[Show abstract][Hide abstract] ABSTRACT: We investigated the effect of chemoradiotherapy with PP2 and temozolomide (TMZ) on malignant glioma cells using clonogenic assays and in vivo brain tumor model.
The effect of PP2 on radiosensitivity of U251 and T98G cells was investigated using clonogenic assays. The expression of E-cadherin, MMP2, EphA2, and VEGF was measured by Western blotting and an accumulation of γH2AX foci 6 h after radiotherapy was measured after PP2 treatment. The effect of PP2 on migration, invasion, and vasculogenic mimicry formation (VMF) of U251 cells was evaluated. In an orthotopical brain tumor model with U251 cells, PP2 was injected intraperitoneally with or without oral TMZ before, during and after whole brain radiotherapy. Bioluminescence images were taken to visualize in vivo tumors and immunohistochemical staining of VEGF, CD31, EphA2, and HIF1a was performed.
PP2 increased radiosensitivity of U251 and T98G cells without decreasing survival of normal human astrocytes. Chemoradiotherapy with PP2 and TMZ resulted in increased accumulation of γH2AX foci. PP2 induced overexpression of E-cadherin and suppression of MMP2, VEGF, and EphA2. PP2 also compromised invasion, migration, and VMF of U251 cells. In brain tumors, chemoradiotherapy with PP2 and TMZ decreased tumor volume best, but not statistically significantly compared with chemoradiotherapy with TMZ. The expression of VEGF and CD31 was suppressed in PP2-treated tumors.
s PP2 enhances radiosensitivity of malignant glioma cells and suppresses invasion and migration of U251 cells. Chemoradiotherapy with PP2 and TMZ resulted in non-significant tumor volume decrease.
Cancer Research and Treatment 06/2015; DOI:10.4143/crt.2014.320 · 2.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intracerebral hemorrhage (ICH) is one of the devastating types of stroke. Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have potential benefits in recovery from brain damage following ICH. This study aimed to identify the beneficial effects of hUCB-MSCs and investigate whether they have anti-inflammatory effects on the ICH brain via neurotrophic factors or cytokines. hUCB-MSCs were transplanted into a collagenase-induced ICH rat model. At 2, 9, 16, and 30 days after ICH, rotarod and limb placement tests were performed to measure behavioral outcomes. ICH rats were sacrificed to evaluate the volume of lesion using H&E staining. Immunostaining was performed to investigate neurogenesis, angiogenesis, and anti-apoptosis at 4 weeks after transplantation. Inflammatory factors (TNF-α, COX-2, microglia, and neutrophils) were analyzed by immunofluorescence staining, RT-PCR, and Western blot at 3 days after transplantation. hUCB-MSCs were associated with neurological benefits and reduction in lesion volume. The hUCB-MSCs-treated group tended to reveal high levels of neurogenesis, angiogenesis, and anti-apoptosis (significant for angiogenesis). The expression levels of inflammatory factors tended to be reduced in the hUCB-MSCs-treated group compared with the controls. Our study suggests that hUCB-MSCs may improve neurological outcomes and modulate inflammation-associated immune cells and cytokines in ICH-induced inflammatory responses.
[Show abstract][Hide abstract] ABSTRACT: Parkinson's disease (PD) is characterized by the selective loss of dopaminergic neurons of the substantia nigra pars compacta (SNc) with motor and nonmotor symptoms. Defective mitochondrial function and increased oxidative stress (OS) have been demonstrated as having an important role in PD pathogenesis, although the underlying mechanism is not clear. The etiopathogenesis of sporadic PD is complex with variable contributions of environmental factors and genetic susceptibility. Both these factors influence various mitochondrial aspects, including their life cycle, bioenergetic capacity, quality control, dynamic changes of morphology and connectivity (fusion, fission), subcellular distribution (transport), and the regulation of cell death pathways. Mitochondrial dysfunction has mainly been reported in various non-dopaminergic cells and tissue samples from human patients as well as transgenic mouse and fruit fly models of PD. Thus, the mitochondria represent a highly promising target for the development of PD biomarkers. However, the limited amount of dopaminergic neurons prevented investigation of their detailed study. For the first time, we established human telomerase reverse transcriptase (hTERT)-immortalized wild type, idiopathic and Parkin deficient mesenchymal stromal cells (MSCs) isolated from the adipose tissues of PD patients, which could be used as a good cellular model to evaluate mitochondrial dysfunction for the better understanding of PD pathology and for the development of early diagnostic markers and effective therapy targets of PD. In this review, we examine evidence for the roles of mitochondrial dysfunction and increased OS in the neuronal loss that leads to PD and discuss how this knowledge further improve the treatment for patients with PD.
[Show abstract][Hide abstract] ABSTRACT: Subthalamic deep brain stimulation (STN DBS) is an established treatment for the motor symptoms in patients with advanced Parkinson's disease (PD). In addition to improvements in motor symptoms, many studies have reported changes in various nonmotor symptoms (NMSs) after STN DBS in patients with PD. Psychiatric symptoms, including depression, apathy, anxiety, and impulsivity, can worsen or improve depending on the electrical stimulation parameters, the locations of the stimulating contacts within the STN, and changes in medications after surgery. Global cognitive function is not affected by STN DBS, and there is no increase in the incidence of dementia after STN DBS compared to that after medical treatment, although clinically insignificant declines in verbal fluency have been consistently reported. Pain, especially PD-related pain, improves with STN DBS. Evidence regarding the effects of STN DBS on autonomic symptoms and sleep-related problems is limited and remains conflicting. Many symptoms of nonmotor fluctuations, which are occasionally more troublesome than motor fluctuations, improve with STN DBS. Although it is clear that NMSs are not target symptoms for STN DBS, NMSs have a strong influence on the quality of life of patients with PD, and clinicians should thus be aware of these NMSs when deciding whether to perform surgery and should pay attention to changes in these symptoms after STN DBS to ensure the optimal care for patients.
[Show abstract][Hide abstract] ABSTRACT: Intracranial arteriovenous malformations (AVMs) display venous signals on arterial spin labeling (ASL) magnetic resonance (MR) imaging due to the presence of arteriovenous shunting. Our aim was to quantitatively correlate AVM signal intensity on ASL with the degree of arteriovenous shunting estimated on digital subtraction angiography (DSA) in AVMs.
MR imaging including pseudo-continuous ASL at 3 T and DSA were obtained on the same day in 40 patients with intracranial AVMs. Two reviewers assessed the nidus and venous signal intensities on ASL images to determine the presence of arteriovenous shunting. Interobserver agreement on ASL between the reviewers was determined. ASL signal intensity of the AVM lesion was correlated with AVM size and the time difference between normal and AVM venous transit times measured from the DSA images.
Interobserver agreement between two reviewers for nidus and venous signal intensities was excellent (κ = 0.80 and 1.0, respectively). Interobserver agreement regarding the presence of arteriovenous shunting was perfect (κ = 1.0). AVM signal intensity showed a positive relationship with the time difference between normal and AVM venous transit times (r = 0.638, P < 0.001). AVM signal intensity also demonstrated a positive relationship with AVM size (r = 0.561, P < 0.001).
AVM signal intensity on ASL in patients with AVM correlates well with the degree of early vein opacification on DSA, which corresponds to the degree of arteriovenous shunting.
[Show abstract][Hide abstract] ABSTRACT: Pain is a common and distressing feature in Parkinson disease (PD). The major indication of subthalamic nucleus deep brain stimulation (STN DBS) is motor complications in advanced PD; however, pain reduction after STN DBS has been noted.
To evaluate the long-term effect of STN DBS on pain in PD.
Twenty-four patients who underwent STN DBS at the Movement Disorder Center at Seoul National University Hospital from June 1, 2005, through March 31, 2006, were studied. The assessments of pain were performed preoperatively and 8 years after surgery. Because 13 of the total 24 patients had additional 2-year postoperative data, the serial change between the preoperative and the 2- and 8-year follow-ups after surgery was also evaluated.
Motor symptoms were assessed using the Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr staging scale. The severity of pain was scored according to an ordinal scale ranging from 0 (absent) to 10 (maximal pain) in 7 parts of the body (head, neck, trunk, and the upper and lower extremities on each side of the body). For each body part, the quality of pain was grouped into 1 of 4 categories: dystonic, musculoskeletal, radiculoneuritic, and central.
Sixteen of the 24 patients (67%) experienced pain at baseline when not taking medication (off-state). All off-state pain at baseline improved or disappeared at 8 years after surgery. The number of body parts with pain was 21 at baseline and decreased to 11 at 8 years after the surgery. The mean (SD) and median scores of the off-state pain were 6.2 (2.5) and 7.0 at baseline and improved to 3.5 (2.2) and 2.5 at 8 years after the surgery, respectively. However, new pain developed in 18 of 24 patients (75%) during the 8-year follow-up period. The number of body parts with newly developed pain was 47, and the mean (SD) and median scores for new pain were 4.4 (3.0) and 3.0, respectively. The types of new pain at 8 years were musculoskeletal in 11 patients, central in 4 patients, radiculoneuritic in 3 patients, and dystonic in 1 patient.
Pain associated with PD is improved by STN DBS, and the beneficial effect persists after a long-term follow-up of 8 years. In addition, new pain, especially the musculoskeletal type, developed in most patients, becoming a long-term distressing problem.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study to develop new deep-brain stimulation system for long-term use in animals, in order to develop a variety of neural prostheses.
Our system has two distinguished features, which are the fully implanted system having wearable wireless power transfer and ability to change the parameter of stimulus parameter. It is useful for obtaining a variety of data from a long-term experiment.
To validate our system, we performed pre-clinical test in Parkinson's disease-rat models for 4 weeks. Through the in vivo test, we observed the possibility of not only long-term implantation and stability, but also free movement of animals. We confirmed that the electrical stimulation neither caused any side effect nor damaged the electrodes.
We proved possibility of our system to conduct the long-term pre-clinical test in variety of parameter, which is available for development of neural prostheses.
Journal of Korean Neurosurgical Society 03/2015; 57(3):152-8. DOI:10.3340/jkns.2015.57.3.152 · 0.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Successful recovery from brain ischemia is limited due to poor vascularization surrounding the ischemic zone. Cell therapy with strong angiogenic factors could be an effective strategy to rescue the ischemic brain. We investigated whether cartilage oligomeric matrix protein (COMP)-Ang1, a soluble, stable and potent Ang1 variant, enhances the angiogenesis of human cord blood derived endothelial progenitor cells (hCB-EPCs) for rescuing brain from ischemic injury. COMP-Ang1 markedly improved the tube formation of capillaries by EPCs and incorporation of EPCs into tube formation with human umbilical vein endothelial cells (HUVECs) upon incubation on matrigel in vitro. COMP-Ang1 stimulated the migration of EPCs more than HUVECs in a scratch wound migration assay. The transplanted EPCs and COMP-Ang1 were incorporated into the blood vessels and decreased the infarct volume in the rat ischemic brain. Molecular studies revealed that COMP-Ang1 induced an interaction between Tie2 and FAK, but AKT was separated from the Tie2-FAK-AKT complex in the EPC plasma membrane. Tie2-FAK increased pp38, pSAPK/JNK, and pERK-mediated MAPK activation and interacted with integrins ανβ3, α4, β1, finally leading to migration of EPCs. AKT recruited mTOR, SDF-1, and HIF-1α to induce angiogenesis. Taken together, it is concluded that COMP-Ang1 potentiates the angiogenesis of EPCs and enhances the vascular morphogenesis indicating that combination of EPCs with COMP-Ang1 may be a potentially effective regimen for ischemic brain injury salvage therapy.
[Show abstract][Hide abstract] ABSTRACT: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is widely used in the treatment of Parkinson’s disease. DBS surgery is usually performed with the patient under local anesthesia (LA). However, a number of patients do not tolerate LA due to anxiety or severe pain. These patients require surgery under sedation or general anesthesia. Unfortunately, anesthetic drugs interfere with the intraoperative microelectrode recordings. A debate regarding the usefulness of sedation or general anesthesia during DBS surgery is still in progress. In this study, we evaluated whether the differences in anesthetic methods affect STN single-unit activity and movement symptoms of Parkinson’s disease. Eight patients underwent surgery to implant bilateral STN DBS electrodes. Our study compares STN single-unit activity under both LA and monitored anesthesia care (MAC) in the same patients as well as movement symptoms of Parkinson’s disease. The primary results revealed no significant difference in the mean firing rate of STN single-unit activity under LA and MAC. However, there were differences in the spike characteristics and firing patterns of STN activity between the two anesthetic methods. These findings contribute valuable insight into the effects of different anesthetic methods on STN single-unit activity for precise electrode localization during DBS surgery.
International Journal of Precision Engineering and Manufacturing 03/2015; 16(3):573-579. DOI:10.1007/s12541-015-0077-2 · 1.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECT There is inconsistency among the perioperative management strategies currently used for chronic subdural hematoma (cSDH). Moreover, postoperative complications such as acute intracranial bleeding and cSDH recurrence affect clinical outcome of cSDH surgery. This study evaluated the risk factors associated with acute intracranial bleeding and cSDH recurrence and identified an effective perioperative strategy for cSDH patients. METHODS A retrospective study of patients who underwent bur hole craniostomy for cSDH between 2008 and 2012 was performed. RESULTS A consecutive series of 303 cSDH patients (234 males and 69 females; mean age 67.17 years) was analyzed. Postoperative acute intracranial bleeding developed in 14 patients (4.57%) within a mean of 3.07 days and recurrence was observed in 37 patients (12.21%) within a mean of 31.69 days (range 10-104 days) after initial bur hole craniostomy. The comorbidities of hematological disease and prior shunt surgery were clinical factors associated with acute bleeding. There was a significant risk of recurrence in patients with diabetes mellitus, but recurrence did not affect the final neurological outcome (p = 0.776). Surgical details, including the number of operative bur holes, saline irrigation of the hematoma cavity, use of a drain, and type of postoperative ambulation, were not significantly associated with outcome. However, a large amount of drainage was associated with postoperative acute bleeding. CONCLUSIONS Bur hole craniostomy is an effective surgical procedure for initial and recurrent cSDH. Patients with hematological disease or a history of prior shunt surgery are at risk for postoperative acute bleeding; therefore, these patients should be carefully monitored to avoid overdrainage. Surgeons should consider informing patients with diabetes mellitus that this comorbidity is associated with an increased likelihood of recurrence.
Journal of Neurosurgery 02/2015; 123(1):1-10. DOI:10.3171/2014.12.JNS141189 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Identifying a neural circuit mechanism that is differentially involved in tremor would aid in the diagnosis and cure of such cases. Here, we demonstrate that tremor-related cortical potential (TRCP) is differentially expressed in two different mouse models of tremor.ResultsHybrid tremor analysis of harmaline-induced and genetic tremor in mice revealed that two authentic tremor frequencies for each type of tremor were conserved and showed an opposite dependence on CaV3.1 T-type Ca2+ channels. Electroencephalogram recordings revealed that a1-/-;a1G-/- mice double-null for the GABA receptor a1 subunit (Gabra1) and CaV3.1 T-type Ca2+ channels (Cacna1g), in which the tremor caused by the absence of Gabra1 is potentiated by the absence of Cacna1g, showed a coherent TRCP that exhibited an onset that preceded the initiation of behavioral tremor by 3 ms. However, harmaline-induced tremor, which is known to be abolished by a1G-/-, showed no TRCP.Conclusions
Our results demonstrate that the a1-/-;a1G-/- double-knockout tremor model is useful for studying cortical mechanisms of tremor.
[Show abstract][Hide abstract] ABSTRACT: Urokinase plasminogen activator (uPA) and urokinase plasminogen activator receptor (uPAR) play a major role in the infiltrative growth of glioblastoma. Downregulatoion of the uPA and uPAR has been reported to inhibit the growth glioblastoma. Here, we demonstrate that tristetraprolin (TTP) inhibits the growth of U87MG human glioma cells through downregulation of uPA and uPAR. Our results show that expression level of TTP is inversely correlated with those of uPA and uPAR in human glioma cells and tissues. TTP binds to the AU-rich elements within the 3' untranslated regions of uPA and uPAR and overexpression of TTP decreased the expression of uPA and uPAR through enhancing the degradation of their mRNAs. In addition, overexpression of TTP inhibited the growth and invasion of U87MG cells. Our findings implicate that TTP can be used as a promising therapeutic target to treat human glioma.
[Show abstract][Hide abstract] ABSTRACT: Pompe disease, an inherited deficiency of lysosomal acid alpha-glucosidase (GAA), is a metabolic myopathy with heterogeneous clinical presentations. Late-onset Pompe disease (LOPD) is a debilitating progressive muscle disorder that can occur anytime from early childhood to late adulthood. Enzyme replacement therapy (ERT) with recombinant human GAA is currently available for Pompe patients. Although ERT shows some benefits, the reversal of skeletal muscle pathology - lysosomal glycogen accumulation and autophagic buildup - remains a challenge. In this study, we examined the clinical status and muscle pathology of 22 LOPD patients and one atypical infantile patient on ERT to understand the reasons for muscle resistance to ERT.
The patients were divided into three groups for analysis, based on the age of onset and diagnosis: adult-onset patients, juvenile-onset patients, and those identified through newborn screening (NBS). The areas of autophagic buildup found in patients’ biopsies of all three groups, contained large autofluorescent inclusions which we show are made of lipofuscin, an indigestible intralysosomal material typically associated with ageing. These inclusions, analysed by staining, spectral analysis, time-resolved Fluorescence Lifetime Imaging (FLIM), and Second Harmonic Generation (SHG) imaging, were the major pathology remaining in many fibers after ERT. The best outcome of ERT both clinically and morphologically was observed in the NBS patients.
The muscle biopsy, in spite of its shortcomings, allowed us to recognize an underreported, ERT-resistant pathology in LOPD; numerous lysosomes and autolysosomes loaded with lipofuscin appear to be a hallmark of LOPD skeletal muscle. Lipofuscin accumulation - a result of inefficient lysosomal degradation - may in turn exacerbate both lysosomal and autophagic abnormalities.
[Show abstract][Hide abstract] ABSTRACT: Objective
While several prognostic models have been presented in NSCLC patients with brain metastasis, none of these models have included molecular markers as an index. The aim of our study was to evaluate the prognostic value of EGFR mutations and to integrate these EGFR mutations into the prognostic index in NSCLC patients with brain metastasis.
Materials and Methods
We analyzed retrospectively 292 lung adenocarcinoma patients with brain metastasis. Clinico-pathological features and overall survival (OS) were compared between patients with EGFR mutations and patients with EGFR wild type. EGFR mutation status was integrated with lung specific Graded Prognostic Assessment (GPA) score.
Among 292 patients, EGFR mutation status was tested in 183 patients. One hundred and five patients (57.4%) had EGFR activating mutations, 14 (7.7%) had EGFR non-activating mutations and 64 (35.0%) had EGFR wild type. OS was significantly longer in patients with EGFR activating mutations than in those with EGFR wild type patients (20.4 vs. 10.1 months, p = 0.002). However, patients with EGFR non-activating mutations did not show superior OS compared with EGFR wild type patients (14.6 vs. 10.1 months, p = 0.83). Multivariate analysis revealed that the presence of EGFR activating mutation is an independent positive prognostic factor for OS (adjusted hazard ratio 0.56, p = 0.002).
EGFR activating mutations have a prognostic role in lung adenocarcinoma patients with brain metastasis that is independent of other known prognostic factors. The frequency of EGFR mutation was higher than expected. The presence of EGFR activating mutations should be included as an index in the prognostic models for lung adenocarcinoma patients with brain metastasis.
Lung Cancer 10/2014; 86(3). DOI:10.1016/j.lungcan.2014.10.001 · 3.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Destruction of dopaminergic neurons in the substantia nigra pars compacta (SNpc) is a common pathophysiology of Parkinson's disease (PD). Characteristics of PD patients include bradykinesia, muscle rigidity, tremor at rest and disturbances in balance. For about four decades, PD animal models have been produced by toxin-induced or gene-modified techniques. However, in mice, none of the gene-modified models showed all 4 major criteria of PD. Moreover, distinguishing between PD model pigs and normal pigs has not been well established. Therefore, we planned to produce a pig model for PD by chronic subcutaneous administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), neurotoxin. Changes in behavioral patterns of pigs were thoroughly evaluated and a new motor scoring system was established for this porcine model that was based on the Unified Parkinson's Disease Rating Scale (UPDRS) in human PD patients. In summary, this motor scoring system could be helpful to analyze the porcine PD model and to confirm the pathology prior to further examinations, such as positron emission tomography-computed tomography (PET-CT), which is expensive, and invasive immunohistochemistry (IHC) of the brain.
[Show abstract][Hide abstract] ABSTRACT: We investigated the effect of propofol and fentanyl on microelectrode recording (MER) and its clinical applicability during subthalamic nucleus (STN) deep brain stimulation (DBS) surgery. We analyzed 8 patients with Parkinson's disease, underwent bilateral STN DBS with MER. Their left sides were done under awake and then their right sides were done with a continuous infusion of propofol and fentanyl under local anesthesia. The electrode position was evaluated by preoperative MRI and postoperative CT. The clinical outcomes were assessed at six months after surgery. We isolated single unit activities from the left and the right side MERs. There was no significant difference in the mean firing rate between the left side MERs (38.7±16.8 spikes/sec, n=78) and the right side MERs (35.5±17.2 spikes/sec, n=66). The bursting pattern of spikes was more frequently observed in the right STN than in the left STN. All the electrode positions were within the STNs on both sides and the off-time Unified Parkinson's Disease Rating Scale part III scores at six months after surgery decreased by 67% of the preoperative level. In this study, a continuous infusion of propofol and fentanyl did not significantly interfere with the MER signals from the STN. The results of this study suggest that propofol and fentanyl can be used for STN DBS in patients with advanced Parkinson's disease improving the overall experience of the patients.
Journal of Korean Medical Science 09/2014; 29(9):1278-86. DOI:10.3346/jkms.2014.29.9.1278 · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A 45-yr-old female patient was admitted with one-month history of headache and progressive left hemiparesis. Brain magnetic resonance imaging (MRI) demonstrated a mass lesion in her right frontal lobe. Her brain tumor was confirmed as a small cell glioblastoma. Her follow-up brain MRI, taken at 8 months after her initial surgery demonstrated tumor recurrence in the right frontal lobe. Contrast-enhanced 7.0T brain magnetic resonance imaging (MRI) was safely performed before surgery and at the time of recurrence. Compared with 1.5T and 3.0T brain MRI, 7.0T MRI showed sharpened images of the brain tumor contexture with detailed anatomical information. The fused images of 7.0T and 1.5T brain MRI taken at the time of recurrence demonstrated no significant discrepancy in the positions of the anterior and the posterior commissures. It is suggested that 7.0T MRI can be safely utilized for better images of the maligant gliomas before and after surgery.
Journal of Korean Medical Science 07/2014; 29(7):1012-7. DOI:10.3346/jkms.2014.29.7.1012 · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Object Neurofibromatosis Type 2 (NF2) is an autosomal-dominant inherited disease, characterized by multiple neoplasia syndromes, including meningioma, schwannoma, glioma, and ependymoma. In this report, the authors present their clinical experience with pediatric NF2 patients. In particular, they focused on the clinical course of vestibular schwannoma (VS), including the natural growth rate, tumor control, and functional hearing outcomes. Methods From May 1988 to June 2012, the authors recruited patients who were younger than 18 years and fulfilled the Manchester criteria. In total, 25 patients were enrolled in this study. The authors analyzed the clinical course of these patients. In addition, they measured the natural growth rate of VS before any treatment in these children with NF2. Then, they evaluated the tumor control rate and functional hearing outcomes after the treatment of VS. Results The mean age at the onset of NF2-related symptoms was 9.9 ± 4.5 years (mean ± SD, range 1-17 years). The mean age at the diagnosis of NF2 was 12.9 ± 2.9 years (range 5-17 years). The mean follow-up period was 89.3 months (range 12-311 months). As initial manifestations, nonvestibular symptoms were frequently observed in pediatric patients with NF2. The mean natural growth rate of VS was 0.33 ± 0.41 cm(3)/year (range 0-1.35 cm(3)/year). The tumor control rate of VS was 35.3% at 3 years after Gamma Knife surgery (GKS). The actuarial rate of useful hearing preservation was 67% in the 1st year and 53% in the 5th year after GKS. Conclusions Clinical manifestations in children with NF2 were highly variable, compared with their adult counterparts. The natural growth rate of VS in children is slow, and this oncological feature may explain the diverse clinical manifestations besides vestibular symptoms in children with NF2. The treatment outcome of GKS for VS in children with NF2 was not favorable compared with previous reports of affected adults.