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.

Accuracy of Electrode Position in Sphenopalatine Ganglion Stimulation in Correlation With Clinical Efficacy.

INTRODUCTION: Sphenopalatine ganglion (SPG) stimulation is an efficient treatment for cluster headache. The target for the SPG microstimulator in the pterygopalatine fossa lies between the vidian canal and foramen rotundum, ideally two contacts should be placed in this area. However, placement according to the manufacturers recommendations is frequently not possible. It is not known whether a suboptimal electrode placement interferes with postoperative outcomes. MATERIALS AND METHODS: SPG stimulation was performed in 13 patients between 2015 and 2018 in a single center. Lead location was determined by intraoperative computed tomography scan and correlated with the planned lead position as well as clinical data and stimulation parameters. Patients with a reduction of 50% or more in pain intensity or frequency were considered responsive. RESULTS: Eleven patients (84.6%) responded to SPG stimulation with eight being frequency responders (61.5%). In seven cases, there were less than two electrodes between vidian canal and foramen rotundum, there was no significant correlation with negative stimulation results (p = 0.91). The mean distance of lead location between pre- and postoperative images did not correlate with clinical outcomes (p = 0.84) and was even bigger in responders (4.91 mm vs. 4.53 mm). The closest electrode contact to the vidian canal was in the stimulation area in all but one patient, regardless of its overall distance to canal. The distance of the closest electrode to the vidian canal was, however, not significantly correlated to the percentage of frequency (p = 0.68) or intensity reduction (p = 0.61). CONCLUSION: There was no significant correlation regarding aberrations of lead position from the planned position with clinical outcome. However, this study might be underpowered to detect such a correlation. The closest electrode contact to the vidian canal was in the stimulation area in all but one patient in the final programming. This indicates that, overall, the lead location does play a crucial role in SPG stimulation for cluster headache.

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.

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.

Synergetic efficacy of simultaneous DRG- and traditional spinal cord stimulation.

BACKGROUND: Dorsal root ganglion stimulation has established its role in chronic pain states and is commonly used as an alternative treatment to traditional spinal cord stimulation. Due to its approach, DRG stimulation is preferably used in pain conditions affecting a small area or a distinct nerve root. In selected patients, a combination of both techniques might be useful. METHODS: We report a series of five patients with chronic pain treated with DRG stimulation and traditional spinal cord stimulation from 2011 to 2018. Pain was reported on the VAS scale at the baseline, before and 12 months after the second procedure. RESULTS: All patients suffered from back and lower limb pain, four with a FBSS syndrome, one with CRPS. In all but one patient, SCS was implanted first and complemented with a DRG in the course (4-90 months between procedures). An additional stimulation system was implanted because the previous stimulation failed to reach the pain area or because the patient had an altered perception of other pain component after stimulation. All but one patient had a consistent and satisfying therapeutic effect with both systems activated. CONCLUSION: The combination of dorsal root ganglion and traditional spinal cord stimulation is surgically and technically feasible. In selected patients, the combination of both methods offers an option to alleviate pain states not sufficiently or not efficiently treated with one method alone. The introduction of IPGs combining SCS and DRG stimulation paradigms might be useful to increase acceptance of this option.

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.

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.

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.

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.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage.

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

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.

The Influence of Positioning and Muscle Activity on Motor Threshold during Motor Cortex Stimulation Programming.

Background: Stimulation parameters are crucial for the efficacy and safety of motor cortex stimulation (MCS). Motor threshold (MT) can be defined as the lowest voltage that produces motor contraction. The final stimulation parameters are always a smaller percentage of MT in order to avoid seizures. We determined how patient position and activity affect MT. Methods: Prospective MT measurements were made while patients were either lying down or sitting up, and in a resting state or while actively contracting the target muscle. Paired 1-tailed t tests were performed to assess for statistically significant differences between MT measurements made under the 4 different combinations of position and activity. Results: The MT was lower when the target muscle was being actively contracted compared to resting in both supine and upright positions (both p < 0.001). The MT was also lower when upright compared to supine in both resting and active states of muscle contraction (both p < 0.001). The mean difference between supine resting and upright active states is 0.79 V. Conclusion: When selecting final stimulation parameters for MCS, clinicians should be aware that the lowest MT is elicited while patients are seated upright and actively contracting the target muscle. Using this method of determining the MT when calculating the final stimulation parameters could reduce the chance of MCS-induced seizures. © 2015 S. Karger AG, Basel.

Long-term follow-up of motor cortex stimulation for neuropathic pain in 23 patients.

BACKGROUND: Motor cortex stimulation (MCS) is being offered to patients suffering from neuropathic pain. Outcome prediction, programming and especially sustaining a long-term treatment effect represent major challenges. We report a retrospective long-term analysis of our patients treated with MCS over a median follow-up of 39.1 months. OBJECTIVES: To investigate the time course of the treatment effect in MCS for neuropathic pain. METHODS: Twenty-three closely followed patients treated with MCS were retrospectively analyzed. Reduction in pain measured on a visual analogue scale (VAS) was defined as the primary outcome parameter. VAS pain level and adverse events were documented at the 1-, 3-, 6-, 12-, 18- and 24-month follow-ups. RESULTS: The mean VAS under best medical treatment was 7.8 (SD 1.2, range 5-9) with escalation to 9.3 (SD 0.9, range 6-10) when the patients' medications were missed or delayed. About half of the patients (47.8%) experienced a satisfactory (>50%) reduction in pain during the first month of treatment. The best treatment results were seen at the 3-month follow-up (mean VAS 4.8, SD 1.9, -37.2% compared to baseline). A decline in the treatment effect was generally observed at the subsequent follow-up assessments. Six patients had their devices explanted during the follow-up period due to loss of treatment effect. CONCLUSIONS: In this study, MCS failed to provide long-term pain control for neuropathic pain. Many aspects of MCS still remain unclear, especially the neural circuits involved and their response to long-term stimulation. Means must be developed to overcome the problems in this promising technique.

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.

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.

Motor Threshold: A Possible Guide to Optimizing Stimulation Parameters for Motor Cortex Stimulation.

OBJECTIVES: No widely accepted programming guidelines for motor cortex stimulation (MCS) exist. We propose that an individual's effective stimulation voltage can be predicted as their percentage of motor threshold (PMT). MATERIALS AND METHODS: Seven patients already successfully treated with MCS for neuropathic pain were included. Patients received stimulation that was the same as their baseline PMT ("medium"), 10% higher ("high") or 10% lower ("low") in a blinded, randomized study. Outcome was assessed after 14 days with the visual analogue scale for pain, the McGill pain questionnaire, and the SF-36 questionnaire. RESULTS: The best treatment response (mean VAS 3.4) was seen with the medium setting which was at a mean of 62% PMT. High and low settings both resulted in a significant increase in pain compared with the medium setting (mean VAS 6.0 and 6.3, respectively) and a significant decrease in SF-36 scores. No significant difference in pain control was observed between the high and low settings. The mean time from changes in treatment settings to reported change in pain level was 2.9 days (±1.0 day). CONCLUSIONS: We propose that the PMT represents an important parameter that measures the degree to which MCS may be affecting the motor cortex. A mean PMT of 62% was required for effective pain relief. Higher settings did not result in increased therapeutic efficacy but rather in a significant increase in pain. Targeting therapy to a PMT level may speed initial programming, allow more consistent longitudinal follow-up, and be a basis for a standardized programming paradigm.

Evaluation of post-operative complications associated with repeat resection and BCNU wafer implantation in recurrent glioblastoma.

BACKGROUND: Patients with glioblastoma treated with BCNU wafer implantation for recurrence frequently receive frontline chemoradiotherapy with temozolomide as part of the Stupp protocol. A retrospective investigation was conducted of surgical complications in a cohort of these patients treated at a single institution. METHODS: We searched our institutional database for patients treated between January 2006 and October 2012 who had recurrent glioblastoma previously treated with open surgery followed by the Stupp protocol and then underwent repeat resection with or without BCNU wafers for recurrent disease. Rates of select post-operative complications within 3 months of surgery were estimated. RESULTS: We identified 95 patients with glioblastoma who underwent resection followed by the Stupp protocol as frontline treatment. At disease recurrence (first and second recurrence), 63 patients underwent repeat resection with BCNU wafer implantation and 32 without implantation. Generally, BCNU wafer use was associated with minor to moderate increases in rates of select complications versus non-implantation-wound healing abnormalities (14.2 vs. 6.2 %), cerebrospinal fluid leak (7.9 vs. 3.1 %), hydrocephalus requiring ventriculoperitoneal shunt (6.3 vs. 9.3 %), chemical meningitis (3.1 vs. 0 %), cerebral infections (3.1 vs. 0 %), cyst formation (3.1 vs. 3.1 %), cerebral edema (4.7 vs. 0 %), and empyema formations (1.5 vs. 0 %). Performance status was well maintained post-operatively in both groups. Median progression-free survival from the time of first recurrence was 6.0 and 5.0 months, respectively. CONCLUSIONS: The use of the Stupp protocol as frontline therapy in patients with glioblastoma does not preclude the use of BCNU wafers at the time of progression.