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

Surgical outcomes of trigonal intraventricular meningiomas: a single-centre study

Trigonal meningiomas are rare intraventricular tumours that present a surgical challenge. There is no consensus on the optimal surgical approach to these lesions, though the transtemporal and transparietal approaches are most frequently employed. We aimed to examine the approach-related morbidity and surgical nuances in treating trigonal meningiomas. This retrospective review assimilated data from 64 trigonal meningiomas operated over 15 years. Details of clinicoradiological presentation, surgical approach and intraoperative impression, pathology and incidence of various postoperative deficits were recorded. In our study, Trigonal meningiomas most frequently presented with headache and visual deterioration. The median volume of tumours was 63.6cc. Thirty-one meningiomas each (48.4%) were WHO Grade 1 and WHO Grade 2, while 2 were WHO Grade 3. The most frequent approach employed was transtemporal (38 patients, 59.4%), followed by transparietal (22 patients, 34.4%). After surgery features of raised ICP and altered mental status resolved in all patients, while contralateral limb weakness resolved in 80%, aphasia in 60%, seizures in 70%, and vision loss in 46.2%. Eighteen patients (28.13%) developed transient postoperative neurological deficits, with one patient (1.5%) developing permanent morbidity. Surgery for IVMs results in rapid improvement of neurological status, though visual outcomes are poorer in patients with low vision prior to surgery, longer duration of complaints and optic atrophy. The new postoperative deficits in some patients tend to improve on follow up. Transtemporal and transparietal approaches may be employed, based on multiple factors like tumour extension, loculation of temporal horn, size of lesion with no significant difference in their safety profile.

Resection of the tumor in the trigone of the lateral ventricle via the contralateral posterior interhemispheric transfalcine transprecuneus approach with multi-modern neurosurgery technology: a case report

Choroid plexus papilloma (CPP) is a rare benign intracranial tumor origin that predominantly manifests in the lateral ventricle in children, accounting for 0.3%-0.6% of all primary intracranial tumors. It is extremely rare to have the CPP in the trigone of the lateral ventricle through the contralateral posterior interhemispheric transfalcine transprecuneus approach (PITTA). Herein, we report this rare case. A 7-year-old girl presented with headache. Magnetic resonance imaging of the brain showed periatrial lesions, and histopathological examination confirmed CPP (WHO grade I). The contralateral PITTA is a safe, effective, reasonable, and appropriate for some lesions in the trigone of the lateral ventricle. It provides a wider surgical angle (especially for the lateral extension) and reduces the risk of disturbance of the optic radiation compared with the conventional approaches. The use of multiple modern neurosurgical techniques, including interventional embolization, intraoperative navigation, microscope, and electrophysiological monitoring, make the procedure much easier and more accurate, and the neuroendoscope adds to the visualization of the microscope and can reduce surgical complications.

Successful Surgical Treatment of a Giant Intraventricular Meningioma: A Case Report and Literature Review

In our study, we document the case of a 48-year-old patient who presented at our clinic with various neurological disturbances. Magnetic Resonance Imaging revealed the presence of an intraventricular meningioma located in the body of the left lateral ventricle measuring 60 mm in diameter. This tumor was classified as a giant meningioma, accompanied by a significant amount of digitiform-type edema. A surgical procedure was conducted, resulting in a gross total resection of the tumor. Histopathological analysis identified the tumor as a fibrous meningioma. Postoperative assessments, as well as follow-ups conducted at 3 months and 1 year post-surgery, indicated considerable neurological improvement. The patient exhibited a remission of hemiparesis and gait disturbances along with a marginal improvement in the status of expressive aphasia. This case report underscores the significance of achieving total and safe resection of the tumor and includes an analysis of various cases from the literature, particularly focusing on those that describe minimally invasive surgical approaches and highlight the benefits of radiosurgery in the treatment of giant intraventricular meningiomas.

Intraventricular Tumors: Surgical Considerations in Lateral and Third Ventricular Tumors

Management of lateral and third ventricular tumors has been a challenge for neurosurgeons. Advances in imaging and pathology have helped in a better understanding of the treatment options. Technical refinement of microsurgical technique and addition of endoscopy has enabled more radical excision of tumors, when indicated, and added more safety.A proper understanding of the pathology at various ages and treatment options is continuously evolving. Many pediatric tumors are amenable to conservative surgical methods with effective complementary treatments. However, radical surgery is required in many adults as the main treatment and for many benign tumors. Various intraventricular lesions encountered and their surgical management is reviewed here for their efficacy, safety, and outcome, encompassing changes in our practice over the last 20 years.

An endoscopic-assisted contralateral paramedian supracerebellar infratentorial approach in the treatment of thalamic hemorrhage with hematoma extension into the brainstem: a case report

Objective

Thalamic hemorrhage (TH) with hematoma extension into the brainstem can lead to poor outcomes. In this study, we discuss the feasibility of the endoscopic-assisted contralateral paramedian supracerebellar infratentorial (SCIT) approach as a therapeutic method for treating such patients.

Case presentation

A patient suffered from a sudden loss of consciousness and right limb weakness, and a CT scan indicated TH with hematoma extension into the brainstem. She consented to undergo surgery by the endoscopic-assisted contralateral paramedian SCIT approach.

Results

Now, the patient can open her eyes on her own and move her left arm in response to commands.

Conclusion

The endoscopic-assisted contralateral paramedian SCIT approach may be a viable therapeutic method for treating TH patients with hematoma extension into the brainstem.

Atrium meningioma: Transtubular posterior intraparietal sulcus approach

Meningiomas that arise in the atria of the lateral ventricles are relatively rare lesions, that pose a unique challenge for surgery due to their deep-seated location and proximity to critical white matter tracts. Size and anatomical variations can affect the best approach for these tumors, with several approaches described to access the atrium including the interhemispheric trans-precuneus, trans-supramarginal gyrus, distal trans-sylvian, supracerebellar trans-collateral sulcus, and finally the trans-intraparietal sulcus approach, which was the choice for this case. Minimally invasive techniques that preserve the surrounding tissue are becoming increasingly popular and are perfectly suited to deep seated lesions. The relevant subcortical anatomy surrounding the atrium is discussed. The optic radiations form the lateral wall of the atrium, whereas commissural fibers of the tapetum form the roof of the atrium, and superficial to these fibers we have the superior longitudinal fasciculus that have vertical rami that communicate with the superior parietal lobule. Utilizing the posterior half of the intraparietal sulcus can preserve these fibers. The use of neuronavigation, brain magnetic resonance imaging with diffusion tensor imaging (DTI) tractography may be helpful in the surgical planning. In this article, we present a surgical video of a trans-tubular interparietal sulcus approach for resection of an atrium meningioma. A 43-year-old right-handed female who presented with progressive headaches and a diagnosis of idiopathic intracranial hypertension was found to have an atrial meningioma that grew in follow-up and surgery was recommended. We chose the posterior intraparietal sulcus approach as it provides a good angle of attack while preserving the optic radiations and most of the superior longitudinal fasciculus, using a tubular retractor to minimize tissue damage. Gross total resection of the tumor was achieved with complete preservation of patient neurological function.

The Ipsilateral Interhemispheric Transprecuneal Approach to the Atrium: Technical Considerations and Clinical Outcome on a Series of 7 Patients

Surgical removal of tumors of the atrium is challenging due to their deep location, vascularization, and to their complex three-dimensional relationships with the highly functional white matter fibers of the region. To assess the feasibility and the effectiveness of the ipsilateral interhemispheric transprecuneus approach (IITA) for tumors involving the atrium and the posterior third of the temporal horn, a retrospective chart review of all patients who had undergone a surgical treatment for intraventricular tumors between January 2008 and January 2017 was performed, and the step-by-step approach is described. Ten patients affected by lesions of the atrium of the lateral ventricle underwent surgical treatment, seven of which were approached through the IITA. The mean age was 42.8 years (range 6–63 years). The symptoms presented included severe, drug-resistant headache (90%), lateral homonymous hemianopsia (50%), seizures (30%), and speech disturbances (30%). Histological examinations revealed seven patients with meningioma (70%), one with a metastasis (10%), one with a choroid plexus papilloma (10%) and one with a cavernoma (10%). In all cases, a gross total removal was obtained. All patients had a significant improvement in their headache. Two patients experienced a worsening of the pre-operative visual disturbances, while two patients had a significant improvement. No patients without pre-operative visual disturbances described a post-operative worsening of visual symptoms. The IITA represents a feasible approach for tumors of the atrium. The three-quarter prone position facilitates the enlargement of the interhemispheric fissure by increasing the working angle and facilitating the exposure of the lateral wall of the atrium.

Anatomy of the optic radiations from the white matter fiber dissection perspective: A literature review applied to practical anatomical dissection

Background:

Knowledge of the anatomical course of the optic radiations and its relationship to medial temporal lobe structures is of great relevance in preoperative planning for surgery involving the temporal lobe to prevent damage that may result in postsurgical visual field deficits.

Methods:

In this anatomical study, we reviewed the literature on this topic and applied the information to practical anatomical dissection. The three-dimensional relationship between the course of the optic radiations and structures accessed in the main microneurosurgical approaches to the medial temporal lobe was examined by applying Klingler’s white matter fiber dissection technique to five formalin-fixed human brains. The dissections were performed with an operating microscope at magnifications of ×3–×40. High-resolution images were acquired during dissection for identification of the anatomical structures, focusing on the characterization of the course of the optic radiations in relation to medial temporal lobe structures.

Results:

In all five dissected brains, we could expose and clearly define the relationship between the optic radiations and medial temporal lobe structures, improving our understanding of these complex structures.

Conclusion:

The knowledge gained by studying these relationships will help neurosurgeons to develop risk-adjusted approaches to prevent damage to the optic radiations in the medial temporal region, which may result in a disabling visual field deficit.

Cerebral corridor creator for resection of trigone ventricular tumors: Two case reports

BACKGROUND

Resection of deep intracranial tumors requires significant brain retraction, which frequently causes brain damage. In particular, tumor in the trigone of the lateral ventricular presents a surgical challenge due to its inaccessible location and intricate adjacent relationships with essential structures such as the optic radiation (OR) fibers. New brain retraction systems have been developed to minimize retraction-associated injury. To date, there is little evidence supporting the superiority of any retraction system in preserving the white matter tract integrity. This report illustrates the initial surgical excision in two patients using a new retraction system termed the cerebral corridor creator (CCC) and demonstrates its advantage in protecting OR fibers.

CASE SUMMARY

We report two patients with nonspecific symptoms, who had trigone ventricular lesions that involved the neighboring OR identified on preoperative diffusion tensor imaging (DTI). Both patients underwent successful surgical excision using the CCC. Total tumor removal was achieved without additional neurological deficit. DTI showed that the OR fibers were preserved along the surgical field. Preoperative symptoms were alleviated immediately after surgery. Clinical outcomes were improved according to the Glasgow-Outcome-Scale and Activity-of-Daily-Living Scale assessments.

CONCLUSION

In the two cases, the CCC was a safe and useful tool for creating access to the deep trigonal area while preserving the white matter tract integrity. The CCC is thus a promising alternative brain retractor.

The posterior interhemispheric transparieto-occipital fissure approach to the atrium of the lateral ventricle: a fiber microdissection study with case series

The surgical approach to the atrium of the lateral ventricle remains a challenge because of its deep location and close relationship to important neurovascular structures. We present an alternative and safer approach to lesions of the atrium using a natural pathway through the parieto-occipital fissure. We demonstrate this approach through cadaveric anatomical microdissection and a case series. Five formalin-fixed brain specimens (10 hemispheres) were dissected with the Klingler technique. Transillumination was used to show the trajectory of the approach in cadaveric specimens. Clinical data from five patients who underwent this approach were reviewed. This data included intraoperative ultrasound images, operative images, pre- and postoperative magnetic resonance imaging, MR tractography, and visual field examination. The parieto-occipital fissure is a constant, uninterrupted fissure that can be easily identified in cadavers. Our anatomical dissection study revealed that the atrium of the lateral ventricle can be approached through the parieto-occipital fissure with minor damage to the short association fibers between the precuneus and cuneus, and a few fibers of the forceps major. In our series, five patients underwent total resection of their atrial lesions via the posterior interhemispheric transparieto-occipital fissure. No morbidity or mortality was observed, and the disruption of white matter was minimal, as indicated on postoperative tractography. The postoperative visual fields were normal. The posterior interhemispheric transparieto-occipital fissure approach is an alternative to remove lesions in the atrium of the lateral ventricle, causing the least damage to white matter tracts and preserving visual cortex and optic radiation.

Paramedian transparietal approach to a dominant hemisphere intraventricular meningioma: illustrative case

BACKGROUND

Meningiomas of the atrium of the lateral ventricle present a unique operative challenge. Parietal transcortical approaches have been described with an oblique approach, but a strictly paramedian approach may offer advantages in a dominant hemisphere atrial meningioma.

OBSERVATIONS

The patient presented with several weeks of intermittent headaches. Magnetic resonance imaging (MRI) showed an enhancing intraventricular mass in the atrium of the left lateral ventricle. Three-dimensional reconstructions were created from a preoperative MRI, with 1-mm slices for neuronavigation. Diffusion tensor imaging (DTI) was obtained, and tracts were reconstructed in the patient’s three-dimensional brainspace. DTI tractography delineated a paramedian transparietal corridor devoid of functional white matter tracks. The patient was positioned supine, in a semislouch position. A left parietal craniotomy was performed. Neuronavigation identified a gyrus posterior to the sensory cortex, anterior to the optic radiations and medial to superior longitudinal and arcuate fasciculus fiber tracts. The tumor was debulked to allow mobilization to coagulate capsular blood supply. Gross total resection was achieved. The patient was discharged postoperatively on day 3 without neurological deficits.

LESSONS

A paramedian transparietal approach to a dominant hemisphere meningioma of the lateral ventricle can be a safe and effective way to resect tumors in this anatomically unique operative corridor.

Customising the surgical management for intraventricular meningiomas - 'one size doesn't fit all'

BACKGROUND

Intraventricular meningiomas are uncommon and gross total resection is the recommended treatment. However, total resection may not always be possible, especially in locations in which the lesions are adherent to veins and neural structures. We share our experience with intraventricular meningiomas, focusing on the management strategies and outcomes.

PATIENTS AND METHODS

We describe the data of 7 patients with intraventricular meningiomas operated at our institute over the last 9 years. Three patients had a third ventricular tumor of which two had lesions straddling across the foramen of Monro. The remaining 4 patients had trigonal mass. The clinico-radiological features, management strategies and outcomes have been elaborated with a mean follow-up of 57 months.

RESULTS

The common clinical presentations were raised intracranial pressure symptoms, visual field defects and memory deficits. One patient had multiple meningiomas. Total excision was achieved in all except in 2 patients in whom the lesion straddled across the foramen of Monro with dense adhesions to veins and neural structures. Staged resection was required in one patient with a large trigonal mass. All patients had a low-grade lesion. The tumor recurred in one patient (post-pregnancy) after partial resection. All the patients improved neurologically, and none had added deficits.

CONCLUSIONS

Gross total resection of intraventricular meningiomas although desirable may not be possible in certain cases in which the risks outweigh the benefits. These tumors often are of low histological grade and the treatment strategies should be individualized. Regular follow-up is warranted as these tumors may recur despite a low histological grade.

The Neuroanatomic Studies of Albert L. Rhoton Jr. in Historical Context: An Analysis of Origin, Evolution, and Application

The incorporation of perspective into art and science revolutionized the study of the brain. Beginning in about 1504, Leonardo da Vinci began to model the ventricles of the brain in three dimensions. A few years later, Andreus Vesalius illustrated radically novel brain dissections. Thomas Willis' work, Cerebri Anatome (1664), illustrated by Christopher Wren, remarkably showed the brain undersurface. Later, in the early 1800s, Charles Bell's accurate images of neural structures changed surgery. In the 1960s, Albert L. Rhoton Jr. (1932-2016) began to earn his place among the preeminent neuroanatomists by focusing his lens on microanatomy to harness a knowledge of microneurosurgery, master microneurologic anatomy, and use it to improve the care of his patients. Although his biography and works are well known, no analysis has been conducted to identify the progression, impact, and trends in the totality of his publications, and no study has assessed his work in a historical context compared with the contributions of other celebrated anatomists. We analyzed 414 of 508 works authored by Rhoton; these studies were analyzed according to subjects discussed, including anatomic region, surgical approaches, subjects covered, anatomic methods used, forms of multimedia, and subspecialty. Rhoton taught detailed neuroanatomy from a surgical perspective using meticulous techniques that evolved as the technical demands of neurosurgery advanced, inspiring students and contemporaries. His work aligns him with renowned figures in neuroanatomy, arguably establishing him historically as the most influential anatomist of the neurosurgical era.

Quiescent and Activated Fibroblasts in Lateral Ventricular Meningioma With a Dura-like Membrane

BACKGROUND

Lateral ventricular meningioma (LVM) is a rare entity, accounting for 0.5%-5% of all intracranial meningiomas. This type of meningioma arises from meningothelial inclusion bodies in the tela choroidea and/or mesenchymal stroma of the choroid plexus. Although not yet fully characterized, a membranous structure is frequently observed around LVMs. This study analyzed quiescent and activated fibroblast phenotypes in LVMs with focus on the relationship between tumor growth and development of the membranous structure.

METHODS

This retrospective study analyzed 9 LVM cases for which gross total removal was achieved. Expression of the ependymal cell marker (Forkhead Box J1 [FoxJ1]) was histopathologically evaluated. The distribution of quiescent and activated fibroblasts was also analyzed using anti-fibroblast-specific protein-1 (FSP1)/S100A4 antibody and anti-α-smooth muscle actin (αSMA) antibody, respectively. The control group was 5 cases with primary convexity meningioma for which Simpson grade I removal was achieved.

RESULTS

Small LVMs (≤30 mm) were covered by a FoxJ1-positive(+) ependymal cell monolayer; no αSMA(+) cells were detected in the tumor; and a thick membrane capsule was not observed. None of the convexity meningiomas showed FoxJ1(+) cells. Large LVMs (>30 mm) had thick membrane capsules without an ependymal cell monolayer, which resembled dura mater. The FSP1/S100A4(+) and αSM(+) cells were clearly concentrated in the peripheral area just below the thick dura mater-like membrane capsules.

CONCLUSIONS

This study found an association between activated fibroblasts and dura mater-like membrane capsules in LVMs. The characteristics of membranous structure in LVMs may differ depending on tumor size.

An alternative path to atrial lesions through a contralateral interhemispheric transfalcine transcingular infra-precuneus approach: A case report

Background:

The surgical management of lesions located in the trigone of the lateral ventricle remains a neurosurgical challenge. Previously described approaches to the atrium include the transtemporal, parietal transcortical, parietal trans intraparietal sulcus, occipital transcingulate, posterior transcallosal, and transfalcine transprecuneus. However, reaching this area specifically through the cingulate cortex below the subparietal sulcus has not been described thus far.

Case Description:

We present here the removal of a left atrial meningioma through a right parietal “contralateral interhemispheric transfalcine transcingular infra-precuneus” approach and compare it with previously described midline approaches to the atrium. To accomplish this, a right parietal craniotomy was performed. After the left subprecuneus cingulate cortex was exposed through a window in the falx, a limited corticotomy was performed, which allowed the tumor to be reached after deepening the bipolar dissection by 8 mm. Postoperative magnetic resonance imaging showed complete resection of the lesion sparing the corpus callosum, forceps major, and sagittal stratum. Although this approach disrupts the posterior cingulate fasciculus, no deficits have been described so far after unilaterally disrupting the posterior cingulate cortex or the posterior part of the cingulate fasciculus. In fact, a thorough postoperative cognitive examination did not show any deficits.

Conclusion:

The “contralateral interhemispheric transfalcine transcingular infra-precuneus” approach combines the advantages of several previously described approaches. Since it conserves the major white matter tracts that surround the atrium and has a shorter attack angle than the contralateral transfalcine transprecuneus approach, we believe that it could be a potentially new alternative path to reach atrial lesions.

Management of large intraventricular meningiomas with minimally invasive port technique: a three-case series

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective. To date, most of the literature regarding the tubular retractors used in brain surgery is comprised of individual case reports that describe the successful resection of deep-seated lesions such as thalamic pilocytic astrocytomas, colloid cysts in the third ventricle, hematomas, and cavernous angiomas. The authors describe their experience using a tubular retractor system with three different cases involving large intraventricular meningiomas and examine radiographic and patient outcomes. A single-institution, retrospective case series was performed from a skull base database. Patients who underwent resection of intraventricular > 4-cm meningiomas with port technology were identified. The authors reviewed three cases to illustrate the feasibility of minimal access port surgery for the resection of these lesions. Complete resection was achieved in all cases. None of the patients developed permanent neurological deficits. There were no major complications related to surgery and no mortalities. Good clinical and surgical outcomes for atrium meningiomas can be achieved through the minimally invasive port technique and tumor size does not appear to be a limitation.

Parietal interhemispheric transfalcine transtentorial approach for posterior incisural space lesions: from the lab to the operative room

The operative approach to the posterior incisural space is challenging because of its deep location, the surrounding eloquent areas, and the intimate relationship with the deep veins. Several approaches have been proposed to manage the lesions in this region: supratentorial, infratentorial and a combination of them. Brain retraction, injury to the occipital lobe and corpus callosum, and venous bleeding are the principle drawbacks of these routes. We performed anatomical dissection study using 10 embalmed human cadaver specimens injected with colored latex exploring a different route, parietal interhemispheric transfalcine transtentorial (PITT). Then we used a PITT approach on two patients with posterior incisural space (PIS) lesions. The PITT approach led to successful and safe complete removal of PIS lesions in our cases. No complications were reported. The present approach could be a valuable option in case of PIS lesions, especially those associated with downward displacement of the deep venous complex; thanks to the gravity it reduce the complications related to the occipital lobe retraction and manipulation. Moreover, cutting the superior-anterior edge of the tentorium, the sub-tentorial space could be reached.

Transcorticosubcortical Approach for Left Posterior Mediobasal Temporal Region Gliomas: A Case Series and Anatomic Review of Relevant White Matter Tracts

BACKGROUND AND OBJECTIVE

The goal of this study is to show using 5 illustrative cases that the transcortical route for resection of mediobasal temporal region (MBTR) lesions is safe and effective when performed with awake functional mapping and knowledge of the relevant subcortical anatomy. Although several have been proposed, there is a paucity of reports on transcorticosubcortical approaches to these lesions, particularly in patients with posterior-superior extension. We present a case series of 5 patients with left posterior MBTR gliomas and summarize the relevant subcortical anatomy knowledge of what is a prerequisite for safe resection.

METHODS

Five patients with left posterior MBTR gliomas underwent awake resection with functional corticosubcortical electric mapping. Details of the approach are presented with a review of relevant anatomy.

RESULTS

Gross total resection was achieved in 4 patients. One patient who had previously undergone radiation therapy had a subtotal resection. There were 4 cases of World Health Organization grade II glioma and 1 case of World Health Organization grade IV glioma. All patients underwent preoperative and postoperative neurologic and neuropsychological assessment and there were no new or worsening sensorimotor, visual, language, or cognitive deficits.

CONCLUSIONS

The transcorticosubcortical approach is a safe and effective approach to lesions of the posterior MBTR. The approach is safe and effective even in patients with superior extension, if the surgical approach is predicated on knowledge of individual functional anatomy. Awake resection with cortical and axonal mapping with well-selected paradigms is invaluable in maximizing extent of resection and ensuring patient safety.

Comparison Between Transcortical and Interhemispheric Approaches to the Atrium of Lateral Ventricle Using Combined White Matter Fiber Dissections and Magnetic Resonance Tractography

OBJECTIVE

The objective of this study was to compare transcortical and posterior interhemispheric approaches to the atrium using a combined approach of white matter fiber dissections and magnetic resonance (MR) tractography.

METHODS

Ten cerebral hemispheres were examined and dissected from the lateral-to-medial surface and from the medial-to-lateral surface, with special attention to the white matter tracts related to the atrium. MR tractography was used to show the relationship of three-dimensional white matter fibers with the atrium of the lateral ventricle and to compare with cadaveric dissection results.

RESULTS

The atrium was related laterally to the superior longitudinal fasciculus II and III, middle longitudinal fasciculus, arcuate fasciculus, vertical occipital fasciculus, and sagittal stratum. Medially, it is related to the superior longitudinal fasciculus I, cingulum, sledge runner, and forceps major.

CONCLUSIONS

A combined approach of cadaveric white matter fiber dissections and MR tractography were used to describe the main white matter tracts related to the posterior interhemispheric approach and the transcortical approach, providing an in-depth understanding of the three-dimensional anatomy of white matter fibers and the atrium. In the present study, among approaches examined, the posterior interhemispheric parasplenial transprecuneus approach placed fewer eloquent tracts at risk; however, traversing the sledge runner and the forceps major is unavoidable by this approach.

The ipsilateral interhemispheric transprecuneal approach: microsurgical anatomy, indications, and neurosurgical applications

Surgical treatment of intraventricular lesions is challenging because of their deep location, vascularization, and their complex relationships with white matter fibers. The authors undertook this study to describe the microsurgical anatomy of the white matter fibers covering the lateral wall of the atrium and temporal horn and to demonstrate how the ipsilateral interhemispheric transprecuneal approach can be safely used to remove lesions of this region sparing the anatomo-functional integrity of the fibers themselves. A detailed description of the approach including operative measurements is also given. The Klingler' technique with progressive identification of white matter fibers covering the lateral wall of the atrium and temporal horn was performed on ten formalin-fixed human hemispheres. Then, ten fresh, non-formalin-fixed non-silicon-injected adult cadaveric heads were analyzed for the simulation of the ipsilateral interhemispheric transprecuneal approach. Three illustrative cases are presented. The simulation of the interhemispheric transprecuneal approach on ten fresh non-formalin-fixed specimens showed that a 10 to 20 mm corticotomy perpendicular to the parieto-occipital sulcus at the junction with the cingulum allows a wide corridor for the exposure of the entire atrial cavity and the posterior third of the temporal horn. The ipsilateral interhemispheric transprecuneus approach represents a safe and effective option for tumors involving the atrium and the posterior third of the temporal horn.

Latency-shift of intra-operative visual evoked potential predicts reversible homonymous hemianopia after intra-ventricular meningioma surgery

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Amplitude of intraoperative VEPs is used to monitor the function of optic radiation during neurosurgery.

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We present a case where significant unilateral latency shift of the P100 component was observed.

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VEP latency shifts may predict visual outcome during surgery for tumors close to the optic radiation.

Objectives

Intraoperative visual evoked potentials (VEPs) are used to monitor the function of optic radiation during neurosurgery with the P100 amplitude decrement as a predictor of post-operative visual deficit. However, there is currently no evidence of early VEP changes indicating reversible visual field affection.

Methods

In this case report, we used VEPs during surgery for a benign meningioma located in the atrium of the right lateral ventricle. The tumor was accessed through a transcortical approach via a two-centimeter corticotomy in the lateral aspect of the superior parietal lobule. We performed flash VEPs and simultaneous recordings of electroretinography alongside with multimodal intraoperative monitoring.

Results

We observed a significant and sustained unilateral latency shift of the P100 component of VEPs, while amplitudes temporarily dropped to 80% of baseline but recovered entirely at the end of surgery. After the operation, the patient had a left-sided lower-quadrant anopia, which recovered completely during the following three months. Diagnostic VEP with pattern reversal monocular full field stimulation at one month postoperatively showed normal latencies bilaterally.

Conclusion

Our case indicates that the VEP (P100) latency may be a new and valuable indicator (in addition to VEP amplitude) of the visual pathways.

Significance

Monitoring VEPs may be useful to detect an imminent injury and a potentially reversible functional deficit.

White Matter Relationships Examined by Transillumination Technique Using a Lateral Transcortical Parietal Approach to the Atrium: Three-Dimensional Images and Surgical Considerations

BACKGROUND

Numerous lesions are found in the ventricular atrium (VA). Access is gained through many white matter tracts with great relevance and specific neurologic functions. It is important to understand the configuration of the most relevant structures surrounding this zone and, thus, select the safest entry zone on the lateral cerebral surface.

OBJECTIVE

We studied the white matter layers traversed in the lateral transcortical parietal approach through the intraparietal sulcus (IPS), adding a transillumination technique. With this knowledge, we selected the safest highway to improve this particular approach.

METHODS

An in-depth study of the white matter tracts was performed on 24 cerebral hemispheres (12 human whole brains). The Klingler technique and microsurgical dissection techniques were used under ×6 to ×40 magnification. The transillumination technique (torch illuminating the ventricular cavity) was used to expose the layers surrounding the VA and, thus, guide the dissection.

RESULTS

Taking the IPS on the cerebral surface as a reference, we identified the following white matter layers ordered from the surface to the ependyma: U fibers, superior longitudinal fascicle, arcuate fascicle, vertical occipital fascicle, sagittal stratum with the optic radiations, and tapetum fibers. The transillumination technique allowed for the easier identification of the white matter deep periventricular layers.

CONCLUSIONS

Knowledge of the main fascicles in the path and neighborhood of the VA allowed us to understand how certain neurologic functions can be affected by lesions at this level and to select the most appropriate way to avoid damaging relevant fascicles.

Innovations in the Art of Microneurosurgery for Reaching Deep-Seated Cerebral Lesions

Deep-seated cerebral lesions have fascinated and frustrated countless surgical innovators since the dawn of the microneurosurgical era. To determine the optimal approach, the microneurosurgeon must take into account the characteristics and location of the pathological lesion as well as the operator's range of technical expertise. Increasingly, microneurosurgeons must select between multiple operative corridors that can provide access to the surgical target. Innovative trajectories have emerged for many indications that provide more flexible operative angles and superior exposure but result in longer working distances and more technically demanding maneuvers. In this article, we highlight 4 innovative surgical corridors and compare their strengths and weaknesses against those of more conventional approaches. Our goal is to use these examples to illustrate the following principles of microneurosurgical innovation: (1) discover more efficient and flexible exposures with superior working angles; (2) ensure maximal early protection of critical neurovascular structures; and (3) effectively handle target pathology with minimal disruption of normal tissues.

Defining the relationship of the optic radiation to the roof and floor of the ventricular atrium: a focused microanatomical study

OBJECTIVE

The authors investigated the specific topographic relationship of the optic radiation fibers to the roof and floor of the ventricular atrium because the current literature is ambiguous.

METHODS

Thirty-five normal, adult, formalin-fixed cerebral hemispheres and 30 focused MRI slices at the level of the atrium were included in the study. The correlative anatomy of the optic radiation with regard to the atrial roof and floor was investigated in 15 specimens, each through focused fiber microdissections. The remaining 5 hemispheres were explored with particular emphasis on the trajectory of the collateral sulcus in relation to the floor of the atrium. In addition, the trajectory of the collateral sulcus was evaluated in 30 MRI scans.

RESULTS

The atrial roof was observed to be devoid of optic radiations in all studied hemispheres, whereas the atrial floor was seen to harbor optic fibers on its lateral part. Moreover, the trajectory of the intraparietal sulcus, when followed, was always seen to correspond to the roof of the atrium, thus avoiding the optic pathway, whereas that of the collateral sulcus was found to lead to either the lateral atrial floor or outside the ventricle in 88% of the cases, therefore hitting the visual pathway.

CONCLUSIONS

Operative corridors accessing the ventricular atrium should be carefully tailored through detailed preoperative planning and effective use of intraoperative navigation to increase patient safety and enhance the surgeon's maneuverability. The authors strongly emphasize the significance of accurate anatomical knowledge.

Trigonal and Peritrigonal Lesions of the Lateral Ventricle: Presurgical Tractographic Planning and Clinic Outcome Evaluation

BACKGROUND

Surgery of lesions within the atrium of the lateral ventricle remains a challenging procedure because of the deep location and the relationship to vascular structures. The aim of this study was to determine the usefulness of tractography to evaluate the position of white matter tracts located along the course of the surgical access to trigonal and peritrigonal lesions.

METHODS

Diffusion tensor imaging (DTI) was acquired in 19 patients. All patients underwent surgical resection of brain tumors. Pre- and postoperative clinical conditions were evaluated by a neurosurgeon, using the Karnofsky Performance Status Scale. The corticospinal tract, optic radiation, and arcuate fasciculum were reconstructed because of their location close to the trigonal region. Two neurosurgeons were asked to assess the surgical approach with and without tractography.

RESULTS

According to the tractographic reconstructions, the surgical access was chosen from the middle temporal gyrus in 12 patients (63%) and the posterior parietal gyrus in 7 patients (37%), leading to an a priori change in the surgical approach in 14 patients (73%). Six patients (31%) showed new postsurgical transient symptoms, whereas in 2 patients (10%) the deficits were permanent. After 30 days, the Karnofsky Performance Status Scale evaluation showed an improvement or a substantial stability of symptoms in 90% of cases. In 2 patients, a worsening of 30% of clinical performance was appreciable.

CONCLUSIONS

The use of DTI in preoperative planning of trigonal and peritrigonal lesions may help in description of the best surgical approach for patient; this technique allows to reach the tumors, saving the white matter tracts, when it is possible.

Quantitative Endoscopic Comparison of Contralateral Interhemispheric Transprecuneus and Supracerebellar Transtentorial Transcollateral Sulcus Approaches to the Atrium

OBJECTIVE

The contralateral interhemispheric transprecuneus approach (CITP) and the supracerebellar transtentorial transcollateral sulcus approach (STTC) are 2 novel approaches to access the atrium of the lateral ventricle. We quantitatively compared the 2 approaches.

METHODS

Both approaches were performed in 6 sides of fixed and color-injected cadaver heads. We predefined the 6 targets in the atrium for measurement and standardization of the approaches. Using a navigation system, we quantitatively measured the working distance, cortical transgression, angle of attack, area of exposure, and surgical freedom.

RESULTS

The distances from the craniotomy edge to the posterior pole of the choroid plexus of the CITP (mean ± standard deviation, 67 ± 5.3 mm) and STTC (mean, 57 ± 4.0 mm) differed significantly (P < 0.01). Cortical transgression with the CITP (mean, 27 ± 2.8 mm) was significantly greater than that with the STTC (mean, 21 ± 6.7 mm; P = 0.03). The CITP showed a significantly wider rostrocaudal angle of attack than that with the STTC (P = 0.01). The STTC showed a significantly wider mediolateral angle (P < 0.01). No significant difference was found for surgical freedom of any target except for point E, for which the CITP was larger. The exposure area did not differ significantly between the 2 approaches (P = 0.07).

CONCLUSIONS

Both approaches were feasible for accessing the atrium. The STTC provided a shorter working distance and wider mediolateral angle, CITP provided a wider rostrocaudal angle of attack and better exposure and maneuverability to the anterior and superior atrium. In contrast, the STTC was more favorable for the inferior and posterior regions.

Structure of corona radiata and tapetum fibers in ventricular surgery

In this study the three-dimensional anatomy of the corona radiata and tapetum via the fiber dissection and diffusion tensor imaging of the brain for ventricular surgery was demonstrated. Ten formalin-fixed cerebral hemispheres were dissected for corona radiata and tapetum via Klingler's fiber dissection method under an operating microscope. The corona radiata and tapetum were dissected through lateral and medial surfaces of the cerebral hemisphere, respectively. All surgical routes for ventricular lesions were evaluated for white matter fibers during and after dissections. Corona radiata and tapetum fibers were demonstrated by dissecting hemispheres through lateral and medial aspects of the brain. The internal capsule contains all fibers that extend from thalamus to cortex and cortex to thalamus, brainstem, and spinal cord. These fan-shaped fibers extending from cortex to internal capsule were named the corona radiata. The corona radiata is not a specific pathway, and it is composed of several different fiber pathways. The tapetum contains splenium and body fibers of the corpus callosum. Tapetum is located immediately medial to the ependymal line of the ventricular wall and forms a fiber layer in the medial optical radiation on the coronal and axial sections. Surgical planning for ventricular lesions requires detailed information regarding white matter fibers that can be obtained by the fiber dissection and diffusion tensor imaging of the brain to decrease surgical complications.

Case series of trigonal meningiomas

BACKGROUND

Trigonal meningiomas have unique clinical presentation, unlike those in other areas of brain. Situated deep in the brain, the surgical nuances of this tumour are distinctive. We present our experience with this tumour including a discussion of surgical corridors that may be employed.

METHODS

At our centre, 12 trigonal meningiomas were operated over past two decades. A retrospective analysis of case records of these cases was undertaken as regards age, sex clinical presentation, imaging and surgical approach.

RESULTS

Mean time from heralding symptom to presentation was 10.4 months. At presentation, the most commonly encountered symptoms were those of non-localising symptoms attributable to raised ICP. Majority of lesions were more than 6 cm and on left side and the preferred surgical approach was inferior temporo-parietal. Most symptoms were relieved on long-term follow-up except homonymous hemianopia.

CONCLUSION

The incidence of deficit is low on employing the "shortest route" approach, even in the dominant hemisphere and through eloquent area. This may be secondary to possible shift of eloquent area function due to longstanding lesion and may thus be a "workable" surgical option, especially in resource-limited centres where such resources as neuronavigation and tractography may be unavailable.

Selection of Surgical Approach for Trigonal Meningiomas in Consideration of Visual Outcome

OBJECTIVES

We report the surgical outcome of trigonal meningiomas through 3 different approaches with attention to visual outcomes.

METHODS

Between 1994 and 2017, 23 patients underwent resection of trigonal meningiomas. We performed tumor removal using 3 different surgical approaches through the superior parietal lobule, middle temporal gyrus (MTG), and modified MTG. The patients were retrospectively identified, and surgical results including visual outcome were analyzed.

RESULTS

Twenty-three patients with a mean age of 45 years formed the study group. The most common symptom and sign were headache (N = 14, 60.9%) and visual disturbance (N = 6, 26.1%). All patients underwent surgical resection, 6 via a translateral approach through MTG, 8 via a translateral approach through modified MTG, and 9 via a transparietal approach through the superior parietal lobule (SPL). Gross total resection was achieved in all patients. We found that visual preservation rate was 25% (1/4) in the MTG group, 62.5% (5/8) in the modified MTG group, and 100% (7/7) in the SPL group, respectively (P = 0.044). Permanent complication rate was 50% (3/6) in the MTG group, 50% (n = 4/8) in the modified MTG group, and 11.1% (n = 1/9) in the SPL group.

CONCLUSIONS

The superior parietal lobule approach is a safe and applicable procedure with a great visual preservation and an acceptable risk of morbidity for trigonal meningiomas when there is a chance of visual recovery or preservation.

Microsurgical Anatomy of the Vertical Rami of the Superior Longitudinal Fasciculus: An Intraparietal Sulcus Dissection Study

BACKGROUND

A number of vertical prolongations of the superior longitudinal fasciculus, which we refer to as the vertical rami (Vr), arise at the level of the supramarginal gyrus, directed vertically toward the parietal lobe.

OBJECTIVE

To provide the first published complete description of the white matter tracts (WMT) of the Vr, their relationship to the intraparietal and parieto-occipital sulci (IPS-POS complex), and their importance in neurosurgical approaches to the parietal lobe.

METHODS

Subcortical dissections of the Vr and WMT of the IPS were performed. Findings were correlated with a virtual dissection using high-resolution diffusion tensor imaging (DTI) tractography data derived from the Human Connectome Project. Example planning of a transparietal, transsulcal operative corridor is demonstrated using an integrated neuronavigation and optical platform.

RESULTS

The Vr were shown to contain component fibers of the superior longitudinal fasciculus (SLF)-II and SLF-III, with contributions from the middle longitudinal fasciculus merging into the medial bank of the IPS. The anatomic findings correlated well with DTI tractography. The line extending from the lateral extent of the POS to the IPS marks an ideal sulcal entry point that we have termed the IPS-POS Kassam-Monroy (KM) Point, which can be used to permit a safe parafascicular surgical trajectory to the trigone.

CONCLUSION

The Vr are a newly conceptualized group of tracts merging along the banks of the IPS, mediating connectivity between the parietal lobe and dorsal stream/SLF. We suggest a refined surgical trajectory to the ventricular atrium utilizing the posterior third of the IPS, at or posterior to the IPS-POS Point, in order to mitigate risk to the Vr and its considerable potential for postsurgical morbidity.

A purely functional Imaging based approach for transcortical resection of lesion involving the dominant atrium: Towards safer, imaging-guided, tailored cortico-leucotomies

BACKGROUND AND STUDY OBJECT

The Dominant Atrium (DA) is a crossroad of eloquent white matter bundles difficult to preserve with a standard "anatomical" approach. The aim of this work is to evaluate the results of a cohort of patients who underwent surgery with the aid of a purely functional MRI and DTI-based approach.

MATERIALS AND METHODS

43 patients suffering from lesions involving the DA have been included in the final cohort and studied in regards to quality of life (KPS); a special attention was lent on the incidence of new or worsening of preexisting neurological deficits, with a focus on motor, visual and speech disturbances after the surgical treatment. Patient, surgery and lesion-related data were recorded to identify the relationships with outcome. Eloquent areas fMRI and the course of Arcuate Fasciculus (AF), Inferior frontooccipital fasciculus (IFOF), Optic radiation (OR) and corticospinal tract (CST) have been investigated with preoperative MRI sequences and DTI reconstruction.

RESULTS

The final cohort consisted of 43 patients, 19 males and 24 females; average age was 56.8 years. We recorded 9 transient and 3 permanent postoperative deficits, only one of those was caused by an edema interference with DTI reconstruction. Preoperative functional status, histology and volume of the lesion proved to be independent factors affecting results.

CONCLUSIONS

A purely functional surgical approach to the DA provided promising preliminary results. A direct DTI-fMRI visualization of the eloquent structures proximal to DA allows surgeon to conceive an ultra-precise and "tailored" cortico-leucotomy for an optimal exposure of the lesion.

Clinical features and neurosurgical treatment of trigonal cavernous malformations

The goals of this study were to analyze the incidence, clinical manifestations, neuroimaging findings, surgical treatments, and neurological outcomes of trigonal cavernous malformations (TCMs). Among 1395 cases of intracranial and intraspinal cavernous malformations (CMs) surgically treated between 2003 and 2016 at Beijing Tiantan Hospital, a series of 12 patients with TCM was chosen for analysis and their records were reviewed. We also performed an exhaustive literature search using PubMed to identify all previously reported cases in the literatures. TCMs accounted for 0.86% of the entire series of the central nervous system (CNS) CMs. The case series consisted of five male and seven female patients (ratio 1:1.4), with an average age at presentation of 32.9 years (7-53 years). In all the cases, headache was the most common initial symptom (66.7%). Complete resection without surgical mortality was achieved in all the cases. Postoperative complications included fever, lower limb weakness, sensory aphasia, and calculational capacity declination. Follow-up period after diagnosis was 15 to 74 months (mean 48.3 months); no patient was lost to follow-up. All the patients were considered to be in excellent clinical condition. TCMs are rare lesions; they can reach large size, and their symptoms and signs commonly resulted from mass effect. Surgical intervention is the treatment of choice for TCMs; patients can obtain favorable neurological outcomes after complete resection.

Microsurgical and endoscopic approaches to the pulvinar

OBJECTIVE

Approaches to the pulvinar remain challenging because of the depth of the target, surrounding critical neural structures, and complicated arterial and venous relationships. The purpose of this study was to compare the surgical approaches to different parts of the pulvinar and to examine the efficacy of the endoscope as an adjunct to the operating microscope in this area.

METHODS

The pulvinar was examined in 6 formalin-fixed human cadaveric heads through 5 approaches: 4 above and 1 below the tentorium. Each approach was performed using both the surgical microscope and 0° or 45° rigid endoscopes.

RESULTS

The pulvinar has a lateral ventricular and a medial cisternal surface that are separated by the fornix and the choroidal fissure, which wrap around the posterior surface of the pulvinar. The medial cisternal part of the pulvinar can be further divided into upper and lower parts. The superior parietal lobule approach is suitable for lesions in the upper ventricular and cisternal parts. Interhemispheric precuneus and posterior transcallosal approaches are suitable for lesions in the part of the pulvinar forming the anterior wall of the atrium and adjacent cisternal part. The posterior interhemispheric transtentorial approach is suitable for lesions in the lower cisternal part and the supracerebellar infratentorial approach is suitable for lesions in the inferior and medial cisternal parts.

The microscope provided satisfactory views of the ventricular and cisternal surfaces of the pulvinar and adjacent neural and vascular structures. The endoscope provided multi-angled and wider views of the pulvinar and adjacent structures.

CONCLUSIONS

A combination of endoscopic and microsurgical techniques allows optimal exposure of the pulvinar.

Endoscopic Supracerebellar Transtentorial Approach to Atrium of Lateral Ventricle: Preliminary Surgical and Optical Considerations

OBJECTIVE

We sought to report the operative techniques of the endoscopic supracerebellar transtentorial approach (ESTA) to the atrium of the lateral ventricle, especially focusing on the role of the endoscope and analyzing optically related issues.

METHODS

A retrospective data review was performed on 5 patients with lesions in the atrium of the lateral ventricle undergoing the ESTA. The patients were positioned in the three quarters prone position, and a paramidline linear incision was used. After performing a suboccipital craniotomy extending immediately above the transverse sinus and tentorium incision with precisely neuronavigation, corticotomy in the posterior mediobasal temporal region created a corridor to the tumor. All of the procedures were performed with an endoscope in a pneumatic arm holder. The preoperative and postoperative perimetry test and diffusion tensor imaging fiber tracking of the optic radiations were compared and analyzed.

RESULTS

Three patients had meningiomas, and 2 patients had high-grade gliomas in the atrium. The meningiomas were totally removed, and the gliomas were subtotally resected. One patient with glioblastoma died 2 months later after surgery because of the tumor progression; the remaining 4 patients had a visual field deficit without any other neurologic complications. The endoscope improved the surgical viewing angle, which was restricted by the microscope and slope of the tentorium.

CONCLUSIONS

ESTA is an alternative route to the atrium of the lateral ventricle. However, the collateral sulcus, which is highly relied on in neuronavigation, is illegible in the limited area. And the visual field deficit remains the primary challenge with this approach.

Transtentorial transcollateral sulcus approach to the ventricular atrium: an endoscope-assisted anatomical study

OBJECTIVE

Conventional approaches to the atrium of the lateral ventricle may be associated with complications related to direct cortical injury or brain retraction. The authors describe a novel approach to the atrium through a retrosigmoid transtentorial transcollateral sulcus corridor.

METHODS

Bilateral retrosigmoid craniotomies were performed on 4 formalin-fixed, colored latex–injected human cadaver heads (a total of 8 approaches). Microsurgical dissections were performed under 3× to 24× magnification, and endoscopic visualization was provided by 0° and 30° rigid endoscope lens systems. Image guidance was provided by coupling an electromagnetic tracking system with an open source software platform. Objective measurements on cortical thickness traversed and total depth of exposure were recorded. Additionally, the basal occipitotemporal surfaces of 10 separate cerebral hemisphere specimens were examined to define the surface topography of sulci and gyri, with attention to the appearance and anatomical patterns and variations of the collateral sulcus and the surrounding gyri.

RESULTS

The retrosigmoid approach allowed for clear visualization of the basal occipitotemporal surface. The collateral sulcus was identified and permitted easy endoscopic access to the ventricular atrium. The conical corridor thus obtained provided an average base working area of 3.9 cm2 at an average depth of 4.5 cm. The mean cortical thickness traversed to enter the ventricle was 1.4 cm. The intraventricular anatomy of the ipsilateral ventricle was defined clearly in all 8 exposures in this manner. The anatomy of the basal occipitotemporal surface, observed in a total of 18 hemispheres, showed a consistent pattern, with the collateral sulcus abutted by the parahippocampal gyrus medially, and the fusiform and lingual gyrus laterally. The collateral sulcus was found to be caudally bifurcated in 14 of the 18 specimens.

CONCLUSIONS

The retrosigmoid supracerebellar transtentorial transcollateral sulcus approach is technically feasible. This approach has the potential advantage of providing a short and direct path to the atrium, hence avoiding violation of deep neurovascular structures and preserving eloquent areas. Although this approach appears unconventional, it may provide a minimally invasive option for the surgical management of selected lesions within the atrium of the lateral ventricle.

Approaching the Atrium Through the Intraparietal Sulcus: Mapping the Sulcal Morphology and Correlating the Surgical Corridor to Underlying Fiber Tracts

BACKROUND: Although the operative corridor used during the intraparietal transsulcal approach to the atrium has been previously investigated, most anatomical studies focus on its relationship to the optic radiations.

OBJECTIVE: To study the intraparietal sulcus (IPS) morphology and to explore the subcortical anatomy with regard to the surgical trajectory used during the intraparietal transsulcal tranventricular approach.

METHODS: Twenty-five adult, formalin fixed, cerebral hemispheres were investigated. Fifteen underwent the Klingler procedure and were dissected in a lateromedial direction using the fiber microdissection technique. The trajectory of the dissection resembled that of real operative settings. The remaining 10 hemispheres were cut along the longitudinal axis of the sulcus in order to correlate its surface anatomy to corresponding parts of the ventricular system.

RESULTS: IPS demonstrated an interrupted course in 36% of the specimens while its branching pattern was variable. The sulcus anterior half was found to overly the atrium in all occasions. Four discrete, consecutive white matter layers were identified en route to the atrium, ie, the arcuate fibers, the arcuate segment of the superior longitudinal fasciculus, the corona radiata and tapetum, with the arcuate segment being near to the dissection trajectory.

CONCLUSION: Given the angle of brain transgression during the intraparietal approach, we found the optimal dissection area to be the very middle of the sulcus. The IPS–postcentral sulcus meeting point, in contrast to previous thought, proved to risk potential injury to the arcuate segment of the superior longitudinal fasciculus, thus affecting surgical outcome.

Paraventricular meningioma revealed by mental disorder

BACKGROUND

Ventricular meningioma constitutes 2% of intracranial meningioma, representing a challenging disease for neurosurgeons. Although cognitive impairment is one of the major symptoms of ventricular tumors, few studies have reported the details of cognitive impairment before and after their surgical removal. The expected effects on cognitive function should also be considered when choosing a surgical approach.

CASE DESCRIPTIONS

We report the case of a large lateral ventricle meningioma revealed by cognitive dysfunction and moderate intellectual disability. The patient underwent subtotal resection of the tumor which had partial improvement in cognitive disorders. It is important to precisely assess neuropsychological function in patients with large brain tumors, and judicious preoperative plan, adequate knowledge of anatomy, and use of correct microsurgical techniques are fundamental in achieving complete resection of paraventricular meningioma with low morbidity.

CONCLUSION

Pre and postoperative precise neuropsychological examinations may identify the potential cognitive impairment and beneficial effects of surgery in patients with large lateral ventricle meningiomas.

[The paramedian supracerebellar transtentorial approach to the mediobasal temporal region]

The mediobasal temporal region (MTR) is located near the brain stem and surrounded by the eloquent neurovascular structures. The supracerebellar transtentorial approach (STA) is safe access to the posterior MTR structures, however its use for resection of anterior MTR lesions still remains controversial. The article describes the technique and outcome of surgery for different MTR structures using STA.

MATERIAL AND METHODS

The paramedian STA was used in 18 patients (13 females and 5 males) for 7 years. Ten patients presented with glial MTR tumors, 3 patients with cavernomas, 2 patients with arteriovenous malformations (AVMs), 2 patients with intraventricular meningiomas, and 1 patient with mesial temporal sclerosis. The patient age ranged from 19 to 57 years. In 10 cases, lesions were localized on the left. Epilepsy was the leading symptom in 14 cases. Patients underwent preoperative high-resolution MRI, electroencephalography video monitoring before and after surgery, intraoperative corticography (if necessary), and postoperative CT and MRI.

RESULTS

Lesions were located in the anterior third of MTR in 5 patients, in the anterior and middle thirds in 2 patients, in the middle third in 5 patients, in the middle and posterior thirds in 2 patients, in the posterior third in 1 patient, in the anterior, middle, and posterior thirds in 1 patient, and in the ventricular triangle area in 2 patients. In all patients with intraventricular tumors, AVMs, and cavernous malformations and in 8 patients with glial MTR tumors, the lesions were totally resected. Two patients with intracerebral tumors underwent subtotal resection. A patient with intractable epilepsy and mesial temporal sclerosis underwent resection of the anterior two-thirds of the hippocampus and parahippocampal gyrus and, partially, amygdala using intraoperative corticography. There was no surgical mortality; 2 patients developed a transient neurological deficit, and 1 patient had a cerebellar hematoma that was successfully removed during surgery.

CONCLUSION

STA enables resection of lesions localized in all parts of the MTR, without damage to the surrounding nerve and vascular structures.

The white matter tracts of the cerebrum in ventricular surgery and hydrocephalus

OBJECTIVE The relationship of the white matter tracts to the lateral ventricles is important when planning surgical approaches to the ventricles and in understanding the symptoms of hydrocephalus. The authors' aim was to explore the relationship of the white matter tracts of the cerebrum to the lateral ventricles using fiber dissection technique and MR tractography and to discuss these findings in relation to approaches to ventricular lesions. METHODS Forty adult human formalin-fixed cadaveric hemispheres (20 brains) and 3 whole heads were examined using fiber dissection technique. The dissections were performed from lateral to medial, medial to lateral, superior to inferior, and inferior to superior. MR tractography showing the lateral ventricles aided in the understanding of the 3D relationships of the white matter tracts with the lateral ventricles. RESULTS The relationship between the lateral ventricles and the superior longitudinal I, II, and III, arcuate, vertical occipital, middle longitudinal, inferior longitudinal, inferior frontooccipital, uncinate, sledge runner, and lingular amygdaloidal fasciculi; and the anterior commissure fibers, optic radiations, internal capsule, corona radiata, thalamic radiations, cingulum, corpus callosum, fornix, caudate nucleus, thalamus, stria terminalis, and stria medullaris thalami were defined anatomically and radiologically. These fibers and structures have a consistent relationship to the lateral ventricles. CONCLUSIONS Knowledge of the relationship of the white matter tracts of the cerebrum to the lateral ventricles should aid in planning more accurate surgery for lesions within the lateral ventricles.

Microsurgical resection of tumors of the lateral and third ventricles: operative corridors for difficult-to-reach lesions

Tumors of the lateral and third ventricles are cradled on all sides by vital vascular and eloquent neural structures. Microsurgical resection, which always requires attentive planning, plays a critical role in the contemporary management of these lesions. This article provides an overview of the open microsurgical approaches to the region highlighting key clinical perspectives.