Adult ; Female ; Humans ; Magnetic Resonance Imaging ; Neuroma, Acoustic ; pathology ; surgery

OBJECTIVE: By detecting the myelin structure in acoustic tumor tissues, the cell origin and state of acoustic tumor tissues were investigated. METHOD: Immunofluorescence labeling, immunoblot analysis and electron microscopic study were performed to identify myelin structure and myelin protein in acoustic tumor tissues. RESULT: In this work, we found some early stage of myelin forming in acoustic tumor tissues, but there were no axon nor compact myelin formed and the myelin basic protein whose expression indicates the beginning of myelination was negative detected. We also found that the cell of acoustic tumor express p75,a marker for immature Schwann cells and mature non-myelin-forming Schwann cells. CONCLUSION The date shown in this experiment indicates that the cell of acoustic tumor is in a remyelinating state.
Humans ; Microscopy, Electron ; Myelin Sheath ; pathology ; ultrastructure ; Neuroma, Acoustic ; pathology ; Schwann Cells ; pathology

Humans ; Neoplasms, Cystic, Mucinous, and Serous ; pathology ; therapy ; Neuroma, Acoustic ; pathology ; therapy

BACKGROUNDDetermining the nerve of origin for vestibular schwannoma (VS), as a method for predicting hearing prognosis, has not been systematically considered. The vestibular test can be used to investigate the function of the superior vestibular nerve (SVN) and the inferior vestibular nerve (IVN). This study aimed to preoperatively distinguish the nerve of origin for VS patients using the vestibular test, and determine if this correlated with hearing preservation.

METHODSA total of 106 patients with unilateral VS were enrolled in this study prospectively. Each patient received a caloric test, vestibular-evoked myogenic potential (VEMP) test, and cochlear nerve function test (hearing) before the operation and 1 week, 3, and 6 months, postoperatively. All patients underwent surgical removal of the VS using the suboccipital approach. During the operation, the nerve of tumor origin (SVN or IVN) was identified by the surgeon. Tumor size was measured by preoperative magnetic resonance imaging.

RESULTSThe nerve of tumor origin could not be unequivocally identified in 38 patients (38/106, 35.80%). These patients were not subsequently evaluated. In 26 patients (nine females, seventeen males), tumors arose from the SVN and in 42 patients (18 females, 24 males), tumors arose from the IVN. Comparing with the nerve of origins (SVN and IVN) of tumors, the results of the caloric tests and VEMP tests were significantly different in tumors originating from the SVN and the IVN in our study. Hearing was preserved in 16 of 26 patients (61.54%) with SVN-originating tumors, whereas hearing was preserved in only seven of 42 patients (16.67%) with IVN-originating tumors.

CONCLUSIONSOur data suggest that caloric and VEMP tests might help to identify whether VS tumors originate from the SVN or IVN. These tests could also be used to evaluate the residual function of the nerves after surgery. Using this information, we might better predict the preservation of hearing for patients.

Adult ; Female ; Hearing ; Humans ; Male ; Neuroma, Acoustic ; pathology ; physiopathology ; Vestibular Nerve ; physiology

Medulloblastoma is a common malignant central nervous system neoplasm found mainly in children. One the contrary, medulloblastoma of the cerebellopontine angle, the location of the tumor is very unusual. This is the the first case of the medullomyoblastoma, a rare form of medulloblastoma, occurring in the cerebellopontine angle. A 15-year-old boy experienced a sudden hearing loss in the left ear. Conservative medical treatment failed, and temporal MR imaging revealed a heterogeneously enhancing mass at the left cerebellopontine angle cistern and in the internal auditory canal; therefore, the lesion was regarded as a typical acoustic neuroma. Few days before surgery, an ipsilateral facial palsy developed, and a follow-up MR imaging showed a rapid growth of the previous lesion. The extended translabyrinthine approach permitted surgical removal. And under pathological diagnosis of malignancy, radiation therapy and series of chemotherapy was performed.
Adolescent ; Cerebellar Neoplasms/*pathology/surgery ; Cerebellopontine Angle/*pathology ; Diagnosis, Differential ; Humans ; Magnetic Resonance Imaging ; Male ; Medulloblastoma/*pathology/surgery ; Neuroma, Acoustic/*pathology

We describe a rare case of malignant transformation in a vestibular schwannoma in a 33-yr-old woman. She presented herself with headache, tinnitus, and hearing loss and underwent posterior fossa explorations three times during the short period of 3 months. The clinicopathological features of the original tumor were typical of benign vestibular schwannoma. Despite a comlpete microsurgical excision, two months later, the tumor recurred locally with a rapid increase in size causing a progressive worsening of neurological symptoms. A diagnosis of malignant schwannoma was made for the recurrent tumor on the basis of the microscopic findings of high cellularity, moderate pleomorphism, and the presence of mitotic cells. Repeat magnetic resonance imaging performed a month after the second surgery unexpectedly showed definite tumor enlargement. She remained clinically stable following the third debulking of the tumor and adjuvant radiotherapy. We propose that this recurrent tumor represent malignant transformation from a benign vestibular schwannoma which was an unusual occurrence in a patient without neurofibromatosis.
Adult ; Case Report ; Cell Transformation, Neoplastic ; Cranial Nerve Neoplasms/*pathology ; Female ; Human ; Magnetic Resonance Imaging ; Neoplasm Recurrence, Local ; Nerve Sheath Tumors/*pathology ; Neuroma, Acoustic/*pathology

The posterior fossa, which contains about one fourth of the intracranial contents, is the site of known about two thirds of pediatric intracranial tumors. In about such tumors are less common and the prognosis may bevery poor. However, it is important to recognize the earliest symptoms because of the relatively high ease rate of operable management and the possibility for a high cure rate in some cases. A series of 51 pathologically verified posterior fossa tumors seen at the Department of Neurosurgery, Yonsei University, Severance Hospital over several years were studied. These tumors were explored surgically, and the diagnosis being made through histological examination. The cases were reviewed as to history, development and progression of the neurological features, laboratory findings, roentgenograms, differential diagnosis, operative methods and findings, and pathology. The authors emphasized some interesting points which are illustrated as follows; 1. Among 51 cases of posterior fossa tumors, 25 cases of acoustic neuroma, 9 cases of astrocytoma, 9 cases of medulloblastoma, 2 cases of ependymoma, 3 cases of pontine glioma and 3 cases of cysticercosis in the fourth ventricle were found, comprising 21 males and 30 females. 2. The 25 operated cases of acoustic neuroma were between the age of 20 and 60. Eighteen cases(69.2%) of the remaining posterior fossa tumors were below the age of 15. 3. The author was able to make the correct plain film diagnosis of acoustic neuroma in 13 cases(51%) of 25 cases. The prominent angiographic and ventriculographic finding of posterior fossa tumors was ventricular dilatation. 4. Vntriculogram was very important in the diagnosis of the fourth ventricle tumors. The Conray ventriculogram had the special benefit in accurately outlining and demonstrating the invasive pattern of fourth ventricle tumors. The Conray showed C.S.F. flow in malignant and other large tumors in the fourth ventricle better than was shown by previous pneumo-ventriculograms. 5. The Electroencephalogram showed an abnormal pattern in 62.2 per cent of 29 posterior fossa tumors.
Astrocytoma ; Cysticercosis ; Diagnosis ; Diagnosis, Differential ; Dilatation ; Electroencephalography ; Ependymoma ; Female ; Fourth Ventricle ; Glioma ; Humans ; Infratentorial Neoplasms* ; Male ; Medulloblastoma ; Neuroma, Acoustic ; Neurosurgery ; Pathology ; Prognosis

BACKGROUND: Intraoperative neurophysiologic monitoring(INM) is well known to be useful method to reduce intraoperative complications during tumor surgery in cerebellopontine angle(CPA). We investigated the changes of INM during the surgery. It might be helpful to keep one's eyes on which monitoring modalities are reluctant to change during the operation. METHODS: We included 49 subjects who had undergone CPA tumor surgery under INM. Their pathology was as follows; vestibular schwannoma in 37, other cranial nerve schwannoma in 3, meningioma in 5 , cyst in 2. The modalities of monitoring were short latency auditory evoked potentials(AEP), somatosensory evoked potentials(SEP) , facial and trigeminal nerve EMG(EMG). Stimulation of SEP was on left or right median, posterior tibial nerves. We studied the frequency of abnormal INM changes and the factors affecting it. RESULTS: The subjects who had abnormal changes in at least one monitoring modality were 19(38.8.%). AEP changes were in 6.1%, SEP in 12.2% and EMG in 24.5%. The AEP monitoring had no potentials from II through V wave in 28 subjects(57.1%). SEP monitoring had improvement in 2 subjects and aggravation in 6, especially involved in median nerve SEP. Tonic EMG activities were observed in 3 facial muscles of 3 subjects, 2 of 4, 1 of 5. Regarding the pathology of tumor, meningioma had much more changed INM than vestibular schwannoma. The volume of tumor was bigger in abnormal INM group than normal group although it is not statistically significant. Also abnormal SEP and EMG group had bigger mass than normal group. CONCLUSIONS: INM has frequent electrophysiologic changes during tumor surgery in CPA. Especially EMG can be changed the most frequently. The larger tumor are, the more frequently abnormal changes in INM of CPA tumor surgery are.
Cerebellopontine Angle* ; Cranial Nerves ; Facial Muscles ; Intraoperative Complications ; Median Nerve ; Meningioma ; Monitoring, Intraoperative ; Neurilemmoma ; Neuroma, Acoustic ; Pathology ; Tibial Nerve ; Trigeminal Nerve

BACKGROUND AND OBJECTIVES:Vestibular evoked myogenic potential (VEMP) has become a valuable diagnostic tool evaluating the integrity of sacculocollic reflex and has been done using click sound in most previous clinical trials. This study aims to investigate VEMP responses generated by 500 Hz tone burst in unilateral peripheral vestibulopathy and compare the response with caloric test and subjective visual vertical (SVV). MATERIALS AND METHOD:Clinical records of 37 patients (18 men and 19 women, aged 14-80 years) with unilateral peripheral vestibulopathy were reviewed. Diagnoses were Meniere's disease (n=13), vestibular schwannoma (n=4) and acute peripheral unilateral vestibulopathy (n=20). They underwent 500Hz tone burst VEMP, caloric test and SVV test. Thirteen healthy volunteers (26 ears, 8 men and 5 women, 25~41 years) with normal hearing were enrolled as control group. RESULTS:VEMP response was present in every control ear using 500 Hz tone burst stimuli. In Meniere's disease, VEMPs were positive in 57% (4/7) of patients with abnormal caloric response group and 83% (5/6) with normal caloric response. In acute peripheral vestibulopathy, VEMPs were positive in 47% (9/19) of patients with abnormal caloric response, 0% (0/1) with normal caloric response. The average of CP (canal paresis) in positive VEMP group was 62.4% and that in negative VEMP group was 48.2% (P>0.05). CONCLUSION:Reliable and reproducible test results can be obtained using 500 Hz tone burst stimuli. VEMP results were not in concordance with other vestibular tests, which reflects the dynamic process of dizziness and variable extent of pathology in each case.
Caloric Tests ; Diagnosis ; Dizziness ; Ear ; Evoked Potentials ; Female ; Healthy Volunteers ; Hearing ; Humans ; Male ; Meniere Disease ; Neuroma, Acoustic ; Pathology ; Reflex ; Vestibular Function Tests ; Vestibular Neuronitis

OBJECTIVETo analyze the surgical outcomes and share experience in the surgical management of acoustic neuroma(AN).

METHODSA retrospective review was performed in 134 patients with sporadic large ANs operated from Jan. 2001 to Dec. 2012. The patients' information, tumor size, tumor cystic degeneration, surgical approach, intraoperative anatomical facial nerve integrity rate, postoperative facial nerve function and complications were recorded.

RESULTSThere were one hundred and twenty-nine patients (96.3%) received surgeries within one month after first diagnosis of vestibular schwannoma(VS) or definite diagnosis of recurrence.Five patients (3.7%) hesitated to be operated until tumor was found to be growing on MRI during the follow-up. The average tumor diameter was about (40.9 ± 6.8) mm (31.0-70.0 mm). The cystic tumor percentage arrived at 35.1% (47/134). The surgical approaches included 118(88.1%) translabyrinthine approaches, comprising 16(11.9%) modified enlarged translabyrinthine approaches, and 16 (11.9%) transaortic approaches. Total, near total, and subtotal tumor removal rate was 91.0% (122/134), 6.7% (9/134) and 2.2% (3/134), respectively. The anatomical facial nerve integrity was preserved in 88.8% (19/134) of all patients. And it was significantly lower in cystic VS (80.9% vs 93.1%, P = 0.044). There were 32.3% (43/133) and 36.8% (49/133) of patients had a good postoperative facial nerve function in short-term (discharge from hospital) and long-term (1 year) follow-up, respectively.General rate of complications was 17.9% (24/134). CSF leakage occurred in 7.5% of patients. Mortality rate was 0.7% (1/134). Follow-up time ranged from 1 to 5 years, average time was(2.7 ± 0.4)years.Four cases occurred recurrence.

CONCLUSIONSMajor management strategy of large AN is surgical resection.Even for those who had temporary antagonism for surgery, the wait and scan policy is necessary. Although the tumor removal is safe and accompanies extremely low mortality and incidence of complication, the patient with large AN must be informed in detail about the possible surgical risks. The tumor cystic degeneration is an important crucial factor which influences the surgical outcomes of AN, especially in postoperative facial nerve function.

Adolescent ; Adult ; Aged ; Child ; Ear, Inner ; surgery ; Female ; Humans ; Male ; Middle Aged ; Neuroma, Acoustic ; pathology ; surgery ; Postoperative Complications ; Retrospective Studies ; Treatment Outcome ; Young Adult