Churl-Su Kwon

Predictors of cranioplasty complications in stroke and trauma patients

OBJECT Decompressive craniectomy mandates subsequent cranioplasty. Complications of cranioplasty may be independent of the initial craniectomy, or they may be contingent upon the craniectomy. Authors of this study aimed to identify surgery- and patient-specific risk factors related to the development of surgical site infection and other complications following cranioplasty. METHODS A consecutive cohort of patients of all ages and both sexes who had undergone cranioplasty following craniectomy for stroke or trauma at a single institution in the period from May 2004 to May 2012 was retrospectively established. Patients who had undergone craniectomy for infectious lesions or neoplasia were excluded. A logistic regression analysis was performed to model and predict determinants related to infection following cranioplasty. RESULTS Two hundred thirty-nine patients met the study criteria. The overall rate of complication following cranioplasty was 23.85% (57 patients). Complications included, predominantly, surgical site infection, hydrocephalus, and new-onset seizures. Logistic regression analysis identified previous reoperation (OR 3.25, 95% CI 1.30-8.11, p = 0.01) and therapeutic indication for stroke (OR 2.45, 95% CI 1.11-5.39, p = 0.03) as significantly associated with the development of cranioplasty infection. Patient age, location of cranioplasty, presence of an intracranial device, bone flap preservation method, cranioplasty material, booking method, and time interval > 90 days between initial craniectomy and cranioplasty were not predictive of the development of cranioplasty infection. CONCLUSIONS Cranioplasty complications are common. Cranioplasty infection rates are predicted by reoperation following craniectomy and therapeutic indication (stroke). These variables may be associated with patient-centered risk factors that increase cranioplasty infection risk.

Dye-Enhanced Multimodal Confocal Imaging as a Novel Approach to Intraoperative Diagnosis of Brain Tumors

Intraoperative diagnosis plays an important role in accurate sampling of brain tumors, limiting the number of biopsies required and improving the distinction between brain and tumor. The goal of this study was to evaluate dye‐enhanced multimodal confocal imaging for discriminating gliomas from nonglial brain tumors and from normal brain tissue for diagnostic use. We investigated a total of 37 samples including glioma (13), meningioma (7), metastatic tumors (9) and normal brain removed for nontumoral indications (8). Tissue was stained in 0.05 mg/mL aqueous solution of methylene blue (MB) for 2–5 minutes and multimodal confocal images were acquired using a custom‐built microscope. After imaging, tissue was formalin fixed and paraffin embedded for standard neuropathologic evaluation. Thirteen pathologists provided diagnoses based on the multimodal confocal images. The investigated tumor types exhibited distinctive and complimentary characteristics in both the reflectance and fluorescence responses. Images showed distinct morphological features similar to standard histology. Pathologists were able to distinguish gliomas from normal brain tissue and nonglial brain tumors, and to render diagnoses from the images in a manner comparable to haematoxylin and eosin (H&E) slides. These results confirm the feasibility of multimodal confocal imaging for intravital intraoperative diagnosis.

Identifying brain neoplasms using dye-enhanced multimodal confocal imaging.

Brain tumors cause significant morbidity and mortality even when benign. Completeness of resection of brain tumors improves quality of life and survival; however, that is often difficult to accomplish. The goal of this study was to evaluate the feasibility of using multimodal confocal imaging for intraoperative detection of brain neoplasms. We have imaged different types of benign and malignant, primary and metastatic brain tumors. We correlated optical images with histopathology and evaluated the possibility of interpreting confocal images in a manner similar to pathology. Surgical specimens were briefly stained in 0.05 mg/ml aqueous solution of methylene blue (MB) and imaged using a multimodal confocal microscope. Reflectance and fluorescence signals of MB were excited at 642 nm. Fluorescence emission of MB was registered between 670 and 710 nm. After imaging, tissues were processed for hematoxylin and eosin (H&E) histopathology. The results of comparison demonstrate good correlation between fluorescence images and histopathology. Reflectance images provide information about morphology and vascularity of the specimens, complementary to that provided by fluorescence images. Multimodal confocal imaging has the potential to aid in the intraoperative detection of microscopic deposits of brain neoplasms. The application of this technique may improve completeness of resection and increase patient survival.

The art of management decision making: from intuition to evidence-based medicine.

This article summarizes available evidence on various management options for vestibular schwannoma as they relate to the decision-making strategies used in selection. After a brief consideration of individual options, the literature directly comparing two or more management options is examined, noting the level of evidence supporting their claims. A discussion of the strategies developed to guide decision making follows. The article closes with a summary of the evidence-based findings and suggestions for further research. The focus is on management of sporadic, unilateral vestibular schwannomas, because patients with neurofibromatosis type 2 pose different management problems best discussed separately.

Utility of foramen ovale electrodes in mesial temporal lobe epilepsy.

To determine the ability of foramen ovale electrodes (FOEs) to localize epileptogenic foci after inconclusive noninvasive investigations in patients with suspected mesial temporal lobe epilepsy (MTLE).

Long-term seizure outcomes following resection of supratentorial cavernous malformations

OBJECTIVE Symptomatic supratentorial cavernous malformations may present with seizure, headache, neurological deficit, or a combination thereof. Factors that contribute to treatment algorithms commonly include patient age, lesion size and location, lesion multiplicity, hemorrhage history, and the ability to control seizure activity with medication. A better appreciation of the impact of patient and lesion characteristics on post-operative seizure control may provide insight into management strategies. To determine long-term seizure outcomes following surgical resection of supratentorial cavernous malformations, the predictive value of characteristics including seizure duration and number, presence of generalized seizures, and lesion multiplicity and size on seizure control rate was evaluated. METHODS We performed a single institution retrospective review of consecutive patients with supratentorial cavernous malformations presenting with at least one seizure between 1995 and 2008. Univariate and multivariate analyses were used to determine the influence of patient and lesion characteristics on postoperative seizure control. RESULTS Fifty-six patients met inclusion criteria. Mean follow-up duration was 87.9 months. At last follow-up there were 46 patients (82.1%) that were free from impairing seizures (Engel Class 1). Ten patients (17.9%) were classified as Engel Class 2-4. Univariate analysis demonstrated that only the presence of multiple cavernomas was associated with worse post-operative seizure outcome (p=0.006). Multivariate analysis demonstrated that multiple cavernomas remained a significant predictor for development of worse seizure outcome controlling for number and duration of seizures prior to operation, presence of generalized tonic-clonic seizures, and size (odds ratio, 0.17; 95% confidence interval, 0.03, 0.99). CONCLUSION Resection of supratentorial cavernomas is associated with a high rate of postoperative seizure freedom. The presence of multiple cavernomas is predictive of seizure persistence following surgery.

Time interval to surgery and outcomes following the surgical treatment of acute traumatic subdural hematoma

Although the pre-surgical management of patients with acute traumatic subdural hematoma prioritizes rapid transport to the operating room, there is conflicting evidence regarding the importance of time interval from injury to surgery with regards to outcomes. We sought to determine the association of surgical timing with outcomes for subdural hematoma. A retrospective review was performed of 522 consecutive patients admitted to a single center from 2006-2012 who underwent emergent craniectomy for acute subdural hematoma. After excluding patients with unknown time of injury, penetrating trauma, concurrent cerebrovascular injury, epidural hematoma, or intraparenchymal hemorrhage greater than 30 mL, there remained 45 patients identified for analysis. Using a multiple regression model, we examined the effect of surgical timing, in addition to other variables on in-hospital mortality (primary outcome), as well as the need for tracheostomy or gastrostomy (secondary outcome). We found that increasing injury severity score (odds ratio [OR] 1.146; 95% confidence interval [CI] 1.035-1.270; p=0.009) and age (OR1.066; 95%CI 1.006-1.129; p=0.031) were associated with in-hospital mortality in multivariate analysis. In this model, increasing time to surgery was not associated with mortality, and in fact had a significant effect in decreasing mortality (OR 0.984; 95%CI 0.971-0.997; p=0.018). Premorbid aspirin use was associated with a paradoxical decrease in mortality (OR 0.019; 95%CI 0.001-0.392; p=0.010). In this patient sample, shorter time interval from injury to surgery was not associated with better outcomes. While there are potential confounding factors, these findings support the evaluation of rigorous preoperative resuscitation as a priority in future study.

Resective focal epilepsy surgery - Has selection of candidates changed? A systematic review.

OBJECTIVE No standard, widely accepted criteria exist to determine who should be referred for an epilepsy surgical evaluation. As a result, indications for epilepsy surgery evaluation vary significantly between centers. We review the literature to assess what criteria have been used to select patients for resective epilepsy surgery and examine whether these have changed since the publication of the first epilepsy surgery randomized controlled trial in 2001. METHODS A systematic review was conducted using PubMed and EMBASE, bibliographies of reviews and book chapters identifying focal epilepsy resective series. Abstract, full text review and data abstraction (i.e. indications for surgery) were performed independently by two reviewers. Descriptive historical analysis was done to examine indications over time. RESULTS Out of 5061 articles related to epilepsy surgery, 384 articles met all eligibility criteria. Most common criteria for selecting patients for evaluation for resective surgery were: AED resistance (n=303, most commonly >2 AEDs=46), epilepsy duration (n=53, most commonly >1 year=42) and seizure frequency (most commonly at least one seizure/month, n=29). Out of the prospective studies the most notable change over time (pre-2000 vs. post-2000) was failure of ≥2 AEDs (8% vs. 43% respectively, p<0.001). CONCLUSIONS Important variations between studies make it difficult to identify consistent criteria to guide surgical candidacy or changes in indications over time. With increasing evidence that earlier surgery is associated with better outcomes, it is recommended that patients be evaluated as soon as they have failed two AEDs, consistent with the new definition of drug resistant epilepsy. Furthermore, low seizure frequency should not be a barrier to epilepsy surgery. Anyone with drug resistant epilepsy should be promptly evaluated for possible surgery, regardless of seizure frequency.

The Absence of Fever or Leukocytosis Does Not Exclude Infection Following Cranioplasty.

BACKGROUND Cranioplasty encompasses various cranial reconstruction techniques that are used following craniectomy due to stroke or trauma. Despite classical infectious signs, symptoms, and radiologic findings, however, the diagnosis of infection following cranioplasty can be elusive, with the potential to result in definitive treatment delay. We sought to determine if fever or leukocytosis at presentation were indicative of infection, as well as to identify any factors that may limit its applicability. METHODS Following institutional review board approval, a retrospective cohort of 239 patients who underwent cranioplasty following craniectomy for stroke or trauma was established from 2001-2011 at a single center (Massachusetts General Hospital). Analysis was then focused on those who developed a surgical site infection, as defined by either frank intra-operative purulence or positive intra-operative cultures, and subsequently underwent operative management. RESULTS In 27 total cases of surgical site infection, only two had a fever and four had leukocytosis at presentation. This yielded a false-negative rate for fever of 92.6% and for leukocytosis of 85.2%. In regard to infectious etiology, 22 (81.5%) cases generated positive intra-operative cultures, with Propionibacterium acnes being the most common organism isolated. Median interval to infection was 99 days from initial cranioplasty to time of infectious presentation, and average follow-up was 3.4 years. CONCLUSIONS The utilization of fever and elevated white blood cell count in the diagnosis of post-cranioplasty infection is associated with a high false-negative rate, making the absence of these features insufficient to exclude the diagnosis of infection.