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Severin Schramm, Aashna Mehta, Kurtis I. Auguste, and Phiroz E. Tarapore

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy.

METHODS

A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses.

RESULTS

Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0–17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients).

CONCLUSIONS

Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.

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Severin Schramm, Aashna Mehta, Kurtis I. Auguste, and Phiroz E. Tarapore

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy.

METHODS

A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses.

RESULTS

Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0–17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients).

CONCLUSIONS

Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.

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Seunggu J. Han, Stephen T. Magill, Phiroz E. Tarapore, Jonathan C. Horton, and Michael W. McDermott

Tuberculum sellae meningiomas frequently produce visual loss by direct compression from tumor, constriction of the optic nerve (ON) under the falciform ligament, and/or ON ischemia. The authors hypothesized that changes in visual function after tumor removal may be related to changes in blood supply to the ON that might be seen in the pial circulation at surgery. Indocyanine green (ICG) angiography was used to attempt to document these changes at surgery. The first patient in whom the technique was used had a left-sided, 1.4-cm, tuberculum meningioma. Time-lapse comparison of images was done postsurgery, and the comparison of video images revealed both faster initial filling and earlier complete filling of the ON pial circulation, suggesting improved pial blood flow after surgical decompression. In follow-up the patient had significant improvements in both visual acuity and visual fields function. Intraoperative ICG angiography of the ON can demonstrate measurable changes in pial vascular flow that may be predictive of postoperative visual outcome. The predictive value of this technique during neurosurgical procedures around the optic apparatus warrants further investigation in a larger cohort.

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Phiroz E. Tarapore, Michael E. Sughrue, Lewis Blevins, Kurtis I. Auguste, Nalin Gupta, and Sandeep Kunwar

Object

Pituitary adenomas are uncommon in childhood. Although medical treatment can be effective in treating prolactinomas and some growth hormone (GH)–secreting tumors, resection is indicated when visual function is affected or the side effects of medical therapy are intolerable. The authors of this report describe their 10-year experience in managing pituitary adenomas via the microscopic endonasal transsphenoidal approach in a pediatric population.

Methods

They performed a retrospective review of a surgical case series based at a single institution and consisting of 34 consecutive pediatric patients with endocrine-active (32 patients) and endocrine-inactive (2 patients) adenomas. These patients were surgically treated via an endonasal transsphenoidal approach between 1999 and 2008. Patient charts were reviewed, and clinical data were compiled and analyzed using the chi-square and Kaplan-Meier tests.

Results

The patient cohort consisted of 20 girls and 14 boys, with ages ranging from 9 to 18 years and a median age of 16 years. Thirty-two patients (94%) underwent surgery for endocrine-active tumors, including 10 (29%) with Cushing disease, 21 (62%) with prolactinomas, and 1 (3%) with GH-secreting tumors. Two patients with nonsecreting adenomas underwent surgery for apoplexy. The mean tumor volume was 5.4 cm3, and 13 patients (38%) had suprasellar extension and 7 (21%) had cavernous sinus invasion. Gross-total resection was achieved in 26 patients (76%), although it was significantly less likely to be achieved in the setting of cavernous sinus invasion (p < 0.001) but was unaffected by suprasellar extension. Residual tumor was treated with radiation therapy in 6 patients (18%). The average duration of hospital stay was 1.6 days. The median follow-up time was 18 months. After surgery, 19 patients (56%) had normal hormone function without adjuvant therapy, 8 (24%) had normal function with adjuvant therapy, and 5 (15%) had persistently elevated hormone levels. Patients with a macroprolactinoma were significantly more likely to require postoperative adjuvant therapy than were those with a microprolactinoma (p < 0.03).

Conclusions

Endonasal transsphenoidal resection is a safe, well-tolerated, and potentially curative treatment option for pituitary adenomas in children. Despite the technical challenges associated with this approach in the pediatric population, these tumors can be effectively managed with minimal morbidity. Endocrine function is usually preserved, and the majority of patients will not require lifelong medical therapy.

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Phiroz E. Tarapore, Matthew C. Tate, Anne M. Findlay, Susanne M. Honma, Danielle Mizuiri, Mitchel S. Berger, and Srikantan S. Nagarajan

Object

Direct cortical stimulation (DCS) is the gold-standard technique for motor mapping during craniotomy. However, preoperative noninvasive motor mapping is becoming increasingly accurate. Two such noninvasive modalities are navigated transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG) imaging. While MEG imaging has already been extensively validated as an accurate modality of noninvasive motor mapping, TMS is less well studied. In this study, the authors compared the accuracy of TMS to both DCS and MEG imaging.

Methods

Patients with tumors in proximity to primary motor cortex underwent preoperative TMS and MEG imaging for motor mapping. The patients subsequently underwent motor mapping via intraoperative DCS. The loci of maximal response were recorded from each modality and compared. Motor strength was assessed at 3 months postoperatively.

Results

Transcranial magnetic stimulation and MEG imaging were performed on 24 patients. Intraoperative DCS yielded 8 positive motor sites in 5 patients. The median distance ± SEM between TMS and DCS motor sites was 2.13 ± 0.29 mm, and between TMS and MEG imaging motor sites was 4.71 ± 1.08 mm. In no patients did DCS motor mapping reveal a motor site that was unrecognized by TMS. Three of 24 patients developed new, early neurological deficit in the form of upper-extremity paresis. At the 3-month follow-up evaluation, 2 of these patients were significantly improved, experiencing difficulty only with fine motor tasks; the remaining patient had improvement to 4/5 strength. There were no deaths over the course of the study.

Conclusions

Maps of the motor system generated with TMS correlate well with those generated by both MEG imaging and DCS. Negative TMS mapping also correlates with negative DCS mapping. Navigated TMS is an accurate modality for noninvasively generating preoperative motor maps.

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Hansen Deng, John K. Yue, Ethan A. Winkler, Sanjay S. Dhall, Geoffrey T. Manley, and Phiroz E. Tarapore

OBJECTIVE

Pediatric firearm injury is a leading cause of death and disability in the youth of the United States. The epidemiology of and outcomes following gunshot wounds to the head (GSWHs) are in need of systematic characterization. Here, the authors analyzed pediatric GSWHs from a population-based sample to identify predictors of prolonged hospitalization, morbidity, and death.

METHODS

All patients younger than 18 years of age and diagnosed with a GSWH in the National Sample Program (NSP) of the National Trauma Data Bank (NTDB) in 2003–2012 were eligible for inclusion in this study. Variables of interest included injury intent, firearm type, site of incident, age, sex, race, health insurance, geographic region, trauma center level, isolated traumatic brain injury (TBI), hypotension in the emergency department, Glasgow Coma Scale (GCS) score, and Injury Severity Score (ISS). Risk predictors for a prolonged hospital stay, morbidity, and mortality were identified. Odds ratios, mean increases or decreases (B), and 95% confidence intervals were reported. Statistical significance was assessed at α < 0.001 accounting for multiple comparisons.

RESULTS

In a weighted sample of 2847 pediatric patients with GSWHs, the mean age was 14.8 ± 3.3 years, 79.2% were male, and 59.0% had severe TBI (GCS score 3–8). The mechanism of assault (63.0%), the handgun as firearm (45.6%), and an injury incurred in a residential area (40.6%) were most common. The mean hospital length of stay was 11.6 ± 14.4 days for the survivors, for whom suicide injuries involved longer hospitalizations (B = 5.9-day increase, 95% CI 3.3–8.6, p < 0.001) relative to those for accidental injuries. Mortality was 45.1% overall but was greater with injury due to suicidal intent (mortality 71.5%, p < 0.001) or caused by a shotgun (mortality 56.5%, p < 0.001). Lower GCS scores, higher ISSs, and emergency room hypotension predicted poorer outcomes. Patients with private insurance had lower mortality odds than those with Medicare/Medicaid (OR 2.4, 95% CI 1.7–3.4, p < 0.001) or government insurance (OR 3.6, 95% CI 2.2–5.8, p < 0.001). Management at level II centers, compared to level I, was associated with lower odds of returning home (OR 0.3, 95% CI 0.2–0.5, p < 0.001).

CONCLUSIONS

From 2003 to 2012, with regard to pediatric TBI hospitalizations due to GSWHs, their proportion remained stable, those caused by accidental injuries decreased, and those attributable to suicide increased. Overall mortality was 45%. Hypotension, cranial and overall injury severity, and suicidal intent were associated with poor prognoses. Patients treated at level II trauma centers had lower odds of being discharged home. Given the spectrum of risk factors that predispose children to GSWHs, emphasis on screening, parental education, and standardization of critical care management is needed to improve outcomes.

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Visish M. Srinivasan, Phiroz E. Tarapore, Stefan W. Koester, Joshua S. Catapano, Caleb Rutledge, Kunal P. Raygor, and Michael T. Lawton

OBJECTIVE

Rare arteriovenous malformations (AVMs) of the optic apparatus account for < 1% of all AVMs. The authors conducted a systematic review of the literature for cases of optic apparatus AVMs and present 4 cases from their institution. The literature is summarized to describe preoperative characteristics, surgical technique, and treatment outcomes for these lesions.

METHODS

A comprehensive search of the English-language literature was performed in accordance with established Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all published cases of AVM in the optic apparatus in the PubMed, Web of Science, and Cochrane databases. The authors also searched their prospective institutional database of vascular malformations for such cases. Data regarding the clinical and radiological presentation, visual acuity, visual fields, extent of resection, and postoperative outcomes were gathered.

RESULTS

Nine patients in the literature and 4 patients in the authors’ single-surgeon series who fit the inclusion criteria were identified. The median age at presentation was 29 years (range 8–39 years). Among these patients, 11 presented with visual disturbance, 9 with headache, and 1 with multiple prior subarachnoid hemorrhages; the AVM in 1 case was found incidentally. Four patients described prior symptoms of headache or visual disturbance consistent with sentinel events. Visual acuity was decreased from baseline in 10 patients, and 11 patients had visual field defects on formal visual field testing. The most common visual field defect was temporal hemianopia, found in one or both eyes in 7 patients. The optic chiasm was affected in 10 patients, the hypothalamus in 2 patients, the optic nerve (unilaterally) in 8 patients, and the optic tract in 2 patients. Six patients underwent gross-total resection; 6 patients underwent subtotal resection; and 1 patient underwent craniotomy, but no resection was attempted. Postoperatively, 9 of the patients had improved visual function, 1 had no change, and 3 had worse visual acuity. Eight patients demonstrated improved visual fields, 1 had no change, and 4 had narrowed fields.

CONCLUSIONS

AVMs of the optic apparatus are rare lesions. Although they reside in a highly eloquent region, surgical outcomes are generally good; the majority of patients will see improvement in their visual function postoperatively. Microsurgical technique is critical to the successful removal of these lesions, and preservation of function sometimes requires subtotal resection of the lesion.

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Laura B. Ngwenya, Catherine G. Suen, Phiroz E. Tarapore, Geoffrey T. Manley, and Michael C. Huang

OBJECTIVE

Blood loss and moderate anemia are common in patients with traumatic brain injury (TBI). However, despite evidence of the ill effects and expense of the transfusion of packed red blood cells, restrictive transfusion practices have not been universally adopted for patients with TBI. At a Level I trauma center, the authors compared patients with TBI who were managed with a restrictive (target hemoglobin level > 7 g/dl) versus a liberal (target hemoglobin level > 10 g/dl) transfusion protocol. This study evaluated the safety and cost-efficiency of a hospital-wide change to a restrictive transfusion protocol.

METHODS

A retrospective analysis of patients with TBI who were admitted to the intensive care unit (ICU) between January 2011 and September 2015 was performed. Patients < 16 years of age and those who died within 24 hours of admission were excluded. Demographic data and injury characteristics were compared between groups. Multivariable regression analyses were used to assess hospital outcome measures and mortality rates. Estimates from an activity-based cost analysis model were used to detect changes in cost with transfusion protocol.

RESULTS

A total of 1565 patients with TBI admitted to the ICU were included in the study. Multivariable analysis showed that a restrictive transfusion strategy was associated with fewer days of fever (p = 0.01) and that patients who received a transfusion had a larger fever burden. ICU length of stay, ventilator days, incidence of lung injury, thromboembolic events, and mortality rates were not significantly different between transfusion protocol groups. A restrictive transfusion protocol saved approximately $115,000 annually in hospital direct and indirect costs.

CONCLUSIONS

To the authors’ knowledge, this is the largest study to date to compare transfusion protocols in patients with TBI. The results demonstrate that a hospital-wide change to a restrictive transfusion protocol is safe and cost-effective in patients with TBI.

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Ethan A. Winkler, John K. Yue, Harjus Birk, Caitlin K. Robinson, Geoffrey T. Manley, Sanjay S. Dhall, and Phiroz E. Tarapore

OBJECT

Traumatic fractures of the thoracolumbar spine are common injuries, accounting for approximately 90% of all spinal trauma. Lumbar spine trauma in the elderly is a growing public health problem with relatively little evidence to guide clinical management. The authors sought to characterize the complications, morbidity, and mortality associated with surgical and nonsurgical management in elderly patients with traumatic fractures of the lumbar spine.

METHODS

Using the National Sample Program of the National Trauma Data Bank, the authors performed a retrospective analysis of patients ≥ 55 years of age who had traumatic fracture to the lumbar spine. This group was divided into middle-aged (55–69 years) and elderly (≥ 70 years) cohorts. Cohorts were subdivided into nonoperative, vertebroplasty or kyphoplasty, noninstrumented surgery, and instrumented surgery. Univariate and multivariable analyses were used to characterize and identify predictors of medical and surgical complications, mortality, hospital length of stay, ICU length of stay, number of days on ventilator, and hospital discharge in each subgroup. Adjusted odds ratios, mean differences, and associated 95% CIs were reported. Statistical significance was assessed at p < 0.05, and the Bonferroni correction for multiple comparisons was applied for each outcome analysis.

RESULTS

Between 2003 and 2012, 22,835 people met the inclusion criteria, which represents 94,103 incidents nationally. Analyses revealed a similar medical and surgical complication profile between age groups. The most prevalent medical complications were pneumonia (7.0%), acute respiratory distress syndrome (3.6%), and deep venous thrombosis (3%). Surgical site infections occurred in 6.3% of cases. Instrumented surgery was associated with the highest odds of each complication (p < 0.001). The inpatient mortality rate was 6.8% for all subjects. Multivariable analyses demonstrated that age ≥ 70 years was an independent predictor of mortality (OR 3.16, 95% CI 2.77–3.60), whereas instrumented surgery (multivariable OR 0.38, 95% CI 0.28–0.52) and vertebroplasty or kyphoplasty (OR 0.27, 95% CI 0.17–0.45) were associated with decreased odds of death. In surviving patients, both older age (OR 0.32, 95% CI 0.30–0.34) and instrumented fusion (OR 0.37, 95% CI 0.33–0.41) were associated with decreased odds of discharge to home.

CONCLUSIONS

The present study confirms that lumbar surgery in the elderly is associated with increased morbidity. In particular, instrumented fusion is associated with periprocedural complications, prolonged hospitalization, and a decreased likelihood of being discharged home. However, fusion surgery is also associated with reduced mortality. Age alone should not be an exclusionary factor in identifying surgical candidates for instrumented lumbar spinal fusion. Future studies are needed to confirm these findings.

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Phiroz E. Tarapore, Anne M. Findlay, Sara C. LaHue, Hana Lee, Susanne M. Honma, Danielle Mizuiri, Tracy L. Luks, Geoffrey T. Manley, Srikantan S. Nagarajan, and Pratik Mukherjee

Object

Traumatic brain injury (TBI) is one of the leading causes of morbidity worldwide. One mechanism by which blunt head trauma may disrupt normal cognition and behavior is through alteration of functional connectivity between brain regions. In this pilot study, the authors applied a rapid automated resting state magnetoencephalography (MEG) imaging technique suitable for routine clinical use to test the hypothesis that there is decreased functional connectivity in patients with TBI compared with matched controls, even in cases of mild TBI. Furthermore, they posit that these abnormal reductions in MEG functional connectivity can be detected even in TBI patients without specific evidence of traumatic lesions on 3-T MR images. Finally, they hypothesize that the reductions of functional connectivity can improve over time across serial MEG scans during recovery from TBI.

Methods

Magnetoencephalography maps of functional connectivity in the alpha (8- to 12-Hz) band from 21 patients who sustained a TBI were compared with those from 18 age- and sex-matched controls. Regions of altered functional connectivity in each patient were detected in automated fashion through atlas-based registration to the control database. The extent of reduced functional connectivity in the patient group was tested for correlations with clinical characteristics of the injury as well as with findings on 3-T MRI. Finally, the authors compared initial connectivity maps with 2-year follow-up functional connectivity in a subgroup of 5 patients with TBI.

Results

Fourteen male and 7 female patients (17–53 years old, median 29 years) were enrolled. By Glasgow Coma Scale (GCS) criteria, 11 patients had mild, 1 had moderate, and 3 had severe TBI, and 6 had no GCS score recorded. On 3-T MRI, 16 patients had abnormal findings attributable to the trauma and 5 had findings in the normal range. As a group, the patients with TBI had significantly lower functional connectivity than controls (p < 0.01). Three of the 5 patients with normal findings on 3-T MRI showed regions of abnormally reduced MEG functional connectivity. No significant correlations were seen between extent of functional disconnection and injury severity or posttraumatic symptoms (p > 0.05). In the subgroup undergoing 2-year follow-up, the second MEG scan demonstrated a significantly lower percentage of voxels with decreased connectivity (p < 0.05) than the initial MEG scan.

Conclusions

A rapid automated resting-state MEG imaging technique demonstrates abnormally decreased functional connectivity that may persist for years after TBI, including cases classified as “mild” by GCS criteria. Disrupted MEG connectivity can be detected even in some patients with normal findings on 3-T MRI. Analysis of follow-up MEG scans in a subgroup of patients shows that, over time, the abnormally reduced connectivity can improve, suggesting neuroplasticity during the recovery from TBI. Resting state MEG deserves further investigation as a prognostic and predictive biomarker for TBI.