Cognitive issues in patients with IDH mutant gliomas: from neuroscience to clinical neuropsychology.

PURPOSE: The understanding of cognitive symptoms in patients with IDH-Mutant gliomas (IDH-Mut) is rapidly developing. In this article, we summarize the neuroscientific knowledge base regarding the influence of IDH-Mut tumors and their treatment on cognition and provide guidance regarding the management of these symptoms in patients. METHODS: We performed a review of peer reviewed publications relevant to IDH-Mut glioma and cognitive outcomes and provide an overview of the literature as well as a case example to clarify management strategies. RESULTS: At the time of presentation, patients with IDH-Mut gliomas have a favorable cognitive profile as compared with those with IDH-wild type (WT) tumors. The relatively low cognitive burden may reflect the slower growth rate of IDH-Mut tumors, which is less disruptive to both local and widespread neural networks. Human connectomic research using a variety of modalities has demonstrated relatively preserved network efficiency in patients with IDH-Mut gliomas as compared with IDH-WT tumors. Risk of cognitive decline from surgery can potentially be mitigated by careful integration of intra-operative mapping. Longer term cognitive risks of tumor treatment, including chemotherapy and radiation, are best managed by instituting neuropsychological assessment as part of the long-term care of patients with IDH-Mutant glioma. A specific timeline for such integrative care is provided. CONCLUSIONS: Given the relative recency of the IDH-mutation based classification of gliomas, as well as the long time course of this disease, a thoughtful and comprehensive strategy to studying patient outcomes and devising methods of cognitive risk reduction is required.

Secondary dystonia following parenchymal brain tumors.

BACKGROUND: Secondary dystonia has been associated with diverse etiologies. Dystonia associated with brain tumors has not been well characterized. OBJECTIVES: To characterize dystonia and relationship with parenchymal brain tumors. METHODS: We present six patients (1.03%) with dystonia related to parenchymal brain tumors, among 580 screened cases. RESULTS: Contralateral hemidystonia was observed in four cases, followed by focal limb (n = 1) and cervical dystonia (n = 1). Dystonia presented during the phase of tumor growth in four cases, and following tumor treatment in two, one case had re-emergent dystonia. Tumors were low-grade (WHO I or II) and located in the basal ganglia (n = 3), cortical areas (n = 2), thalamus (n = 1) and cerebral peduncle (n = 1). CONCLUSIONS: Secondary dystonia may be caused by brain tumors in diverse locations including basal ganglia, cortex and thalamus. It may be the presenting symptom of brain tumor or follow surgical resection combined with ancillary therapy.

Intracranial phosphaturic mesenchymal tumors. A case report and review of literature.

Most osteomalacia-inducing tumors (OITs) are phosphaturic mesenchymal tumors (PMTs) that secrete fibroblast growth factor 23 (FGF23). These tumors usually occur in the bone and soft tissues, and intracranial OITs are rare. Therefore, intracranial OIT is difficult to diagnose and treat. This paper presents a case of intracranial OIT and shows a review of previous cases. A 45-year-old man underwent nasal cavity biopsy and treatment with active vitamin D3 and neutral phosphate for hypophosphatemia. Amplification of FGF23 mRNA level within the tumor was detected. Subsequently, the surgical specimen was diagnosed with a PMT and was considered the cause of the patient's osteomalacia. The patient was referred to a neurosurgery department for the excision of the intracranial tumor extending to the nasal cavity. After tumor removal, the serum levels of FGF23 and phosphorus were normalized as compared to preoperative those. The patient remains disease-free, without additional treatment, approximately 10 years after surgery, with no tumor recurrence. As per the literature, intracranial OITs usually occur in patients aged 8-69 years. Bone and muscle pain are major complaints. Approximately 60% of the patients reported previously had symptoms because of intracranial tumors. In some cases, it took several years to diagnose OIT after the onset of the osteomalacia symptoms. Laboratory data in such cases show hypophosphatemia and elevated FGF23 levels. Because FGF23 levels are associated with the severity of osteomalacia symptoms, total tumor resection is recommended. PMT and hemangiopericytoma (HPC) are histologically similar, but on immunochemistry, PMT is negative for signal transducer and activator of transcription 6 (STAT6), whereas HPC is positive. FGF23 amplification is seen in PMTs but not in HPCs. Therefore, the analysis of FGF23 and STAT6 was helpful in distinguishing PMTs from HPCs. In cases of hypophosphatemia and osteomalacia without a history of metabolic, renal, or malabsorptive diseases, the possibility of oncogenic osteomalacia should be considered.

Topical vancomycin reduces surgical site infections in patients subjected to craniotomy for primary brain tumor resection: A comprehensive cancer center experience.

BACKGROUND: Craniotomies for resection of neoplastic lesions are at increased risk for surgical site infections (SSIs) as compared to non-neoplastic pathologies. SSIs can be detrimental due to delay in pivotal adjuvant therapies. OBJECTIVE: The purpose of this study was to determine the rate of SSI in primary brain tumors, to analyze risk factors, and to evaluate effectiveness of topical vancomycin in reducing SSIs. METHODS: A retrospective cohort study was conducted at a National Cancer Institutedesignated Comprehensive Cancer Center. Patients with primary brain tumors (n = 799) who were subjected to craniotomy from 2004 to 2014 were included. Patient demographics, tumor characteristics, use of topical vancomycin and clinical outcomes were analyzed. RESULTS: Topical vancomycin was associated with a significantly lower rate of SSI (0.8%) compared to standard care (5%), ( p = 0.00071; OR = 0.15; 95% CI = 0.02 - 0.5). Narcotic use ( p = 0.043; OR = 2.24; 95% CI = 0.96 - 4.81), previous brain radiation ( p = 0.043; OR = 2.08; 95% CI = 1.02 - 4.29), length of hospitalization ( p = 0.01; OR= 1.04; 95% CI = 1.01 - 1.08), and 30 day re-operation ( p = 1.58 ×10 -10; OR = 15.23; 95% CI = 7.06 - 32.71) were associated with increased risk for SSI. CONCLUSION: Topical vancomycin effectively reduced the rate of SSI in patients subjected to craniotomy for primary brain tumor resection. Furthermore, preoperative narcotic use, previous head/brain radiation, length of hospitalization, and 30-day reoperation were associated with increased risk of SSI.

Survival and functional outcomes in paediatric thalamic and thalamopeduncular low grade gliomas.

BACKGROUND: Childhood thalamopeduncular gliomas arise at the interface of the thalamus and cerebral peduncle. The optimal treatment is total resection but not at the cost of neurological function. We present long-term clinical and oncological outcomes of maximal safe resection. METHODS: Retrospective review of prospectively collected data: demography, symptomatology, imaging, extent of resection, surgical complications, histology, functional and oncological outcome. RESULTS: During 16-year period (2005-2020), 21 patients were treated at our institution. These were 13 girls and 8 boys (mean age 7.6 years). Presentation included progressive hemiparesis in 9 patients, raised intracranial pressure in 9 patients and cerebellar symptomatology in 3 patients. The tumour was confined to the thalamus in 6 cases. Extent of resection was judged on postoperative imaging as total (6), near-total (6) and less extensive (9). Surgical complications included progression of baseline neurological status in 6 patients, and 5 of these gradually improved to preoperative status. All tumours were classified as low-grade gliomas. Disease progression was observed in 9 patients (median progression-free survival 7.3 years). At last follow-up (median 6.1 years), all patients were alive, median Lansky score of 90. Seven patients were without evidence of disease, 6 had stable disease, 7 stable following progression and 1 had progressive disease managed expectantly. CONCLUSION: Paediatric patients with low-grade thalamopeduncular gliomas have excellent long-term functional and oncological outcomes when gross total resection is not achievable. Surgery should aim at total resection; however, neurological function should not be endangered due to excellent chance for long-term survival.

The death of localizationism: The concepts of functional connectome and neuroplasticity deciphered by awake mapping, and their implications for best care of brain-damaged patients.

Although clinical neurology was mainly erected on the dogma of localizationism, numerous reports have described functional recovery after lesions involving presumed non-compensable areas in an inflexible view of brain processing. Here, the purpose is to review new insights into the functional connectome and the mechanisms underpinning neural plasticity, gained from intraoperative direct electrostimulation mapping and real-time behavioral monitoring in awake patients, combined with perioperative neuropsychological and neuroimaging data. Such longitudinal anatomo-functional correlations resulted in the reappraisal of classical models of cognition, especially by highlighting the dynamic interplay within and between neural circuits, leading to the concept of meta-network (network of networks), as well as by emphasizing that subcortical connectivity is the main limitation of neuroplastic potential. Beyond their contribution to basic neurosciences, these findings might also be helpful for an optimization of care for brain-damaged patients, such as in resective oncological or epilepsy neurosurgery in structures traditionally deemed inoperable (e.g., in Broca's area) as well as for elaborating new programs of functional rehabilitation, eventually combined with transcranial brain stimulation, aiming to change the connectivity patterns in order to enhance cognitive competences following cerebral injury.

Assessment and Management of Cognitive Symptoms in Patients With Brain Tumors.

Cognitive symptoms occur in almost all patients with brain tumors at varying points in the disease course. Deficits in neurocognitive function may be caused by the tumor itself, treatment (surgery, radiation, or chemotherapy), or other complicating factors (e.g., seizures, fatigue, mood disturbance) and can have a profound effect on functional independence and quality of life. Assessment of neurocognitive function is an important part of comprehensive care of patients with brain tumors. In the neuro-oncology clinic, assessment may include cognitive screening tools and inquiry into subjective cognitive function. Neuropsychological assessment is an important adjunct to identify cognitive symptoms and can be used as an opportunity to intervene through transformative feedback and treatment planning. Preventative measures can be taken to reduce cognitive side effects of treatment, such as awake craniotomies with intraoperative mapping during neurosurgery or prophylactic measures during radiation therapy (e.g., hippocampal avoidance, neuroprotectant treatment with memantine). Rehabilitative therapies, including cognitive rehabilitation and computerized cognitive exercise, are options for managing cognitive problems in an individualized manner. Pharmacotherapy, including use of stimulant medications and acetylcholinesterase inhibitors, has shown benefits for patients with brain tumors when tailored to an individual's cognitive profile. Identification and management of co-occurring issues, such as sleep disturbance, fatigue, and depression, can also improve neurocognitive function. There are promising therapies under development that may provide new options for treatment in the future. Integrating careful assessment and treatment of cognition throughout the disease course for patients with brain tumors can improve functional outcomes and quality of life.

Orengedokuto and shosaikoto for intractable intracranial carmustine implant-induced fever in a patient with brain tumor: A case report.

INTRODUCTION: Anaplastic astrocytoma has a dismal prognosis with conventional treatment. Multidisciplinary treatment is needed to control the disease; however, side effects of the treatment reduce a patient's quality of life (QOL). Carmustine-impregnated wafers (Gliadel®, Eisai Co., Ltd., Tokyo, Japan), one of the treatment modalities for anaplastic astrocytoma, has been reported to have drug-induced fever as a side effect. CASE REPORT: A 36-year-old man underwent excision for a recurrent brain tumor. Histopathological examination established a diagnosis of anaplastic astrocytoma and an intracranial carmustine implant was placed for local chemotherapy. Postoperatively, the patient developed high fever, which could not be controlled using antipyretics. The high fever ameliorated dramatically after the administration of Kampo medicines, specifically orengedokuto and shosaikoto, and the patient could continue chemotherapy. CONCLUSION: To the best of our knowledge, this is the first report of successful treatment of intractable carmustine implant-induced fever using Kampo medicine. In this case, Kampo medicine led to an improvement of QOL.

Hypothalamic-Pituitary Axis Dysfunction after Whole Brain Radiotherapy - A Cohort Study.

BACKGROUND/AIM: Hypothalamic-pituitary (HT-P) dysfunction is one of the most common endocrine late effects following cranial radiotherapy. However, there are currently no specific data describing this complication in adult-onset cancer patients after whole brain radiotherapy (WBRT). The present cohort study aims to establish the prevalence of HT-P axis dysfunction in this group of patients. PATIENTS AND METHODS: Twenty-six cancer patients previously treated with WBRT (median follow-up=20.5 months) received standardized endocrine check-up focusing on HT-P function. RESULTS: In 50% of the patients, impaired hypothalamic-pituitary function was detected during follow-up. While functional loss of a single hormonal axis was evident in 34.6% of patients, 7.7% showed an impairment of multiple endocrine axes, and one patient developed adrenocorticotropic hormone deficiency. Hypothalamic-pituitary dysfunction did not directly correlate with the applied WBRT total doses. CONCLUSION: In our cohort, hypothalamic-pituitary dysfunction appeared to be common after WBRT and was diagnosed as early as 6 months following radiation. This finding highlights the need for routine endocrine follow-up even in patients with limited life expectancy.

Severe chronic nonlichenoid oral mucositis in pembrolizumab-treated patients: new cases and a review of the literature.

Aim: To report of severe chronic oral mucositis (OM) in two pembrolizumab-treated cancer patients. Materials & methods: A retrospective chart review was performed. Inclusion/exclusion criteria detected patients that developed OM during pembrolizumab immunotherapy. In addition, we searched the literature for nonlichenoid OM in immunotherapy-treated cancer patients. Results: Two male patients treated for anaplastic astrocytoma and lung adenocarcinoma were included. Extensive painful OM (grade 4) developed in both patients during the course of immunotherapy and the ulcerations remained >30 weeks (>16 weeks after stopping immunotherapy). Superficial mucocele appeared in one patient. In one patient, pain relief was achieved with photobiomodulation (low-level laser) therapy. Conclusion: OM induced by immunotherapy may be a major cause of suffering and eating difficulties. In most cases, the OM lasted for months even after the drug was stopped. There is a controversy regarding the beneficial effect of corticosteroids on OM in these patients.

Laser Interstitial Thermotherapy for Treatment of Symptomatic Peritumoral Edema After Radiosurgery for Meningioma.

BACKGROUND: Symptomatic peritumoral edema (PTE) is a known complication after radiosurgical treatment of meningiomas. Although the edema in most patients can be successfully managed conservatively with corticosteroid therapy or bevacizumab, some medically refractory cases may require surgical resection of the underlying lesion when feasible. Laser interstitial thermotherapy (LITT) continues to gain traction as an effective therapeutic modality for the treatment of radiation necrosis where its biggest impact is through the control of peritumoral edema. CASE DESCRIPTION: A 56-year-old woman with neurofibromatosis 2 presented with a symptomatic, regrowing left frontotemporal lesion that had previously been radiated, then resected with confirmed recurrence of grade I meningioma, and subsequently radiated again for lesion recurrence. Given her history of 2 prior same-side craniotomies, including a complication of wound infection, she was not a candidate for further open surgical resection. Having failed conservative management, she underwent LITT with intraoperative biopsy demonstrating viable grade I meningioma. Postoperatively, she demonstrated radiographic marked, serial reduction of PTE and experienced resolution of her symptoms. CONCLUSIONS: This case demonstrates that LITT may be a viable alternative treatment for patients with meningioma with symptomatic PTE who have failed medical therapy and require surgical intervention.

Potential role of cannabidiol for seizure control in a patient with recurrent glioma.

Glioma-related epilepsy significantly impact on patients' quality of life, and can often be difficult to treat. Seizures cause significant morbidity for example neurocognitive deterioration, which may result from seizures themselves or due to adverse effects from antiepileptic drugs. Management of tumour with surgery, radiotherapy and chemotherapy may contribute to seizure control, but tumour related epilepsy is often refractory despite adequate treatment with standard anti-epileptic medications. Given the increasing interest in medicinal cannabis (or cannabidiol or CBD) as an anti-epileptic drug, CBD may help with seizure control in glioma patients with treatment-refractory seizures. Here we present a case of a young lady with recurrent glioma who had refractory seizures despite multiple anti-epileptic agents, who had significant benefit with CBD.

Outcomes in Patients Treated with Laser Interstitial Thermal Therapy for Primary Brain Cancer and Brain Metastases.

Laser interstitial thermal therapy (LITT) is an emerging modality to treat benign and malignant brain lesions. LITT is a minimally invasive method to ablate tissue using laser-induced tissue heating and serves as both a diagnostic and therapeutic modality for progressive brain lesions. We completed a single-center retrospective analysis of all patients with progressive brain lesions treated with LITT since its introduction at our center in August of 2015. Twelve patients have been treated for a total of 13 procedures, of which 10 patients had brain metastases and 2 patients had primary malignant gliomas. Biopsies were obtained immediately prior to laser-induced tissue heating in 10 procedures (76.9%), of which seven biopsies showed treatment-related changes without viable tumor. After laser ablation, two of three patients previously on steroids were successfully weaned on first attempt. The results of this analysis indicate that LITT is a well-tolerated procedure enabling some patients to discontinue steroids that may be effective for diagnosing and treating radiation necrosis and tumor progression.

Dosimetry of the brain and hypothalamus predicting acute lymphopenia and the survival of glioma patients with postoperative radiotherapy.

BACKGROUND: The aim of this study was to investigate dosimetric factors for predicting acute lymphopenia and the survival of glioma patients with postoperative intensity-modulated radiotherapy (IMRT). METHODS: A total of 148 glioma patients were reviewed. Acute lymphopenia was defined as a peripheral lymphocyte count (PLC) lower than 1.0 × 109 /L during radiotherapy with a normal level at pretreatment. PLCs with the corresponding dates and dose volume histogram parameters were collected. Univariate and multivariate Cox regression analyses were constructed to assess the significance of risk factors associated with lymphopenia and overall survival (OS). RESULTS: Sixty-nine (46.6%) patients developed lymphopenia during radiotherapy. Multivariate analyses revealed that the risk increased with the maximal dose of the hypothalamus (HT Dmax) ≥56 Gy (58.9% vs 28.5%, P = 0.002), minimal dose of the whole brain (WB Dmin) ≥2 Gy (54.3% vs 33.9%, P = 0.006), or mean dose of the WB (WB Dmean) ≥34 Gy (56.0% vs 37.0%, P = 0.022). Patients with older age, high-grade glioma, development of lymphopenia, high HT Dmax, WB Dmin, and WB Dmean had significantly inferior OS in the multivariate analyses. CONCLUSIONS: HT Dmax, WB Dmin, and WB Dmean are promising indicators of lymphopenia and the survival of glioma patients undergoing postoperative IMRT. The necessity and feasibility of dosimetric constraints for HT and WB is warranted with further investigation.

Glutamate weighted imaging contrast in gliomas with 7 Tesla magnetic resonance imaging.

INTRODUCTION: Diffuse gliomas are incurable malignancies, which undergo inevitable progression and are associated with seizure in 50-90% of cases. Glutamate has the potential to be an important glioma biomarker of survival and local epileptogenicity if it can be accurately quantified noninvasively. METHODS: We applied the glutamate-weighted imaging method GluCEST (glutamate chemical exchange saturation transfer) and single voxel MRS (magnetic resonance spectroscopy) at 7 Telsa (7 T) to patients with gliomas. GluCEST contrast and MRS metabolite concentrations were quantified within the tumour region and peritumoural rim. Clinical variables of tumour aggressiveness (prior adjuvant therapy and previous radiological progression) and epilepsy (any prior seizures, seizure in last month and drug refractory epilepsy) were correlated with respective glutamate concentrations. Images were separated into post-hoc determined patterns and clinical variables were compared across patterns. RESULTS: Ten adult patients with a histo-molecular (n = 9) or radiological (n = 1) diagnosis of grade II-III diffuse glioma were recruited, 40.3 +/- 12.3 years. Increased tumour GluCEST contrast was associated with prior adjuvant therapy (p = .001), and increased peritumoural GluCEST contrast was associated with both recent seizures (p = .038) and drug refractory epilepsy (p = .029). We distinguished two unique GluCEST contrast patterns with distinct clinical and radiological features. MRS glutamate correlated with GluCEST contrast within the peritumoural voxel (R = 0.89, p = .003) and a positive trend existed in the tumour voxel (R = 0.65, p = .113). CONCLUSION: This study supports the role of glutamate in diffuse glioma biology. It further implicates elevated peritumoural glutamate in epileptogenesis and altered tumour glutamate homeostasis in glioma aggressiveness. Given the ability to non-invasively visualise and quantify glutamate, our findings raise the prospect of 7 T GluCEST selecting patients for individualised therapies directed at the glutamate pathway. Larger studies with prospective follow-up are required.

Results of Phosphorus Magnetic Resonance Spectroscopy for Brain Metastases Correlate with Histopathologic Results.

BACKGROUND: Brain metastases (BMs) are classically well-circumscribed lesions. Still, the amount of edema in these neoplasms suggests either mechanisms of infiltration or defense. A better understanding of the mechanisms within the edema of BMs seems reasonable to preoperatively identify areas of potential infiltration and resect them. BMs represent tumors with high energy demand and cell turnover; therefore, they qualify for preoperative investigation with phosphorus-31 magnetic resonance spectroscopy (31PMRS), which reveals information about those characteristics. METHODS: Ten patients with BMs were included in this trial. All underwent preoperative standard magnetic resonance imaging with additional 31PMRS. In all patients, 1 voxel within the contrast-enhancing tumor (CE+), 1 voxel at the border (including CE+ areas and surrounding T2-hyperintensive [T2+] areas), and 1 distant voxel purely including T2+ areas were determined by a neuroradiologist and a neurosurgeon. A frameless stereotactic biopsy was performed after craniotomy. Subsequently, the metabolites of the 31PMRS were analyzed and compared with the histopathologic results. RESULTS: Ratios, reflecting resynthesis (CE+/border/T2+: 1.109 ± 0.192/1.112 ± 0.158/1.083 ± 0.097), hydrolysis (0.303 ± 0.089/0.360 ± 0.122/0.321 ± 0.089), energy demand (4.227 ± 2.35/3.453 ± 1.284/3.599 ± 0.833), and membrane turnover (1.239 ± 0.2611/3.453 ± 1.284/3.599 ± 0.283) were calculated and compared intraindividually with a voxel from the contralateral side (resynthesis/hydrolysis/energy demand/membrane turnover: 1.063 ± 0.085/0.335 ± 0.073/3.317 ± 0.7573/0.784 ± 0.186), respectively. Resynthesis showed a trend toward higher ratios in CE+ and border biopsies without reaching statistical significances. This trend was also seen concerning energy demand. Membrane turnover was significantly higher in CE+, border zone, and also in the T2+ areas compared with controls (P > 0.001). CONCLUSIONS: 31PMRS in BMs provides information on metabolic changes in tumor and surrounding edema. There is proof of enhanced metabolism in tissue without histologic tumor manifestation.

Local recurrence of brain metastasis reduced by intra-operative hyperthermia treatment.

PURPOSE: Brain metastasis is a common complication in cancer patients. Local recurrence after total resection of metastatic brain tumor has been frequently reported. In this study, we developed a new hyperthermia device and applied it to metastatic brain tumor patients intra-operatively to study if hyperthermia treatment could reduce local tumor recurrence. MATERIALS AND METHODS: A total of 63 metastatic brain patients were enrolled in the study with an informed consent obtained from every patient. After total resection of the tumor, the hyperthermia device was applied intra-operatively to the resection cavity. The surrounding brain tissue at 5 mm in depth from the tumor resection margin was raised to 42.5 °C for a total of 60 minutes (Clinical Research Information Service Registration Number: KCT0001308). RESULTS: A total of 10 local recurrences were observed in 63 patients who received hyperthermia treatment showing a local recurrence rate of 15.8%. It was significantly lower than the local recurrence rate of those who received conventional treatment (34%) when analyzed with one tailed z-test (p value: .001). Kaplan-Meier analysis also showed a significantly lower recurrence rate in the hyperthermia treatment group (p value: .0003). Complications included two cases of seizures and two cases of wound infection. CONCLUSIONS: Results of this study suggest that intra-operative hyperthermia treatment after total resection of metastatic brain tumor could reduce local recurrence of tumor. We believe that intra-operative hyperthermia treatment could be used as an adjuvant therapy to surgery and post-operative radiotherapy, or as a salvage treatment in patients who cannot receive further radiotherapy.

Use of hyperbaric oxygen therapy in pediatric neuro-oncology: a single institutional experience.

INTRODUCTION: Hyperbaric oxygen therapy (HBOT) has been utilized as adjunctive treatment of CNS tumors and for radiation necrosis (RN) with reported success. The safety and efficacy in pediatric patients is less understood. METHODS: Seven patients (ages 10-23 years, six females) were treated with HBOT (3-60 sessions) for either RN (n = 5) or tumor-associated edema (n = 2). Tumor diagnosis included low-grade glioma (n = 4, two with neurofibromatosis type 1), meningioma (n = 1), medulloblastoma (n = 1) and secondary high grade glioma (n = 1). Prior therapies included: surgery (n = 4), chemotherapy (n = 4) and radiation (N = 5: four focal, one craniospinal). Three underwent biopsy: one confirming RN, one high-grade glioma, and one low-grade glioma. Patients were assessed for clinical and radiographic changes post HBOT. RESULTS: Median time to clinical and radiographic presentation was 8.5 months (range 6 months-11 years) in those who had prior radiation. Clinical improvement after HBOT (median: 40 sessions) was observed in four of seven patients. Symptoms were stable in two and worsened in one patient. Radiographic improvement was seen in four patients; three had radiographic disease progression. In the subgroup treated for presumed and biopsy-confirmed RN (n = 5), four of five (80%) had clinical and radiographic improvement. There were no long-term adverse events due to HBOT. CONCLUSIONS: HBOT is safe and well-tolerated in pediatric and young adult patients with CNS tumors. Clinical and radiographic improvements were observed in over half of patients. Clinical trials are needed to establish safety and efficacy of HBOT as adjunct therapy in pediatric CNS tumors.