that variations in voltage and frequency of thalamic stimulation have differential effects in a thalamo-cortical circuitry. Increasing stimulation amplitude was associated with a linear raise in rCBF at the thalamic stimulation site, but with a nonlinear rCBF response in the primary sensorimotor cortex (M1/S1). The reverse pattern in rCBF changes was observed with increasing stimulation frequency. These results indicate close connectivity between the stimulated nucleus (VIM) and primary sensorimotor cortex. Likewise, stimulation parameter-specific modulation occurs at this simple interface between an electrical and a cerebral system and suggests that the scope of DBS extends beyond an ablation-like on-off effect: DBS could rather allow a gradual tuning of activity within a neuronal circuit.

Aged↗

PubMed2002

[Neurosurgical therapy of facial neuralgias].

INTRODUCTION: Neuralgias of the face, especially trigeminal neuralgia and glossopharyngeal neuralgia are indications for surgical interventions after failed medical therapy. In contrast to other forms of headache or atypical facial pain, where surgical measures are considered to be contraindicated, percutaneous procedures or microvascular decompression are able to produce immediate and longstanding pain relief. Careful preoperative evaluation is essential to confirm the clinical diagnosis and to rule out other causes as multiple sclerosis or tumors afflicting the cranial nerves. The following study will summarize the common surgical techniques and their role considering a mechanism-based therapy as well as document long-term results of these measures. METHODS: Between 1977 and 1997 316 thermo-controlled radiofrequency trigeminal rhizotomies (TK) and 379 microvascular decompressions (MVD) were performed in our hospital to treat trigeminal neuralgia; additional 6 MVDs for glossopharyngeal neuralgia and one MVD of the intermediate facial nerve were carried out. Questionnaires were sent out to all patients still living in 1981, 1982, 1992 and 1998. For all other patients, interviews with relatives or the general practitioners were conducted. A retrospective analysis of postoperative pain relief was performed using Kaplan-Meier curves at the latest follow-up. Additionally 80 patients underwent careful quantitative sensory testing with Von-Frey-hairs. RESULTS: 225 patients who underwent microvascular decompression and 206 with radiofrequency trigeminal rhizotomies were further analyzed. There was a 50% risk for pain recurrence two years after radiofrequency rhizotomy. On the other hand 64% of patients who underwent microvascular decompression remained painfree 20 years postoperatively. Patients with microvascular decompression without sensory deficit were painfree significantly longer than patients with postoperative hypesthesia. DISCUSSION: Etiology and pathogenesis of facial neuralgias are far from understood despite several hypotheses. Based on current models there is no explanation for the immediate pain relief especially after microvascular decompression. Some authors even discuss surgical trauma as the only cause for postoperative pain relief.

Diagnosis, Differential↗

PubMed2002

High frequency stimulation of the basal ganglia for the treatment of movement disorders: current status and clinical results.

High frequency stimulation of the basal ganglia has gained much interest during the last years. Based on the reevaluation of the results of functional neurosurgery for movement disorders from Leksell's group, pallidotomy as lesional procedure was the first functional operation that underwent a renaissance for the treatment of movement disorders. The work by Benabid and Siegfried who carried out thalamic high frequency stimulation to suppress tremor, the knowledge about deep brain stimulation (DBS) for the treatment of chronic pain as well as better understanding in basal ganglia physiology and the development of reliable stimulation hardware led to an increasing number of centers worldwide who currently apply high frequency DBS for different movement disorders. In the present review the current status of DBS for movement disorders is presented and the results with high frequency stimulation targeted at different brain areas are summarized.

Animals↗

PubMed2002

Subthalamic nucleus stimulation affects striato-anterior cingulate cortex circuit in a response conflict task: a PET study.

The subthalamic nucleus (STN) has generally been considered as a relay station within frontal-subcortical motor control circuitry. Little is known about the influence of the STN on cognitive networks. Clinical observations and studies in animals suggest that the STN participates in non-motor functions which can now be probed in Parkinson's disease patients with deep brain stimulation of the STN, allowing selective and reversible modulation of this nucleus. Using PET, we studied changes in regional cerebral blood flow (rCBF) associated with a response conflict task (Stroop task) in Parkinson's disease patients ON and OFF bilateral STN stimulation. The Stroop task requires subjects to name the font colour of colour words (e.g. "blue") printed in an incongruent colour ink (e.g. yellow). During STN stimulation, impaired task performance (prolonged reaction times) was associated with decreased activation in both right anterior cingulate cortex (ACC) and right ventral striatum. Concomitant increased activation in left angular gyrus indicative of ongoing word processing during stimulation is consistent with an impairment to inhibit habitual responses. ACC and ventral striatum are part of the ACC circuit associated with response conflict tasks. The decreased activation during STN stimulation in the ACC circuit, while response conflict processing worsened, provides direct evidence of STN modulating non-motor basal ganglia-thalamocortical circuitry. Impairment in ACC circuit function could account for the subtle negative effects on cognition induced by STN stimulation.

Adult↗

PubMed2001

Thalamic stimulation for essential tremor activates motor and deactivates vestibular cortex.

BACKGROUND: The functional effects of deep brain stimulation in the nucleus ventralis intermedius (VIM) of the thalamus on brain circuitry are not well understood. The connectivity of the VIM has so far not been studied functionally. It was hypothesized that VIM stimulation would exert an effect primarily on VIM projection areas, namely motor and parietoinsular vestibular cortex. METHODS: Six patients with essential tremor who had electrodes implanted in the VIM were studied with PET. Regional cerebral blood flow was measured during three experimental conditions: with 130 Hz (effective) and 50 Hz (ineffective) stimulation, and without stimulation. RESULTS: Effective stimulation was associated with regional cerebral blood flow increases in motor cortex ipsilateral to the side of stimulation. Right retroinsular (parietoinsular vestibular) cortex showed regional cerebral blood flow decreases with stimulation. CONCLUSIONS: Beneficial effects of VIM stimulation in essential tremor are associated with increased synaptic activity in motor cortex, possibly due to nonphysiologic activation of thalamofrontal projections or frequency-dependent neuroinhibition. Retroinsular regional cerebral blood flow decreases suggest an interaction of VIM stimulation on vestibular-thalamic-cortical projections that may explain dysequilibrium, a common and reversible stimulation-associated side effect.

Adult↗

PubMed2001

Comparison of intraoperative MR imaging and 3D-navigated ultrasonography in the detection and resection control of lesions.

OBJECT: The authors undertook a study to compare two intraoperative imaging modalities, low-field magnetic resonance (MR) imaging and a prototype of a three-dimensional (3D)-navigated ultrasonography in terms of imaging quality in lesion detection and intraoperative resection control. METHODS: Low-field MR imaging was used for intraoperative resection control and update of navigational data in 101 patients with supratentorial gliomas. Thirty-five patients with different lesions underwent surgery in which the prototype of a 3D-navigated ultrasonography system was used. A prospective comparative study of both intraoperative imaging modalities was initiated with the first seven cases presented here. In 35 patients (70%) in whom ultrasonography was performed, accurate tumor delineation was demonstrated prior to tumor resection. In the remaining 30% comparison of preoperative MR imaging data and ultrasonography data allowed sufficient anatomical localization to be achieved. Detection of metastases and high-grade gliomas and intraoperative delineation of tumor remnants were comparable between both imaging modalities. In one case of a low-grade glioma better visibility was achieved with ultrasonography. However, intraoperative findings after resection were still difficult to interpret with ultrasonography alone most likely due to the beginning of a learning curve. CONCLUSIONS: Based on these preliminary results, intraoperative MR imaging remains superior to intraoperative ultrasonography in terms of resection control in glioma surgery. Nevertheless, the different features (different planes of slices, any-plane slicing, and creation of a 3D volume and matching of images) of this new ultrasonography system make this tool a very attractive alternative. The intended study of both imaging modalities will hopefully allow a comparison regarding sensitivity and specificity of intraoperative tumor remnant detection, as well as cost effectiveness.

Brain Neoplasms↗

PubMed2001

Treatment of idiopathic trigeminal neuralgia: comparison of long-term outcome after radiofrequency rhizotomy and microvascular decompression.

OBJECTIVE: To evaluate the long-term outcome of patients after either percutaneous trigeminal rhizotomy or microvascular decompression (MVD) for idiopathic trigeminal neuralgia at a single institution. METHODS: From 1977 to 1997, 316 radiofrequency lesion procedures and 378 MVDs were performed. Questionnaires were sent to all patients who were alive in 1981, 1982, 1992, and 1998. For all other patients, interviews were conducted with their relatives and general practitioners. A retrospective comparative analysis was performed with Kaplan-Meier probability curves as of the latest follow-up date. In addition, 80 patients who underwent MVD were examined postoperatively with quantitative sensory measurements by use of von Frey hairs. RESULTS: Two hundred twenty-five patients who underwent MVD and 206 patients who underwent radiofrequency could be analyzed retrospectively in detail. Overall, there was a 50% risk for recurrence of pain 2 years after percutaneous radiofrequency rhizotomy. Conversely, 64% of patients who underwent MVD remained completely pain free 20 years postoperatively. Patients without sensory impairment after MVD were pain free significantly longer than patients who experienced postoperative hypesthesia or partial rhizotomy. CONCLUSION: Because it is curative and nondestructive, MVD is considered the treatment of choice for trigeminal neuralgia in otherwise healthy people. In our study, it proved to be a more effective and long-lasting procedure for patients with typical trigeminal neuralgia than radiofrequency rhizotomy. Patients without postoperative sensory deficit remained pain free significantly longer, which is a strong argument against the "trauma" hypothesis of this procedure.

Decompression, Surgical↗

PubMed2000

An integrated head-holder/coil for intraoperative MRI in open neurosurgery.

With the invention of "open" magnetic resonance imaging (MRI) systems, access to the patient is possible during the imaging procedure. An important application of these systems is intraoperative MRI to control the extent of resection during tumor surgery. Up to now flexible surface coils wrapped around, or placed at each side of the head, were used for imaging. These flexible coils have several disadvantages such as unreliability, interindividual problems, difficult handling, poor hygienic properties, and often unsatisfactory or inhomogeneous image quality. To solve most of these problems, an MR-compatible head-holder in combination with an integrated surface coil for use in a 0.2 T C-shaped magnet was developed. Forty-eight patients with known cranial tumors underwent MRI intraoperatively. In 32 patients (67%), residual tumor was found, and additional surgical resection was performed. The integrated head-holder/coil is a safe and practical tool for intraoperative MRI, providing efficient and reliable resection control during neurosurgical procedures.

Brain↗

PubMed2000

Interventional MRI-guided brain biopsies using inductively coupled surface coils.

The technical realization of inductively coupled surface coils for interventional MR-guided procedures, and the application to brain biopsies in a 0.2 T magnet is described. The advantages compared to standard coils are discussed, and the results of 26 biopsies on eight different neuropathologic diagnoses from varying locations within the brain are presented. Initial experience shows that inductively coupled coils can offer an increased number of indications for interventional procedures in the brain, easier handling of sterility, and often a better access for the surgeon, compared to the use of standard MR head coils.

Biopsy, Needle↗

PubMed2000

[Virtual reality in neurosurgery].

DEFINITION: Virtual reality enables users to immerse themselves in a virtual three-dimensional world and to interact in this world. The simulation is different from the kind in computer games, in which the viewer is active but acts in a nonrealistic world, or on the TV screen, where we are passively driven in an active world. In virtual reality elements look realistic, they change their characteristics and have almost real-world unpredictability. USE OF VIRTUAL REALITY: Virtual reality is not only implemented in gambling dens and the entertainment industry but also in manufacturing processes (cars, furniture etc.), military applications and medicine. Especially the last two areas are strongly correlated, because telemedicine or telesurgery was originated for military reasons to operate on war victims from a secure distance or to perform surgery on astronauts in an orbiting space station. In medicine and especially neurosurgery virtual-reality methods are used for education, surgical planning and simulation on a virtual patient.

Endoscopes↗

PubMed2000

The benefit of neuronavigation for neurosurgery analyzed by its impact on glioblastoma surgery.

Neuronavigation, today a routine method in neurosurgery, has not yet been systematically assessed in direct comparison with conventional microsurgical techniques. The aim of the present study was the direct comparison of the impact of neuronavigation on glioblastoma surgery regarding time consumption, extent of tumor removal and survival. For each of 52 patients operated for primary glioblastoma with neuronavigation, a patient operated on without navigation was matched. Completeness of tumor resection, including volumetric analysis, was examined by early post-operative MRI. Operating and survival times were obtained for all patients. At a rate of 86.5%, surgeons' opinions about neuronavigation were positive. Operating times were identical in the two groups, while preparation times were 30.4 min longer with navigation. Radiological radicality was achieved in 31% of navigation cases vs. 19% in conventional operations. The absolute and relative residual tumor volumes were significantly lower with neuronavigation. Radical tumor resection was associated with a highly significant prolongation in survival (median 18.3 vs. 10.3 months, p < 0.0001). Survival was longer in patients operated on using neuronavigation (median 13.4 vs. 11.1 months). Neuronavigation increases radicality in glioblastoma resection without prolonging operating time. Regarding the problem of brain shift, neuronavigation should be optimized by intraoperative real-time imaging.

Adult↗

PubMed2000

Clinical evaluation and follow-up results for intraoperative magnetic resonance imaging in neurosurgery.

OBJECTIVE: The use of intraoperative magnetic resonance imaging (MRI) in neurosurgery has increased rapidly, and a variety of concepts have recently been presented. Although the feasibility of the procedure has been demonstrated repeatedly, no conclusive analysis of its effects on the surgical procedures, the extent of tumor removal, and outcomes, or its possible problems, has been performed. METHODS: Of 242 operations performed with intraoperative MRI, 97 procedures for supratentorial glioma treatment were analyzed with respect to intraoperative imaging results and postoperative outcomes. Analysis of the images included assessment of imaging artifacts, image quality, and extent of tumor removal. Patients were monitored to determine radiological progression, survival times, postoperative complications, and morbidity rates. RESULTS: No intraoperative complications related to the imaging procedure were observed. Image quality was good or fair in 85.5% of the cases. Different types of surgically induced imaging changes could be identified. In 56 cases, resection was continued using navigation with intraoperative MRI data sets (rereferencing accuracy, 0.9 mm). For high-grade gliomas, the percentage of cases in which residual tumor was identified by MRI could be significantly reduced from 62% intraoperatively to 33% postoperatively, which was paralleled by a significant increase in survival times for patients without residual tumor. Complication and morbidity rates were within the ranges reported for other studies. CONCLUSION: Intraoperative MRI is safe and allows reliable updating of neuronavigational data, with compensation for brain shifting. Surgically induced imaging changes, which have been identified as a possible problem with intraoperative MRI in general, necessitated comparisons with preoperative scans and require future attention. The extent of tumor removal and survival times were increased significantly. Overall, patients seemed to benefit from the method.

Adolescent↗