Surgical treatment of arteriovenous angiomas localised in the corpus callosum,basal ganglia and near the brain stem

Seven cases of deep angiomas, in regions near the midline, were operated on in the National Institute of Neurosurgery, Budapest. In four cases the malformation was not so circumscribed that it could be localized in one structure alone. On two occasions it involved the corpus callosum and the neighbouring hemispheral substance; in one instance it involved the head of the caudate nucleus and the lateral ventricle also. Two intraventricular angiomas, supplied by the choroidal arteries, involved the corpus striatum and the thalamus. Three cases of juxtapeduncular angiomas are described in this series. They were situated in the deep medial part of the temporal lobe, closely adhering to the peduncle, and supplied by branches of the posterior cerebral and the lateral choroidal arteries. In one case the malformation, which involved the thalamus, could be only partly removed. In six cases total extirpation was carried out. All patients ar alive and six are working. No symptoms which were not present before operation have appeared. The importance of adequate radiological studies prior to surgery is emphasized. Attention is drawn to the possibility of eventual obstruction in the CSF circulation in the postoperative period following intraventricular manipulation.     

Choroid plexus arteriovenous malformations.

Among 24 arteriovenous malformations (AVMs) involving the choroid plexus, 11 were plexal type AVMs predominantly located in the choroid plexus of the lateral ventricle, and 13 were parenchymal type AVMs mainly situated in the paraventricular cerebral parenchyma. 83% of all AVMs involved both the choroid plexus and the paraventricular cerebral parenchyma. Most cases presented with intracranial hemorrhage, particularly intraventricular hemorrhage. The most serious surgical problem was a small residual nidus unrecognized at the initial operation causing postoperative hemorrhage. Five parenchymal type AVMs presented residual niduses in the choroid plexus, causing death in two cases. Two plexal type AVMs resulted in residual AVMs supplied by the cisternal segment of the anterior choroidal artery, situated in the medial temporal lobe. To prevent postoperative hemorrhage from a small residual nidus, immediate postoperative angiography while the patient is still under general anesthesia should be performed to identify any residual nidus.     

Periinsular hemispherotomy: surgical technique, intraoperative EEG monitoring and results on seizure outcome

Peri-insular hemispherotomy is a surgical technique used in the treatment of drug-resistant epilepsy of hemispheric origin. It is based on the exposure of insula and semi-circular sulci, providing access to the lateral ventricle through a supra- and infra-insular window. From inside the ventricle, a parasagittal callosotomy is performed. The basal and medial portion of the frontal lobe is isolated. Projections to the anterior commissure are interrupted at the time of amygdala resection. The hippocampal tail and fimbria-fornix are disrupted posteriorly. We report our experience of 18 cases treated with this approach. More than half of them presented with congenital epilepsy. Neuronavigation was useful in precisely determining the center and extent of the craniotomy, as well as the direction of tractotomies and callosotomy, allowing minimal exposure and blood loss. Intra-operative monitoring by scalp EEG on the contralateral hemisphere was used to follow the progression of the number of interictal spikes during the disconnection procedure. Approximately 90% of patients were in Engel's Class I. We observed one case who presented with transient postoperative neurological deterioration probably due to CSF overdrainage and documented one case of incomplete disconnection in a patient presenting with hemimegalencephaly who needed a second operation. We observed a good correlation between a significant decrease in the number of spikes at the end of the procedure and seizure outcome. Peri-insular hemispherotomy provides a functional disconnection of the hemisphere with minimal resection of cerebral tissue. It is an efficient technique with a low complication rate. Intra-operative EEG monitoring might be used as a predictive factor of completeness of the disconnection and consequently, seizure outcome.     

Intraventricular aneurysm of the medial posterior choroid artery clipped via the contralateral transcallosal approach

Summary In lesions located in the lateral ventricle of the dominant hemisphere the contralateral transcallosal approach provides maximum protection of the dominant side as well as excellent visualization of the cella media of the contralateral lateral ventricle. We demonstrated this safe approach in a rare case with intraventricular aneurysm of the left medial choroid artery. The literature on aneurysms in the lateral ventricle is discussed.     

Anaplastic astrocytoma and anaplastic oligodendroglioma occurring 6 years after subtotal resection of a central neurocytoma. Case report

The authors present the case of a 51-year-old man who presented with an anaplastic astrocytoma and anaplastic oligodendroglioma that developed 6 years after subtotal resection of a central neurocytoma in his right lateral ventricle. He had received neither radiation therapy nor chemotherapy after the original resection. On readmission, neuroimaging revealed a mass in the right parietal lobe and a diffuse lesion in the right temporal lobe, insula, and corona radiata. Because both lesions extended to the right lateral ventricle wall, they were regarded as recurrent rather than metachronous tumors. Histological examination revealed anaplastic oligodendroglioma in the parietal lobe and anaplastic astrocytoma in the insula. One year later, the anaplastic astrocytoma was found to have transformed into a glioblastoma multiforme. Fluorescence in situ hybridization analysis and immunohistochemical examinations detected deletions of the lp36 and 19q13 loci, and nuclear accumulation of TP53 protein in the anaplastic oligodendroglioma but not in the glioblastoma multiforme. These findings suggest that central neurocytoma or progenitor cells have the potential for oligodendrocytic and astrocytic transformation with different genetic aberrations.     

Trigonal cavernous angioma presenting with selective ventricular exclusion

We present a case of a patient with an intraventricular cavernous angioma originating from the splenium of the corpus callosum presenting with intracranial hypertension syndrome. In our case the growth of the lesion from the corpus callosum toward the ventricular spaces determined the direct exclusion of the occipital and temporal horn of the left lateral ventricle.     

Microanatomy of the subependymal arteries of the lateral ventricle

BACKGROUND: Scarce information about the anatomy of the subependymal arteries (SEAs) is present in the scientific literature. METHODS: Twenty cerebral hemispheres with injected arteries were microdissected, and the magnetic resonance imaging scans of 100 patients with lacunar infarcts were examined. RESULTS: The SEAs were found to range in diameter from 40 to 490 microm (mean, 149 microm) and in number between 3 and 12 (average, 5.2). Of these, numbers from 1 to 3 originated from the anterior choroidal artery (AChA), between 1 and 10 from the lateral posterior choroidal artery (LPChA), 1 from the medial posterior choroidal artery (MPChA), and 1 from the internal carotid artery. The SEAs most often arose from the choroidal branches (90%) and less frequently from the thalamic (30%), caudate (35%), or thalamocaudate twigs (20%). The SEAs of the AChA supplied the walls of the temporal horn (100%), the occipital horn (85%), and the atrium (35%). Those of the LPChA perfused the walls of the occipital horn (15%), the atrium (65%), the body of the ventricle (100%), and partially the frontal horn. The SEAs of the MPChA partially nourished the body and the frontal horn (10%). The SEAs may also occasionally supply the caudate nucleus (20%) and the stria terminalis. The anastomoses involving the SEAs were absent. In spite of this, ischemia in the territory of a single SEA was noticed in only 1% of our patients. CONCLUSIONS: The SEAs are tiny vessels that supply the walls of the lateral ventricle, as well as the caudate nucleus and the stria terminalis occasionally. The obtained anatomic data can have important neurosurgical implications in intraventricular operations.     

Microsurgical anatomy of the distal anterior cerebral artery

The microsurgical anatomy of the distal anterior cerebral artery (ACA) has been defined in 50 cerebral hemispheres. The distal ACA, the portion beginning at the anterior communicating artery (ACoA), was divided into four segments (A2 through A5) according to Fischer. The distal ACA gave origin to central and cerebral branches. The central branches passed to the optic chiasm, suprachiasmatic area, and anterior forebrain below the corpus callosum. The cerebral branches were divided into cortical, subcortical, and callosal branches. The most frequent site of origin of the cortical branches was as follows: orbitofrontal and frontopolar arteries, A2; the anterior and middle internal frontal and callosomarginal arteries, A3; the paracentral artery, A4; and the superior and inferior parietal arteries, A5. The posterior internal frontal artery arose with approximately equal frequency from A3 and A4 and callosomarginal artery. All the cortical branches arose more frequently from the pericallosal than the callosomarginal artery. Of the major cortical branches, the internal frontal and paracentral arteries arose most frequently from the callosomarginal artery. The distal ACA of one hemisphere sent branches to the contralateral hemisphere in 64% of brains. The anterior portions of the hemisphere between the 5-cm and 15-cm points on the circumferential line showed the most promise of revealing a recipient artery of sufficient size for an extracranial-intracranial artery anastomosis. The distal ACA was the principal artery supplying the corpus callosum. The recurrent artery, which arose from the A2 segment in 78% of hemispheres, sent branches into the subcortical area around the anterior limb of the internal capsule.     

Microsurgical anatomy of the superficial veins of the cerebrum

The microsurgical anatomy of the superficial cortical veins was examined in 20 cerebral hemispheres. The superficial cortical veins are divided into three groups based on whether they drain the lateral, medial, or inferior surface of the hemisphere. The veins on the three surfaces are further subdivided on the basis of the lobe and cortical area that they drain. The superficial cerebral veins collect into four groups of bridging veins: a superior sagittal group, which drains into the superior sagittal sinus; a sphenoidal group, which drains into the sphenoparietal and cavernous sinuses on the inner surface of the sphenoid bone; a tentorial group, which converges on the sinuses in the tentorium; and a falcine group, which empties into the inferior sagittal or straight sinus or their tributaries. The superior sagittal group drains the superior part of the medial and lateral surfaces of the frontal, parietal, and occipital lobes and the anterior part of the basal surface of the frontal lobe. The sphenoidal group drains the parts of the frontal, temporal, and parietal lobes adjoining the sylvian fissure. The tentorial group drains the lateral surface of the temporal lobe and the basal surface of the temporal and occipital lobes. The falcine group drains an area that includes the cingulate and parahippocampal gyri and approximates the cortical parts of the limbic lobe of the brain. The relationship of these veins to the venous lacunae was also examined.     

A case of large basal ganglia AVM totally removed by staged operation

Large basal ganglia AVMs have been deemed inoperable because of their location in critical structures. Nonetheless, the unfavorable natural history of an untreated ruptured AVM in a young patient induced us to approach these lesions. We presented a case of a large basal ganglia AVM totally removed by a three-staged operation. A 26-year-old man who had twice experienced intracranial hemorrhage was admitted for examination. On admission, mild left hemiparesis, hypesthesia and left hemianopsia were disclosed. CT scan showed the AVM was located in the posterior thalamus with the hematoma cavity laterally. Right carotid and vertebral angiograms demonstrated a large AVM, 5cm in diameter, supplied by the anterior choroidal artery (AchoA), the lateral lenticulostriate arteries (I-LSAs), the lateral posterior choroidal artery (LPchoA) and the thalamo-perforating artery. Drainage was via the internal cerebral vein and the basal vein of Rosenthal. MRI demonstrated more clearly the anatomical relationship of the nidus and surrounding structures. The patient underwent a three staged operation. At the first operation AchoA was interrupted in the inferior horn of the lateral ventricle (IHL) via the hematoma cavity using the trans-sylvian approach. The anterior part of the nidus was dissected with all except one of the I-LSAs being disconnected. At the next operation by occipital interhemispheric approach, some feeders from the posterior cerebral artery were coagulated and disconnected. The medial and posterior part of the nidus was dissected from the thalamus along with the choroid plexus of the trigone of the lateral ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anatomy of the periventricular white matter

The lateral ventricle (LV) has a deep position within the cerebral hemisphere. The LV is covered by white matter with important functional role in the dominant hemisphere. Lateral wall of the frontal horn is covered by the inferior occipitofrontal fasciculus (IOFF) and its roof by the corpus callosum (CC). The body of the LV has the same cranial relationship and is covered laterally by fibers of internal capsula and arcuate fasciculus; its lower part is in relationship with the body of the fornix. The atrium of the LV is covered by the arcuate fasciculus and its lower part is covered by the IOFF and optic radiations. The inferior horn or temporal horn is covered by optic radiations in depth of middle temporal gyrus (T2). The auditive radiations crossed the optic radiations at the level of the roof of the inferior horn.     

Retinotopy with coordinates of lateral occipital cortex in humans

OBJECT: The lateral occipital cortex in humans is known as the "extrastriate visual cortex." It is, however, an unexplored field of research, and the anatomical nomenclature for its surface has still not been standardized. This study was designed to investigate whether the lateral occipital cortex in humans has retinotopic representation. METHODS: Four right-handed patients with a diagnosis of intractable epilepsy from space-occupying lesions in the occipital lobe or epilepsy originating in the occipital lobe received permanently implanted subdural electrodes. Electrical cortical stimulation was applied directly applied to the brain through metal electrodes by using a biphasic stimulator. The location of each electrode was measured on a lateral skull x-ray study. Each patient considered a whiteboard with vertical and horizontal median lines. The patient was asked to look at the midpoint on the whiteboard. If a visual hallucination or illusion occurred, the patient recorded its outline, shape, color, location, and motion on white paper one tenth the size of, and with vertical and horizontal median lines similar to those on, the whiteboard. Polar angles and eccentricities of the midpoints of the phosphenes from the coordinate origin were measured on the paper. On stimulation of the lateral occipital lobe, 44 phosphenes occurred. All phosphenes were circular or dotted, with a diameter of approximately 1 cm, except one that was like a curtain in the peripheral end of the upper and lower visual fields on stimulation of the parietooccipital region. All phosphenes appeared in the visual field contralateral to the cerebral hemisphere stimulated. On stimulation of the lateral occipital lobe, 22 phosphenes moved centrifugally or toward a horizontal line. From three-dimensional scatterplots and contour maps of the polar angles and eccentricities in relation to the x-ray coordinates of the electrodes, one can infer that the lateral occipital cortex in humans has retinotopic representation. CONCLUSIONS: The authors found that phosphenes induced by electrical cortical stimulation of the lateral occipital cortex represent retinotopy. From these results one can assert that visual field representation with retinotopic relation exists in the extrastriate visual cortex.     

Arteriovenous malformations of the lateral ventricle

Nine cases with arteriovenous malformations (AVM's) predominantly involving the lateral ventricle are presented. All the AVM's were small, but caused intraventricular hemorrhage in eight cases. Only two patients had an intracerebral hemorrhage large enough to warrant evacuation. Eight patients were under the age of 40 years at the onset of their disease. Computerized tomography demonstrated intraventricular hemorrhage in eight patients, and after intravenous administration of contrast medium a small area of enhancement with dilated subependymal draining veins was seen in seven. The lateral ventricles were of normal size in seven cases, and only two patients required a shunting procedure. Angiography demonstrated that the lesion was an AVM in eight patients, and did not visualize the lesion in the ninth. One patient suffered a recurrent intraventricular hemorrhage when the AVM was demonstrated, although repeated angiography had failed to disclose a vascular lesion at his first intraventricular hemorrhage 14 months before. All nine lesions were resected by microsurgical techniques, and the results were excellent in eight patients. Of four caudate lesions, three were resected through a frontal transcortical approach and the other was operated on through an anterior transcallosal approach; the results were excellent in three of these patients. Only one (Case 4) was left with neurological deficits; he had confusion and disorientation following a right frontal transcortical approach. Even in the dominant hemisphere, lesions in the head of the caudate nucleus could be safely resected by an anterior transcallosal approach. Two choroidal lesions located in the temporal horn and trigone on the dominant side were resected through a middle temporal gyrus approach, and three thalamic lesions through a posterior transcallosal approach, all with excellent results. In all cases the brain opening required was about the width of the retractor (maximum 2.0 cm, average 1.5 cm).     

Accessory intraventricular prominence of the occipital horn of the lateral ventricle

OBJECT: Knowledge of normal variations in ventricular morphological features is important in endoscopic neurosurgery. Classically, two elevations are described on the medial wall of the occipital horn of the lateral ventricle: an upper bulb and a lower calcar avis. Nevertheless, a third, as yet unreported elevation may be present at the junction of the medial wall and the floor of the occipital horn. The authors report the frequency with which this third elevation was found in a series of cadaveric brains. METHODS: The medial wall of the occipital horn of the lateral ventricle was studied in the three orthogonal planes in 45 formalin-fixed cadaveric hemispheres. The underlying structures responsible for the observed intraventricular prominences were exposed by microdissection. A third elevation was present, lying ventrorostral to the calcar avis, in seven (47%) of the 15 single hemispheres, and bilaterally in six (40%) of the 15 whole brains. After microdissection, a fiber bundle from the splenium of the corpus callosum was seen emerging in the occipital horn at the angle between the tail of the hippocampus and the bulb of the occipital horn. The most rostral fibers fanned out inferolaterally along the floor of the collateral trigone. The larger, posterior part protruded into the medial wall along the ventral border of the calcar avis as far as the tip of the occipital horn. CONCLUSIONS: Besides its importance as a variation of normal ventricular morphological features, the close relationship of this accessory intraventricular prominence to the tail of the hippocampus should be kept in mind when intervening neurosurgically so that damage to the underlying commissural fibers can be avoided.     

Manual occipital ventricular puncture for cerebrospinal fluid shunt surgery: can aiming be standardized?

The manual occipital ventricular puncture is a standard surgical procedure, but specific targeting has not received sufficient attention despite the experience of anatomical disorientation. This study tried to identify an exact site for the ideal trajectory with this method, especially in the sagittal plane, which avoids contact with the choroid plexus that may be the major source of complications. A total of 44 consecutive adult cases undergoing cerebrospinal fluid shunting through the occipital route for hydrocephalus were retrospectively reviewed for the following: correlations between burr hole site, direction of puncture, and location of the ventricular catheter based on postsurgical radiological studies; calculation of the ideal trajectory to place the catheter tip in the anterior horn of the lateral ventricle without contact with the choroid plexus through the standard occipital burr hole. In addition, the relationships between the location of the ventricular structure, the cranial base line connecting the nasion and inion, and the size of the ventricle were evaluated. Incorrect catheter emplacement was found in five cases, which suggested that this procedure using the standard burr hole site and aim point might result in incorrect catheter placement. The ideal external aim points were widely distributed because of the variable heights of ventricular structures from the cranial baseline. No correlation between the locations of the anatomical points and ventricular size was found. The present study could not define a standard external aim point. Tailored preoperative planning of the trajectory is recommended.     

Sylvian fissure arteriovenous malformations

We have operated on 16 cases of arteriovenous malformation (AVM) in and around the sylvian fissure. We call these lesions "sylvian fissure AVMs" and classify them into four subdivisions, namely, pure, lateral, medial, and deep AVMs. By others, they have been variously called AVMs of the basal ganglia, insula, anterior choroidal artery, frontal lobe, or temporal lobe. These sylvian fissure AVMs showed similar angiographic findings: the feeders in all cases were branches of the middle cerebral artery; in some cases, additional feeders from the anterior and posterior choroidal and posterior communicating arteries were present also. We describe the characteristic features of these AVMs from the anatomical and surgical points of view. The surgical results were satisfactory in 15 cases (no additional neurological deficits), and 1 patient died.     

Traumatic imtraventricular haemorrhage

Summary The findings of computerized tomography and clinical features were studied in 19 patients with traumatic intraventricular haemorrhage. Blood was found in various portion of the ventricles. Main sites of the blood was as follows: around the foramen of Monro, 6 patients; in the body and occipital horn of the lateral ventricle, 5 patients; solely in the occipital horn, 8 patients. The haemorrhage around the foramen of Monro, resulting from contusion of the ventral portion of the corpus callosum, septum pellucidum, and fornix, showed an interesting CT finding. Intracranial co-existing lesions were seen in 17 patients, and extracranial lesions were seen in 13 patients, suggesting the external force was excessive. Both the Glasgow coma scale scores on admission and Glasgow outcome scale were generally unfavourable, but 4 patients showed good recovery. The final outcome was mainly influenced by the severity of the coexisting intracranial lesions.     

Ipsilateral symptomatology in left temporal lobe lesions

Two cases of ipsilateral symptomatology related to left temporal lobe lesions are presented. The possibility of ipsilateral symptoms after temporal lobe lesions has to be considered, mainly when they occur in the dominant hemisphere. Direct or indirect damage to the insula of Reil's sensory-motor secondary area seems to be the motive of these ipsilateral symptoms.     

Blood-oxygenation-level-dependent functional magnetic resonance imaging for evaluating cerebral regions of female sexual arousal response

Objectives. To evaluate, for the first time, the cerebral regions associated with female sexual arousal evoked by visual stimulation using noninvasive blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI).Methods. A total of 6 healthy right-handed female volunteers (mean age 33 years, range 25 to 41) underwent fMRI on a 1.5-T MR scanner, in which the BOLD technique was used to create fMR images reflecting local brain activities. Real-time visual stimulation was performed with alternatively combined erotic and nonerotic films to identify the activated brain regions associated with sexual response. The perceived sexual arousal response was assessed using a scale ranging from 1 (no change) to 5 (maximal increase).Results. The mean score for perceived sexual arousal by erotic visual stimulation was 2.7 on the 5-point scale and was unchanged by nonerotic stimulation. During the visual task, the occipital cortex was activated by both the erotic and the nonerotic films; however, the following cerebral areas were significantly (P <0.05) activated, varying from 4 of 6 to 6 of 6 women: inferior frontal lobe, cingulate gyrus, insula gyrus, corpus callosum, thalamus, caudate nucleus, globus pallidus, and inferior temporal lobe.Conclusions. This study is the first to evaluate noninvasive BOLD-fMRI in identifying cerebral regions associated with sexual arousal response evoked by visual stimulation in women.