Influences of venous involvement on postoperative brain damage following the anterior interhemispheric approach

Mini anterior interhemispheric approach for A3 segment distal anterior cerebral artery aneurysms

INTRODUCTION

Aneurysms of the A3 segment of the distal anterior cerebral artery (DACA), in relation to the genu of the corpus callosum, are specific sub-group which pose unique surgical challenges due to their discrete anatomical location. We describe a mini-anterior interhemispheric approach which can be safely utilised to clip these aneurysms rather than the traditional bifrontal approach.

METHODS

Retrospective analysis of the clinical and radiological data of ruptured DACA-A3 aneurysms operated between 2014 and 2021 at our institute. A curvilinear scalp incision within the hairline followed by raising small, unilateral, free frontal bone flap, avoiding the opening of frontal sinus. Superior sagittal sinus is displaced medially, inter-hemispheric dissection carried out with posterior trajectory and small callosotomy is performed. DACA is skeletonised, proximal control is established, and the A3 aneurysm is dissected and clipped.

RESULT

Our cohort of 18 patients had a definite female preponderance (F:M::2:1) with mean age of 55.6 years. On admission three patients were categorized as WFNS Grade I, thirteen in Grade II, and two in Grade III for subarachnoid haemorrhage. All the patients had evidence of blood in the interhemispheric fissure; intraparenchymal haemorrhage was seen in seven, with intraventricular haemorrhage in six patients. Within the A3 segment six aneurysms were infragenu (inferior), eight were at the genu (anterior) and four were supragenu (superior). Two (11.1%) elderly patients succumbed post-surgery following ischemic infarcts and associated complications. At the time of follow-up at 3 months of the remaining sixteen (72.2%) patients, thirteen had a good outcome (mRS 0-3) and three (16.7%) had a poor outcome (mRS > 3).

CONCLUSION

The mini anterior interhemispheric is an effective minimally invasive alternative for A3 segments aneurysms and helps to avoid the complications of the conventional bifrontal interhemispheric approach.

The Superficial Anastomosing Veins of the Human Brain Cortex: A Microneurosurgical Anatomical Study

Introduction: In this microneurosurgical and anatomical study, we characterized the superficial anastomosing veins of the human brain cortex in human specimens.

Material and Methods: We used 21 brain preparations fixed in formalin (5%) that showed no pathological changes and came from the autopsy sections. The superficial veins were dissected out of the arachnoid with the aid of a surgical microscope.

Results: We dissected nine female and 12 male brain specimens, with an average age of 71 ± 11 years (range 51–88 years). We classified the superficial veins in five types: (I) the vein of Trolard as the dominat vein; (II) the vein of Labbé as the dominant vein; (III) a dominant sylvian vein group, and the veins of Trolard and Labbé nonexistent or only rudimentary present without contact to the Sylvian vein group; (IV) very weak sylvian veins with the veins of Trolard and Labbé codominant; and V) direct connection of Trolard and Labbé bypassing the Sylvian vein group. The vein of Trolard was dominant (Type I) in 21.4% and the vein of Labbé (Type II) in 16.7%. A dominant sylvian vein group (Type III) was found in 42.9%. Type IV and Type V were found in 14.3 and 4.7% respectively.

Conclusion: No systematic description or numerical distribution of the superior anastomotic vein (V. Trolard) and inferior anastomotic vein (V. Labbé) has been found in the existing literature. This study aimed to fill this gap in current literature and provide data to neurosurgeons for the practical planning of surgical approaches.

Keyhole Superior Interhemispheric Approach to Midline Meningiomas of the Far Frontal Region of the Anterior Skull Base: Cadaveric Study and Illustrative Cases

OBJECTIVE

Unique challenges can present in the treatment of small to mid-sized meningiomas that arise from the region of the anterior most aspect of the falx cerebri including its junction with the anterior skull base, what we call the far frontal region. Although this region of the anterior skull base is considered in the surgical approach of olfactory groove meningiomas invading this space, important differences exist between these tumors and those of the far frontal region.

METHODS

Toward refining surgical selection, our cadaveric study details a minimally invasive keyhole superior interhemispheric approach to the far frontal region and 2 illustrative cases show the feasibility of this approach.

RESULTS

Our cadaveric study defines 5 steps of the approach from the incision, craniectomy, dural opening, approaching the skull base and ipsilateral exposure, and finally falcine resection and bilateral skull base exposure. Two illustrative cases with the approach confirmed visualization of the full extent of tumor and gross total resection with preservation of the unaffected olfactory bulb.

CONCLUSIONS

To the best of our knowledge, our anatomic study is distinctively unique in quantifying the working distance of the keyhole superior interhemispheric exposure and refining visualization of the far frontal region. We discuss these benefits and limitations (i.e., substantial involvement of tumor beyond midline) and differences with large meningiomas of the olfactory groove and far frontal region with significant posterior or lateral extension for which conventional exposures are appropriate.

Importance of Veins for Neurosurgery as Landmarks Against Brain Shifting Phenomenon: An Anatomical and 3D-MPRAGE MR Reconstruction of Superficial Cortical Veins

Modern neurosurgery uses preoperative imaging daily. Three-dimensional reconstruction of the cortical anatomy and of the superficial veins helps the surgeons plan and perform neurosurgical procedures much more safely. The target is always to give the patient maximum benefit in terms of outcome and minimize intraoperative and postoperative complications. This study aims to develop a method for the combined representation of the cerebral cortex anatomy and the superficial cerebral veins, whose integration is beneficial in daily practice. Only those patients who underwent surgical procedures with craniotomy and a large opening of the dura mater were included in this study, for a total of 23 patients, 13 females (56.5%) and 10 males (43.5%). The average age was 50.1 years. We used a magnetic resonance tomograph Magnetom Vision® 1.5T (Siemens AG). Two sequences were applied: a strongly T1-weighted magnetization-prepared rapid acquisition with gradient echo (MPRAGE) sequence to visualize cerebral anatomical structures, and a FLASH-2D-TOF angiography sequence to visualize the venous vessels on the cortical surface after the administration of a paramagnetic contrast agent. The two data sets were superimposed manually, co-registered in an interactive process, and merged to create a combined data set, segmented and visualized as a three-dimensional reconstruction. Furthermore, we present our method for visualizing superficial veins, which helps manage brain shift (BS). We also performed anatomical observations on the reconstructions. The reconstructions of the cortical and venous anatomy proved to be a valuable tool in surgical planning and positively influenced the surgical procedure. Due to the good correlation with the existing surgical site, this method should be validated on a larger cohort or in a multicentric study.

Relationship of superior sagittal sinus with sagittal midline: A surgical application

Background:

Interhemispheric approach is widely used to surgical management of midline tumors and vascular lesion in and around the third ventricle. Complete exposure of the superior sagittal sinus to obtain adequate working space of midline lesion is difficult, because of the risk to inadvertent injury to the sinus and bridging veins, which may cause several neurological deficits. Understanding the SSS neuroanatomy and its relationships with external surgical landmarks avoid such complications. The objective of this study is to accurately describe the position of SSS and its displacement in relation with sagittal midline by magnetic resonance imaging.

Methods:

A retrospective cross-sectional, observational study was performed. Magnetic resonance image of 76 adult patients with no pathological imaging was analyzed. The position of the halfway between nasion and bregma, bregma, halfway between bregma and lambda, and lambda was performed. The width and the displacement of the superior sagittal sinus accordingly to the sagittal midline were assessed in those landmarks.

Results:

The mean width of superior sagittal sinus at halfway between nasion and bregma, bregma, halfway between bregma and lambda, and lambda was 5.62 ± 2.5, 6.5 ± 2.8, 7.4 ± 3.2, and 8.5 ± 2.1 mm, respectively, without gender discrepancy. The mean displacement according to the midline at those landmarks showed a statistically significant difference to the right side among sexes.

Conclusion:

In this study, we demonstrate that sagittal midline may approximate external location of the superior sagittal sinus. Our data showed that in the majority of the cases, the superior sagittal sinus is displaced to the right side of sagittal midline as far as 16.3 mm. The data we obtained provide useful information that suggest that neurosurgeons should use safety margin to perform burr holes and drillings at the sagittal midline.

Anterior interhemispheric approach for clipping of subcallosal distal anterior cerebral artery aneurysms: case series and technical notes

Distal anterior cerebral artery (DACA) aneurysms are rare, accounting for 1-9% of all intracranial aneurysms. Previous systematic reviews have highlighted that given the markedly increased incidence of major complications after endovascular treatment, microsurgical clipping is the more attractive treatment option with generally excellent clinical outcomes. Subcallosal DACA aneurysms constitute a rare subset of these aneurysms, requiring special anatomic considerations-particularly with regard to the approach. The aim of this study is to review the technical nuances of microsurgical treatment of subcallosal DACA aneurysms, including review of contemporary techniques through presentation of a microneurosurgical operative video. This is a retrospective case series and intraoperative microsurgical videos review. Three subcallosal DACA aneurysms were identified via retrospective query of our institutional neurosurgical database from December 2017 to May 2018. Two were female; median age was 74 years (range 70-83); all 3 underwent bifrontal craniotomy via bicoronal skin incision for aneurysm clipping. Aneurysms were located in left pericallosal-callosomarginal artery junction, bifurcation of azygos A2, and pericallosal artery related with azygos A2, and the anterior interhemispheric approach was used in all 3 operations. No acute stroke, hemorrhage, or major complications occurred, and all patients remained neurologically intact at the time of last follow-up (median 3 months, range 1-6). Although DACA aneurysms are rare, they represent an important variant for cerebrovascular neurosurgeons where microsurgical clipping can have better angiographic outcomes than endovascular treatment. Detail-oriented anterior interhemispheric arachnoid dissection through bifrontal craniotomy with its lower margin sitting at the superior orbital rim maximizes safe and effective clipping of subcallosal DACA aneurysms.

The interhemispheric approach in children: our experience and review of the literature

OBJECTIVE

The interhemispheric approach (IA) has been extensively described for treating pathologies located at the lateral or third ventricle, pineal region, and periventricular locations. While these anatomical locations are the target of many pediatric pathologies, very few series have analyzed the morbidity and outcome of the IA in children. The aim of this study is to describe our experience using the IA in children, emphasizing the approach-related morbidity.

METHODS

Twenty-six patients underwent 28 procedures using the IA between the years 2012 and 2016. Data for these patients was retrospectively analyzed. Surgical and approach-related morbidity were collected and analyzed.

RESULTS

The mean age of the cohort was 10.1 ± 4.2 years and included 15 females (57.7%). Approach-related morbidity occurred following eight surgeries (28.6%; seven with anterior IA and one with posterior IA), including two pseudomeningoceles (7.1%), three persistent subdural effusions (10.7%), of which two were locally drained and one required subduro-peritoneal shunting, one epidural bleed (3.6%) which resolved spontaneously, and two infections (3.6%) treated with antibiotics. Cerebrospinal fluid leaks, supplementary motor area syndrome, seizures, and subdural hematomas did not occur in any of the patients. None of the approach-related complications led to permanent morbidity or to mortality.

CONCLUSION

The IA for lesions in and around the ventricular system is feasible and associated with a low permanent complication rate. When choosing this approach, the morbidity, although rarely permanent, should be considered.

A systematic autopsy survey of human infant bridging veins

In the first years of life, subdural haemorrhage (SDH) within the cranial cavity can occur through accidental and non-accidental mechanisms as well as from birth-related injury. This type of bleeding is the most common finding in victims of abusive head trauma (AHT). Historically, the most frequent cause of SDHs in infancy is suggested to be traumatic damage to bridging veins traversing from the brain to the dural membrane. However, several alternative hypotheses have been suggested for the cause and origin of subdural bleeding. It has also been suggested by some that bridging veins are too large to rupture through the forces associated with AHT. To date, there have been no systematic anatomical studies on infant bridging veins. During 43 neonatal, infant and young child post-mortem examinations, we have mapped the locations and numbers of bridging veins onto a 3D model of the surface of a representative infant brain. We have also recorded the in situ diameter of 79 bridging veins from two neonatal, one infant and two young children at post-mortem examination. Large numbers of veins, both distant from and directly entering the dural venous sinuses, were discovered travelling between the brain and dural membrane, with the mean number of veins per brain being 54.1 and the largest number recorded as 94. The mean diameter of the bridging veins was 0.93 mm, with measurements ranging from 0.05 to 3.07 mm. These data demonstrate that some veins are extremely small and subjectively, and they appear to be delicate. Characterisation of infant bridging veins will contribute to the current understanding of potential vascular sources of subdural bleeding and could also be used to further develop computational models of infant head injury.

Technique for rerouting a bridging vein that hinders the anterior interhemispheric approach: a technical note

BACKGROUND

The frontal bridging vein, which is the venous drainage route of the frontal cortex into the superior sagittal sinus (SSS), sometimes poses an obstacle in the anterior interhemispheric approach during surgery for anterior cerebral artery aneurysms. Although severe complications including venous infarction or edema due to damage to the bridging vein are well known, only a few reports have discussed how to avoid venous injury when we must sacrifice the bridging vein to obtain an appropriate surgical field. This report describes a microvascular technique performed in two patients who underwent rerouting of the bridging vein to obtain an appropriate anterior interhemispheric surgical corridor to treat a ruptured anterior cerebral artery aneurysm. The hindering bridging vein was resected from the entrance to the SSS and anastomosed toward the adjacent cortical vein.

METHODS

A 65-year-old male and a 43-year-old male were admitted to our hospital for sudden headache. Computed tomography, magnetic resonance angiogram, or digital subtraction angiography demonstrated a subarachnoid hemorrhage and an anterior cerebral artery aneurysm in both patients. In both cases, a relatively robust bridging vein, which appeared problematic to sacrifice, was draining into the SSS, resulting in a limited surgical corridor. Thus, we performed cortical vein reconstruction, and the aneurysms were successfully clipped under a wider surgical view.

RESULTS

We confirmed completed clipping without postoperative venous complications. One patient demonstrated patency of reconstructed venous flow by digital subtraction angiography. No apparent cognitive impairment was seen in either patient.

CONCLUSIONS

This technique may be useful for obtaining an appropriate surgical corridor when the frontal bridging vein may be damaged.

Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

The anterior interhemispheric approach: a safe and effective approach to anterior skull base lesions

BACKGROUND

Many approaches to the anterior skull base have been reported. Frequently used are the pterional, the unilateral or bilateral frontobasal, the supraorbital and the frontolateral approach. Recently, endoscopic transnasal approaches have become more popular. The benefits of each approach has to be weighted against its complications and limitations. The aim of this study was to investigate if the anterior interhemispheric approach (AIA) could be a safe and effective alternative approach to tumorous and non-tumorous lesions of the anterior skull base.

METHODS

We screened the operative records of all patients with an anterior skull base lesion undergoing transcranial surgery. We have used the AIA in 61 patients. These were exclusively patients with either olfactory groove meningioma (OGM) (n = 43), ethmoidal dural arteriovenous fistula (dAVF) ( n = 6) or frontobasal fractures of the anterior midline with cerebrospinal fluid (CSF) leakage ( n = 12). Patient records were evaluated concerning accessibility of the lesion, realization of surgical aims (complete tumor removal, dAVF obliteration, closure of the dural tear), and approach related complications.

RESULTS

The use of the AIA exclusively in OGMs, ethmoidal dAVFs and midline frontobasal fractures indicated that we considered lateralized frontobasal lesions not suitable to be treated successfully. If restricted to these three pathologies, the AIA is highly effective and safe. The surgical aim (complete tumor removal, complete dAVF occlusion, no rhinorrhea) was achieved in all patients. The complication rate was 11.5 % (wound infection (n = 2; 3.2 %), contusion of the genu of the corpus callosum, subdural hygroma, epileptic seizure, anosmia and asymptomatic bleed into the tumor cavity (n = 1 each). Only the contusion of the corpus callosum was directly related to the approach (1.6 %). Olfaction, if present before surgery, was preserved in all patients, except one (1.6 %).

CONCLUSIONS

The AIA is an effective and a safe approach to tumorous, vascular and traumatic pathologies of the midline anterior skull base. This approach should be part of the armamentarium of skull base surgeons.

Surgical approaches to tumors of the anterior gyrus cinguli

BACKGROUND

Tumors of the gyrus cinguli are deep-seated, and may require a variety of surgical options. We focused on anterior tumors, which have specific anatomic and surgical features.

OBJECTIVE

To evaluate different approaches and indications through detailed description and a review of our experience.

METHODS

These approaches include unilateral interhemispheric or combined: bilateral interhemispheric, unilateral plus superior frontal gyrectomy, or unilateral plus frontal polectomy. The relevance of this retrospective analysis is stressed by the extremely limited literature in this regard.

RESULTS

In the past 5 years we operated on 38 patients with gliomas. We compared the following variables: location (perigenual, prerolandic), pathology (glioblastoma, other gliomas), size (<4 cm, > or =4 cm), extension (unilateral, bilateral), and approach (unilateral interhemispheric, combined). The only significant association we found was between tumor location (perigenual) and bilateral extension (P < .01). However, combined approaches were adopted only slightly more frequently in this region than in the prerolandic area, and this resulted in a lower rate of total removal (33% vs 76%, P < .01). Gross total removal was achieved in 28 cases (66%) and was significantly associated with combined approaches (77% vs 50%, P < .05).

CONCLUSIONS

The choice of a combined approach to anterior gyrus cinguli tumors is critical to improving the quality of resection in selected cases. We recommend a combined approach in the surgical treatment of large tumors of the perigenual area.

Fronto-basal interhemispheric approach for tuberculum sellae meningiomas; long-term visual outcome

We report our experience with the treatment of tuberculum sellae meningiomas using the fronto-basal interhemispheric approach. A retrospective analysis was performed on a series of 24 patients with tuberculum sellae meningiomas who were operated between March 2000 and January 2007. Patients' presenting symptoms, radiological images, operative reports, and clinical follow-up data were reviewed with special consideration for visual outcome. Visual deterioration was the presenting symptom in all patients, followed by headache in 9 patients (37.5%). The average duration of visual symptoms was 17.6 months. The average tumor diameter was 2.63 cm; encasement of the carotid artery was identified in 7 patients (29%). Complete tumor removal was achieved in 21 patients (87.5%). Mean follow-up period was 52 months. Vision improved in 19 patients (79%), remained stable in 4 (17%) and deteriorated in 1 patient (4%). The degree of tumor removal or visual outcome were both unrelated to the tumor size (p = 0.2 and p = 0.6 respectively). While the degree of preoperative visual deficit did not affect the visual improvement rate in the whole group (p = 0.9), those patients with improvement to good functional vision (>20/40) after the surgery, had a less severe preoperative deficit (p < 0.001). The most common complication was anosmia (29.1%) and there was no mortality. The frontobasal interhemispheric approach is safe and provides a direct anatomical approach to tuberculum sellae meningiomas with relatively low incidence of complications. Patients with improved vision to good functional level had a better preoperative visual status.

Surgery of the anterior part of the frontal lobe and of the central region: normative morphometric data based on magnetic resonance imaging

Modern magnetic resonance imaging (MRI) techniques have improved the planning of surgery to remove lesions in or around the frontal lobe. Since MRI-based morphometric analyses of the anterior part of the frontal lobe and the central region as part of it have not yet been performed, the present study was undertaken to obtain relative normative morphometric data. Median sagittal MRI scans from 53 magnetization prepared rapid acquisition gradient echo (MPRAGE) sequences of individual brains without pathological lesions were analyzed. The AC-PC line (anterior commissure-posterior commissure line) with vertical lines through the AC and PC were chosen as reference lines. Measurements of the anterior part of the frontal lobe included distances between different landmarks (frontal pole, tuberculum sellae, AC, outer point and inner surface of the genu of the corpus callosum, and the cortex at this level). For the measurements around the central region distances were obtained from the following landmarks: coronal suture, central sulcus, marginal sulcus, intersection point of the vertical line through the PC with the cortex, and PC. Knowledge of these distances will allow exact planning of surgical approaches to the anterior part of the frontal lobe, for example, the subfrontal or anterior interhemispheric approach and surgery around the central region.