Arteries and veins of the lateral ventricle

Tumors of the frontal horn of the lateral ventricle (LV) are only supplied by the posteromedial choroidal artery. Tumors of the body of the LV are supplied by the same artery. Tumors of the atrium of the LV with anterior extension are supplied by both posteromedial choroidal and posterolateral arteries. Tumors of the atrium with inferior extension are supplied by both anterior choroidal artery and posterolateral choroidal arteries. Tumors of the inferior horn are only supplied by anterior choroidal artery. The tumoral venous drainage is organized with three main groups of veins: a medial group, a lateral group and a choroidal group.     

The surgical anatomy of the perforating branches of the anterior choroidal artery.

BACKGROUND: The available information about certain microanatomic features of the AChA perforators is incomplete. Precise knowledge of these vessels is necessary to understand the consequences of their occlusion and to safely operate in their region. METHODS: The AChA perforators were microdissected and examined under the stereoscopic microscope in 10 vascular casts and in 20 hemispheres injected with india ink or radiopaque substance. RESULTS: The perforating branches ranged in number from 2 to 9 (mean, 4.6) and in diameter between 90 microm and 600 microm (mean, 317 microm). The most proximal perforator arose 3.2 mm on average caudal to the AChA origin. The most distal (capsulothalamic) perforator varied in size from 200 microm to 610 microm (mean, 431 microm). One or more of the perforators always originated from the AChA (100%), but some of them also from the uncal (33.3%) or parahippocampal branch (10%) of the AChA, either as individual vessels only (70%) or from common trunks (30%). The perforators gave off the peduncular (20%), optic (23.3%), or uncal side branches (26.7%). CONCLUSIONS: Our findings concerning the origin, position, number, size, branching, penetration site, and relationships of the AChA perforators gave the anatomic basis for safe operations in patients with AChA aneurysms or mediobasal limbic epilepsy.     

Subchoroidal approach to the third ventricle microsurgical anatomy

The third ventricle can be approached by performing a few surgical maneuvers: (a) dividing the ependyma on the inferolateral aspect of the choroid plexus of the lateral ventricle; (b) separating leptomeningeal bundles within the tela chorioidea, and (c) dividing the roof of the third ventricle along the stria medullaris. Main landmarks are the thalamostriate vein and the direct lateral vein. Small subependymal veins or neural branches of the posterior medial choroidal artery, or both, occasionally cross the access route. The third ventricle is seen through both the opening in the roof and the foramen of Monro. A wider exposure can be obtained by cutting the terminal segment of the thalamostriate vein.     

Distal anterior choroidal artery aneurysm in a patient with moyamoya disease: case report

OBJECTIVE AND IMPORTANCE: Distal anterior choroidal artery (AChA) aneurysms in moyamoya disease are rare, with few surgically verified reported cases. CLINICAL PRESENTATION: We report a rare case of distal AChA aneurysm associated with moyamoya disease in a 48-year-old man who presented with vomiting and severe headache. Computed tomographic scans revealed an intracerebral hematoma in the right temporoparietal lobe and a diffuse intraventricular hemorrhage. INTERVENTION: The hematoma was removed via computed tomography-guided stereotactic aspiration and ventricular drainage. Cerebral angiography showed a saccular aneurysm located at the distal branch of the right AChA. By means of magnetic resonance imaging, a small signal void lesion was detected in the periventricular area lateral to the trigone of the right lateral ventricle. The aneurysm was accurately accessed via a parietal cortical incision by use of magnetic resonance imaging-guided stereotactic localization. The aneurysm was successfully resected after undergoing trapping of the parent artery, and when the patient was discharged, he had no evidence of neurological deficit. The aneurysm was histologically verified to be a true aneurysm. CONCLUSION: Direct surgery should be considered in cases of ruptured distal AChA aneurysms located in the periventricular or intraventricular regions.     

Use of microvascular Doppler sonography in aneurysm surgery on the anterior choroidal artery

Anterior choroidal artery (AChA) syndrome is still one of the most serious complications of the clipping of internal carotid artery aneurysms. No monitoring method can detect ischemia in the area of the AChA during surgery. This artery may be obstructed when a clip is applied to the neck of the aneurysm, and patency is sometimes difficult to confirm by microscopy because of the artery's small size and site of origin (usually behind the internal carotid artery as viewed surgically). However, microvascular Doppler sonography (MVDS) can detect flow instantaneously even in such a small vessel. In our series, AChA syndrome occurred in three of 19 patients treated for AChA aneurysm before the introduction of MVDS, but only one of 19 patients treated with the aid of this device. In that patient, one of the two AChA branches was intentionally sacrificed by applying a clip to the prematurely ruptured aneurysm. MVDS detected hypoperfusion of the AChA after clipping in five other patients, and so the clip was readjusted to preserve AChA flow. Use of MVDS is very effective to prevent inadvertent injury to the AChA during aneurysm surgery on this artery.     

Ischemic complications of surgery for anterior choroidal artery aneurysms

OBJECT: Anterior choroidal artery (AChA) aneurysms account for 4% of all intracranial aneurysms. The surgical approach is similar to that for other supraclinoid carotid artery lesions, but surgery may involve a higher risk of debilitating ischemic complications because of the critical territory supplied by the AChA. METHODS: Between 1968 and 1999, 51 AChA aneurysms in 50 patients were treated using craniotomy and clipping at the Mayo Clinic. There were 22 men (44%) and 28 women (56%) whose average age was 53 years (range 27-79 years). Twenty-four AChA aneurysms (47%) had hemorrhaged; nine patients (18%) had subarachnoid hemorrhage from another aneurysm. Three AChA aneurysms (6%) were associated with symptoms other than rupture. Forty-one patients (82%) achieved a Glasgow Outcome Scale (GOS) score of 4 or 5 at long-term follow up. The surgical mortality rate was 4%, and major surgical morbidity (GOS < or = 3) was 10%. Eight patients (16%) had clinically and computerized tomography-demonstrated AChA territory infarcts. Five of these strokes manifested in a delayed fashion 6 to 36 hours after the operation, and progressed from mild to complete deficit over hours. In 41 patients the aneurysm arose from the internal carotid artery adjacent to the AChA, and in nine patients the aneurysm arose directly from the origin of the AChA itself; four of these nine patients had postoperative infarction. CONCLUSIONS: Surgical treatment of AChA aneurysms involves a significant risk of debilitating ischemic complications. Most postoperative strokes occur in a delayed fashion, offering a potential therapeutic window. Patients with aneurysms arising from the AChA itself have an extremely high risk for postoperative stroke.     

Surgical approaches to the atrium of the lateral ventricle: microsurgical anatomy

BACKGROUND: Managing lesions situated in the atrium of the lateral ventricle remains a challenging neurosurgical problem. The purposes of this study were to examine the microsurgical anatomy of the atrium of the lateral ventricle and the optic radiation and to define the differences in the exposure obtained by various surgical approaches. METHODS: Fifteen adult cadaveric specimens were studied using magnification x3 to x40 after perfusion of the arteries and veins with colored silicone. The microsurgical anatomy of the atrium of the lateral ventricle was examined. The relationship between the optic radiation and the atrium was studied using the white matter fiber dissection technique. Surgical approaches to the atrium of the lateral ventricle were examined in stepwise dissection. RESULTS: The medial and inferior walls of the atrium were free from optic radiation fibers. Surgical approaches to the atrium of the lateral ventricle are divided into 3 routes: (1) anterior approach: transsylvian approach, (2) posterior approaches: posterior transcortical, posterior transcallosal, occipital, and supracerebellar transtentorial approaches, and (3) lateral approaches: transtemporal and subtemporal approaches. CONCLUSION: Knowledge of the microsurgical anatomy of the atrium of the lateral ventricle and surrounding vital structures and the choice of an appropriate surgical approach will help surgeons perform safe and minimally invasive surgery.     

Accessory cerebral ventricle of the occipital lobe. Morphogenesis and clinical and pathological appearance

Small separated accessory ventricles in the occipital lobe were observed in 21.3% of 404 patients, as seen by computerized tomogram. There was no significant preponderance in regard to sex or laterality. The accessory ventricles were clinically not significant. As seen at autopsy, accessory ventricles were found in the subcalcarine white matter, posterior to the occipital horn of the lateral ventricle, in 29.5% of 200 "normal" brains. Again, there were no significant sex and laterality differences. Accessory ventricles were never found in brains of fetuses or newborn babies. The youngest child in whom an accessory ventricle was found was 1 month old. No accessory ventricles were larger than 1 cm in diameter; they were slit-like, triangular or oval in shape. Histologically, they showed subtotal loss of the ependymal layer, subependymal gliosis, and/or fibrosis, and, in some cases, hyalinofibrotic capillary degeneration. Electron microscopy of the remaining ependymal cells in the accessory ventricle showed marked atrophy. Accessory ventricles are formed at the tip of the occipital horn postnatally through the expansion of the deep calcarine fissure, increase in brain volume in the region, and subsequent fusion of the mediolateral ventricular walls.     

Two adult cases of moyamoya disease with intraventricular hemorrhage--angiographic evaluation of periventricular vascular anatomy

In order to show the vascular anatomy in periventricular region, two adult cases of moyamoya disease with intracerebral hemorrhage extending into lateral ventricle were presented. And we discussed the relation between the vascular anatomy and the form of hemorrhage in moyamoya disease. The first case was a 46-year-old woman admitted for nausea and vomiting following headache for four days. CT scan revealed a high density area in the upper portion of body of right lateral ventricle showing intracerebral hemorrhage which extended into the lateral ventricle. On angiogram, typical moyamoya disease was noted. The ventriculofugal arteries from the posterior lateral choroidal artery was detected which indicated developed ventriculofugal perfusion. The second case was a 52-year-old man who was hospitalized sudden onset of headache, vomiting and consciousness disturbance. CT scan revealed a high density area suggesting of hemorrhage in the head of right caudate nucleus. It perforated into the right anterior horn of lateral ventricle with spreading over the other ventricles. We observed similar findings on the angiograms to the first case. In this case, however, the lateral striate arteries were involved instead of the posterior lateral choroidal artery. It should be pointed out that, in both cases, the area of hemorrhage in CT scan coincided with the area of developed ventriculofugal perfusion in angiograms.     

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)     

Saccular aneurysm of the distal anterior choroidal artery--case report.

The authors report a case of a distal anterior choroidal artery aneurysm in a 75-year-old female who presented with nausea, vomiting, and severe headache. Computed tomographic (CT) scans revealed a hematoma in the right lateral ventricle and a subarachnoid hemorrhage in the right parasellar-Sylvian cistern. Cerebral angiography showed a saccular aneurysm at the right distal anterior choroidal artery. The authors intended to operate at the chronic stage, and carried out conservative management. After 1 month her condition suddenly worsened and she died, although a CT scan showed no remarkable changes. At autopsy, a pulmonary artery thrombosis was considered the cause of death. The aneurysm was identified in the temporal horn of the right lateral ventricle, and was a true aneurysm.     

Ruptured cerebral pseudoaneurysm caused by the removal of a ventricular catheter. Case report

A rare case of cerebral pseudoaneurysm located at the internal carotid artery (ICA) was caused by the removal of a ventricular catheter in an infant. This 4-month-old girl underwent ventriculoperitoneal shunt revision, during which the old ventricular catheter was removed from the posterior horn of the left lateral ventricle, but the choroid plexus was pulled out by the tip of the catheter. Intraventricular hemorrhage (IVH) and subarachnoid hemorrhage were observed postoperatively. Magnetic resonance (MR) angiography performed on the 12th postoperative day revealed ICA stenosis and aneurysm formation at the C1 portion of the left ICA. Contrast-enhanced computerized tomography (CT) scans obtained on the 21st postoperative day revealed recurrent IVH and enlargement of the lesion. The patient underwent surgery for treatment of the aneurysm. Operative findings revealed a pseudoaneurysm arising from the left ICA at the proximal end of the anterior choroidal artery (AChA). The aneurysm was removed and the wall of the ICA was reconstructed. Postoperative three-dimensional CT scanning and MR angiography demonstrated disappearance of the aneurysm and preservation of the ICA. The patient was discharged without additional neurological deficits. Many complications, including IVH, are associated with removal of a ventricular catheter. This case shows that pseudoaneurysm formation can occur in a remote region due to avulsion of the AChA from the ICA. In most circumstances a ventricular catheter can be removed without difficulty. However, precision and caution should be exercised when removing a ventricular catheter.     

The anatomy of the heart

The normal heart is the size of the patient's closed fist. The venae cavae drain into the right atrium, which bears the fossa ovalis and receives the coronary sinus and the anterior cardiac vein. The atrium empties into the right ventricle through the tricuspid valve. Both ventricles have trabeculated walls (trabeculae carneae), and from some project the papillary muscles, bearing the chordae tendinae attached to the free borders of the tricuspid valve. The same arrangement is seen on the left side. The right ventricle leads to the pulmonary trunk, guarded by its three valve cusps. Oxygenated blood returns to the left atrium via the four pulmonary veins and passes to the left ventricle via the mitral valve. Exit is through the tricuspid aortic valve. The right and left coronary arteries arise above the valves, their orifices lying in the sinuses of Valsava. The right coronary artery lies in the right part of the atrioventricular groove and gives off the posterior interventricular artery. The left coronary arteries divide into the anterior (descending) interventricular branch and the circumflex branch. Major veins accompany the arteries, except for the anterior cardiac vein, which drains directly into the right atrium.     

The anatomy of the heart

The normal heart is the size of the patient’s closed fist. The venae cavae drain into the right atrium, which bears the fossa ovalis and receives the coronary sinus and the anterior cardiac vein. The atrium empties into the right ventricle through the tricuspid valve. Both ventricles have trabeculated walls (trabeculae carneae), and from some project the papillary muscles, bearing the chordae tendinae attached to the free borders of the tricuspid valve. The same arrangement is seen on the left side. The right ventricle leads to the pulmonary trunk, guarded by its three valve cusps. Oxygenated blood returns to the left atrium via the four pulmonary veins and passes to the left ventricle via the mitral valve. Exit is through the tricuspid aortic valve. The right and left coronary arteries arise above the valves, their orifices lying in the sinuses of Valsava. The right coronary artery lies in the right part of the atrioventricular groove and gives off the posterior interventricular artery. The left coronary arteries divide into the anterior (descending) interventricular branch and the circumflex branch. Major veins accompany the arteries, except for the anterior cardiac vein, which drains directly into the right atrium.     

Experience with the high occipital transcortical approach in the treatment of intraventricular hemorrhage. Report of two cases

Two patients with intraventricular hemorrhage (IVH) were treated by direct removal of their intraventricular hematomas via a high occipital transcortical approach with successful results. This approach lies between the parietooccipital transcortical approach and the occipital transcortical approach. The patients were a 90-year-old woman with idiopathic IVH and a 60-year-old man with hemorrhage caused by bleeding in the thalamus. In both cases, the hematoma was tightly packed in the lateral ventricle. In the former case, the inferior horn of the lateral ventricle was extremely swollen, and the patient was at risk for development of uncal herniation. With the goals of complete elimination of the hematoma in the inferior horn and identification of the source of bleeding, a high occipital transcortical approach was applied, and the hematoma was removed under direct vision. With the patient in the lateral position, a minor craniotomy of approximately 3 cm was performed around the puncture site of the posterior horn (8 cm craniad from the inion and 3 cm lateral from the midline). A 1-cm cortical incision was made and the posterior horn was reached. First, the portion of hematoma at this site was removed, and then the remainder was completely removed from the interior horn and corpus. Using this method, the entire region of the lateral ventricle, including the inferior horn, corpus, and posterior horn, can be covered in a single operative field, and it is also possible to have sufficient working space for the operation.     

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.     

Ventricular catheter trajectories from traditional shunt approaches: a morphometric study in adults with hydrocephalus

OBJECT: The purpose of this study was to compare the margins of error of different shunt catheter approaches to the lateral ventricle and assess surface anatomical aiming landmarks for free-hand ventricular catheter insertion in adult patients with hydrocephalus. METHODS: Four adults who had undergone stereotactic brain magnetic resonance (MR) imaging and had normal ventricles, and 7 prospectively recruited adult patients with acute hydrocephalus were selected for inclusion in this study. Reconstructed MR images obtained prior to surgical intervention were geometrically analyzed with regard to frontal, parietal, and parietooccipital (occipital) approaches in both hemispheres. RESULTS: The ventricular target zones were as follows: the frontal horn for frontal and occipital approaches, and the atrium/posterior horn for parietal approaches. The range of possible angles for successful catheter insertion was smallest for the occipital approach (8 degrees in the sagittal plane and 11 degrees in the coronal plane), greater for parietal catheters (23 and 36 degrees ), and greatest for the frontal approach in models of hydrocephalic brains (42 and 30 degrees; p < 0.001 for all comparisons except frontal vs parietal, which did not reach statistical significance). There was no single landmark for aiming occipital or parietal catheters that achieved ventricular target cannulation in every case. Success was achieved in only 86% of procedures using occipital trajectories and in 66% of those using parietal trajectories. CONCLUSIONS: The occipital approach to ventricular catheter insertion provides the narrowest margin of error with regard to trajectory but has less aiming point variability than the parietal approach. The use of patient-specific stereotaxy rather than generic guides is required for totally reliable, first-pass ventricular catheterization via a posterior approach to shunt placement surgery in adults.     

Blood flow disturbance in perforating arteries attributable to aneurysm surgery

OBJECT: The object of this study was to investigate patients with cerebral infarction in the area of the perforating arteries after aneurysm surgery. METHODS: The authors studied the incidence of cerebral infarction in 1043 patients using computed tomography or magnetic resonance imaging and the affected perforating arteries, clinical symptoms, prognosis, and operative maneuvers resulting in blood flow disturbance. RESULTS: Among 46 patients (4.4%) with infarction, the affected perforating arteries were the anterior choroidal artery (AChA) in nine patients, lenticulostriate artery (LSA) in nine patients, hypothalamic artery in two patients, posterior thalamoperforating artery in five patients, perforating artery of the vertebral artery (VA) in three patients, anterior thalamoperforating artery in nine patients, and recurrent artery of Heubner in nine patients. Sequelae persisted in 21 (45.7%) of the 46 patients; 13 (28.3%) had transient symptoms and 12 (26.1%) were asymptomatic. Sequelae developed in all patients with infarctions in perforating arteries in the area of the AChA, hypothalamic artery, or perforating artery of the VA; in four of five patients with posterior thalamoperforating artery involvement; and in two of nine with LSA involvement. The symptoms of anterior thalamoperforating artery infarction or recurrent artery of Heubner infarction were mild and/or transient. The operative maneuvers leading to blood flow disturbance in perforating arteries were aneurysmal neck clipping in 21 patients, temporary occlusion of the parent artery in nine patients, direct injury in seven patients, retraction in five patients, and trapping of the parent artery in four patients. CONCLUSIONS: The patency of the perforating artery cannot be determined by intraoperative microscopic inspection. Intraoperative motor evoked potential monitoring contributed to the detection of blood flow disturbance in the territory of the AChA and LSA.     

Microsurgical anatomy of the choroidal fissure

The microsurgical anatomy of the choroidal fissure was examined in 25 cadaveric heads. The choroidal fissure, the site of attachment of the choroid plexus in the lateral ventricle, is located between the fornix and thalamus in the medial part of the lateral ventricle. The choroidal fissure is divided into three parts: (a) a body portion situated in the body of the lateral ventricle between the body of the fornix and the thalamus, (b) an atrial part located in the atrium of the lateral ventricle between the crus of the fornix and the pulvinar, and (c) a temporal part situated in the temporal horn between the fimbria of the fornix and the lower surface of the thalamus. The three parts of the fissure are the thinnest sites in the wall of the lateral ventricle bordering the basal cisterns and the roof of the third ventricle. Opening through the body portion of the choroidal fissure from the lateral ventricle exposes the velum interpositum and third ventricle. Opening through the temporal portion of the choroidal fissure from the temporal horn exposes the structures in the ambient and crural cisterns. Opening through the atrial portion of the fissure from the atrium exposes the quadrigeminal cistern, the pineal region, and the posterior portion of the ambient cistern. The neural, arterial, and venous relationships of each part of the fissure are reviewed. The operative approaches directed through each part of the fissure are also reviewed.     

Intraoperative monitoring of blood flow insufficiency in the anterior choroidal artery during aneurysm surgery

OBJECT: The lack of a specified intraoperative method for monitoring anterior choroidal artery (AChA) blood flow insufficiency (BFI) led the authors to devise a method for checking the BFI in this artery during aneurysm surgery. To this end, the authors relied on the intraoperative motor evoked potentials (MEPs) elicited by electrical stimulation of the hand motor cortex. METHODS: The study population consisted of 108 patients with internal carotid artery (ICA) aneurysms who underwent surgery via a standard frontotemporal craniotomy. After the dura mater had been opened, a grid electrode strip with 16 small electrodes was inserted subdurally into the hand motor cortex from the edge of the craniotomy. To check BFI in the AChA, the hand motor cortex was stimulated at an intensity level between 10 and 18 mA. The MEPs were successfully recorded from the contralateral thenar muscles in all 108 patients. There was no postoperativemotor paresis in 88 patients in whom the MEPs remained unchanged during the performance of various surgical maneuvers. Among the other 20 patients, 19 manifested transient MEP changes, but 15 of those patients experienced no postoperative motor paresis. In four patients who exhibited transient MEP changes, either after aneurysm clipping or during temporary occlusion of the ICA and/or AChA, hemiparesis occurred postoperatively but disappeared within 24 hours. In one patient with an ICA-posterior communicating artery aneurysm, the MEP disappeared and did not reappear by the time of dural closure. Severe hemiplegia developed in this patient and a computerized tomography scan obtained postoperatively revealed a new low-density area in the internal capsule. CONCLUSIONS: The findings of this study suggest that the monitoring method that is introduced here is safe and reliable for detecting intraoperative BFI in the AChA.