Isolated subependymal giant cell astrocytoma (SEGA) in the absence of clinical tuberous sclerosis: two case reports and literature review.

PURPOSE: Subependymal giant cell astrocytoma (SEGA) is a WHO grade I pediatric glioma arising in 5-15% of patients with tuberous sclerosis (TSC). Rare cases of isolated SEGA without TSC have been described. The etiology, genetic mechanisms, natural history, and response to treatment of these lesions are currently unknown. We describe two such cases of isolated SEGA with follow-up. METHODS: Retrospective review was performed at a single institution to describe the clinical course of pathology-confirmed SEGA in patients with germline testing negative for TSC mutations. RESULTS: Two cases of isolated SEGA were identified. Genetic analysis of the tumor specimen was available for one, which revealed an 18 base pair deletion in TSC1. Both cases were managed with surgical resection, one with preoperative embolization. In spite of a gross total resection, one patient experienced recurrence after three years. Treatment with an mTOR inhibitor led to a significant interval reduction of the mass on follow-up MRI. The patient tolerated the medication well for 6 years and is now off of treatment for 2 years with a stable lesion. CONCLUSION: Cases of SEGA outside of the context of TSC are exceedingly rare, with only 48 cases previously described. The genetic mechanisms and treatment response of these lesions are poorly understood. To date, these lesions appear to respond well to mTOR inhibitors and may behave similarly to SEGAs associated with TSC. However, given that experience is extremely limited, these cases should be followed long term to better understand their natural history and treatment response.

Utility of prolonged prophylactic systemic antibiotics for wound drains in posterior spine surgery: a systematic review and meta-analysis.

OBJECTIVE: Closed suction drains, often used after posterior spinal surgery, pose a potential risk of infection. To combat this risk, many surgeons opt for a prolonged prophylactic antibiotic regimen. Since 2015, several studies have shown that prolonged prophylactic systemic antibiotics (PPSA) for drains provides no additional benefit in reducing surgical site infection (SSI) rates. However, most of these studies lacked sufficient power to make reliable conclusions. To date, there has been no meta-analysis conducted to further investigate this issue. The aim of this study was to investigate whether a regimen of PPSA reduces the incidence of deep SSIs in adult patients with closed suction drains following posterior spinal surgeries. METHODS: The protocol of the current systematic review was registered with PROSPERO. A systematic review of the literature in PubMed (Medline), Europe PMC, Embase, and Cochrane Review databases was conducted for all relevant literature with the keywords "spine," "antibiotics," "surgical site infection," "prophylaxis," and "drain." Retrospective and prospective studies investigating the effectiveness of PPSA in patients 18 years or older who underwent posterior cervical or thoracolumbar surgery and had postoperative wound drains were included. The primary outcome was the odds ratio for deep SSI based on the intervention (PPSA vs non-PPSA). The secondary outcomes were the rates of superficial and overall SSIs. RESULTS: From a total of 2558 titles identified from the search, 7 studies were chosen for final analysis. Three were randomized controlled trials (RCTs), and 4 were retrospective reviews. A total of 2446 patients were analyzed; 1149 received a PPSA regimen and 1297 received a non-PPSA regimen. Deep SSIs occurred in 45 patients (3.9%) and 46 patients (3.5%) in the PPSA and non-PPSA groups, respectively. The odds ratio for deep SSIs in the PPSA group compared with the non-PPSA group was 1.10 (95% CI 0.69-1.74), which was not statistically significant. Additionally, there were no differences in the rates of superficial and overall SSIs. There was a trend toward increased infections with multidrug-resistant bacteria (Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus) in the PPSA group; however, it was not possible to perform a durable statistical analysis because of the small number of reported organisms in the selected publications. CONCLUSIONS: This meta-analysis demonstrates that there is no reduction in rate of deep, superficial, and overall SSIs with prolonged prophylactic antibiotics after posterior spinal surgery involving the use of closed suction drains.

Does the Modified Arrhenius Model Reliably Predict Area of Tissue Ablation After Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Pediatric Lesional Epilepsy?

BACKGROUND: Commercial magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) systems utilize a generalized Arrhenius model to estimate the area of tissue damage based on the power and time of ablation. However, the reliability of these estimates in Vivo remains unclear. OBJECTIVE: To determine the accuracy and precision of the thermal damage estimate (TDE) calculated by commercially available MRgLITT systems using the generalized Arrhenius model. METHODS: A single-center retrospective review of pediatric patients undergoing MRgLITT for lesional epilepsy was performed. The area of each lesion was measured on both TDE and intraoperative postablation, postcontrast T1 magnetic resonance images using ImageJ. Lesions requiring multiple ablations were excluded. The strength of the correlation between TDE and postlesioning measurements was assessed via linear regression. RESULTS: A total of 32 lesions were identified in 19 patients. After exclusion, 13 pairs were available for analysis. Linear regression demonstrated a strong correlation between estimated and actual ablation areas (R2 = .97, P < .00001). The TDE underestimated the area of ablation by an average of 3.92% overall (standard error (SE) = 4.57%), but this varied depending on the type of pathologic tissue involved. TDE accuracy and precision were highest in tubers (n = 3), with average underestimation of 2.33% (SE = 0.33%). TDE underestimated the lesioning of the single hypothalamic hamartoma in our series by 52%. In periventricular nodular heterotopias, TDE overestimated ablation areas by an average of 13% (n = 2). CONCLUSION: TDE reliability is variably consistent across tissue types, particularly in smaller or periventricular lesions. Further investigation is needed to understand the accuracy of this emerging minimally invasive technique.

Comparison of Clinical and Radiographic Outcomes After Standalone Versus Cage and Plate Constructs for Anterior Cervical Discectomy and Fusion.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) has conventionally been performed using an allograft cage with a plate-and-screw construct. Recently, standalone cages have gained popularity due to theorized decreases in operative time and postoperative dysphagia. Few studies have compared these outcomes. Here, we directly compare the outcomes of plated versus standalone ACDF constructs. METHODS: A single-center retrospective review of patients undergoing ACDF after June 2011 with at least 6 months of follow up was conducted. Clinical outcomes were analyzed and compared between standalone and plated constructs. Multivariate regression analysis of the primary outcome, need for revision surgery, as well as several secondary outcomes, procedure duration, estimated blood loss (EBL), length of hospital stay, disposition, and incidence of dysphagia, hoarseness, or surgical site infection, was completed. RESULTS: A total of 321 patients underwent ACDF and met inclusion-exclusion criteria, with mean follow-up duration of 20 months. Forty-six (14.3%) patients received standalone constructs, while 275 (85.7%) received plated constructs. Fourteen (4.4%) total revisions were necessary, 4 in the standalone group and 10 in the plated group, yielding revision rates of 8.7% and 3.6%, respectively (P = .125). Mean EBL was 98 mL in the standalone group and 63 mL in the plated group (P = .001). Mean procedure duration was 147 minutes in the standalone group and 151 minutes in the plated group (P = .800). Mean hospital stay was 3.6 days in the standalone group and 2.5 days in the plated group (P = .270). There was no significant difference in incidence of dysphagia (P = .700) or hoarseness (P = .700). CONCLUSIONS: Standalone ACDF demonstrates higher, but not statistically significant, revision rates than plate-and-screw constructs, without the hypothesized decreased incidence of dysphagia or hoarseness and without decreased procedure duration or EBL. Surgeons may consider limiting use of these constructs to cases of adjacent segment disease. Larger studies with longer follow up are necessary to make more definitive conclusions. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: This study will help spine surgeons decide between using standalone or cage-and-plate constructs for ACDF.

A cross-sectional analysis of variables associated with morbidity and mortality in postoperative neurosurgical patients diagnosed with sepsis.

BACKGROUND: Sepsis is a systemic, inflammatory response to infection associated with significant morbidity and mortality. There is a considerable lack of literature exploring sepsis in neurosurgery. We aimed to identify variables that were correlated with mortality and increased morbidity as defined by readmission and increased length of stay in postoperative neurosurgical patients that met a sepsis diagnosis. METHODS: A retrospective chart review was conducted of 105 patients who underwent a neurosurgical operation at our institution from 2012 to 2017 who were discharged with at least one sepsis diagnosis code and who did not have a preoperative infection. We identified variables that were correlated with mortality, readmission, and increased length of stay. RESULTS: Patients who survived were preferentially distributed towards lower ASA Physical Status Classification scores. A larger percentage of patients who did not survive had cranial surgery, whereas patients who survived were more likely to have undergone spinal surgery. Higher respiratory rates, higher maximum lactic acid levels, positive sputum cultures, and lower incoming Glasgow Coma Scores (GCS) were significantly correlated with mortality. A larger fraction of readmitted patients had positive surgical site cultures but had negative sputum cultures. Length of hospitalization was correlated with incoming GCS, non-elective operations, and Foley catheter, arterial line, central line, and endotracheal tube duration. CONCLUSIONS: Neurosurgical postoperative patients diagnosed with sepsis may be risk stratified for mortality, readmission, and increased length of stay based on certain variables that may help direct their care. Further prospective studies are needed to explore causal relationships.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for the Treatment of Nonlesional Insular Epilepsy in Pediatric Patients: Technical Considerations.

INTRODUCTION: The insula presents anatomic challenges to surgical exploration and intervention. Open neurosurgical intervention is associated with high rates of complications despite improved seizure control. Minimally invasive techniques using novel energy delivery methods have gained popularity due to their relative safety and ability to overcome access-related barriers. The goal of this paper is to present an operative technical report and methodological considerations on the application of magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) for the treatment of nonlesional, medically refractory, insular epilepsy in pediatric patients. METHODS: Visualase laser probe(s) were implanted using ROSA robotic stereotactic guidance into the insula using a parasagittal trajectory. After confirmation of placement using intraoperative MRI, thermal energy was delivered under real-time MR guidance. Laser wire pullback was performed when the initial dose of thermal energy was insufficient to ablate the target in its entirety. Thermal ablation within the intended target was confirmed using gadolinium-enhanced brain MRI. Following removal of laser wires, a final T1-weighted axial brain MRI was performed to confirm no evidence of hemorrhage. RESULTS: Three patients underwent MRgLITT of nonlesional insular epilepsy over an 11-month period. The epileptogenic focus was localized to the insula using stereoelectroencephalography. The anterior and middle portions of the insula were accessed using a parasagittal trajectory. Laser ablation was performed for up to 3 min using an output of 10.5 W. No complications were encountered, and all patients were discharged within 24 h after the surgery. At the most recent follow-up, all patients had an Engel I outcome without any new neurologic deficits. CONCLUSION: This small cohort shows that insular ablation can be achieved safely with promising seizure outcomes in the short term.

Cerebellar mutism syndrome: current approaches to minimize risk for CMS.

PURPOSE: Cerebellar mutism syndrome (CMS) is a serious source of morbidity following posterior fossa surgery in the pediatric population. However, methods for effectively decreasing its incidence and impact remain unclear. It is our aim to examine the impact of adjusting surgical factors, namely the use of a telovelar approach and avoidance of cavitronic ultrasonic aspirator, on the incidence of CMS in our population as well as outlining potential pre-, intra-, and postoperative factors that may contribute to its development. METHODS: Retrospective review was performed to identify patients undergoing posterior fossa surgery for resection of a medulloblastoma. Demographic, surgical, and postoperative data were collected. These data were analyzed for possible correlations to the risk of developing CMS via univariate analysis. For factors found to be significant, a multivariate analysis was performed to assess their independence. RESULTS: Seven of 65 patients (10.8%) developed CMS postoperatively. Factors found to be significantly associated with a higher risk of CMS were the degree of retraction utilized during the procedure (p = 0.0000) and incision of the vermis (p = 0.0294). Although they did not reach the threshold of statistical significance, tumor vascularity (p = 0.19), adoption of a transvermian approach (p = 0.19), and lack of intraoperative imaging (p = 0.17) exhibited strongly suggestive trends towards a correlation with CMS. DISCUSSION: In an effort to reduce the incidence and severity of CMS in our population, our institution adopted surgical practices that minimize tissue trauma and mitigate postoperative edema. This included the use of a telovelar over a transvermian approach to obviate the need for vermian incision, avoidance of the CUSA, and minimization of heavy retraction during surgery. This was successful in reducing the incidence of CMS from 39% in our medulloblastoma patients to 10.8%. The development of CMS after posterior fossa surgery appears to be a "two-hit" phenomenon requiring a combination of existing predisposition, surgical injury, and postoperative exacerbation. Therefore, it is critical to identify the factors involved at each stage and investigate treatments to target them appropriately.

"Laser and the Tuber": thermal dynamic and volumetric factors influencing seizure outcomes in pediatric subjects with tuberous sclerosis undergoing stereoencephalography-directed laser ablation of tubers.

PURPOSE: Tuberous sclerosis (TSC) is a well-known cause of medically refractory epilepsy (MRE). Stereoencephalography-directed magnetic resonance-guided laser interstitial thermal therapy (SEEG-directed MRgLITT) is an emerging minimally invasive technique that appears aptly suited for the surgical management of TSC. Our aims are to present our experiences with patients who had undergone SEEG-directed MRgLITT to identify and treat cortical tubers responsible for clinical seizures and to perform an in-depth analysis of volumetric and thermal dynamic factors that may be related to seizure outcomes. METHODS: We studied all pediatric patients with MRE due to TSC who underwent SEEG-directed MRgLITT, investigating seizure outcomes in relation to thermal dynamic and volumetric factors. RESULTS: Eight cortical tubers from three pediatric patients were analyzed. Two of three patients had Engel I outcomes at last follow-up (median 18 months). Average A/T (ablation volume/tuber volume) ratio for Engel I outcomes was 1.28 (variance, 0.16) and 0.84 (variance, < 0.01) for all other outcomes (P = 0.035). There was a moderate positive correlation when comparing ablation energy to ablation volume (R2 = 0.65) in cortical tuber tissue. When the calcified tuber is excluded, the correlation is stronger (R2 = 0.77). Thus, the calculated energy needed to ablate 1 cm3 of cortical tuber tissue is 1263.6 J (calcified tuber) or 1089.5 J (non-calcified tuber). CONCLUSIONS: SEEG-directed MRgLITT appears to be a safe and effective technique in the management of pediatric patients with MRE due to TSC. The A/T ratio may be a useful indicator in predicting seizure outcomes.

Magnetic resonance-guided laser interstitial thermal therapy for the treatment of non-lesional insular epilepsy in pediatric patients: thermal dynamic and volumetric factors influencing seizure outcomes.

PURPOSE: To investigate the safety and efficacy of stereoelectroencephalography (sEEG) directed magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) in medically refractory insular epilepsy in pediatric patients, define the relationship between ablation volumes and seizure control, and analyze the relationship between thermal energy and ablation volumes. METHODS: A single-institution, retrospective review of pediatric patients with insular epilepsy who underwent sEEG directed MRgLITT over a 10-month period was performed. Perioperative, imaging, and outcome data were analyzed. Seizure outcomes were determined based on Engel score (Engel I versus Engel II-IV). Insula and ablation volumes were measured, and the proportion of insula volume ablated was calculated. Thermal energy was calculated in joules. RESULTS: Four patients underwent sEEG directed MRgLITT of insular epileptogenic foci. The ablation volume was higher in patients with Engel I outcome (3.93 cm3) compared to Engel II-IV outcome (1.02 cm3). The proportion of ablation to insula volume was lowest in patients with Engel II-IV outcome (25.09%). The mean energy requirement to create a unit volume of ablation in the insula is 1205.86 J. A linear trend was noted between thermal ablation energy and ablation volume (R2 = 0.884). Over a mean follow-up period of 104 days, three patients were seizure-free (Engel I), and one patient saw significant improvement in seizure frequency (Engel III). CONCLUSIONS: The proportion of insula ablated, as well as the volume of ablation, are related to seizure outcome with increasing ablation volumes corresponding to improved seizure control. Further analysis of insula laser ablation thermal dynamics and volumes is needed.

Early outcomes of stereoelectroencephalography followed by MR-guided laser interstitial thermal therapy: a paradigm for minimally invasive epilepsy surgery.

OBJECTIVE Stereoelectroencephalography (sEEG) and MR-guided laser interstitial thermal therapy (MRgLITT) have both emerged as minimally invasive alternatives to open surgery for the localization and treatment of medically refractory lesional epilepsy. Although some data are available about the use of these procedures individually, reports are almost nonexistent on their use in conjunction. The authors' aim was to report early outcomes regarding efficacy and safety of sEEG followed by MRgLITT for localization and ablation of seizure foci in the pediatric population with medically refractory lesional epilepsy. METHODS A single-center retrospective review of pediatric patients who underwent sEEG followed by MRgLITT procedures was performed. Demographic, intraoperative, and outcome data were compiled and analyzed. RESULTS Four pediatric patients with 9 total lesions underwent sEEG followed by MRgLITT procedures between January and September 2017. The mean age at surgery was 10.75 (range 2-21) years. Two patients had tuberous sclerosis and 2 had focal cortical dysplasia. Methods of stereotaxy consisted of BrainLab VarioGuide and ROSA robotic guidance, with successful localization of seizure foci in all cases. The sEEG procedure length averaged 153 (range 67-235) minutes, with a mean of 6 (range 4-8) electrodes and 56 (range 18-84) contacts per patient. The MRgLITT procedure length averaged 223 (range 179-252) minutes. The mean duration of monitoring was 6 (range 4-8) days, and the mean total hospital stay was 8 (range 5-11) days. Over a mean follow-up duration of 9.3 (range 5.1-16) months, 3 patients were seizure free (Engel class I, 75%), and 1 patient saw significant improvement in seizure frequency (Engel class II, 25%). There were no complications. CONCLUSIONS These early data demonstrate that sEEG followed by MRgLITT can be used safely and effectively to localize and ablate epileptogenic foci in a minimally invasive paradigm for treatment of medically refractory lesional epilepsy in pediatric populations. Continued collection of data with extended follow-up is needed.