Usefulness of Transcranial Motor Evoked Potential in Clipping Surgery for Cerebral Aneurysms-Introduction of a New Protocol for Stable Monitoring.

The usefulness of transcranial motor evoked potentials (Tc-MEPs) in clipping surgery has been reported. However, numerous false positive and false negative cases were reported. We report the usefulness of a new protocol compared with direct cortical MEP (Dc-MEP).Materials were 351 patients who underwent aneurysmal clipping under simultaneous monitoring of Tc- and Dc-MEPs. A total of 337 patients without hemiparesis and 14 with hemiparesis were separately analyzed. Intraoperative changes of Tc-MEP thresholds were examined in the first 50 patients without hemiparesis. The stimulation strength of Tc-MEP was set at +20% of the stimulation threshold. As thresholds changed intraoperatively, thresholds were examined every 10 min and changed stimulation strength.Stimulation thresholds of Tc-MEP were significantly decreased after craniotomy and significantly increased after CSF aspiration. The recording ratios of Tc- and Dc-MEPs were 98.8% and 90.5%, respectively. Out of 304 patients without MEP change, 5 patients developed transient or mild hemiparesis with infarction of the territory of the perforating artery arising from the posterior communicating artery. Out of 31 patients whose MEP transiently disappeared, 3 patients developed transient or mild hemiparesis. The other two patients without MEP recovery manifested persistent hemiparesis. In 14 patients with preoperative hemiparesis, 3 patients whose healthy/affected ratio of Tc-MEP was large developed severe persistent hemiparesis.We clarified the intraoperative changes of Tc-MEP thresholds for the first time. A new protocol of Tc-MEP that followed thresholds and changed stimulation strength to +20% of thresholds is useful for stable monitoring. The usefulness of Tc-MEP is the same as that or better than that of Dc-MEP.

Subarachnoid Hemorrhage Caused by Ruptured Aneurysm of the Artery of Adamkiewicz: a Case Report.

A 66-year-old man presented with a 6-day history of progressive posterior cervical pain that included lower back pain and fever. Neurological examinations revealed neck stiffness. Computed tomography demonstrated convexity subarachnoid hemorrhage. A spinal T2-weighted image revealed a hypointense signal lesion with contrast enhancement of the intradural extramedullary space at Th12-L1. Digital subtraction angiography showed a fusiform aneurysm with a 10 mm diameter in the artery of Adamkiewicz. We diagnosed the patient's condition as a ruptured aneurysm of the artery of Adamkiewicz. By day 41 the aneurysm had disappeared following conservative treatment. Aneurysms arising from the artery of Adamkiewicz are extremely rare and can cause both convexity and spinal subarachnoid hemorrhages. Clinicians should therefore look for spinal lesions if patients with convexity subarachnoid hemorrhage of an unknown origin have lower back pain as their initial symptom.

[Temporal Profiles of Neuroimaging Features of Non-haemorrhagic and Non-ischemic Vertebral Artery Dissections for Conservative Treatment].

Most patients with non-hemorrhagic and non-ischemic vertebral artery dissections(VADs)are likely to recover with good outcomes. In contrast, some cases of uneventful outcomes have also been reported. Therefore, whether surgical treatment or prolonged follow-up should be utilized for each case remains controversial. In this study, we retrospectively investigated the radiological features and changes in non-hemorrhagic and non-ischemic VADs during the follow-up period. We reviewed the medical records of 15 consecutive patients with VADs without hemorrhage or ischemic lesions diagnosed between 2008 and 2017; all patients reported severe occipital headache. All hemorrhagic and ischemic lesions were categorized into morphological types according to the initial radiological findings. The following morphological types of dissections were observed: six cases, pearl and string type; six cases, dilatation type; two cases, stenosis type; and one case, occlusion type. We observed morphological aggravation in four cases, and among them, three underwent surgical interventions. Seven patients recovered during the follow-up period, and five of them showed marked radiological changes within 2 months. One patient died fromethe clinical onset. Therefore, careful follow-up radiological imaging is presumably necessary for patients with non-hemorrhagic and non-ischemic VADs, within at least 2 months of the clinical onset because of the tendency of VADs for rapid morphological changes during that period.

Clinical diagnostic utility of contrast-enhanced three-dimensional fluid-attenuated inversion recovery for selection of brain biopsy sites in neurosarcoidosis: A case report.

Neurosarcoidosis is difficult to diagnose, because definite diagnosis requires detailed histology of the central nervous system. Three-dimensional contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR) is more useful for detecting leptomeningeal lesions compared with 3D CE-T1 weighted imaging. However, the clinical diagnostic utility of 3D CE-FLAIR for neurosarcoidosis is unclear. We describe a case of a 46-year-old Japanese woman who was admitted to our department due to chronic headache with fever and diplopia. Using 3D CE-FLAIR, we performed brain biopsy from right cerebellar lesion. The histological examination revealed typical non-caseating granulomas, indicating neurosarcoidosis. Our findings suggest that 3D CE-FLAIR may detect leptomeningeal lesions that are candidates for biopsy in chronic meningitis undetermined etiology.

Fourth Ventricle Outlet Obstruction with Expanding Space on the Surface of Cerebellum.

BACKGROUND: Hydrocephalus is classified as noncommunicating and communicating based on whether all ventricular and subarachnoid spaces are communicating. Although the diagnosis between the two different states is crucial, it is difficult in certain conditions. In particular, communicating hydrocephalus and noncommunicating hydrocephalus owing to fourth ventricle outlet obstruction are highly misdiagnosed. We describe a case of fourth ventricle outlet obstruction of unknown origin that was initially misdiagnosed as communicating hydrocephalus. CASE DESCRIPTION: A 66-year-old woman with gait disturbance and incontinence caused by hydrocephalus underwent ventriculoperitoneal shunt surgery. After 9 months, her fourth ventricle became enlarged and could not be controlled by lowering the shunt pressure. Magnetic resonance imaging (MRI) demonstrated obstruction at the foramen of Magendie, foramina of Luschka, and the cerebral aqueduct. Endoscopic surgery for aqueduct plasty with third ventriculostomy was planned. Because the aqueduct was observed to open spontaneously, only the standard third ventriculostomy was performed. When MRI findings were reviewed retrospectively, an unnatural space was observed between the lower cranial nerves and cerebellar hemisphere that grew along with the fourth ventricular enlargement. This space was determined by MRI cisternography to be the cystic membrane ballooning out from the foramen of Luschka. The primary hydrocephalus likely resulted from fourth ventricle outlet obstruction. CONCLUSIONS: Enlargement of the whole ventricular system with an expanded space between the lower cranial nerves and cerebellar hemisphere can be caused by fourth ventricle outlet obstruction. In such cases, preoperative evaluation of anatomic architecture and cerebrospinal fluid obstruction using MRI cisternography is essential and leads to a successful endoscopic strategy.

A study of prognostic factors in 45 cases of atypical meningioma.

BACKGROUND: Atypical meningioma differs from Grade I meningioma in terms of high recurrence rate and short life expectancy. We evaluated the clinical course of atypical meningioma and investigated prognostic factors affecting its outcomes. METHOD: We reviewed 45 patients with atypical meningioma who underwent surgical intervention between January 2000 and December 2013. The mean age of the patients and mean follow-up period was 58.7 years and 81.0 months, respectively. Analyses included factors such as patient age, gender, location and size of tumor, extent of surgical resection (Simpson Grading System), and MIB-1 labeling index (LI). Univariate analysis was used to detect prognostic factors associated with recurrence and survival. RESULTS: The 5-year recurrence-free rate for all 45 patients was 58.4 %; 5- and 10-year survival rates were 83.2 % and 79.9 %, respectively. In univariate analyses, age >60 years, and MIB-1 LI correlated with disease recurrence, whereas age >60 years, subtotal surgical resection, MIB-1 LI, and indication for radiotherapy correlated with death. MIB-1 LI levels higher than 12.8 % and 19.7 % predicted recurrence and death, respectively. In our cohort, 26 patients received postoperative radiotherapy including conventional radiation (n = 21) or gamma knife radiosurgery (n = 5). Postoperative radiotherapy did not decrease recurrence rates in our cohort (p = 0.63). Six and two patients who died during the study period underwent conventional radiation and radiosurgery, respectively. CONCLUSIONS: Age, male gender, extent of surgical resection, and higher MIB-1 LI influenced the outcome of atypical meningioma. In our cohort, postoperative radiotherapy failed to provide long-term tumor control. Following incomplete surgical resection of atypical meningioma in elderly patients, adjuvant postoperative radiotherapy may not be an ideal treatment option, particularly when MIB-1 LI is higher than 19.7 %.

Intraspinal dissemination of intracranial hemangiopericytoma: Case report and literature review.

BACKGROUND: The authors report the case of a 53-year-old woman suffering from thoracic myelopathy caused by intraspinal dissemination of hemangiopericytoma. In literature, hemangiopericytoma is commonly found as an intracranial lesion, and often hematogenously metastasizes to the bone or liver; however, intradural spinal dissemination is extremely rare. CASE DESCRIPTION: The patient presented with gait disturbance due to thoracic myelopathy 6 years after surgical treatment for intracranial hemangiopericytoma. Magnetic resonance imaging demonstrated intradural disseminated lesions compressing the spinal cord. Although the patient underwent resection of the intradural spinal tumor, the lesion was tightly adherent to the dorsal surface of the spinal cord. Therefore, it resulted in subtotal removal. Immediately after the surgery, symptoms related to the thoracic myelopathy resolved. The patient was free from disease progression for 14 months after whole spine radiotherapy. CONCLUSION: Recognition of this type of progression is important in the clinical management of intracranial hemangiopericytoma because intradural spinal dissemination dramatically degrades neurological functions.

[Perforating Artery Injury during Microsurgery for Internal Carotid Artery Bifurcation Aneurysms].

Internal carotid artery bifurcation aneurysms(ICB-ANs)are relatively rare and are difficult to occlude by direct clipping without perforating artery injury(PAI). We retrospectively analyzed 11 aneurysms in 10 cases. PAI was identified in 5 of 10 cases on postoperative computed tomography(CT)or magnetic resonance imaging(MRI), and 2 of these patients were symptomatic. PAIs were distributed in the caudate nucleus and/or the genu of the internal capsule. PAI occurred in 3 of 5 cases in which indocyanine green videoangiography(ICG-VAG)was performed. ICG-VAG is a helpful tool visualizing blood flow of vessels in surgical fields. However, PAI is a potential risk in direct clipping of ICB-ANs even if adjacent perforating arteries were observed using ICG-VAG.

Compression neuropathy caused by cancer metastasis to the optic nerve canal.

BACKGROUND: Cancerous cells are known to metastasize to different ocular structures. This happens especially to the choroid in males with lung cancer and females with breast cancer. However, we observed two cases of cancerous metastasis to the optic canal region. Both cases showed only a progressive decrease in vision without any other remarkable ophthalmological symptoms or abnormalities in the affected eye. CASE PRESENTATION: Two females, a 60-year-old and a 73-year-old, came to our hospital because of progressive loss of vision. These patients showed no remarkable symptoms or signs in their eyes except visual acuity loss. Several ophthalmoscopic examinations, such as slit lamp microscopy and fundoscopy, showed no abnormal changes in their affected eye but magnetic resonance imaging indicated a massive legion around the optic nerve. CONCLUSION: It is possible for cancer to metastasize to the optic canal region and the existence of primary tumors should be considered.

Subarachnoid hemorrhage in a patient with a meningioma and an unruptured aneurysm.

Subarachnoid hemorrhage (SAH) is usually elicited by cerebrovascular disease and infrequently by brain tumors. A 64-year-old woman presented with SAH with a left petrous meningioma and an unruptured left internal carotid-posterior communicating artery (IC-PcomA) aneurysm. She suffered sudden onset of headache and nausea followed by consciousness disturbance 7 days after onset. Computed tomography (CT) revealed diffuse SAH and a tumor at the petrous portion. Angiography demonstrated a left IC-PcomA aneurysm. Under a diagnosis of a ruptured aneurysm and a coincidental meningioma, we performed neck clipping of the aneurysm. However, intraoperatively we found that the aneurysm was unruptured and we subsequently performed tumor resection. Intraoperatively we could not find the cause of SAH during resection of the meningioma. The histological diagnosis was transitional meningioma with deposition of fibrin on the surface of the tumor. The findings of initial CT and magnetic resonance imaging, and pathological results could not conclude the definitive etiology of SAH in this case.

Use of microscope-integrated near-infrared indocyanine green videoangiography in the surgical treatment of intramedullary cavernous malformations: report of 8 cases.

OBJECT: The characteristics and efficacy of indocyanine green (ICG) videoangiography in cavernous malformation (CM) have not been fully elucidated. The purpose of this paper is to examine the potential utility of ICG videoangiography in the surgical treatment of intramedullary CMs. METHODS: The authors conducted a retrospective review of 8 cases involving 5 men and 3 women who had undergone surgery for intramedullary CM between January 2008 and July 2011. All patients were evaluated by means of MRI. The MRI findings and clinical history in all cases suggested intramedullary CM as a preoperative diagnosis. In 2 of 8 cases, dilated venous structures associated with CMs were demonstrated. In one of these cases, there were coexisting extramedullary CMs. Intraoperatively, ICG fluorescence was observed for 5 minutes using microscope-integrated videoangiography. RESULTS: In all 8 cases, intra- and extramedullary CMs were seen as avascular areas on ICG videoangiography. Indocyanine green videoangiography helped surgeons to localize and predict margins of the lesions before performing myelotomy. Importantly, in the cases with associated venous anomalies, ICG videoangiography was useful in delineating and preserving the venous structures. In extramedullary CMs located dorsal to the spinal cord, gradual ICG infiltration was seen, starting at 110 seconds and maximal at 210 seconds after injection. Postoperative MRI confirmed total removal of the lesions in all cases, and subsequent recovery of all patients was uneventful. CONCLUSIONS: Indocyanine green videoangiography provided useful information with regard to the detection of lesion margins by demonstrating intramedullary CMs as avascular areas. In cases associated with venous anomalies, ICG contributed to safe and complete removal of the CMs by visualizing the venous structure. In extramedullary CMs, ICG videoangiography demonstrated the characteristic of slow blood flow within CMs.

An analysis of flow dynamics in cerebral cavernous malformation and orbital cavernous angioma using indocyanine green videoangiography.

BACKGROUND: Cerebral cavernous malformations (CCMs) are known to be vascular anomalies with low perfusion because of being angiographically occult. We attempted direct visualization of blood flow within CCMs and orbital cavernous angiomas (CAs), and analyzed flow dynamics using indocyanine green videoangiography (ICG-VAG). METHODS: This series included seven CCMs and two orbital CAs. ICG-VAG was performed to visualize blood flow of the lesions before resection. Time to peak of staining was evaluated by reviewing recorded ICG-VAG. RESULTS: In five of seven CCMs, stain was identified. CCMs were seen as avascular areas in both arterial and venous phases, and were stained gradually. Stain was maximized late after venous phase. The orbital CAs were also stained lately, but more intensely than CCMs. CONCLUSIONS: The present study directly demonstrated slow and low perfusion within CCM and orbital CA using ICG-VAG. On the basis of characteristic flow dynamics of CCMs, intraoperative ICG-VAG provides useful information in microsurgical resection.

[A case of late-onset aqueductal membranous occlusion and a successful treatment with neuro-endoscopic surgery].

A 57 year-old man developed broad-based unsteady gait and memory loss over a period of one year. On admission, bradykinesia and impairment of postural reflex were evident. Mini-mental state examination scored 27/ 30. Urinary control was normal. MRI revealed symmetric dilatation of lateral and 3rd ventricles, but the 4th ventricle appeared normal. Partial obstruction of the aqueduct with a membranous structure was disclosed by fast imaging employing steady state acquisition (FIESTA), and the diagnosis of late-onset aqueductal membranous occlusion (LAMO) was made. The symptoms were ameliorated shortly after endoscopic aqueductoplasty (EAP) and endoscopic third ventriculostomy (ETV). Membranous occlusion of the aqueduct can be detected by FIESTA and it can be cured by neuro-endoscopic measures.

Ruptured peripheral aneurysms in a collateral pathway associated with stenosis of a major cerebral artery: Report of two cases.

BACKGROUND: While hemodynamic stress can result in aneurysm formation, it rarely contributes to the development of peripheral aneurysms in collateral pathways. We report two patients with ruptured distal aneurysms in a collateral pathway associated with stenosis of a major cerebral artery. CASE DESCRIPTION: A 67-year-old man presented with intracerebral hemorrhage in the right frontal lobe. Digital subtraction angiography (DSA) revealed severe stenosis of the right middle cerebral artery and two aneurysms in the collateral pathway of the right anterior cerebral artery. The ruptured aneurysm was trapped and resected; histologically, it was a true saccular aneurysm. The unruptured aneurysm was clipped and the patient was discharged without additional neurological deficits. The second patient was a 73-year-old woman with subarachnoid hemorrhage. DSA revealed three arterial dilations. On the 7(th) day of hospitalization, one of the aneurysms in a posterior inferior cerebellar artery-anterior inferior cerebellar artery anastomosis that functioned as a collateral pathway in the presence of severe basilar artery stenosis was found to be enlarged. It was treated by selective aneurysmal coil embolization with parent artery preservation. Her postoperative course was uneventful and she was discharged without any neurological deficits. CONCLUSION: We document the successful treatment of two patients with ruptured aneurysms in the peripheral portion of a collateral pathway. We discuss the histology of peripheral aneurysms and present a review of the literature.

Development of intratumoral cyst or extratumoral arachnoid cyst in intracranial schwannomas following gamma knife radiosurgery.

PURPOSE: Intracranial schwannomas presenting with cyst formation following gamma knife radiosurgery (GKRS) were investigated to clarify their clinicopathological characteristics. METHODS: Between 1994 and 2006, 492 patients presenting with intracranial schwannomas underwent GKRS. Among them, seven cases demonstrated either new formation of cysts or enlargement of preexisting cysts, which were treated with microsurgical intervention. These cases were retrospectively reviewed with regard to neuroradiological findings and histopathology. RESULTS: These seven cases included five vestibular and two trigeminal schwannomas. Preexisting cysts were enlarged following GKRS in three cases, while they were newly formed in four cases. Salvage microsurgery was carried out at 7-167 months after the GKRS, and subtotal resection was achieved in three, partial resection with or without cyst fenestration in four. Neurological symptoms were improved in all six symptomatic cases. Preoperative MRI demonstrated two characteristic types of cyst. One was the intratumoral type, indicating hemorrhagic change on the MRI. Histopathological analysis demonstrated a cavernous angioma within the solid compartment of tumor. These two cases demonstrated enlargement of residual tumor with new cyst formation after resection of only the cyst. The other type was extratumoral cyst, which had a structure with a thin cyst wall without contrast enhancement, and the cyst was composed of arachnoid cells without tumor cells. Extratumoral cysts enlarged despite effective control of the tumor itself, which may be caused by osmotic gradient induced by tumor degeneration following GKRS. CONCLUSIONS: There were two types of cysts, intratumoral cyst and extratumoral arachnoid cyst, which developed following GKRS in intracranial schwannomas. Resection of the solid compartment as well as the cyst is required in schwannomas with expanding intratumoral cyst. Conversely, fenestration of the cyst alone might be effective in extratumoral arachnoid cysts.

Extradural dermoid cyst of the parasellar region: a case report.

Dermoid cysts are rare congenital intracranial tumors. Among these tumors, extradural localization is extremely rare. We report a patient with an extradural dermoid cyst of the right parasellar region, causing right visual disturbance. Computed tomography revealed a hypodense mass lesion with rimlike calcification at the right parasellar region, accompanying marked erosion of the adjacent skull base. The tumor appeared as a heterogeneous intensity on magnetic resonance imaging and was surrounded by thin gadolinium enhancement without inner enhancement. The right optic nerve was compressed by the tumor. Surgical resection was successfully performed using a right frontotemporal extradural approach. The entire tumor was completely resided extradurally and was enclosed by saclike, stretched dura mater and extended deeply into the skull base. Histopathologic findings were consistent with the features of dermoid cyst. The postoperative course was uneventful, and the visual disturbance improved. Neuroradiological features, strategies for surgical treatment, and mechanisms responsible for preoperative symptoms are discussed.

Malignant peripheral nerve sheath tumor arising from benign vestibular schwannoma treated by gamma knife radiosurgery after two previous surgeries: a case report with surgical and pathological observations.

BACKGROUND: Gamma knife radiosurgery (GKRS) is an effective treatment for vestibular schwannomas with lower morbidity and mortality. However, malignant transformation associated with GKRS, although uncommon, has been reported in recent publications. METHODS: We describe a case presenting with malignant peripheral nerve sheath tumor (MPNST) at 8 years after GKRS after incomplete resections. RESULTS: The tumor appeared to be a typical benign schwannoma at the surgery preceding GKRS, and rapidly enlarged after long-term control, causing progressive neurological deterioration. Operative findings showed that the tumor was composed of two different components, and histopathology distinctively demonstrated MPNST and benign schwannoma. CONCLUSIONS: The coexistence of benign and malignant components might indicate that the present MPNST had arisen from the benign schwannoma by transformation in association with GKRS.

[C2 neurinoma with intracranial extension: a case report].

We report a rare case presenting with a C2 neurinoma, which extended beyond the foramen magnum, producing a huge mass at the clivus. A 10-year-old boy with medical history of glycogenosis type VIII and attention-deficit hyperactivity disorder had been suffering from progressing foramen magnum syndrome for 36 months. MRI demonstrated a huge tumor, 70 mm in a diameter, which distributed in both the intra- and extra-spinal canal at the C2 level and extended into the intracranial space beyond the foramen magnum. The tumor was totally removed via the trascondylar fossa approach with C1 hemilaminectomy. Operative findings indicated that the tumor arising from extradural C2 nerve intruded into the intradural space, and extended beyond the foramen magnum. Foramen magnum tumors sometimes remain unrecognized until severe neurological deficits develop because of bizarre symptomatology. Surgical strategies with less invasiveness based on early diagnosis lead to successful recovery of neurological function.

Surgical and histological observations of trochlear neurinoma: case report.

A 47-year-old woman presented with an extremely rare case of trochlear nerve neurinoma manifesting as left hemiparesis. Magnetic resonance imaging demonstrated a cystic tumor, 4 cm in diameter, in the right ambient and cerebellopontine cisterns, compressing the midbrain and upper pons. The preoperative diagnosis was trigeminal neurinoma. However, the tumor was identified arising from the trochlear nerve, and was totally removed via the posterior transpetrosal approach. The histological diagnosis was neurinoma. The patient's hemiparesis improved postoperatively. Preoperative diagnosis of trochlear neurinoma must distinguish the neurological presentations of trochlear and trigeminal neurinomas and to analyze the microanatomy of the tumor and skull base structures on neuroimaging.