Awake craniotomy for supratentorial tumors or epileptogenic lesions in pediatric patients: a 16-year retrospective cohort study.

OBJECTIVE: Awake craniotomy with intraoperative mapping is the widely accepted procedure for adult patients undergoing supratentorial tumor or epileptogenic focus resection near eloquent cortex. In children, awake craniotomies are notably less common due to concerns for compliance and emotional or psychological repercussions. Despite this, successfully tolerated awake craniotomies have been reported in patients as young as 8 years of age, with success rates comparable to those of adults. The authors sought to describe their experience with pediatric awake craniotomies, including insight regarding feasibility and outcomes. METHODS: A retrospective review was completed for all pediatric (age < 18 years) patients at Children's Wisconsin for whom an awake craniotomy was attempted from January 2004 until March 2020. Institutional review board approval was granted. RESULTS: Candidate patients had intact verbal ability, cognitive profile, and no considerable anxiety concerns during neuropsychology assessment. Nine patients presented with seizure. Five patients were diagnosed with tumor and secondary epilepsy, 3 with tumor only, and 3 with epilepsy only. All patients who underwent preoperative functional MRI successfully completed and tolerated testing paradigms. A total of 12 awake craniotomies were attempted in 11 patients, with 1 procedure aborted due to intraoperative bleeding. One patient had a repeat procedure. The mean patient age was 15.5 years (range 11.5-17.9 years). All patients returned to or maintained baseline motor and speech functions by the latest follow-up (range 14-130 months). Temporary deficits included transient speech errors, mild decline in visuospatial reasoning, leg numbness, and expected hemiparesis. Of the 8 patients with a diagnosis of epilepsy prior to surgery, 7 patients achieved Engel class I designation at the 1-year follow-up, 6 of whom remained in class I at the latest follow-up. CONCLUSIONS: This study analyzes one of the largest cohorts of pediatric patients who underwent awake craniotomy for maximal safe resection of tumor or epileptogenic lesions. For candidate patients, awake craniotomy is safe, feasible, and effective in carefully selected children.

Prophylactic Spinal Cord Untethering in Children with Spinal Dysraphism Undergoing Thoracolumbar Fusion for Scoliosis.

BACKGROUND: It remains unclear whether spinal cord untethering is necessary to reduce the chances of neurologic decline in children with myelomeningocele and complex closed spinal dysraphism who undergo thoracolumbar fusion for scoliosis. We sought to determine the neurologic and functional outcomes of children with spinal dysraphism undergoing spinal fusion for scoliosis with and without prophylactic spinal cord untethering. METHODS: Retrospective, single-center review of patients with spinal dysraphism treated with thoracolumbar fusion over the last 10 years (2009-2019) with or without prophylactic spinal cord untethering. RESULTS: Seventeen patients with myelomeningocele and complex closed spinal dysraphism underwent spinal fusion for scoliosis. Mean age at time of surgery was 13.9 years. Prophylactic spinal cord untethering was performed in 8 of 17 (47%) patients. The change in Cobb angle after surgery was similar between the 2 groups (19.4° untethered vs. 19.9° no untethering). The ambulatory status was similar between the groups, with 37% of the untethered cohort and 44% of the non-untethered cohort being community or household ambulators. There were no changes in intraoperative motor or sensory evoked potentials in any patient during fusion surgery. No patient had a change in motor level or ambulatory status after scoliosis surgery. CONCLUSIONS: Our data suggest that prophylactic spinal cord untethering in children with spinal dysraphism undergoing thoracolumbar fusion for scoliosis may not be necessary in patients with moderate curvatures. Our conclusions are limited by the small sample size. A larger review of registry data may yield more powerful conclusions on the necessity of prophylactic spinal cord untethering in this patient population.

Variability in neurosurgical management and associated comorbidities and complications among preterm patients with posthemorrhagic hydrocephalus in the United States.

OBJECTIVE: Posthemorrhagic hydrocephalus (PHH) remains a major morbidity of premature birth resulting from intraventricular hemorrhage (IVH). National consensus guidelines for the timing of surgical interventions are lacking, which leads to considerable variations in management among neonatal intensive care units (NICUs). Early intervention (EI) has been shown to improve outcomes, but the authors hypothesized that the timing from IVH to intervention affects the comorbidities and complications associated with PHH management. The authors used a large national inpatient care data set to characterize comorbidities and complications associated with PHH management in premature infants. METHODS: The authors used hospital discharge data from the 2006-2019 Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID) to conduct a retrospective cohort study of premature pediatric patients (weight < 1500 g) with PHH. The predictor variable was the timing of the PHH intervention (EI ≤ 28 days vs late intervention [LI] > 28 days). Hospital stay data included hospital region, gestational age, birth weight (BW), length of stay (LOS), PHH treatment procedures, comorbidities, surgical complications, and death. Statistical analysis included chi-square and Wilcoxon rank-sum tests, Cox proportional hazards regression, logistic regression, and a generalized linear model with Poisson and gamma distributions. Analysis was adjusted for demographic characteristics, comorbidities, and death. RESULTS: Of the 1853 patients diagnosed with PHH, 488 (26%) had documented timing of surgical interventions during their hospital stay. More patients had LI than EI (75%). The patients in the LI group of patients had younger gestational age and lower BW. There were significant regional differences in the timing of treatment: hospitals in the West performed EI, whereas hospitals in the South performed LI, even after adjustment for gestational age and BW. The LI group was associated with longer median LOS and more total hospital charges compared with the EI group. More temporary CSF diversion procedures occurred in the EI group, whereas more permanent CSF-diverting shunts were placed in the LI group. Shunt/device replacement and complications did not differ between the two groups. The LI group had 2.5-fold higher odds of sepsis (p < 0.001) and almost 2-fold higher odds of retinopathy of prematurity (p < 0.05) than the EI group. CONCLUSIONS: The timing of PHH interventions differs by region in the United States, whereas the association of potential benefits with treatment timing suggests the importance of national consensus guidelines. Development of these guidelines can be informed by data regarding treatment timing and patient outcomes available in large national data sets, which provide insights into comorbidities and complications of PHH interventions.

Trends in the early care of infants with myelomeningocele in the United States 2012-2018.

PURPOSE: The early care of children with spina bifida has changed with the increasing availability of fetal surgery and evidence that fetal repair improves the long-term outcomes of children with myelomeningocele. We sought to determine current trends in the prevalence and early care of children with myelomeningocele using a national administrative database. METHODS: This is a retrospective, cross-sectional cohort study of infants with spina bifida admitted within the first 28 days of life using the 2012-2018 Healthcare Cost and Utilization Project National Inpatient Database. Patients with spina bifida were identified by ICD code and stratified into a cohort with a coded neonatal repair of the defect and those without a coded repair. This database had no identifier specific for fetal surgery, but it is likely that a substantial number of infants without a coded repair had fetal surgery. RESULTS: We identified 5,090 patients with a coded repair and 5,715 without a coded repair. The overall prevalence of spina bifida was 3.94 per 10,000 live births. The percentage of patients without neonatal repair increased during the study period compared to those with repair (p = 0.0002). The cohort without neonatal repair had a higher risk of death (p < 0.001), prematurity (p < 0.001), and low birth weight (p < 0.001). More shunts were placed in patients who underwent neonatal repair (p < 0.001). Patients without neonatal repair were less likely to have public insurance (p = 0.0052) and more likely to reside in zip codes within the highest income quartile (p = 0.0002). CONCLUSIONS: The prevalence of spina bifida from 2012 to 2018 was 3.94 per 10,000 live births, with an increasing number of patients without neonatal repair of the defect, suggesting increased utilization of fetal surgery. Patients without neonatal repair had a higher risk of death, prematurity, and low birth weight but were more likely to have commercial insurance and reside in high-income zip codes.

Time to shunt failure in children with myelomeningocele: an analysis of the National Spina Bifida Patient Registry.

OBJECTIVE: Hydrocephalus is common among children with myelomeningocele and is most frequently treated with a ventriculoperitoneal shunt (VPS). Although much is known about factors related to first shunt failure, relatively less data are available about shunt failures after the first one. The purpose of this study was to use a large data set to explore time from initial VPS placement to first shunt failure in children with myelomeningocele and to explore factors related to multiple shunt failures. METHODS: Data were obtained from the National Spina Bifida Patient Registry. Children with myelomeningocele who were enrolled within the first 5 years of life and had all lifetime shunt operations recorded in the registry were included. Kaplan-Meier survival curves were constructed to evaluate time from initial shunt placement to first shunt failure. The total number of children who experienced at least 2 shunt failures was calculated. A proportional means model was performed to calculate adjusted hazard ratios (HRs) for shunt failure on the basis of sex, race/ethnicity, lesion level, and insurance status. RESULTS: In total, 1691 children met the inclusion criteria. The median length of follow-up was 5.0 years. Fifty-five percent of patients (938 of 1691) experienced at least 1 shunt failure. The estimated median time from initial shunt placement to first failure was 2.34 years (95% confidence interval [CI] 1.91-3.08 years). Twenty-six percent of patients had at least 2 shunt failures, and 14% of patients had at least 3. Male children had higher likelihood of shunt revision (HR 1.25, 95% CI 1.09-1.44). Children of minority race/ethnicity had a lower likelihood of all shunt revisions (non-Hispanic Black children HR 0.74, 95% CI 0.55-0.98; Hispanic children HR 0.74, 95% CI 0.62-0.88; children of other ethnicities HR 0.80, 95% CI 0.62-1.03). CONCLUSIONS: Among the children with myelomeningocele, the estimated median time to shunt failure was 2.34 years. Forty-five percent of children never had shunt failure. The observed higher likelihood of shunt revisions among males and lower likelihood among children of minority race/ethnicity illustrate a possible disparity in hydrocephalus care that warrants additional study. Overall, these results provide important information that can be used to counsel parents of children with myelomeningocele about the expected course of shunted hydrocephalus.

Symptomatic Dermal Inclusion Cysts in Infants following Fetal Surgery for Myelomeningocele: Report of Two Cases and Review of the Literature.

INTRODUCTION: It remains unclear if fetal repair of myelomeningocele (MM) is associated with a greater risk of developing symptomatic dermal inclusion cysts (ICs) at the neural placode. We report two infants treated with fetal surgery who developed symptomatic IC at less than 1 year of age, and we discuss the current literature on symptomatic IC in children with MM. CASE PRESENTATION: Two infants underwent fetal MM repair at 24 weeks of gestational age. Case 1 was born at 30 weeks and had two revisions of the MM wound early in life. At 8 months of age, the patient presented with meningismus and imaging findings of an IC, which was resected at the time of presentation. At 3 years of age, this patient was found to have recurrence of the IC after presenting with worsening bladder function and underwent repeat debulking with no recurrence at 6 years of age. Case 2 was born at 32 weeks of gestational age with uncomplicated recovery. At 8 months of age, the patient presented with irritability and fullness at the lumbar repair site. Imaging showed a large IC with restricted diffusion and extension into the subcutaneous tissue; this was resected completely at the time of presentation, see intraoperative photographs. There has been no sign of recurrence at age of 15 months. CONCLUSIONS: Careful monitoring for IC in infancy in MM patients who have had fetal surgery is recommended.

Controversies in Fetal Surgery: Prenatal Repair of Myelomeningocele in the Modern Era.

Fetal surgery is a constantly evolving field that showed noticeable progress with the treatment of myelomeningocele (MMC) using prenatal repair. Despite this success, there are ongoing questions regarding the optimal approach for fetal myelomeningocele repair, as well as which patients are eligible. Expansion of the inclusion and exclusion criteria is an important ongoing area of study for myelomeningocele including the recent Management of Myelomeningocele Plus trial. The significant personal and financial burden required of families seeking treatment has likely limited its accessibility to the general population.

Sociodemographic disparities in fetal surgery for myelomeningocele: a single-center retrospective review.

OBJECTIVE: Fetal surgery for myelomeningocele has become an established treatment that offers less risk of requiring a ventricular shunt and improved functional outcomes for patients. An increasing body of literature has suggested that social determinants of health have a profound influence on health outcomes. The authors sought to determine the socioeconomic and racial and ethnic backgrounds of patients who were treated with fetal surgery versus those who underwent postnatal repair. METHODS: Demographic data, the method of myelomeningocele repair, insurance status, and zip code data for patients entered into the National Spina Bifida Patient Registry (NSBPR) from Children's Wisconsin were collected. The zip code was used to determine the Distressed Communities Index (DCI) score, a composite socioeconomic ranking with scores ranging from 0 (no distress) to 100 (severe distress). The zip code was also used to determine the median household income for each patient based on the US Census Bureau 2013-2017 American Community Survey 5-year estimates. RESULTS: A total of 205 patients were identified with zip code and insurance data. There were 23 patients in the fetal surgery group and 182 patients in the postnatal surgery group. All patients were born between 2000 and 2019. Patients in the fetal surgery group were more likely to have commercial insurance (100% vs 52.2%, p < 0.001). Fetal surgery patients were also more likely to be non-Hispanic White (95.7% vs 68.7%, p = 0.058), just missing the level of statistical significance. Patients who underwent fetal surgery tended to reside in zip codes with a higher median household income (mean $66,507 vs $59,133, p = 0.122) and less-distressed communities (mean DCI score 31.3 vs 38.5, p = 0.289); however, these differences did not reach statistical significance. CONCLUSIONS: Patients treated with fetal surgery were more likely to have commercial insurance and have a non-Hispanic White racial and ethnic background. The preliminary data suggest that socioeconomic and racial and ethnic disparities may exist regarding access to fetal surgery, and investigation of a larger population of spina bifida patients is warranted.

Vacuum-assisted elevation of pediatric ping-pong skull fractures: a case series and technical note.

OBJECTIVE: The management of children with ping-pong skull fractures may include observation, nonsurgical treatments, or surgical intervention depending on the age, clinical presentation, imaging findings, and cosmetic appearance of the patient. There have been 16 publications on nonsurgical treatment using negative pressure with various devices. Herein, the authors report their experience with vacuum-assisted elevation of ping-pong skull fractures and evaluate the variables affecting procedural outcomes. METHODS: The authors performed a retrospective chart review of all ping-pong skull fractures treated via vacuum-assisted elevation at the Children's Hospital of Wisconsin between 2013 and 2017. Data collected included patient age, head circumference, mode of injury, time to presentation, imaging findings, procedural details, treatment outcomes, and complications. RESULTS: Four neonates and 5 infants underwent vacuum-assisted elevation of moderate to severe ping-pong skull fractures during the study period. Modes of injury included birth-related trauma, falls, and blunt trauma. All patients had normal neurological examination findings and no evidence of intracranial hemorrhage. All fractures were deemed severe enough to require elevation by the treating neurosurgeon. All fractures involved the parietal bone. Skull depressions ranged from 23 to 62 mm in diameter and from 4 to 14 mm in depth. Bone thickness ranged from 0.6 to 1.8 mm. The time from fracture to intervention ranged from 7 hours to 8 days. The Kiwi OmniCup vacuum delivery system was used in all cases. Negative pressures were increased sequentially to a maximum of 500 mm Hg. A greater number of sequential vacuum applications was required for patients with a skull thickness greater than 1 mm at the site of depression and for those undergoing treatment more than 72 hours from fracture onset. Successful fracture elevation was attained in 7 of 9 patients. Two patients required subsequent surgical elevation of their fractures. Postprocedure imaging studies revealed no evidence of complications. CONCLUSIONS: Increasing bone thickness and time from fracture onset to intervention appeared to be the greatest limiting factors to the successful elevation of moderate to severe ping-pong fractures via this vacuum-assisted approach. This procedure is a well-tolerated option that should be considered prior to performing an open repair in cases deemed to require fracture elevation. Future efforts will focus on larger-volume studies to better delineate inclusion and exclusion criteria, and volumetric analysis for better fracture-to-suction device customization.

Split laminotomy versus conventional laminotomy: postoperative outcomes in pediatric patients.

OBJECTIVE Split laminotomy is a technique for accessing the spinal canal from the posterior midline that minimizes muscle dissection and bone removal. Benefits of this approach in minimizing postoperative pain and muscle atrophy in the adult population have been reported, but pediatric data are limited. Herein, the authors evaluate the benefits of the split laminotomy technique in pediatric patients. METHODS Data obtained in patients who underwent posterior spine surgery at Children's Hospital of Wisconsin for an intradural midline pathology between April 2008 and June 2015 were reviewed retrospectively. Each patient was assigned to one of two groups, the split-laminotomy or conventional-laminotomy group. The primary outcomes assessed were mean daily pain score, total opioid use over a period of 72 hours after surgery, and the degree of paraspinal muscle atrophy and fat infiltration found on short-term (1-4 months) and long-term (1-4 years) follow-up spine MRI studies. RESULTS A total of 117 patients underwent lumbar-level surgery (83 conventional laminotomy, 34 split laminotomy), and 8 patients underwent thoracic-level surgery (4 in each group). No significant difference in the mean daily pain scores between groups was found. The daily opioid use was significantly lower in the split-laminotomy group on postoperative day 0 (POD0) and POD1 but not on POD2 (p = 0.01, 0.01, and 0.10, respectively). The total opioid use over the 72-hour postoperative period was significantly lower in the split-laminotomy group (p = 0.0008). The fat/muscle ratio was significantly higher in both the short-term and long-term follow-up periods in the conventional-laminotomy group (p = 0.01 and 0.0002, respectively). The rate of change of paraspinal muscle fat infiltration was significantly lower in the split-laminotomy group than in the conventional-laminotomy group (p = 0.007). The incidence of complications was not significantly different between groups (p = 0.08). CONCLUSIONS This study was of the largest series reported thus far of pediatric patients who underwent split laminotomy and the only controlled study that has involved children. The authors' results reinforce the short-term benefit of split laminotomy in minimizing acute postoperative pain and long-term benefits of decreasing muscle atrophy and fatty degeneration, which are known to be associated with the development of chronic pain and spinal instability. Additional efforts for assessing long-term effects in the development of chronic pain, spinal instability, and spinal deformity are still necessary.

En bloc resection of a C-1 lateral mass osteosarcoma: technical note.

Osteosarcoma is an aggressive primary bone tumor. It is currently treated with multimodality therapy including en bloc resection, which has been demonstrated to confer a survival benefit over intralesional resection. The authors present the case of an 8-year-old girl with a C-1 lateral mass osteosarcoma, which was treated with a 4-stage en bloc resection and spinal reconstruction. While technically complex, the feasibility of en bloc resection for spinal osteosarcoma should be explored in the pediatric population.

Penetrating head injuries in children due to BB and pellet guns: a poorly recognized public health risk.

OBJECT Nonpowder guns, defined as spring- or gas-powered BB or pellet guns, can be dangerous weapons that are often marketed to children. In recent decades, advances in compressed-gas technology have led to a significant increase in the power and muzzle velocity of these weapons. The risk of intracranial injury in children due to nonpowder weapons is poorly documented. METHODS A retrospective review was conducted at 3 institutions studying children 16 years or younger who had intracranial injuries secondary to nonpowder guns. RESULTS The authors reviewed 14 cases of intracranial injury in children from 3 institutions. Eleven (79%) of the 14 children were injured by BB guns, while 3 (21%) were injured by pellet guns. In 10 (71%) children, the injury was accidental. There was 1 recognized assault, but there were no suicide attempts; in the remaining 3 patients, the intention was indeterminate. There were no mortalities among the patients in this series. Ten (71%) of the children required operative intervention, and 6 (43%) were left with permanent neurological injuries, including epilepsy, cognitive deficits, hydrocephalus, diplopia, visual field cut, and blindness. CONCLUSIONS Nonpowder guns are weapons with the ability to penetrate a child's skull and brain. Awareness should be raised among parents, children, and policy makers as to the risk posed by these weapons.

Photodynamic therapy (PDT) for malignant brain tumors--where do we stand?

INTRODUCTION: What is the current status of photodynamic therapy (PDT) with regard to treating malignant brain tumors? Despite several decades of effort, PDT has yet to achieve standard of care. PURPOSE: The questions we wish to answer are: where are we clinically with PDT, why is it not standard of care, and what is being done in clinical trials to get us there. METHOD: Rather than a meta-analysis or comprehensive review, our review focuses on who the major research groups are, what their approaches to the problem are, and how their results compare to standard of care. Secondary questions include what the effective depth of light penetration is, and how deep can we expect to kill tumor cells. CURRENT RESULTS: A measurable degree of necrosis is seen to a depth of about 5mm. Cavitary PDT with hematoporphyrin derivative (HpD) results are encouraging, but need an adequate Phase III trial. Talaporfin with cavitary light application appears promising, although only a small case series has been reported. Foscan for fluorescence guided resection (FGR) plus intraoperative cavitary PDT results were improved over controls, but are poor compared to other groups. 5-Aminolevulinic acid-FGR plus postop cavitary HpD PDT show improvement over controls, but the comparison to standard of care is still poor. CONCLUSION: Continued research in PDT will determine whether the advances shown will mitigate morbidity and mortality, but certainly the potential for this modality to revolutionize the treatment of brain tumors remains. The various uses for PDT in clinical practice should be pursued.

Prone positioning for successful gamma knife radiosurgical treatment of far anterior skull base lesions: a technical note.

BACKGROUND: Gamma Knife targeting is geometrically limited by the physical dimensions of the head, helmet, headframe, and the radiation target position. All four aspects need to be considered for accurate treatment planning. Within the available space, delivery of the treatment isodose is based on the target position, which must be brought into the center of the collimator. In cases of anatomically challenging target positions in far eccentric locations of the head, careful treatment planning needs to be performed that does not exceed the limits of the system. CLINICAL PRESENTATION: We describe a case of a challenging far anterior ethmoid sinus hemangiopericytoma in an 80-year-old woman. TECHNIQUE: The tumor was treated successfully by positioning the patient prone on a Model C Gamma unit. The physical restrictions of the Gamma Knife surgical system and the rationale for improved anterior targeting using the prone position are discussed. CONCLUSION: A thoughtful approach to positioning in challenging anterior lesions extends the targeting capabilities of certain Gamma units.

Stereotactic radiosurgery for pediatric arteriovenous malformations.

Children with intracranial arteriovenous malformations (AVM) have a high cumulative risk of hemorrhage and therefore effective treatment of AVMs in the pediatric population is imperative. Treatment options include microsurgical resection, endovascular embolization, staged or single fraction radiosurgery, or some combination of these treatments, with the ultimate goal of eliminating the risk of hemorrhage. In this article the authors review the current data on the use of radiosurgery for the treatment of childhood AVMs. Factors associated with successful AVM radiosurgery in this population are examined, and comparisons with outcomes in adult patients are reviewed.

Allergic reaction to a bovine dural substitute following spinal cord untethering. Case report.

Bovine tissues are now routinely used for dural closure in cranial and spinal surgery. The authors report the case of an 18-year-old woman with a history of myelomeningocele who had symptoms of tethered cord syndrome and presented to a regional hospital. At that hospital she underwent a cord untethering procedure. The spinal dura was closed with Durepair, a dural substitute derived from fetal bovine skin. Her postoperative course was complicated by a cerebrospinal fluid leak that was surgically repaired. Following this, she developed erythroderma, intermittent fevers, eosinophilia, and marked elevation in serum immunoglobulin E. She was then transferred to the authors' institution. A skin antigen test to beef was administered, which revealed a positive reaction. A radioallergosorbent test to beef also yielded positive results. She was taken to the operating room for removal of the bovine graft due to concern for an allergic reaction to the graft. The graft material showed evidence of eosinophilic infiltration. Her clinical symptoms and laboratory values all improved after surgery. To the authors' knowledge this is the first reported case of an allergic reaction to bovine-based dural substitutes.

Placement of C2 laminar screws using three-dimensional fluoroscopy-based image guidance.

The use of C2 laminar screws in posterior cervical fusion is a relatively new technique that provides rigid fixation of the axis with minimal risk to the vertebral artery. The techniques of C2 laminar screw placement described in the literature rely solely on anatomical landmarks to guide screw insertion. The authors report on their experience with placement of C2 laminar screws using three-dimensional (3D) fluoroscopy-based image-guidance in eight patients undergoing posterior cervical fusion. Overall, fifteen C2 laminar screws were placed. There were no complications in any of the patients. Average follow-up was 10 months (range 3-14 months). Postoperative computed tomographic (CT) scanning was available for seven patients allowing evaluation of placement of thirteen C2 laminar screws, all of which were in good position with no spinal canal violation. The intraoperative planning function of the image-guided system allowed for 4-mm diameter screws to be placed in all cases. Using modified Odom's criteria, excellent or good relief of preoperative symptoms was noted in all patients at final follow-up.

Histologic analysis of a human trigeminal nerve after failed stereotactic radiosurgery: case report.

BACKGROUND: Stereotactic radiosurgery is an accepted surgery to treat patients with medically intractable trigeminal neuralgia. However, little is known about the mechanism of pain relief after trigeminal neuralgia radiosurgery. We report the histologic findings of a human trigeminal nerve after failed radiosurgery for trigeminal neuralgia. CASE DESCRIPTION: A 74-year-old patient presented with a 10-year history of refractory trigeminal neuralgia. Prior surgeries included an MVD and PRGR. Gamma knife radiosurgery was performed targeting the proximal trigeminal nerve using one 4-mm isocenter (maximum dose, 85 Gy). She experienced good pain relief (no pain, reduced medications) for 16 months. She had no new trigeminal deficits after this procedure. The pain recurred, and she underwent repeat gamma knife radiosurgery targeting the distal trigeminal nerve using one 4-mm isocenter (maximum dose, 70 Gy). The pain continued to escalate until she required hospitalization for pain control and hydration. Three weeks after her second radiosurgical procedure, she underwent a repeat posterior fossa exploration. During that surgery, her trigeminal nerve was partially sectioned, and a small segment of the proximal to midcisternal nerve was sent for histological examination. There was no histologic evidence of nerve damage. CONCLUSION: This case supports the contention that trigeminal nerve injury is required to provide long lasting pain relief after trigeminal neuralgia radiosurgery.

Imaging characteristics and growth of subependymal giant cell astrocytomas.

OBJECT: Subependymal giant cell astrocytomas (SEGAs) are a common manifestation of tuberous sclerosis (TS). These evolving tumors have a propensity to cause obstructive hydrocephalus, usually due to obstruction at the level of the foramen of Monro. Differentiating SEGAs from subependymal nodules (SENs) before obstruction occurs may improve the morbidity associated with these tumors. In this study the authors' aim was to determine imaging characteristics of proven tumors in a single-center pediatric population. METHODS: The authors retrospectively reviewed all records and images obtained in patients with TS in whom results of biopsy sampling had proven that their tumors were SEGAs. Time to presentation, signs and symptoms at presentation, and imaging characteristics of the evolving tumors were noted. Twelve patients with 14 SEGAs proven by the results of biopsy sampling were reviewed. Resection was recommended for symptomatic and neuroimaging evidence of hydrocephalus (41%), tumor growth without evidence of hydrocephalus (33%), and for poorly controlled seizures (25%). The mean diameter of the tumors at the time of resection was 1.9 cm (range 0.3-4 cm), and no tumor recurred. Because of the pathological and radiographic continuum of SENs and SEGAs, it remains difficult to predict whether and when a given lesion will progress. Tumor growth and contrast enhancement are the most common signs of progression on neuroimages, and may be seen prior to the development of obstructive hydrocephalus. CONCLUSIONS: Patients with SENs and SEGAs should undergo follow-up neuroimaging at yearly intervals, and if lesions show signs of progression (contrast enhancement or growth), these intervals should be shortened and consideration given to early resection.