Intraoperative DBS targeting of the globus pallidus internus by using motor evoked potentials.

OBJECTIVES: Target localization for deep brain stimulation (DBS) is a crucial step that influences the clinical benefit of the DBS procedure together with the reduction of side effects. In this work, we address the feasibility of DBS target localization in the globus pallidus internus (GPi) aided by intraoperative motor evoked potentials (MEP) with emphasis on the reduction of capsular side effects. MATERIAL AND METHODS: Micro-macroelectrode recordings were performed intraoperatively on 20 patients that underwent DBS treatment of the GPi (GPi-DBS). MEP were elicited intraoperatively by microelectrode stimulation during stereotactic DBS surgery. We studied the relationship between MEP thresholds and the internal capsule (IC) proximity. RESULTS: We found a significant correlation between intraoperative MEP thresholds and IC proximity. CONCLUSIONS: We provide further evidence of the role of MEPs for DBS target localization in the GPi, which extends and confirms the usefulness of MEPs as previously reported by DBS target localization studies dealing with the subthalamic and thalamic nuclei. Our approach is advantageous in that it provides criteria to determine the DBS target without the need to rely on a patient's response while avoiding capsular effects.

Anesthesia for deep brain stimulation system implantation: adapted protocol for awake and asleep surgery using microelectrode recordings.

PURPOSE: Deep brain stimulation (DBS), an effective treatment for movement disorders, usually involves lead implantation while the patient is awake and sedated. Recently, there has been interest in performing the procedure under general anesthesia (asleep). This report of a consecutive cohort of DBS patients describes anesthesia protocols for both awake and asleep procedures. METHODS: Consecutive patients with Parkinson's disease received subthalamic nucleus (STN) implants either moderately sedated or while intubated, using propofol and remifentanil. Microelectrode recordings were performed with up to five trajectories after discontinuing sedation in the awake group, or reducing sedation in the asleep group. Clinical outcome was compared between groups with the UPDRS III. RESULTS: The awake group (n = 17) received 3.5 mg/kg/h propofol and 11.6 µg/kg/h remifentanil. During recording, all anesthesia was stopped. The asleep group (n = 63) initially received 6.9 mg/kg/h propofol and 31.3 µg/kg/h remifentanil. During recording, this was reduced to 3.1 mg/kg/h propofol and 10.8 µg/kg/h remifentanil. Without parkinsonian medications or stimulation, 3-month UPDRS III ratings (ns = 16 and 52) were 40.8 in the awake group and 41.4 in the asleep group. Without medications but with stimulation turned on, ratings improved to 26.5 in the awake group and 26.3 in the asleep group. With both medications and stimulation, ratings improved further to 17.6 in the awake group and 15.3 in the asleep group. All within-group improvements from the off/off condition were statistically significant (all ps < 0.01). The degree of improvement with stimulation, with or without medications, was not significantly different in the awake vs. asleep groups (ps > 0.05). CONCLUSION: The above anesthesia protocols make possible an asleep implant procedure that can incorporate sufficient microelectrode recording. Together, this may increase patient comfort and improve clinical outcomes.

Motor Evoked Potentials Improve Targeting in Deep Brain Stimulation Surgery.

OBJECTIVES: One of the main challenges posed by the surgical deep brain stimulation (DBS) procedure is the successful targeting of the structures of interest and avoidance of side effects, especially in asleep surgery. Here, intraoperative motor evoked potentials (MEPs) might serve as tool to identify the pyramidal tract. We hypothesized that intraoperative MEPs are useful to define the distance to the pyramidal tract and reduce the occurrence of postoperative capsular side effects. MATERIALS AND METHODS: Motor potentials were evoked through both microelectrode and DBS-electrode stimulation during stereotactic DBS surgery on 25 subthalamic nuclei and 3 ventral intermediate thalamic nuclei. Internal capsule proximity was calculated for contacts on microelectrode trajectories, as well as for DBS-electrodes, and correlated with the corresponding MEP thresholds. Moreover, the predictivity of intraoperative MEP thresholds on the probability of postoperative capsular side effects was calculated. RESULTS: Intraoperative MEPs thresholds correlated significantly with internal capsule proximity, regardless of the stimulation source. Furthermore, MEPs thresholds were highly accurate to exclude the occurrence of postoperative capsular side effects. CONCLUSIONS: Intraoperative MEPs provide additional targeting guidance, especially in asleep DBS surgery, where clinical value of microelectrode recordings and test stimulation may be limited. As this technique can exclude future capsular side effects, it can directly be translated into clinical practice.

Directional Deep Brain Stimulation of the Thalamic Ventral Intermediate Area for Essential Tremor Increases Therapeutic Window.

OBJECTIVES: Deep brain stimulation (DBS) of the posterior subthalamic area (PSA) and the ventral intermediate thalamic nucleus (VIM) is a well-established therapy for essential tremor (ET), but it is frequently associated with side effects like dysarthria or gait ataxia. Directional DBS (dDBS) may be a way to activate fiber tracts more selectively. Is dDBS for ET superior to omnidirectional DBS (oDBS) regarding therapeutic window and clinically as effective as oDBS? MATERIALS AND METHODS: Ten patients with ET treated with PSA/VIM-DBS were recruited. Therapeutic window served as primary outcome parameter; clinical efficacy, volume of neuronal activation, and total electrical energy delivered (TEED) served as secondary outcome parameters. Therapeutic window was calculated for all three dDBS directions and for oDBS by determining therapeutic thresholds and side effect thresholds. Clinical efficacy was assessed by comparing the effect of best dDBS and oDBS on tremor and ataxia rating scales, and accelerometry. Volume of neural activation and TEED were also calculated for both paradigms. RESULTS: For best dDBS, therapeutic window was wider and therapeutic threshold was lower compared to oDBS. While side effect threshold did not differ, volume of neural activation was larger for dDBS. In terms of clinical efficacy, dDBS was as effective as oDBS. CONCLUSIONS: dDBS for ET widens therapeutic window due to reduction of therapeutic threshold. Larger volume of neural activation for dDBS at side effect threshold supports the notion of persistent directionality even at higher intensities. dDBS may compensate for slightly misplaced leads and should be considered first line for PSA/VIM-DBS.

Asleep Surgery May Improve the Therapeutic Window for Deep Brain Stimulation of the Subthalamic Nucleus.

OBJECTIVE: The effect of anesthesia type in terms of asleep vs. awake deep brain stimulation (DBS) surgery on therapeutic window (TW) has not been investigated so far. The objective of the study was to investigate whether asleep DBS surgery of the subthalamic nucleus (STN) improves TW for both directional (dDBS) and omnidirectional (oDBS) stimulation in a large single-center population. MATERIALS AND METHODS: A total of 104 consecutive patients with Parkinson's disease (PD) undergoing STN-DBS surgery (80 asleep and 24 awake) were compared regarding TW, therapeutic threshold, side effect threshold, improvement of Unified PD Rating Scale motor score (UPDRS-III) and degree of levodopa equivalent daily dose (LEDD) reduction. RESULTS: Asleep DBS surgery led to significantly wider TW compared to awake surgery for both dDBS and oDBS. However, dDBS further increased TW compared to oDBS in the asleep group only and not in the awake group. Clinical efficacy in terms of UPDRS-III improvement and LEDD reduction did not differ between groups. CONCLUSIONS: Our study provides first evidence for improvement of therapeutic window by asleep surgery compared to awake surgery, which can be strengthened further by dDBS. These results support the notion of preferring asleep over awake surgery but needs to be confirmed by prospective trials.

Sphenopalatine Ganglion Stimulation for Chronic Headache Syndromes.

Neuropathic facial pain is notoriously difficult to treat, regardless of its origin and duration. Since the first reported sphenopalatine ganglion blockade by Sluder in 1908, this ganglion has assumed an important role among the structures targeted for the treatment of facial pain. Recent years have witnessed the rise of neuromodulation over ablative procedures, including the development of an implantable stimulation device specially designed for use in the pterygopalatine fossa. Sphenopalatine ganglion stimulation has been demonstrated as effective and safe for refractory cluster headache, today the major indication for this therapy, but increasing evidence shows that the effect on the autonomic system and cerebral circulation could justify an even wider use of sphenopalatine ganglion stimulation for other chronic headache syndromes and vascular diseases.

Is the Intensity of 5-Aminolevulinic Acid-Derived Fluorescence Related to the Light Source?

OBJECTIVE: With the introduction of the 5-aminolevulinic acid (5-ALA) technique, surgical neuro-oncology has made a major advance. 5-ALA fluorescence-guided resection of malignant glioma results in more complete surgical resections and subsequently prolonged survival. However, it remains uncertain how light intensities of the blue light source and 5-ALA-derived fluorescence intensities of the illuminated tissue are connected. The aim of the present study was to compare light intensities of different blue light sources and protoporphyrin (PpIX) fluorescence intensities of PpIX solutions with defined concentrations after illumination with different light sources. MATERIAL AND METHODS: The light spectrum of 7 different blue light sources and the fluorescence intensity of 2 PpIX solutions (0.15 µg/mL and 5 µg/mL) were quantified after illumination. We compared the Zeiss OPMI Pentero microscope, the Zeiss OPMI Pentero 900 microscope, the Leica M530 OH6 microscope, an endoscope equipped with the 5-ALA technique, a mini-spectrometer equipped with a multi-channel light-emitting diode (LED) source emitting monochromatic light, a modified commercially available LED head lamp, and a commercially available unmodified UV-LED lamp. PpIX fluorescence was quantified in a standardized setup using a mini-spectrometer. RESULTS: Maximum light intensities of the evaluated light sources were reached at different wavelengths. All tested devices were able to detect PpIX-induced fluorescence. However, the intensity of PpIX fluorescence of the differently concentrated PpIX solutions (0.15 µg/mL and 5 µg/mL) was significantly dependent on the light source used. CONCLUSIONS: Intensity of the 5-ALA-derived fluorescence is related to the light source used.

Cervical and High-Thoracic Dorsal Root Ganglion Stimulation in Chronic Neuropathic Pain.

INTRODUCTION: Dorsal root ganglion stimulation is a meanwhile established but rather new technique of neuromodulation to treat chronic pain states of different origin. While being primarily used in the lumbar region, dorsal root ganglion (DRG) stimulation also can be used in the upper thoracic and cervical region with slight alterations of the surgical approach. This offers new therapeutic options especially in the treatment of neuropathic pain states of the upper extremities. Data on surgical technique, outcome and complications rates of DRG in this region are limited. MATERIALS AND METHODS: We report a consecutive series of 20 patients treated with DRG stimulation in the upper thoracic and cervical region. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. Main pain etiologies were trauma, spine surgery, postherpetic neuralgia, and peripheral nerve surgery. All patients were trialed with externalized electrodes prior to permanent pulse generator implantation. Routine clinical follow-up was performed during reprogramming sessions. RESULTS: Out of all 20 patients trialed, 18 were successfully trialed and implanted with a permanent stimulation system. The average pain relief after three months compared to the baseline was of 60.9% (mean VAS 8.5 to VAS 3.2). 77.8% of the patients reported a pain relief of at least 50% after three months. One patient developed a transient paresis of the arm caused by the procedure. She completely recovered within three months. CONCLUSION: Cervical and upper thoracic DRG stimulation resulted in good overall response rates to trialing and similar pain relief when compared to DRG stimulation for groin and lower limb pain. A modified surgical approach has to be used when compared with lumbar DRG electrode placement. Surgery itself in this region is more complication prone and challenging.

Is it all a matter of size? Impact of maximization of surgical resection in cerebral tumors.

The oncological impact of cytoreductive surgery for malignant glioma has been analyzed in a few prospective, randomized studies; however, the impact of different cytoreductive surgical techniques of cerebral tumors remains controversial. Despite retrospective analyses revealing an oncological impact of complete surgical resection in cerebral metastases and low-grade glioma, the oncological impact of further extension of resection to a supramarginal resection remains disputable lacking high-grade evidence: supramarginal resections have yet to be analyzed in malignant glioma. Although extension of resection towards a supramarginal resection was thought to improve outcome and prevent malignant transformation in low-grade glioma, the rate of (temporary) deficits was higher than 50% in recent retrospective studies, and the oncological impact and long-term results have to be analyzed in further (prospective and controlled) studies. Cerebral metastases show a growth pattern different from glioma with less and more locally limited brain invasion. Therefore, local control may be achieved by extension of resection after complete lesionectomy of cerebral metastases. Therefore, supramarginal resection may be a promising approach but must be evaluated in further studies.

Open Microsurgical Dorsal Root Ganglion Lead Placement.

INTRODUCTION: Dorsal root ganglion stimulation (DRG) is a new but well-established neuromodulation technique allowing new indications and superiority to pre-existing stimulation techniques such as spinal cord stimulation in selected pain etiologies. Previous surgical procedures in the implantation area pose a challenge for the percutaneous technique and are therefore considered contraindications for DRG stimulation surgery. We describe the successful open DRG electrode placement in two patients with previous surgeries suffering from severe radiculopathy due to foraminal stenosis. METHODS: Percutaneous implantation attempts failed and an open laminotomy/foraminotomy followed by open lead placement was performed. Leads and loops were placed under the microscope, lead location was verified by x-ray during surgery. Leads and loops were kept in position with fibrin glue and fibrin sealant patches. No special tool was required for open lead placement. RESULTS: In both patients, surgery resulted in lead and loop placement resembling the results seen in percutaneous technique. Programming and stimulation results are similar to observations made following percutaneous techniques in one patient significantly lower stimulation amplitudes were necessary. In 18 and 12 months follow-up, respectively, lead location and paresthesia coverage were stable. CONCLUSION: The option of open electrode placement should be taken into account following unsuccessful percutaneous lead placement. A combination of fibrin sealant patch and fibrin glue may be a good option for stabilization of the lead and specially of the strain relief loops in open placement. Knowledge of basic spinal surgery techniques and experience in percutaneous DRG stimulation is necessary to perform this procedure.

Bow Hunter's Syndrome Caused by Compression of the Subaxial Vertebral Artery: Surgical Technique of Anterolateral Decompression (video).

Bow hunter's syndrome is a rare clinical condition. It is caused by dynamic compression of the vertebral artery (VA) either at the level of the transverse foramina (V2 segment) or at the atlantoaxial level (V3 segment). We report a 54-year-old man with typical bow hunter's syndrome caused by compression at the level of C6/C7. He was successfully treated by anterolateral VA decompression without a need for stabilization. We present preoperative imaging (magnetic resonance imaging, computed tomographic angiography, and dynamic angiography) and a high-quality intraoperative video detailing each step of the surgical technique (high-definition video with annotations and audio track of the Doppler ultrasound used as intraoperative control). Furthermore, postoperative imaging and a video of the clinical outcome are presented. Adequate management of bow hunter's syndrome requires good pathophysiologic understanding of the disease and careful clinical examination. Dynamic angiography confirms the exact site of VA compression. Surgical decompression is the treatment of the cause. Surgical techniques include VA decompression by an anterolateral approach (V2 or V3) or a posterior approach (V3). Some authors advocate stand-alone stabilization, which is, however, only an indirect treatment and results in significant loss of head motion. Other nonsurgical treatments such as orthesis, medical therapy, or endovascular stenting have been only anecdotally reported. Bow hunter's syndrome is best treated by VA decompression. This may safely be achieved by good anatomic knowledge and a straightforward surgical technique. Here, the anterolateral approach is presented in detail in a high-definition surgical instruction video.

The impact of cerebral metastases growth pattern on neurosurgical treatment.

The surgical resection of cerebral metastases is one key element in a multimodal therapy of brain oligometastatic patients. Standard surgery alone is often not sufficient to achieve local control. Various reasons have been discussed including microscopic and macroscopic tumor rests after surgery and different growth patterns of cerebral metastases: In this review, we assessed the surgical standard technique and then analyzed the growth pattern of cerebral metastases and discussed its oncologic impact and new strategies in the surgical management of cerebral metastases. A major percentage of cerebral metastases are not sharply delimitated but show an irregular tumor-brain interface or even an infiltrative growth pattern. Different patterns of adjacent brain invasions have been described and may correlate with the prognosis of patients with cerebral metastasis. Even metastases of the same histological subtype and the same origin show a heterogeneous brain invasion pattern. Future therapeutic strategies might have to take this heterogeneity into account. An infiltrative growth pattern of cerebral metastases might be one reason for their extraordinary high local recurrence rate and might have an influence on the individual overall survival. An intraoperative detection of residual tumor and development of more radical surgical techniques is therefore an important neurooncological challenge and might result in better tumor control. Supramarginal resection of cerebral metastases is a promising approach.

Predictors for a further local in-brain progression after re-craniotomy of locally recurrent cerebral metastases.

Treatment of recurrent cerebral metastases is an emerging challenge due to the high local failure rate after surgery or radiosurgery and the improved prognosis of patients with malignancies. A total of 36 patients with 37 metastases who underwent surgery for a local in-brain progression of a cerebral metastasis after previous metastasectomy were retrospectively analyzed. Degree of surgical resection on an early postoperative MRI within 72 h after surgery was correlated with the local in-brain progression rate and overall survival. Complete surgical resection of locally recurrent cerebral metastases as confirmed by early postoperative MRI could only be achieved in 37.8%. Detection of residual tumor tissue on an early MRI following recurrent metastasis surgery correlated with further local in-brain progression when defining a significance level of p = 0.05 but not after Sidák or Bonferroni significance level correction for multiple testing: However, definite local tumor control could finally be achieved in 91.9% after adjuvant therapy. Overall survival after recurrent metastasectomy was significantly higher as predicted by diagnosis-specific graded prognostic assessment (12.9 ± 2.3 vs. 8.4 ± 0.7 months; p < 0.0001). However, our series involved a limited number of heterogeneous patients. A larger, prospective, and controlled study is required. Considering the adequate local tumor control achieved in the vast majority of patients, surgery of recurrent metastases may represent one option in a multi-modal treatment approach of patients suffering from locally recurrent cerebral metastases.

High-Frequency Spinal Cord Stimulation in Surgery-Naïve Patients-A Prospective Single-Center Study.

INTRODUCTION: A multitude of evidence supporting the beneficial effects of spinal cord stimulation (SCS) in patients suffering from chronic pain syndromes following spinal surgery has been published in the last decade. Evidence is scarce, however, for the use of high frequency SCS (HF-SCS) in the treatment of surgery naïve patients suffering from lower back pain (LBP). METHODS: From June 2014 to April 2015, we prospectively enrolled patients suffering from LBP alone or in conjunction with leg pain in a trial of HF-SCS. None of the patients had undergone surgical procedures of the lumbar spine. Patients suffered medically intractable LBP and were deemed ineligible for spine surgery. All patients underwent trial stimulation for at least one week. Pain levels were assessed daily during initial stay, 4 weeks later and then every 3 months. Different preprogrammed modes of HF-SCS were changed if pain persisted or increased during trial or postimplant follow-up (FU). RESULTS: Eight patients (four male, four female) underwent HF-SCS trials. Mean age was 60 ± 4.8 years. Mean numeric rating scale (NRS) baseline intensity for back pain was 8.9 ± 0.23 and 8.1 ± 0.6 for leg pain. All patients achieved meaningful reductions in pain intensities and underwent IPG implantation at a mean interval of 13 days. Mean follow-up was 306 days. Mean back pain reduction from baseline at last follow-up was -4.13 ± 0.85, and -6.2 ± 1.03 for leg pain. Two patients showed skin irritations and localized pain at the IPG site. Both patients underwent surgery to replant the IPG. No infections were seen in any of the eight patients enrolled. CONCLUSIONS: In this prospective cohort of surgery naïve patients, we were able to show good efficacy of HF-SCS with mean NRS reductions of 4.13 and 6.2 for back and leg pain, respectively, after a mean follow-up of 10 months.

Intraoperative neurophysiological monitoring during resection of infratentorial lesions: the surgeon's view.

OBJECTIVE Methods of choice for neurophysiological intraoperative monitoring (IOM) within the infratentorial compartment mostly include early brainstem auditory evoked potentials, free-running electromyography, and direct cranial nerve (CN) stimulation. Long-tract monitoring with somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) is rarely used. This study investigated the incidence of IOM alterations during posterior fossa surgery stratified for lesion location. METHODS Standardized CN and SEP/MEP IOM was performed in 305 patients being treated for various posterior fossa pathologies. The IOM data were correlated with lesion locations and histopathological types as well as other possible confounding factors. RESULTS Alterations in IOM were observed in 158 of 305 cases (51.8%) (CN IOM alterations in 130 of 305 [42.6%], SEP/MEP IOM alterations in 43 of 305 [14.0%]). In 15 cases (4.9%), simultaneous changes in long tracts and CNs were observed. The IOM alterations were followed by neurological sequelae in 98 of 305 cases (32.1%); 62% of IOM alterations resulted in neurological deficits. Sensitivity and specificity for detection of CN deficits were 98% and 77%, respectively, and 95% and 85%, respectively, for long-tract deficits. Regarding location, brainstem and petroclival lesions were closely associated with concurrent CN IOM and SEP/MEP alterations. CONCLUSIONS The incidence of IOM alterations during surgery in the posterior fossa varied widely between different lesion locations and histopathological types. This analysis provides crucial information on the necessity of IOM in different surgical settings. Because MEP/SEP and CN IOM alterations were commonly observed during posterior fossa surgery, the authors recommend the simultaneous use of both modalities based on lesion location.

5-ALA fluorescence of cerebral metastases and its impact for the local-in-brain progression.

Aim of the present study was to analyze the oncological impact of 5-ALA fluorescence of cerebral metastases. A retrospective analysis was performed for 84 patients who underwent 5-ALA fluorescence-guided surgery of a cerebral metastasis. Dichotomized fluorescence behavior was correlated to the histopathological subtype and primary site of the metastases, the degree of surgical resection on an early postoperative MRI within 72 hours after surgery, the local in-brain-progression rate and the overall survival. 34/84 metastases (40.5%) showed either strong or faint and 50 metastases (59.5%) no 5-ALA derived fluorescence. Neither the primary site of the cerebral metastases nor their subtype correlated with fluorescence behavior. The dichotomized 5-ALA fluorescence (yes vs. no) had no statistical influence on the degree of surgical resection. Local in-brain progression within or at the border of the resection cavity was observed in 26 patients (30.9%). A significant correlation between 5-ALA fluorescence and local in-brain-progression rate was observed and patients with 5-ALA-negative metastases had a significant higher risk of local recurrence compared to patients with 5-ALA positive metastases. After exclusion of the 20 patients without any form of adjuvant radiation therapy, there was a trend towards a relation of the 5-ALA behavior on the local recurrence rate and the time to local recurrence, although results did not reach significance anymore. Absence of 5-ALA-induced fluorescence may be a risk factor for local in-brain-progression but did not influence the mean overall survival. Therefore, the dichotomized 5-ALA fluorescence pattern might be an indicator for a more aggressive tumor.

Early surgical occipitocervical stabilization for plasma cell neoplasms at the craniocervical junction: systematic review and proposal of a treatment algorithm.

BACKGROUND CONTEXT: Plasma cell neoplasms (PCNs) of the craniocervical junction (CCJ) are rare. Because of their destructive growth, PCNs may induce spinal instability and harbor the risk of sudden death. Therefore, PCNs at the CCJ require special consideration. Although the commonly used primary treatment of PCN is radiotherapy (RT), treatment guidelines are inexistent for CCJ occurrences. PURPOSE: This study aimed to conduct a systematic review of the literature, evaluate the benefit of early and extended surgical treatment followed by RT, and outline a treatment algorithm based on the data gathered. STUDY DESIGN/SETTING: Case series and systematic review of all reported cases in the English, Spanish and German medical literature were carried out. CASE SERIES: retrospective clinical study, tertiary care center (2004-2014). Patients with a lesion of the CCJ (C0-C2) were identified. Clinical charts, imaging data, operative reports, and follow-up data were analyzed. REVIEW: a systematic literature review was performed using PubMed. Further manuscripts were identified by the web search engine Google. RESULTS: Our series comprised four patients (one female, three males), mean age 58 years. There was one lesion of C1 and three of C2. Two patients with neck pain received vertebroplasty (C1 and C2, respectively) and RT as primary management. Both developed secondary instability of the CCJ after 12 and 5 months, respectively, and required occipitocervical stabilization (OCS). The other two patients underwent OCS and required no additional surgery and no signs of instability at follow-up. Forty-nine cases of OCS were published previously. Spinal stability was achieved significantly more frequently by OCS than by less invasive or medical interventional treatment options (p=.001; two-sided Fisher exact test). CONCLUSIONS: Plasma cell neoplasms are highly radiosensitive. However, at the CCJ, a life-threatening instability may occur early and require surgical treatment. Based on personal experience, we favor OCS in this location. A systematic review of the literature supports this approach. We present a summary of our findings in a concise treatment algorithm for PCN of the CCJ.

Early postoperative magnet resonance tomography after resection of cerebral metastases.

BACKGROUND: In contrast to malignant gliomas, the impact of an early postoperative MRI after surgery of cerebral metastasis is still unclear. The present study analyses early MRI-based postoperative resection controls and incidence of in-brain progression in 116 patients suffering from 130 cerebral metastases. METHODS: The extent of surgical resection was verified by an early postoperative contrast-enhanced 1.5-T MRI within 72 h after surgery of cerebral metastases and correlated with in-brain progression, leptomeningeal carcinomatosis, and progression-free survival. RESULTS: MRI confirmed complete resection was seen in 80 out of 130 metastases (61.5 %). In 24 metastases (18.5 %), no final decision on degree of resection could be made. Residual tumor was seen in 26 cases (20 %). Local in-brain progression was observed in 40 of 130 (30.8 %) cases. The incidence of in-brain progression significantly correlated with dural contact of the metastasis (p < 0.05) and residual tumor on early postoperative MRI (p < 0.0001). The odds ratio for local recurrence with residual tumor is 8.2-fold compared to no residual tumor. CONCLUSIONS: Residual tumor after metastasis extirpation was shown in nearly 20 % of patients by an early postoperative MRI and significantly correlated with local in-brain progression. Furthermore, dural contact of cerebral metastases was identified as a risk factor for local recurrence. Further studies are mandatory to clearly identify the incidence of incomplete resections of cerebral metastases and their oncologic impact. An early postoperative MRI after resection of cerebral metastases is recommended as residual tumor promotes local recurrence.

Incidence of local in-brain progression after supramarginal resection of cerebral metastases.

BACKGROUND: Microsurgical circumferential stripping of intracerebral metastases is often insufficient in achieving local tumor control. Supramarginal resection may improve local tumor control. METHODS: A retrospective analysis was performed for patients who underwent supramarginal resection of a cerebral metastasis by awake surgery with intraoperative cortical and subcortical stimulation, MEPs, and SSEPs. Supramarginal resection was achieved by circumferential stripping of the metastasis and additional removal of approximately 3 mm of the surrounding tissue. Pre- and postsurgical neurological status was assessed by the NIH Stroke Scale. Permanent deficits were defined by persistence after 3-month observation time. RESULTS: Supramarginal resection of cerebral metastases in eloquent brain areas was performed in 34 patients with a mean age of 60 years (range, 33-83 years). Five out of 34 patients (14.7%) had a new transient postoperative neurological deficit, which improved within a few days due to supplementary motor area (SMA) syndrome. Five out of 34 patients (14.7%) developed a local in-brain progression and nine patients (26.4%) a distant in-brain progression. CONCLUSIONS: Supramarginal resection of cerebral metastases in eloquent locations is feasible and safe. Safety might be increased by intraoperative neuromonitoring. The better outcome in the present series may be entirely based on other predictors than extend of surgical resection and not necessarily on the surgical technique applied. However, supramarginal resection was safe and apparently did not lead to worse results than regular surgical techniques. Prospective, controlled, and randomized studies are mandatory to determine the possible benefit of supramarginal resection on local tumor control and overall outcome.

A prospective, randomised, double-blind, placebo-controlled study to examine the effectiveness of burst spinal cord stimulation patterns for the treatment of failed back surgery syndrome.

OBJECTIVES: Spinal cord stimulation (SCS) for the treatment of chronic pain is a well-established therapy. However, the requirement that paresthesia be continually felt by the patient has important downsides. This study evaluated the effectiveness of a new paresthesia-free SCS paradigm, called burst stimulation, for the treatment of failed back surgery syndrome (FBSS) with a prospective, randomized, double-blind, placebo-controlled design. MATERIALS AND METHODS: Twenty patients with FBSS and a preexisting SCS system each received three treatment allocations in random order for a period of one week: 500-Hz tonic stimulation, burst stimulation, and placebo stimulation. The primary outcome measure was pain intensity measured on a numerical rating scale (NRS). Secondary outcome measures were pain quality measured using the Short-Form McGill Pain Questionnaire (SFMPQ) and safety. Additional data were collected relating to pain-related disability measured using the Oswestry Disability Index (ODI). RESULTS: The lowest mean NRS and SFMPQ scores were observed under burst stimulation. For the burst stimulation treatment group, mean NRS and SFMPQ scores were significantly decreased compared with the other treatment groups. Mean NRS and SFMPQ scores were not significantly different between 500-Hz tonic stimulation and placebo stimulation. Although the lowest mean ODI score was observed under burst stimulation, no significant differences were found between the ODI categories. No adverse events occurred, and burst stimulation was significantly preferred by 16 patients (80%). CONCLUSIONS: Overall, burst stimulation resulted in significantly better pain relief and improved pain quality in the short term compared with 500-Hz tonic stimulation and placebo stimulation and was preferred by the majority of patients.