Biomedical subjects

Chen-Nen Chang

Publications and source records attributed to Chen-Nen Chang.

At least 19 recordsLinked to original sources

PubMed2006

Intrasellar cavernous hemangioma.

Reports of intrasellar cavernous hemangioma are rare. They are usually incidental findings at autopsy, or initially mistaken for pituitary adenoma and treated accordingly. There are no specific symptoms. Cranial nerve palsy has occasionally been reported in patients with cavernous hemangioma, with or without sellar extension. However, intrasellar cavernous hemangioma with extension into the cavernous sinus resulting in oculomotor palsy has not been reported. We present a rare case of intrasellar cavernous hemangioma and discuss the diagnosis and management. Total surgical removal is recommended. However, attempts to resect the parasellar component of the lesion may be associated with high morbidity. Therefore, surgical cranial nerve decompression in the acute stage followed by stereotactic radiosurgery for the residual lesion may be an alternative.

Female↗

PubMed2006

Surgical treatment for severe visual compromised patients after pituitary apoplexy.

BACKGROUND: Pituitary apoplexy is a rare neurovascular insult. Early surgical decompression is the most effective treatment, especially for rapid deterioration of visual acuity or for altered consciousness. The timing of rapidly expanded mass was strongly related to the treatment outcome. METHODS: Thirteen patients who presented with severe visual defect after pituitary apoplexy were enrolled retrospectively. Six patients without severe underlying diseases were considered non-complicated and were treated early. Another seven patients who received delayed treatment after medical problems were stabilized and/or conservative management failed were considered to be complicated. The visual acuity of each individual eye was evaluated and organized into six grades based on visual acuity. Twelve patients received transsphenoidal surgery and one craniotomy was performed for tumor removal. RESULTS: The delay of surgical treatment was 3.5 days and 8.7 days in the two groups, respectively. Overall, 19 out of 26 eyes (73%) improved after surgery; 100% in non-complicated group and 50% in complicated group. The average grade of visual improvement was 2.66 vs. 0.71 by each individual eye, and the difference was statistically significant (P<0.000). The ratio of regained useful vision was significant in non-complicated patients (P<0.000). The incidence of requirement long-term hormone replacement was high in the complicated group (2/6 vs. 6/7). The resection rate was total in 8 patients, subtotal in 3, partial in 1, with one loss of image follow-up. CONCLUSIONS: Early decompression significantly improved visual outcomes and the need for hormone replacement was minimal. We postulated old age, underlying malignant diseases, and coagulation disorders played the predisposing factors of poor outcome in these cases.

Adenoma↗

PubMed2005

Dexamethasone enhances NT-3 expression in rat hippocampus after traumatic brain injury.

The cellular events in traumatic brain injury (TBI) are complicated, and the factors mediating neurotrophins to protect and repair the injured brain cells are only beginning to be identified. This study examined the effect of dexamethasone (DEX) on neurotrophin-3 (NT-3) expression following TBI. Levels of NT-3 mRNA and protein in rat hippocampus were measured using in situ hybridization and immunohistochemistry, respectively. After TBI, the NT-3 mRNA expression was down-regulated during the first 24 h. DEX reversed the post-traumatic reduction of NT-3 mRNA expression at 2, 4, 6, and 12 h in the hippocampus, and also decreased the cell death in hippocampal hilum and supraventricular cerebral cortex after 7 days. The NT-3 protein levels generally corresponded to the mRNA levels in the hippocampal region. DEX enhanced the NT-3 expression after TBI, indicating that post-traumatic neuroprotection in the hippocampus is at least partially mediated by NT-3 and thus can be modulated by DEX treatment.

Analysis of Variance↗

PubMed2005

Dexamethasone enhances upregulation of nerve growth factor mRNA expression in ischemic rat brain.

Nerve growth factor (NGF) is well-established as a trophic factor that plays a crucial role in neuroregeneration and plasticity after brain insults. Dexamethasone (DEX), a powerful glucocorticoid steroid, has long been used in the clinical management of neurological disorders. We examined the relationship between NGF and DEX after an ischemic insult to the brain. In situ hybridization was used to measure NGF mRNA expression in the rat hippocampus after 20 min of transient forebrain ischemia. Immunostaining for NGF protein was performed using the avidin-biotin peroxidase method. Immunohistochemistry for glial fibrillary acidic protein (GFAP) was also used to study the astrocyte reaction in the hippocampal CA1 area. Ischemic brain from rats not treated with DEX had a 2 and 3 fold increase in NGF mRNA compared to sham-operated rats at 4 and 6 h after ischemia, respectively. The NGF mRNA expression returned to basal levels 12 h to 7 days post-ischemia. Treatment with DEX potentiated the ischemia-induced increase of NGF mRNA to 4 times that of sham-operated rats at 6 h following reperfusion and NGF protein expression was similarly elevated. Additionally, the number of GFAP positive astrocytes in the CA1 region in the ischemic rats was markedly increased. These data suggest that DEX may play a role in modulating NGF mRNA expression in the hippocampal neuronal response to brain ischemia.

Animals↗

PubMed2004

Synaptic remodeling in the nucleus ambiguus following vagal-hypoglossal nerve anastomosis in the cat.

We reported recently the occurrence of a massive and selective elimination of synaptic boutons on motoneurons in the dorsal motor nucleus of the vagus (DMV) in the cat following vagal-hypoglossal nerve anastomosis (VHA) [J. Comp. Neurol. 458 (2003) 195]. This study was aimed to explore the synaptic reorganization in the other major nucleus associated with the vagus, namely, the nucleus ambiguus (NA) following the same treatment. In view of the tremendous difference in function, the NA and DMV are considered to be two ideal nuclei for explanatory studies seeking to elucidate how VHA could induce different plasticity of brainstem neurons influenced by the newly reestablished neural pathway. The present results showed that the vagal efferent neurons in the NA had responded to VHA in a different manner compared with those in the DMV. Firstly, the numbers of axon terminals containing round (R), round with dense-cored (R+D), pleomorphic (P) or flattened (F) synaptic vesicles contacting the NA motoneurons were markedly increased at 500-day postoperation, the longest reinnervation interval. The percent increases in the synapse frequency for R, R+D, P and F boutons were 8.6%, 274.4%, 238.3% and 400.0%, respectively. Secondly, the formation of astroglial ensheathment around the motoneurons in the DMV following VHA was not evident in the NA. Another striking difference was the extensive dendritic sprouting of the NA neurons as opposed to the dendritic retraction of the DMV neurons as shown by a significant increase in distal dendrites of NA motoneurons. The different modes of neural remodeling between NA and DMV may be attributed to the unique nature of the two nuclei to structures they normally supply and their different compatibility with the newly innervated target, viz. tongue skeletal musculature.

Anastomosis, Surgical↗

PubMed2004

Blood oxygenation level-dependent MRI of cerebral gliomas during breath holding.

PURPOSE: To assess the cerebrovascular responses to short breath holding of cerebral gliomas using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI). MATERIALS AND METHODS: Six patients with a low-grade glioma and one patient with a high-grade glioma were studied using T2*-weighted echo planar imaging (EPI) during repeated periods of 15-second or 20-second breath-holding. Tumor vascularity was evaluated using dynamic susceptibility contrast perfusion MRI. RESULTS: Increases in BOLD signal intensity during repeated breath-holding were consistently identified in patients' normal appearing gray matter, comparable with those in healthy adults. Absence of significant BOLD signal enhancement was noted both in low-grade and high-grade gliomas, which is either due to overwhelming hypoxia in a tumor, inadequacy or absence of hypercapnia-induced vasodilatation of tumor vessels, or both. Breath-hold regulated decreases in BOLD signals occurred only in the high-grade glioma, which is most likely due to the hypercapnia-induced steal effect that redistributes blood flow from tumor regions with unresponsive neovasculature to surrounding normal tissue. CONCLUSION: BOLD MRI during short breath holding can disclose differential cerebrovascular response between normal tissue and cerebral glioma.

Adult↗

PubMed2004

Linear accelerator-based radiosurgery in the management of skull base meningiomas.

From May 1994 to December 1999, 43 patients with meningiomas in the base of the skull underwent linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) at Chung Gung Memorial Hospital. SRS was performed as a primary treatment in 14 patients, and after resection in 29 patients. The mean tumor volume was 5.68 cc, and the mean target surface dose was 16 Gy, delivered with an average of three isocenters. The median follow-up was 74.5 months. The 7-year local control rate and 7-year overall survival rate were 89.7% and 80.2%, respectively. The 7-year local control was 100% and 84.4% in SRS alone group and surgical excision with SRS group (p = 0.21), respectively. A stationary tumor following SRS was seen in 23 (53.5%) patients, partial shrinkage was seen in 16 (37.2%) patients, and complete disappearance in one patient was seen (2.3%). Furthermore, disease progression was noted in three (7%) patients, one of whom died of disease. The median time to tumor response was 15.4 months (range 5.8-52.8 months). Cases remained stable or had improved neurological statuses without any deterioration in 37.9% and 78.7% of the groups treated with surgery and SRS and SRS alone, retrospectively. In summary, LINAC-based SRS is an effective and safe modality of treating unresectable or partially resected meningiomas in the base of the skull. For tumors with diameters of 3 cm or less, particularly in patients without or with minimal clinical neurological symptom, SRS alone can provide a good local control without causing cranial neuropathy.

Adult↗

PubMed2004

Proton magnetic resonance spectroscopic imaging of cerebral gliomas: correlation of metabolite ratios with histopathologic grading.

BACKGROUND: Magnetic resonance spectroscopic imaging (MRSI) can provide spatially encoded metabolite information and improve tissue specificity in human brains. The major goal of this study was to evaluate the correlation of metabolite ratios measured by MRSI with histopathological grading of cerebral gliomas. METHODS: Twenty-seven patients with cerebral gliomas were referred consecutively for pre-surgical evaluation. The lesions included 10 grade II, 5 grade III, and 12 grade IV gliomas. MRSI data were acquired during the same session of conventional magnetic resonance imaging and analyzed in terms of N-acetylaspartate (NAA), creatine-phosphocreatine (Cr), choline-containing compounds (Cho), and lactate. RESULTS: There were significantly lower NAA/Cr and higher Cho/Cr, Cho/NAA and (Cho+Cr)/NAA ratios (ps < 0.001) in gliomas than in normal tissues. There were significantly lower NAA/Cr and higher Cho/NAA and (Cho+Cr)/NAA ratios (ps < or = 0.05) in World Health Organization (WHO) grade III or IV gliomas than in grade II gliomas. A significant correlation was identified between the (Cho+Cr)/NAA ratio and WHO grade (p < 0.05). There was no significant metabolite difference between grade III and grade IV tumors (ps > 0.1), or significant difference in lactate occurrence rates among different grades (p = 0.26). CONCLUSIONS: Proton MRSI can provide in vivo information about the metabolic status of cerebral gliomas, and the (Cho+Cr)/NAA ratio can discriminate different grades better than other metabolite ratios. However, substantial overlap of metabolite ratios among different severities of malignancy makes it impossible to confirm the WHO grade of a specific cerebral glioma by using clinical MRSI.

Adolescent↗

PubMed2003

Sleep deprivation prior to transient global cerebral ischemia attenuates glial reaction in the rat hippocampal formation.

This study was aimed to ascertain the effect of sleep deprivation on subsequent cerebral ischemia in the rat hippocampal formation. Seven days after transient global cerebral ischemia induced by four-vessel occlusion method, most of the pyramidal cells in the hippocampal CA1 subfield underwent disruption and pyknosis as detected by cresyl violet staining. With OX-42, OX-18, OX-6 and ED1 immunohistochemistry, robust microglia/macrophage reactions were observed in the CA1 and dentate hilus. The majority of reactive microglia was rod-shaped, bushy or amoeboidic cells bearing hypertrophic processes. Astrocytes also displayed hypertrophic processes, whose immunostaining for glial fibrillary acidic protein was markedly enhanced. The ischemia-induced neuronal damage and glial reactions, however, were noticeably attenuated in rats subjected to pretreatment with sleep deprivation for five consecutive days. The most drastic effect was the diminution of OX-18, OX-6 and ED1 immunoreactivities, suggesting that the immune potentiality and/or phagocytosis of these cells was suppressed by prolonged sleep deprivation prior to ischemic insult. It is postulated that sleep deprivation may have a preconditioning influence on subsequent lethal cerebral ischemia. Hence, sleep deprivation may be considered as a therapeutic strategy in brain ischemic damage.

Animals↗

PubMed2003

Synaptic remodeling in the dorsal motor nucleus of the vagus nerve following vagal-hypoglossal nerve anastomosis in the cat.

Horseradish peroxidase (HRP) retrograde tracing techniques and morphometric analyses were performed to investigate synaptic remodeling associated with neuronal and glial changes in the dorsal motor nucleus of the vagus (DMV) of cats after vagal-hypoglossal nerve anastomosis (VHA). At 25 days postoperation (dpo), in the early target-reinnervation stage, there were 50% fewer presynaptic boutons containing round vesicles (R) or round and large dense-cored synaptic vesicles (R+D) contacting HRP-labeled DMV motoneurons. The loss of R boutons was maintained throughout the remaining postoperative intervals up to 500 dpo, whereas R+D boutons were further reduced at 123 dpo but were restored at 315 dpo, so that, by 500 dpo, 71.4% of them had gained access to the DMV motoneurons. Boutons containing pleomorphic synaptic vesicles (P) were completely disconnected from the DMV motoneurons at 25 dpo and did not reappear even in the long-term reinnervation stage. Loss and recovery of presynaptic boutons occurred in parallel with changes in astroglial ensheathment of the DMV motoneurons. It is suggested that synaptic remodeling associated with astroglial ensheathment in the DMV may be influenced by some retrogradely transported factors/signals derived from the newly acquired target organ, viz. tongue skeletal musculature. Our results further suggest that the observed changes in boutonal configurations may be attributable to modified functions of the DMV motoneurons induced by VHA.

Anastomosis, Surgical↗

PubMed2003

Preparation of epoxy-SiO2 hybrid sol-gel material for bone cement.

An organic-inorganic hybrid material, epoxy-SiO(2), was prepared by incorporating epoxy structure units covalently into a SiO(2) glass network via the sol-gel approach. The precursor was obtained by the reaction of diglycidyl ether of bisphenol A (DGEBA) with 3-aminopropyl trimethoxysilane (APTS). The precursor was then hydrolyzed and co-condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran (THF) at room temperature to yield epoxy-SiO(2) hybrid sol-gel material having a 50 wt % SiO(2) content. Thermal properties of the hybrid material were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hybrid sol-gel material epoxy-SiO(2) was the solid, powder component of bone cement. The liquid component contains bis-phenol-A glycidyl methacrylate (Bis-GMA), triethyleneglycol dimethacrylate (TEGDMA), and methyl methacrylate (MMA) with 25, 55, and 20 vol %, respectively. We discuss the comparison between the new epoxy-SiO(2) bone cement and the commercial Simplex P bone cement. Mechanical properties such as Young's modulus, compressive strength, hardness, and impact strength of the new epoxy-SiO(2) bone cement exceeded those of Simplex P bone cement. The tensile and bending strengths of the new epoxy-SiO(2) bone cement were approximately the same as those of Simplex P bone cement. In order to evaluate the biocompatibility of the new bone cement, an MTT test and optical microscopy were conducted in cell culture. Results indicated that the new epoxy-SiO(2) bone cement exhibits very low cytotoxicity compared with Simplex P bone cement.

Animals↗

PubMed2003

The use of the facial translocation technique in the management of tumors of the paranasal sinuses and skull base.

OBJECTIVE: We sought to assess the efficacy of facial translocation in the management of tumors of the skull base and paranasal sinuses. STUDY DESIGN AND SETTING: From July 1993 to December 1999, 75 patients, aged 3 to 102 years old, underwent facial translocation. Thirty-three (44%) patients also underwent a combined neurosurgical procedure. Nineteen (25%) had previous surgery. These patients were followed up to 6 years. RESULTS: There were 21 benign and 54 malignant tumors. There were no perioperative deaths. The morbidity rate was 31%. Of the 54 patients with malignant tumors, the actuarial 3-year survival rate was 59%, whereas the local control rate was 54%. CONCLUSION: The facial translocation technique offers favorable exposure of the critical zones of the anterior and middle cranial base, thus facilitating extensive resection and reconstruction. SIGNIFICANCE: This study demonstrates that facial translocation is one of the best surgical approaches to the skull base.

Adolescent↗

PubMed2003

High-dose-rate stereotactic brachytherapy for patients with newly diagnosed glioblastoma multiformes.

PURPOSE: To evaluate high-dose-rate (HDR) stereotactic brachytherapy (STBT) for glioblastoma multiforme (GBM). MATERIALS AND METHODS: Between August 1994 and December 1998, 28 patients with newly diagnosed GBM underwent surgery, external-beam radiotherapy (EBRT) and HDR STBT. STBT eligibility criteria included unifocal lesions, residual tumor < or = 6 cm in maximum diameter, supratentorial lesions, tumors not crossing the midline, tumors without subependymal spread and Karnofsky performance status (KPS) > 60. STBT was delivered over five consecutive days with two fractions per day for a total median dose of 30 Gy. Twenty-eight STBT eligible GBM patients treated with surgery and EBRT only over the same period were matched controls. RESULTS: Median survival times for the STBT group and controls were 19.5 versus 12.5 months; one and two year survival rates were 89% versus 42% and 61% versus 28%, respectively (p = 0.12). Using multivariate analysis, age, KPS and HDR STBT were significant factors predicting survival. By RPA class, 2-year survival rates for STBT and controls were: III--78% versus 50%; IV--40% versus 0%; V--21% versus 15%, respectively. Corresponding median survival times in months were: 41.6 versus 21.2 (p = 0.39); 16.7 versus 12.1 (p = 0.36); 18.7 versus 10.6 (p = 0.02). No major complications were found in the STBT arm. CONCLUSIONS: Because of small patient numbers, median survival time increases were only statistically significant in the RPA Class V patients, but a strong survival time trend emerged favoring patients undergoing HDR STBT. Further prospective study is warranted to fully assess the merits of this technique for GBM management.

Adolescent↗

PubMed2003

Sleep deprivation inhibits expression of NADPH-d and NOS while activating microglia and astroglia in the rat hippocampus.

This study investigated the expression of nitric oxide (NO)-synthesizing enzymes and the glial reaction in the rat hippocampal formation following sleep deprivation for 5 days. Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity was markedly reduced in the hippocampal CA1, CA2 and CA3 sectors as well as in the dentate gyrus, suggesting a suppression of NO production in these areas. Microglial cells were hypertrophic and showed an up-regulation of complement type 3 receptors as determined by antibody OX-42. However, expression of major histocompatibility complex class I and II antigens, and antigen of monocyte/macrophage lineage marked by OX-18, OX-6 and ED1, respectively, was undetected. Astrocytes also displayed hypertrophied processes with enhanced glial fibrillary acidic protein (GFAP) immunoreactivity. Western blots of hippocampal tissues corroborated the above-mentioned morphological findings in that expression of NO-synthase (NOS) was decreased while that of OX-42 and GFAP was increased in the sleep-deprived rats. Since NO is thought to be involved in memory consolidation processes in the hippocampus during sleep, the inhibition of NADPH-d and NOS reactivities may account for the memory decline after long-term sleep deprivation. The concomitant reactions in microglia and astrocytes suggest the involvement of these cells in the deleterious effect of prolonged sleep deprivation.

Animals↗

PubMed2002

Salvage surgery for recurrent nasopharyngeal carcinoma.

OBJECTIVE: To evaluate the results of salvage surgery for patients with primary recurrence of nasopharyngeal carcinoma after radiotherapy. DESIGN: Cohort study. SETTING: Academic tertiary referral center. PATIENTS: Eighteen consecutive patients with primary recurrence of nasopharyngeal carcinoma after radiation failure underwent nasopharyngectomy for cure via a facial translocation approach from July 1, 1993, to December 31, 1999. Follow-up ranged from 3 to 71 months. Five patients with skull base invasion required a combined neurosurgical approach to treatment. Seven patients had additional postoperative radiotherapy. RESULTS: The actuarial 3-year survival was 57%, while the local control was 78%. Four of 5 patients who had skull base invasion achieved local control. There was no surgical mortality, and the morbidity was 22%. CONCLUSION: Advances in skull base surgery make possible the effective control of primary recurrence of nasopharyngeal carcinoma, with acceptable mortality and morbidity.

Adult↗

PubMed2002

Stereotactic radiosurgery for locally recurrent nasopharyngeal carcinoma.

BACKGROUND: Stereotactic radiosurgery has been used to treat intracranial tumors. Recently, it has also been used for the treatment of head and neck tumors involving the base of skull, including recurrent NPC. METHODS: From October 1994 to April 1999, 36 patients with recurrent NPC, were retreated by stereotactic radiosurgery. These patients received radiosurgery as a boost treatment after reirradiation for recurrence. The external RT dose ranged from 20 to 60 Gy. The tumor volume ranged from 3.58 to 24.6 cc. The target surface dose ranged from 8 to 20 Gy. The median follow-up was 22.1 months. RESULTS: The 3-year local control rate was 56%. The 5-year overall survival was 49%. Persistence after radiosurgery had a worse survival than those who had secondary recurrence. Age and gender were marginally significant. No patient had new severe complications after retreatment. Four patients (11%) had nasopharyngeal necrosis after radiosurgery, none had nasal bleeding or headache, but a foul odor was present in one patient. CONCLUSIONS: Conformal radiotherapy and stereotactic radiotherapy provide good local control and survival without severe complications for patients with recurrent NPC.

Adult↗

PubMed2002

Effect of dexamethasone on the expression of brain-derived neurotrophic factor and neurotrophin-3 messenger ribonucleic acids after forebrain ischemia in the rat.

OBJECTIVE: To determine whether a large dose of dexamethasone affected brain damage induced by concurrent cerebral ischemia, we used in situ hybridization to examine the expression of brain-derived neurotrophic factor and neurotrophin-3 messenger ribonucleic acids (mRNAs) in rats with and without dexamethasone administration after transient forebrain ischemia. DESIGN: Prospective experimental study in rats. SETTING: Experimental laboratory in a teaching hospital and university. SUBJECTS: Eighty adult rats. INTERVENTIONS: Twenty minutes of transient forebrain ischemia was induced by occlusion of four vessels in lightly anesthetized rats. Thirty-six animals received dexamethasone (15 mg/kg, intraperitoneally) after initial reperfusion. Thirty-six dexamethasone-control rats were injected with saline, and the remaining animals underwent sham surgery but no ischemia or dexamethasone. MEASUREMENTS AND MAIN RESULTS: Using in situ hybridization, we determined hippocampal brain-derived neurotrophic factor and neurotrophin-3 mRNA expression 2, 4, 6, 12, and 24 hrs and 2, 3, 4, and 7 days after brain ischemia. Additionally, hippocampal CA1 region cell death was measured with Nissl stains. Both brain-derived neurotrophic factor and neurotrophin-3 mRNA exhibited a biphasic response after ischemia. Brain-derived neurotrophic factor mRNA showed two peaks of 4.07-fold and 2.84-fold increases relative to sham operation at 6 hrs and 2 days, respectively. Neurotrophin-3 mRNA initially decreased to 59% of sham levels at 4 hrs and then increased to 146% at 3 days before it returned to basal levels. When the ischemic rats were treated with dexamethasone, the elevation of brain-derived neurotrophic factor mRNA and the reduction of neurotrophin-3 mRNA level were prevented within the first 24 hrs, and hippocampal CA1 neurons were protected from ischemia-induced cell loss 7 days after brain ischemia. The protein levels of both brain-derived neurotrophic factor and neurotrophin-3 in general correspond to the mRNA levels in the hippocampal region. CONCLUSIONS: Dexamethasone modulates the intriguing temporal and spatial expression of brain-derived neurotrophic factor and neurotrophin-3 that predominantly supports neuronal innervation at different times after brain ischemia and also may provide specific trophic support for various neurons in the central nervous system.

Animals↗

PubMed2002

Fourth ventricle central neurocytoma: case report.

OBJECTIVE AND IMPORTANCE: Central neurocytomas (CNs) are typically located in the lateral ventricle. Primary origins in the fourth ventricle are very rare. We discuss the clinical symptoms, imaging findings, and microscopic features of these rare tumors. CLINICAL PRESENTATION: We report a case of a fourth ventricle CN in a 35-year-old male patient with the initial symptoms of progressive headaches and blurred vision for more than 2 months. Computed tomography and magnetic resonance imaging of the brain revealed a slightly enhanced tumor in the fourth ventricle, with obstructive hydrocephalus. INTERVENTION: Total surgical removal of the tumor was performed. The tumor was initially diagnosed as an oligodendroglioma. The final definitive diagnosis as a CN was made after special immunohistochemical studies. CONCLUSION: CNs located in the fourth ventricle are extremely rare. Immunohistochemical stains and transmission electron microscopy can provide useful diagnostic information. Total tumor excision is associated with favorable prognoses. Postoperative radiotherapy may be considered for cases of subtotal excision, anaplastic histological variants, or recurrent tumors.

Cerebral Ventricle Neoplasms↗