Macrovascular Decompression with the Transposition Method Using Teflon Sling for Trigeminal Neuralgia Caused by the Vertebrobasilar Artery.

OBJECTIVE: Complete separation of the vertebrobasilar artery (VBA) from the trigeminal nerve by microvascular decompression is technically challenging. This paper evaluates the transposition method using Teflon sling for trigeminal neuralgia (TN) caused by the VBA. METHODS: Retrospective review of 32 patients including 2 patients with tic convulsif. Mobilization of the VBA in the anteromedial-caudal direction and repositioning of the VBA using Teflon sling and fibrin glue were performed. Pre- and postoperative pain were evaluated with the Barrow Neurological Institute (BNI) pain intensity score. Duration of surgery and postoperative neurologic complications were reviewed. RESULTS: Preoperative BNI score ranged from III to V. Postoperative BNI score I was observed in 30 patients, II in 1 patient, and V in 1 patient as recurrence. Abducens nerve palsy was observed in 9 patients but was transient in 8. Permanent hearing loss was observed in 6 patients. Transient mild lower cranial nerve palsy was recorded in 2 patients with tic convulsif. Average surgical time was 290 minutes. CONCLUSIONS: Our method for trigeminal neuralgia caused by VBA was very effective, but the complication rate of cranial nerve disorders was also high. A high rate of complications implied the technical difficulty of extensive vascular mobilization requiring long duration of surgery. Macrovascular decompression surgery is more descriptive of this surgery instead of microvascular decompression surgery.

Infrafloccular approach effectively prevents hearing complication in microvascular decompression surgery for hemifacial spasm.

OBJECTIVE: The infrafloccular approach in microvascular decompression (MVD) surgery for hemifacial spasm (HFS) was investigated for the prevention of hearing complications. METHODS: Retrospective analysis of 136 patients who underwent MVD for HFS in 2019. The infrafloccular approach for MVD was adopted to resolve the symptom and protect hearing function. Postoperative hearing function was evaluated subjectively and objectively within 30 postoperative days, and later mainly subjectively. Postoperative condition of mastoid air cells based on the CT scan of the following day was also recorded. RESULTS: No final postoperative subjective hearing impairment was found in all patients. Mastoid air cells were opened in 105 patients, and subjective hearing impairment was recorded in 57 patients within 30 postoperative days, but all improved later. Increases in thresholds of greater than 10 dB in air conduction were observed in 28 patients, including 26 of transient conductive hearing loss (increases in the threshold of less than or equal to 10 dB). The other 2 patients with increases in the threshold of greater than 10 dB in both air and bone conduction had improvement confirmed by later audiometry. CONCLUSIONS: Infrafloccular approach in MVD for HFS provides a good hearing outcome. Inclusion of postoperative hearing conditions in the later period is ideal for a precise hearing evaluation.

Primary diffuse large B-cell lymphoma of the cranial vault with Trousseau syndrome: a case report.

BACKGROUND: It is extremely rare for primary non-Hodgkin's lymphomas to occur singly in the cranial vault. One case diagnosed as primary diffuse large B-cell lymphoma is reported, initially misdiagnosed as metastatic skull tumor, complicated with Trousseau syndrome. CASE DESCRIPTION: The patient was a 60-year-old Japanese woman with no particular previous medical history. In a head computed tomography examination for vertigo, bone destructive skull tumor covering the right frontal, parietal, and temporal bones was incidentally discovered. As positron emission tomography indicated an abnormal accumulation in the large intestine and multiple cerebral infarctions suspicious of Trousseau syndrome were observed on magnetic resonance images, a metastatic skull tumor due to colorectal cancer was first considered. However, various tumor markers were negative, and colonoscopic biopsy indicated no colorectal abnormality. After pathological examination of the resected tumor, it was diagnosed as diffuse large B-cell lymphoma. The tumor affected muscles and skin but did not develop in the brain or the dura mater. As further general examination revealed no other abnormalities, we considered that it was primary diffuse large B-cell lymphoma in the cranial vault associated with Trousseau syndrome. Treatment with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone and high-dose methotrexate reduced the residual lesion; coagulation abnormalities, which are frequently associated with Trousseau syndrome, also improved. CONCLUSIONS: Skull tumors can result from a variety of malignancies, and their diagnosis may be complicated with Trousseau syndrome. However, even in cases of a single lesion in the cranial vault without invasion of the central nervous system, diffuse large B-cell lymphoma should be considered as a differential diagnosis.

Neurofibromatosis type 1 with subarachnoid hemorrhage due to multiple and de novo aneurysms: a case report.

BACKGROUND: Neurofibromatosis type 1 causes various lesions in many organs including the skin, and the incidence of complications with intracranial aneurysms is 9-11%. Here we report a case of neurofibromatosis type 1 with subarachnoid hemorrhage due to multiple and de novo aneurysms. CASE PRESENTATION: The patient was a 49-year-old Japanese woman with a history of neurofibromatosis type 1. She was transported to our hospital owing to disturbance of consciousness and was diagnosed with subarachnoid hemorrhage by computed tomography. Computed tomography angiography revealed multiple, small intracranial aneurysms, and we suspected that one of them in the peripheral branch of the left middle cerebral artery was the source of hemorrhage based on the distribution of hematoma. The patient underwent emergency surgery. Because it was difficult to identify an aneurysm in the most peripheral part of the left middle cerebral artery in the initial surgery, only one aneurysm was clipped. Later, a peripheral aneurysm was clipped using the navigation system. Because both aneurysms were small intracranial aneurysms (< 2 mm), either of them could be the source of hemorrhage. The postoperative course was good, and the patient was discharged in healthy condition. Because brain magnetic resonance imaging performed in the previous year did not find aneurysms at the same site, she was diagnosed with rupture of a de novo aneurysm. Neurofibromatosis type 1 might have caused the rupture of multiple intracranial aneurysms in a short period in this patient. CONCLUSION: Neurofibromatosis type 1 may be complicated by the formation of multiple intracranial aneurysms in a short period.

Microvascular Decompression Surgery for Elderly Patients: A Study Based on Proposals from the Joint Committee of the Japan Gerontological Society and the Japan Geriatrics Society.

The present study evaluated the indications for microvascular decompression (MVD) in elderly patients based on the new classification of the elderly population proposed by the joint committee of the Japan Gerontological Society and the Japan Geriatrics Society in 2017.Retrospective analysis of 171 patients with hemifacial spasm (HFS), trigeminal neuralgia (TN), and glossopharyngeal neuralgia (GPN) who underwent MVD in 2018. Patients were divided into three groups based on the proposal: old group, 75-89 years; pre-old group, 65-74 years; and not-old group, 64 years or younger. Preoperative comorbidities were divided into five types and the American Society of Anesthesiologists Physical Status (ASA-PS) was recorded. Outcome of the surgery and neurological complications were evaluated in June 2019.No decrease in activity of daily living occurred in any patient and surgical results showed no difference among the three groups. Rate of preoperative cardiovascular diseases was higher in both the pre-old and old groups compared with the not-old group (p <0.001 and Cramer V = 0.429). In terms of ASA-PS classification, only ASA-PS I and II were found, and rate of ASA-PS II was higher in the pre-old and old groups compared with the not-old group (p <0.001 and Cramer V = 0.407). Some patients suffered from elevated blood pressure after surgery, but were successfully managed.In conclusion, MVD for elderly patients can be achieved safely with careful patient selection and perioperative management. Data should be continuously accumulated for the future development of decision-making algorithm for MVD in the elderly.

Prosthesis Used in Microvascular Decompressions: A Multicenter Survey in Japan Focusing on Adverse Events.

OBJECTIVE: To investigate the characteristics of materials used as prostheses for microvascular decompression surgery (MVDs) in Japan and their possible adverse events (AEs) to determine preferable materials for MVDs. METHODS: A questionnaire was sent to all members of the Japanese Society for MVDs, and answers were obtained from 59 institutions. RESULTS: Among a total of 2789 MVDs, 1088 operations for trigeminal neuralgia, 1670 for hemifacial spasm, and 31 others, including 117 reoperations, were performed between April 2011 and March 2014. Nonabsorbable material was used in 96.5% of MVDs, including polytetrafluoroethylene (PTFE) (80.5%), polyurethane (11.9%), expanded PTFE (2.1%), and silk thread (1.47%). The use of absorbable materials, including fibrin glue (87.5%), cellulose (13.5%), gelatin (4,77%), and collagen (1.76%), was reported. The major combinations were PTFE with fibrin glue (58.7%) followed by PTFE alone (7.60%). Eighty-eight AEs in 85 (3.2%) cases were reported among 2672 first operations. AEs included 51 central nervous system dysfunctions, 15 wound infections/dehiscence, and 10 others, which were presumed to be related to the intraoperative procedure. Among relatively high-, moderate-, and low-volume centers, there were no significant differences in the frequency of AEs (P = 0.077). Tissue-prosthesis adhesion and/or granuloma formation were reported in 13 cases of 117 reoperations. The incidence of adhesion-related recurrence was 11.1% of all reoperations. CONCLUSIONS: The number of AEs was quite low in this survey, and intradural use of any prosthesis reported in this paper might be justified; however, further development of easily handled and less-adhesive prosthesis materials is awaited.

Transposition of the Culprit Artery Passing Between the Facial Nerve and Auditory Nerve in Microvascular Decompression Surgery for Hemifacial Spasm.

BACKGROUND: Decompression of the culprit artery causing hemifacial spasm (HFS), which passes between the facial nerve (cranial nerve [CN] VII) and the auditory nerve (CN VIII), can be difficult, especially if the artery compresses CN VII right after passing between the 2 nerves. Perforators or small arteries branching from near the compression site to adjacent structures can hinder the decompression process because such vessels can anchor the passing condition. The effect of such perforators or small arteries on the decompression process in such cases was investigated. METHODS: The culprit artery passed between any part of CN VII and VIII in 59 of 396 consecutive patients with HFS who underwent microvascular decompression. The culprit artery compressed CN VII right after passing between the 2 nerves in 22 of the 59 cases. Direction of the perforators or small arteries from near the compression site and direction of decompression of the culprit artery were analyzed in these 22 cases. RESULTS: Perforators or small arteries were observed in 20 cases, predominantly in the medial direction. The culprit artery was mobilized toward the petrous bone direction in most cases. No clear relationship was found between the 2 factors. CONCLUSIONS: Variation of curvature or tortuosity of the culprit artery and length of perforators or small branches may also have affected the decompression process and the directions. Adequate dissection near the compression site to obtain maximum mobilization of the culprit artery is necessary to achieve successful decompression in such cases.

Mobilization of the Anterior/Posterior Inferior Cerebellar Artery on the Cerebellar Surface in Microvascular Decompression Surgery for Hemifacial Spasm: Potential Effect on Hearing Preservation.

BACKGROUND: The infrafloccular approach in microvascular decompression (MVD) for hemifacial spasm (HFS) reduces the risk of postoperative hearing impairment. However, location of the anterior/posterior inferior cerebellar artery (AICA/PICA) on the cerebellar surface in the surgical route requires mobilization to maintain the approach direction for the protection of hearing function. OBJECTIVE: To evaluate the effectiveness of mobilization of the AICA/PICA on the cerebellar surface in the surgical route. METHODS: Retrospective review of 101 patients dividing their cases into 2 groups, the mobilized group and nonmobilized group. Surgical results, brainstem auditory evoked potentials (BAEPs), age, and duration of microsurgery were compared. In the mobilized group, whether the artery was responsible for the HFS or not, and whether the artery branched perforators to the cerebellar surface or choroid plexus or not, were analyzed. RESULTS: No permanent hearing impairment occurred in any patient. The AICA/PICA was mobilized in 26 patients. No significant difference was found in surgical results, BAEP findings, and duration of microsurgery between the 2 groups, but age was younger in the mobilized group (P < .01). The mobilized artery was responsible in 14 cases and branched perforators in 7 cases in the mobilized group. The perforators did not obstruct mobilization. CONCLUSION: Mobilization of the AICA/PICA from the cerebellar surface is a useful technique to maintain the infrafloccular approach in MVD for HFS. This technique reduces the risk of postoperative hearing impairment.

Acute Glaucoma Attack Following Microvascular Decompression Surgery for Trigeminal Neuralgia.

Microvascular decompression (MVD) is widely accepted as an effective surgical method to treat trigeminal neuralgia (TN), but the risks of morbidity and mortality must be considered. We experienced a case of acute angle-closure glaucoma attack following MVD for TN in an elderly patient, considered to be caused by lateral positioning during and after the surgery. A 79-year-old female underwent MVD for right TN in the left lateral decubitus position, and TN disappeared after the surgery. Postoperatively, the patient tended to maintain the left lateral decubitus position to prevent wound contact with the pillow, even after ambulation. Two days after the surgery, she complained of persistent left ocular pain with visual disturbance. The left pupil was dilated with only light perception, and the intraocular pressure (IOP) was 44 mmHg. Acute angle-closure glaucoma attack was diagnosed. After drip infusion of mannitol, emergent laser iridotomy was performed. The corrected visual acuity recovered with normalization of IOP (14 mmHg). The subsequent clinical course was uneventful and she was discharged from our hospital. The left lateral positioning during and after the surgery was considered to have contributed to increase IOP of the eye on the dependent side, which resulted in acute angle-closure glaucoma attack. The potential pathology is difficult to assess preoperatively, but patient management should always consider the increased possibility of this condition with age.

Supratentorial acute subdural haematoma during microvascular decompression surgery: report of three cases.

Supratentoiral haemorrhage during posterior fossa surgery is very rare. Authors report three cases of acute subdural haematoma occurred during microvascular decompression (MVD). Bleeding was observed in the suboccipital surgical area during operation but the origin of the bleeding was not confirmed intraoperatively in all cases. Decompression procedure was completed and immediate postoperative computed tomography revealed supratentorial subdural haematoma. This complication was observed during MVD in healthy young patients with hemifacial spasm in our cases. Flexion of the head with reduction of cerebrospinal fluid may have induced rotational movement of the cerebrum resulting in rupture of bridging veins, but no definitive mechanism that fulfils the clinical characteristics was clearly determined.

Fibrin glue injection into the hematoma cavity for refractory chronic subdural hematoma: A case report.

BACKGROUND: Repeat burr hole irrigation and drainage has been effective in most cases of recurrent chronic subdural hematoma (CSDH), however, refractory cases require further procedures or other interventions. CASE DESCRIPTION: An 85-year-old male presented with left CSDH, which recurred five times. The hematoma was irrigated and drained through a left frontal burr hole during the first to third surgery and through a left parietal burr hole during the fourth and fifth surgery. The hematoma had no septation and was well-evacuated during each surgery. Antiplatelet therapy for preventing ischemic heart disease was stopped after the second surgery, the hematoma cavity was irrigated with artificial cerebrospinal fluid at the third surgery, and the direction of the drainage tube was changed to reduce the postoperative subdural air collection at the fourth surgery. However, none of these interventions was effective. He was successfully treated by fibrin glue injection into the hematoma cavity after the fifth surgery. CONCLUSION: This procedure may be effective for refractory CSDH in elderly patients.

Safety of microvascular decompression for elderly patients with trigeminal neuralgia.

OBJECTIVE: The present study compared the safety and efficacy of microvascular decompression (MVD) in groups of elderly patients and non-elderly patients with medically refractory trigeminal neuralgia (TN) and collected detailed perioperative data. METHODS: Retrospective analysis of clinical data was performed in 99 patients who underwent MVD from May 2012 to June 2015. The outcome data from 27 MVD operations for 27 patients aged 70-80 years (mean 74.6 years) were compared with 72 MVD operations with 72 patients aged 25-69 years (mean 55.7 years). Preoperative comorbidities were recorded and postoperative worsening comorbidities and non-neurological complications were evaluated at discharge. Efficacy of the surgery and neurological complications were evaluated in July 2015. RESULTS: No decrease in activity of daily living was found in any patient. Complete pain relief without medication was achieved in 77.8% and partial pain relief in 14.8% in the elderly group, and 83.3% and 9.7%, respectively, in the non-elderly group (p=0.750). Permanent neurological complication was not observed in the elderly group, whereas Vth nerve and VIIIth nerve complications were observed in the non-elderly group. Rates of preoperative multiple comorbidities and of cardiovascular comorbidity were significantly higher in the elderly group (p<0.01). Worsening comorbidity and new pathology at discharge were mainly hypertension in both groups, but glaucoma attack and asthma attack were observed in the elderly group. All pathologies were successfully managed. CONCLUSIONS: MVD for elderly patients with TN can be achieved safely with careful perioperative management. Information of comorbidity should be shared with all staff involved in the treatment, who should work as a team to avoid worsening comorbidity. The possibility of unpredictable events in the elderly patients should always be considered.

Microvascular decompression for hemifacial spasm: how can we protect auditory function?

OBJECTIVE: The nerve function of the VIIIth nerve is at risk during microvascular decompression (MVD) for hemifacial spasm (HFS). Intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) can be useful in decreasing the danger of hearing loss. This study assessed the intraoperative BAEP findings related to the surgical process to clarify the optimum maneuvers of MVD surgery to avoid hearing impairment. METHODS: Hundred consecutive patients undergoing MVD for HFS with intraoperative BAEP monitoring were retrospectively reviewed. Patients were classified into four groups based on the greatest intraoperative latency prolongation and amplitude reduction of wave V of BAEP. Postoperative hearing function and surgical procedures including use of the brain retractor, preservation of arachnoid membrane along the VIIIth nerve, and duration of microscopic manipulation were analyzed in relation to the BAEP findings. RESULTS: Three patients complained of hearing loss after the surgery, but two had complete recovery and only one suffered permanent moderate hearing impairment. Longer duration of microscopic manipulation and greater use of the brain retractor tended to have negative effects on the BAEP findings, whereas preservation of arachnoid membrane along the VIIIth nerve had a positive effect. Statistical analysis showed significant difference in preservation of arachnoid membrane along the VIIIth nerve in Groups 2 and 4 (p = 0.013). CONCLUSION: Stretching of the VIIIth nerve should be avoided to prevent postoperative hearing impairment. Adequate exposure of the lower cranial nerve roots and lateral medulla oblongata from the caudal side without using the brain retractor gives enough space for decompression with minimum stretching of the VIIIth nerve. Maximum preservation of the arachnoid membrane along the VIIIth nerve and shortening of the duration of microscopic manipulation may help in avoiding postoperative hearing impairment.

Exposure of Titanium Mesh after Cranioplasty for Microvascular Decompression Surgery: Two Case Reports.

Two cases of exposed titanium mesh occurred after implantation for cranioplasty after repeated procedures for microvascular decompression (MVD). Case 1 was a 62-year-old female who underwent MVD for left hemifacial spasm followed by repair of cerebrospinal fluid leak after the surgery, and Case 2 was a 75-year-old female who underwent MVD twice for right trigeminal neuralgia. Both patients visited our hospital again with complaints of postauricular lesion. Titanium mesh was visible through the operative scar and was successfully removed with no complication in both cases. Both patients were underweight females, and combined with multistep surgery may have contributed to the pathology. The present cases suggest that use of titanium mesh should be avoided for cranioplasty of posterior fossa surgery, especially for repeated procedures.

Trigeminal neuralgia caused by a trigeminocerebellar artery.

This 31-year-old woman presented with typical right trigeminal neuralgia caused by a trigeminocerebellar artery, manifesting as pain uncontrollable with medical treatment. Preoperative neuroimaging studies demonstrated that the offending artery had almost encircled the right trigeminal nerve. This finding was confirmed intraoperatively, and decompression was completed. The neuralgia resolved after the surgery; the patient had slight transient hypesthesia, which fully resolved within the 1st month after surgery. The neuroimaging and intraoperative findings showed that the offending artery directly branched from the upper part of the basilar artery and, after encircling and supplying tiny branches to the nerve root, maintained its diameter and coursed toward the rostral direction of the cerebellum, which indicated that the artery supplied both the trigeminal nerve and the cerebellum. The offending artery was identified as the trigeminocerebellar artery. This case of trigeminal neuralgia caused by a trigeminocerebellar artery indicates that this variant is important for a better understanding of the vasculature of the trigeminal nerve root.

Negative and positive regulation of MAPK phosphatase 3 controls platelet-derived growth factor-induced Erk activation.

MAPK phosphatases (MKPs) are dual specificity phosphatases that dephosphorylate and thereby inactivate MAPKs. In the present study, we provide evidence that platelet-derived growth factor BB (PDGF-BB) regulates MKP3 (DUSP6), which is considered to be a phosphatase highly selective for Erk. Intriguingly, we observed that Mek is positively regulated by MKP3, whereas Erk itself is negatively regulated. In addition, we found that activation of PDGF receptor alpha or beta leads to a rapid proteasomal degradation of MKP3 in a manner that requires Mek activation; this feed-forward mechanism was found to be essential for efficient Erk phosphorylation. We could also demonstrate that PDGF-BB stimulation induces phosphorylation of MKP3 at Ser-174 and Ser-300; phosphorylation of Ser-174 is involved in PDGF-induced MKP3 degradation, since mutation of this site stabilized MKP3. Moreover, activated Erk induces mkp3 expression, leading to restoration of MKP3 levels after 1-2 h and a concomitant dephosphorylation of Erk in cells with activated PDGFRalpha. Reducing the MKP3 level by small interfering RNA leads to an increased Erk activation and mitogenic response to PDGF-BB. In conclusion, MKP3 is an important regulator of PDGF-induced Erk phosphorylation acting in both a rapid positive feed-forward and a later negative feed-back loop.

Participation of an abnormality in the transforming growth factor-beta signaling pathway in resistance of malignant glioma cells to growth inhibition induced by that factor.

OBJECT: Malignant glioma cells secrete and activate transforming growth factor-beta (TGFbeta) and are resistant to growth inhibition by that factor. Nevertheless, the mechanism underlying this effect remains poorly understood. In this study, the mechanism of the resistance to growth inhibition induced by TGFbeta was investigated. METHODS: The authors examined the expression of downstream components of the TGFbeta receptor, including Smad2, Smad3, Smad4, and Smad7, and the effect of TGFbeta1 treatment on the phosphorylation of Smad2 and the nuclear translocation of Smad2 and Smad3 by using 10 glioma cell lines and the A549 cell line, which is sensitive to TGFbeta-mediated growth inhibition. The expression of two transcriptional corepressor proteins, SnoN and Ski, and the effect of TGFbeta1 treatment on the expression of the SnoN protein and the cell cycle regulators p21, p15, cyclin-dependent kinase-4 (CDK4), and cyclin D1 were also examined. Expression of the Smad2 and Smad3 proteins was lower in the glioma cell lines than in the A549 cell line and in normal astrocytes. In particular, Smad3 expression was low or very low in nine of the 10 malignant glioma cell lines. Expression of Smad4 was low in four glioma cell lines, and expression of the Smad7 protein was similar when compared with protein expression in the A549 cell line and in normal astrocytes. The levels of Smad2 phosphorylation after TGFbeta1 treatment were lower in glioma cell lines than in the A549 cell line, except for one glioma cell line. Seven of the 10 glioma cell lines exhibited lower levels of nuclear translocation of Smad2 and Smad3, and two cell lines that expressed very low levels of Smad3 protein showed no nuclear translocation. All glioma cell lines expressed the SnoN protein and its expression was unaltered by treatment with TGFbeta1. Three glioma cell lines expressed high levels of the Ski protein. The expression of the p21(cip1), p15(INK4B), CDK4, and cyclin D1 proteins was not altered by TGFbeta1, treatment, except in one cell line that displayed a slight increase in p21 protein. Overall, the expression of the Smad2 and Smad3 proteins was low in the glioma cell lines, the phosphorylation and nuclear translocation of Smad2 and Smad3 were impaired, and the TGFbeta receptor signal did not affect the expression of the SnoN, p21, p15, cyclin D1, and CDK4 proteins. CONCLUSIONS: These results suggest that the ability to resist TGFbeta-mediated growth inhibition in malignant glioma cells is due to abnormalities in the TGFbeta signaling pathway.

Establishment and partial characterization of five malignant glioma cell lines.

Five malignant glioma cell lines (YMG1, 2, 3, 4, and 5) were established from surgical specimens obtained from patients with glioblastoma or anaplastic astrocytoma, and these lines were partially characterized. Three glioma cell lines (YMG1, 3, and 5) were weakly positive for GFAP by Western blot analysis and two cell lines were negative. S-100 protein was positive in all glioma cell lines. The expression of p53, p16, p15, cyclin-dependent kinase 4 (CDK4), and EGF receptor (EGFR) proteins was examined by Western blotting. YMG1 and 2 cell lines showed accumulation of p53 protein and loss of p16 and p15 expression. YMG3 and 4 showed accumulation of p53 protein and expression of p16 and p15 proteins. YMG5 revealed weak expression of p53 protein, suggesting wild-type p53, and loss of p16 and p15 expression. All cell lines expressed various levels of CDK4 protein. YMG1, 2, and 3 showed higher EGFR protein expression and YMG4 and 5 showed lower EGFR expression compared to U251 glioblastoma cells, which express high levels of EGFR. Fluorescence in situ hybridization analysis for EGFR gene expression did not show any amplification in the glioma cell lines. Immunohistochemical studies revealed that the patterns of p53 and EGFR expressions in the original tumor tissues were mostly correlated with those in the malignant glioma cell lines. These results suggest that the characteristics of p53 and EGFR expression in the malignant glioma cell lines were passed over from the original tumor tissues. These newly established malignant glioma cell lines can be used for further analysis of the mechanisms of tumor growth and progression.