[Normal Anatomy and Variants of the Anterior Cerebral and Anterior Communicating Arteries].

The anterior cerebral artery(ACA)and anterior communicating artery(AcomA), two important arteries of the cerebral hemisphere, are involved in various disorders, including aneurysms, steno-occlusive diseases, and arteriovenous shunts, among other such conditions. Additionally, these vessels contain normal variants associated with their embryology and development. The ACA particularly shows characteristic variants such as a persistent primitive olfactory artery and an infraoptic course, among other such variations, which is attributable to the fact that it is embryologically older than the middle and posterior cerebral arteries. Aneurysm formation is associated with these variants. Therefore, knowledge of the normal anatomy and variants is important for diagnosis and treatment of conditions involving these arteries. In this article, we describe the normal anatomy and variants of the ACA and AcomA, focused on their embryological development.

[Venous Anatomy of the Superior and Inferior Sagittal Sinuses].

The superior sagittal sinus(SSS)is contained within the dura, which consists of the dura propria and osteal dura at the junction of the falx cerebri, in addition to the attachment of the falx to the cranial vault. The SSS extends anteriorly from the foramen cecum and posteriorly to the torcular Herophili. The superior cerebral veins flow into the SSS, coursing under the lateral venous lacunae via bridging veins. Most of the bridging veins reach the dura and empty directly into the SSS. However, some are attached to the dural or existed in it for some distance before their sinus entrance. The venous structures of the junctional zone between the bridging vein and the SSS existed in the dura are referred to as dural venous channels. The SSS communicates with the lateral venous lacunae connecting the meningeal and diploic veins, as well as the emissary veins. These anatomical variations of the SSS are defined by the embryological processes of fusion and withdrawal of the sagittal plexus and marginal sinus.

Recurrent periventricular hemorrhage in cerebral proliferative angiopathy: Case report.

Cerebral proliferative angiopathy (CPA) is a rare vascular lesion. Bleeding from CPA is uncommon, but the risk of rebleeding is high once it bleeds. We describe a case of CPA with multiple intra- and periventricular hemorrhages during 30-year follow-up. Recurrent bleeding in these areas are common in moyamoya disease. These lesions may share the cause of bleeding: proliferation of the periventricular vessels functioning as collateral pathways. Revascularization surgery for CPA may attenuate the vascular proliferation in the vicinity of the ventricle, which may prevent rebleeding.

Choroid plexus AVM with anomalous origin of the capsulothalamic artery: A case report.

Background and importance Traditionally, it has been believed that the plexal segment of the anterior choroidal artery (AChoA) can be sacrificed safely. Here, we present a case of choroid plexus arteriovenous malformation (AVM) in which the capsulothalamic artery originated from distal plexal segment of the AChoA. Clinical presentation A 45-year-old man was diagnosed with arteriovenous malformation involving the left inferior horn in screening MRI. Preceding stereotactic radiosurgery, transarterial target embolization was performed. In this procedure, 20% n-butyl-2-cyanoacrylate (NBCA) was successfully injected from the lateral plexal branch of the AChoA. After embolization, right homonymous hemianopsia developed due to cerebral infarction on the left optic radiation. This infarction was considered to be within the territory of the capsulothalamic artery. Conclusion This anomalous capsulothalamic artery might be formed by hemodynamic compromise of the brain surrounding AVM in early gestation. We must be aware of this unusual anatomical variation to avoid ischemic complication in embolization of the AChoA.

Angiographic and Clinical Characteristics of Thoracolumbar Spinal Epidural and Dural Arteriovenous Fistulas.

BACKGROUND AND PURPOSE: The purpose of this study is to compare the angiographic and clinical characteristics of spinal epidural arteriovenous fistulas (SEAVFs) and spinal dural arteriovenous fistulas (SDAVFs) of the thoracolumbar spine. METHODS: A total of 168 cases diagnosed as spinal dural or extradural arteriovenous fistulas of the thoracolumbar spine were collected from 31 centers. Angiography and clinical findings, including symptoms, sex, and history of spinal surgery/trauma, were retrospectively reviewed. Angiographic images were evaluated, with a special interest in spinal levels, feeders, shunt points, a shunted epidural pouch and its location, and drainage pattern, by 6 readers to reach a consensus. RESULTS: The consensus diagnoses by the 6 readers were SDAVFs in 108 cases, SEAVFs in 59 cases, and paravertebral arteriovenous fistulas in 1 case. Twenty-nine of 59 cases (49%) of SEAVFs were incorrectly diagnosed as SDAVFs at the individual centers. The thoracic spine was involved in SDAVFs (87%) more often than SEAVFs (17%). Both types of arteriovenous fistulas were predominant in men (82% and 73%) and frequently showed progressive myelopathy (97% and 92%). A history of spinal injury/surgery was more frequently found in SEAVFs (36%) than in SDAVFs (12%; P=0.001). The shunt points of SDAVFs were medial to the medial interpedicle line in 77%, suggesting that SDAVFs commonly shunt to the bridging vein. All SEAVFs formed an epidural shunted pouch, which was frequently located in the ventral epidural space (88%) and drained into the perimedullary vein (75%), the paravertebral veins (10%), or both (15%). CONCLUSIONS: SDAVFs and SEAVFs showed similar symptoms and male predominance. SDAVFs frequently involve the thoracic spine and shunt into the bridging vein. SEAVFs frequently involve the lumbar spine and form a shunted pouch in the ventral epidural space draining into the perimedullary vein.

[Spontaneous cerebrospinal fluid rhinorrhea associated with long-standing overt ventriculomegaly in adults (LOVA)].

OBJECTIVE: Spontaneous cerebrospinal fluid rhinorrhea associated with aqueductal stenosis is rare. CSF diversion is reported to be a failure in the majority of cases. The combination of the repair of the skull base and CSF diversion is reported to be successful. We describe a case successfully treated by intradural repair with ventricular drainage followed by endoscopic third ventriculostomy. CLINICAL PRESENTATION: A 28-year-old woman presented with rhinorrhea, and occasional attacks of headache, vomiting, and unconsciousness for two years. She had been diagnosed as arrested hydrocephalus for 10 years. Magnetic resonance imaging revealed triventriculomegaly with ballooning of the floor of the third ventricle, tonsilar herniation, right anterior horn herniation into the cribriform plate, and bilateral temporal lobe herniation into the temporal base. INTERVENTION: A ventricular drain was inserted followed by dissection of the herniated brain and repair of the enlarged cribriform foramen with periosteal flap. Make sure that the bacterial culture negative, endoscopic third ventriculostomy has been performed. There is no recurrence of hydrocephalus and rhinorrhea for two years. CONCLUSION: Direct communication between the lateral ventricle and the nasal/paranasal sinus is a rare complication of aqueductal stenosis and LOVA. Surgical repair of the skull base followed by cerebrospinal fluid diversion with endoscopic third ventriculostomy was a safe and reliable method.

[Experience in the treatment for intracranial arteriovenous shunts in children].

PURPOSE: To report our experiences in the treatment for intracranial arteriovenous shunts (AV shunts) in the pediatric population. MATERIAL AND METHODS: Twelve children with intracranial AV shunts were treated with endovascular embolization between December 1993 and March 2008. These comprised two cases of vein of Galen aneurysmal malformation, three of dural sinus malformation, two of infantile dural AV shunt, five of pial AV fistula including two of vein of Galen aneurysmal dilatation. There were eleven boys and one girl. The age at the first embolization ranged from day 0 to 9 years. We reviewed their clinical features and outcomes. RESULTS: Six patients including four neonates presented with congestive heart failure, one infant with macrocrania and three children with headache, seizure or ataxia. The number of endovascular embolization ranged from one to five per patient. These included eighteen transarterial embolizations and ten transvenous embolizations. All patients except for one who died eventually from pulmonary hemorrhage showed improvement in their symptoms. Although only five patients achieved complete occlusion of AV shunts, six patients including them developed normally. CONCLUSION: Intracranial AV shunts in the pediatric population present characteristic clinical features depending on the age of the presentation. Endovascular embolization is currently the treatment of choice for them. It is more important to obtain normal development than to achieve normal morphological appearance. It is also important to understand the difference of pathophysiological features of these diseases in the pediatric and adult population.

Transventricular hemispherotomy for surgical treatment of intractable epilepsy.

Surgical procedures for cerebral hemispherotomy may be broadly divided into those using a lateral and those using a vertical approach. However, careful study of surgical procedures using the lateral approach described in the literature shows differences in the approach to the ventricles. We discuss the application of transventricular hemispherotomy as a technique which provides relatively easy ventricular access for cerebral hemispherotomy. Transventricular hemispherotomy was successfully performed in a 36-year-old woman who was diagnosed with intractable epilepsy due to Sturge-Weber disease, and in a 25-year-old man who had developed intractable post-traumatic seizures after suffering cerebral contusion in a traffic accident as a child. These patients had no seizures or complications after surgery, and both patients have been weaned from antiepileptic drugs. The transventricular approach, as compared with other lateral approaches described in the literature, provides easy access to the ventricular cavity. Transventricular hemispherotomy proved to be a useful approach that allowed the following four common steps in cerebral hemispherotomy to be performed safely: (i) interruption of the internal capsule and corona radiata; (ii) resection of the medial temporal structures; (iii) transventricular corpus callosotomy; and (iv) disruption of the frontal horizontal fibers.

[Detection of unknown primary tumor in a patient with cerebellar metastasis using FDG PET-CT: case report].

Identification of unknown primary tumors in patients with brain metastasis is a continued diagnostic challenge. Several clinical reports have suggested that 18F-flouorodeoxyglucose positron emission tomography (FDG PET) is useful for detecting them. PET has incomparable abilities to determine the metabolic activity of tissues. But it needs the assistance of higher-resolution, anatomic information. CT is the easiest and highest-resolution tomographic modality to be integrated into PET imaging. Because of this, the market for PET devices has shifted so dramatically toward PET-CT. We report a case to show that FDG PET-CT was able to detect an unknown primary tumor. A 75-year-old female underwent resection of a left cerebellar tumor. The histological diagnosis was adenocarcinoma metastasis. Conventional systemic evaluation (chest radiography, chest and abdomen CT, abdominal sonography, and so on) did not show any pathologic image. FDG PET-CT was then carried out. A hypermetabolic focus was revealed in the left hilum. In conclusion, from now on, FDG PET-CT will be considered as the first diagnostic process for patients presenting brain metastasis with an unknown primary tumor.

A brainstem cavernoma demonstrating a dramatic, spontaneous decrease in size during follow-up: case report and review of the literature.

BACKGROUND: Many reports have demonstrated a worse prognosis for patients whose cavernomas were subtotally removed than for those whose cavernomas were not surgically treated. Therefore, it is better not to touch the cavernoma if a surgeon is not prepared to totally remove it. This report describes a large brainstem cavernoma showing a spontaneous, dramatic reduction in size after removal of only the biopsy specimen of the lesion. CASE DESCRIPTION: A 42-year-old woman experienced facial numbness, diplopia, and ataxia. A magnetic resonance (MR) study revealed a pontine cavernoma with hemorrhage. Two weeks later, recurrence of the patient's symptoms and consciousness disturbance were noted. An MR study revealed massive hemorrhage from the cavernoma with a ventricle dilatation. An operation on the lesion was conducted 3 months after the initial hemorrhage. However, the operation was aborted when an exploration of the lesion showed a tight adhesion between the lesion and the pons. Removal of only a biopsy specimen and evacuation of the suckable hematoma were done. No neurologic recovery and no decrease in the size of the cavernoma were detected postoperatively. Her family did not wish for further treatments. She was in a bedridden state with severe brainstem dysfunction when she was transferred to a local hospital. Sixteen months after the surgery, her consciousness was clear, and MR imaging confirmed a marked reduction in the size of the cavernoma. CONCLUSION: A dramatic, spontaneous decrease in size does occur even in the case of a large brainstem cavernoma showing hemorrhages. Conservative therapy may be one of the treatment options for the symptomatic brainstem cavernoma.

[Neuroanatomical study of the internal structures of the brain based on brain fiber dissection].

From the beginning of the 17th Century, anatomists started to elucidate numerous tracts and fasciculi of the brain using fiber dissection techniques. Due to the complexities associated with tissue preparation and the time-consuming nature of traditional techniques the popularity of this method has gradually declined with the advent of modern neuroimaging techniques such as MRI. Many novel approaches to deep brain lesions have recently been devised following the development of skull base surgery. In comparison, the study of functional neuroanatomy has been relatively neglected. Understanding how neuronal fibers in the brain interconnect and communicate neuronal functions is critical when performing surgery for malignant glioma and epilepsy, as brain parenchyma has to be resected and neuronal fibers are interrupted. In the preoperative planning process we have applied anatomical studies using brain fiber dissection techniques. Brain fiber dissection offers the advantage of exposing association, commissural and projection fibers of cerebral white matter in three dimensions. Brain fiber dissection appears useful for assisting neurosurgeons to acquire neurosurgical skills and become familiar with neuroanatomical features. The techniques and significance of brain fiber dissection are described herein.

Regrowth and fatal rerupture despite proximal occlusion after coil embolization of a ruptured large basilar bifurcation aneurysm--case report.

A 40-year-old man suffered chronic progressive symptoms of brainstem compression after undergoing endosaccular coil placement in a ruptured large basilar bifurcation aneurysm. Radiographical examinations showed coil compaction and regrowth of the aneurysmal mass with perifocal mesencephalic edema. The symptoms did not resolve even after additional clip occlusion of the upper basilar artery and the patient died of rerupture. At present, direct surgical clipping using a skull base technique with or without hypothermic circulatory arrest or upper basilar artery occlusion with or without bypass surgery may be a better choice as an initial treatment for giant or large basilar bifurcation aneurysm with a wide neck.

[The treatment for asymptomatic meningiomas in the era of radiosurgery].

We evaluated the treatment results in asymptomatic meningiomas in the era of radiosurgery. We encountered 56 patients with asymptomatic meningiomas from January, 1994 to December, 2001. There were 16 male patients and 40 female patients. The most common location was the cerebral convexity. We performed gamma knife radiosurgery for three patients after diagnosis of cavernous sinus meningiomas. The other patients were followed-up after diagnosis for a mean follow-up period of 30.8 months (5 months to 8 years). Tumor growth was verified in 25 patients (43%) and two patients (3.7%) suffered neurological deficits. Among the tumor growth patients, operative resection was performed in six patients (11%) and gamma knife radiosurgery was performed in four patients (7.5%). The other patients were placed under observation. We decided the treatment strategy paying attention to the tumor location, tumor growth speed, tumor size and operative difficulty. The tumor growth rate was 0.1 cm/year among the patients with tumor growth. It was 0.72 cm/year (0.02 to 1.54 cm/year) in the operative group, 0.3 cm/year (0.04 to 0.76 cm/year) in the gamma knife radiosurgery group and 0.08 cm/year (0.01 to 0.76 cm/year) in the observed group. One patient suffered procedure-related deterioration of paresis after operation. The treatment of asymptomatic meningiomas must be decided depending on their natural history and locations. We recommend early radiosurgery for cavernous sinus meningiomas.

[The surgical treatment strategy and results of parasellar meningiomas in the era of radiosurgery].

We evaluated the surgical treatment results of parasellar meningiomas in the era of radiosurgery. We treated 24 patients of parasellar meningiomas surgically. The median age was 60 yrs (ranging from 29 to 82 yrs). The most common tumor location was the sphenoid ridge in 12 patients and the tuberculum sellae in 7 patients. The pterional approach using fronto-temporal craniotomy was performed for all patients. The residual or recurrent tumors were treated by gamma knife radiosurgery (GKS). We are able to follow up these cases for a median of 3.8 yrs (ranging from 1 to 8 yrs) after the operations. The radicality of tumor resection was Simpson grade II in 13 patients (54%), grade III in 3 patients (13%) and grade IV in 7 patients (33%). Clinical improvement was achieved in 81% of the patients. Of the patients who had visual disturbance preoperatively, 8 patients (73%) showed improvement, but 3 patients suffered deterioration postoperatively. None of the patients died. One patient suffered transient memory disturbance and one patient suffered mild facial numbness postoperatively. Boost radiosurgery for the residual tumors was performed for six patients and tumor growth control was able to be achieved in all patients, with a median of 3.1 years follow-up period (ranging from 0.5 to 6 yrs). Five patients with tumor regrowth or recurrence were treated by GKS. We recommend fronto-temporal craniotomy with nonradical resection for parasellar meningiomas and radiosurgery for residual and recurrent tumors. This strategy will achieve good functional outcome with long-term tumor growth control.

Surgery combined with radiosurgery of large acoustic neuromas.

UNLABELLED: The treatment of acoustic neuromas has been improved by advancements in microsurgical techniques and in radiosurgery. To further elucidate the degree of clinical improvement, we evaluated the treatment results of a combination of surgery and radiosurgery for large acoustic neuromas. METHODS: From January 1994 through December 2000, we treated 14 patients with large acoustic neuromas using a combination of surgery and radiosurgery. Of these, 8 were male and 6 were female patients, with an average age of 47 years (range, 18-64). The average maximum diameter of the tumor was 42 mm (range, 30-58 mm). All patients underwent operations using the retrosigmoid approach, and one patient was retreated using the transpetrosal transtentorial approach. The tumors were removed subtotally in thirteen patients and partially in one who had a very large hypervascular acoustic neuroma. There were no mortality and no surgical complications, such as hemorrhage or CSF leakage. Postoperative facial palsy was avoided in 10 patients (71%). Radiosurgery was performed 1 to 6 months (mean, 2.9 months) after surgery. At the time of radiosurgery, the treatment size (mean diameter) became 19.2 mm (range, 9.8-36.1 mm). The average tumor marginal dose was 12.1Gy (range, from 10-14 Gy). The mean follow-up period was 32 months after radiosurgery. RESULTS: The tumor size decreased in 6 patients, unchanged in 5 patients, and increased in 3 patients. Only 1 patient (7%) with extra large tumor needed surgical resection 1 year after radiosurgery. Excellent facial nerve function (House & Brackmann Grade I or II) was preserved in 12 patients (85.7%) in the final follow-up. CONCLUSIONS: In the case of large acoustic neuromas, subtotal removal and subsequent radiosurgery is one option for maintaining cranial nerve function and long-term tumor growth control.

Gamma knife radiosurgery for the treatment of cavernous sinus meningiomas.

OBJECTIVE: We report on the efficacy of gamma knife radiosurgery for cavernous sinus meningiomas. METHODS: Between January 1994 and December 1999, we used gamma knife radiosurgery for the treatment of 43 patients with cavernous sinus meningiomas. Forty-two patients were followed up for a mean of 49.4 months (range, 18-84 mo). The patients' average age was 55 years (range, 18-81 yr). Twenty-two patients (52%) underwent operations before radiosurgery, and 20 patients (48%) underwent radiosurgery after the diagnosis was made by magnetic resonance imaging. The tumor volumes ranged from 1.2 to 101.5 cm(3) (mean, 14.7 cm(3)). The tumors either compressed or were attached to the optic apparatus in 17 patients (40.5%). The marginal radiation dose was 8 to 15 Gy (mean, 11 Gy), and the optic apparatus was irradiated with 2 to 12 Gy (mean, 6.2 Gy). Three patients with a mean tumor diameter greater than 4 cm were treated by two-stage radiosurgery. RESULTS: Thirty-eight patients (90.5%) demonstrated tumor growth control during the follow-up period after radiosurgery. Tumor regression was observed in 25 patients (59.5%), and growth was unchanged in 13 patients (31%). Regrowth or recurrence occurred in four patients (9.5%). The actual tumor growth control rate at 5 years was 92%. Only one patient (2.4%) experienced regrowth within the treatment field; in other patients, regrowth occurred at sites peripheral to or outside the treatment field. Twelve patients (28.6%) had improved clinically by the time of the follow-up examination. None of the patients experienced optic neuropathy caused by radiation injury or any new neurological deficits after radiosurgery. CONCLUSION: Gamma knife radiosurgery may be a useful option for the treatment of cavernous sinus meningiomas not only as an adjuvant to surgery but also as an alternative to surgical removal. We have shown it to be safe and effective even in tumors that adhere to or are in close proximity to the optic apparatus.

[Surgical stress in patients with asymptomatic unruptured intracranial aneurysms].

BACKGROUND: Surgical stress elicits a characteristic response involving induction of synthesis and release of acute-phase proteins such as C-reactive protein (CRP). To objectively evaluate the surgical stress in patients with asymptomatic unruptured intracranial aneurysms, serum levels of CRP after direct clipping via the pterional approach were measured. METHODS: 42 patients who experienced an uneventful postoperative course, were evaluated according to age (less or more than 65 years old [adult or elderly]), aneurysmal location (middle cerebral artery territory [MC], anterior communicating artery [Acom] or internal carotid artery territory [IC]) and intraoperative trauma (positive or negative). We defined intraoperative trauma as intentional vein cutting, perforator vessel injury or suction of the gyrus rectus. All patients received standardized general anesthesia and were treated after the operations according to our standard protocols. Serum levels of CRP on postoperative day 2 were compared in each category. RESULTS: Serum levels of CRP showed no significant difference between the adult group and the elderly group, but were greater in Acom patients than in MC and IC patients (p < 0.01, p < 0.05). As to intraoperative traumas, the positive group (almost all were intentional vein cutting) showed greater CRP levels than the negative group in MC and IC patients (p < 0.05). Operation time and volume of blood loss were almost the same in each category. CONCLUSION: Our study shows that as far as serum levels of CRP are concerned, Acom location and vein cutting are the main factors of surgical stress in cases of unruptured aneurysms.