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.

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.

Evaluation of Venous Drainage Patterns for Skull Base Meningioma Surgery

The evaluation of venous drainage patterns prior to surgery for skull base meningioma is important owing to their deep location and the vulnerability of surrounding vascular structures. In recent years, the microsurgical skull base approach has matured as a surgical technique, making it an important option for reducing complications related to skull base meningioma surgery. In addition, knowledge of the venous anatomy can prevent venous drainage route disturbance and potentially life-threatening complications. Hence, this topic review aimed to provide an overview of normal venous anatomy as it relates to the microsurgical skull base approach, discuss known changes in venous drainage routes that are associated with the progression of skull base meningioma and the selection of an appropriate operative approach with the highest likelihood of preserving venous drainage structures.

Various patterns of the middle cerebral vein and preservation of venous drainage during the anterior transpetrosal approach

OBJECTIVE

The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation.

METHODS

This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required.

RESULTS

The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found.

CONCLUSIONS

The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.

Utility of dynamic computed tomography angiography in the preoperative evaluation of skull base tumors

OBJECT

The anatomical complexity of skull base tumors mandates detailed preoperative planning for safe resection. In particular, the location of critical vascular and bony structures can influence the surgical approach. Traditional methods, such as MRI, MR angiography and/or venography (MRA/MRV), CT angiography and/or venography (CTA/CTV), and digital subtraction angiography, each have their limitations. One alternative that combines the benefits of both detailed anatomy compatible with intraoperative image guidance and visualization of the vascular flow is the 320-detector row dynamic volume CTA/CTV. The authors investigated this technique's impact on the surgical approach used in a series of complex intracranial tumors.

METHODS

All patients with complex intracranial tumors who had undergone preoperative dynamic CTA/CTV as well as MRI in the period from July 2010 to June 2012 were retrospectively reviewed. Those in whom only routine CTA/CTV sequences had been obtained were excluded. Clinical records, including imaging studies, operative reports, and hospital course, were reviewed. Ease in detecting specific major arterial and venous tributaries using dynamic CTA/CTV was graded for each case. Furthermore, 2 skull base neurosurgeons projected a desired surgical approach for each tumor based on MRI studies, independent of the CTA/CTV sequences. The projected approach was then compared with the ultimately chosen surgical approach to determine whether preoperative awareness of vasculature patterns altered the actual operative approach.

RESULTS

Sixty-four patients were eligible for analysis. Dynamic CTA/CTV successfully demonstrated circle of Willis arteries, major draining sinuses, and deep internal venous drainage in all cases examined. The superior petrosal sinus, vein of Labbé, tentorial veins, and middle fossa veins were also identified in a majority of cases, which played an important role in preoperative planning. Visualization of critical vascular-especially venous-anatomy influenced the surgical approach in 39% (25 of 64) of the cases.

CONCLUSIONS

Dynamic CTA/CTV has been applied to few neurosurgical disease pathologies to date. This noninvasive technology offers insight into vascular flow patterns as well as 3D anatomical relationships and provides thin-cut sequences for intraoperative navigation. The authors propose dynamic CTA as an addition to the preoperative planning for complex skull base tumors.

Preservation of the superior petrosal sinus during the petrosal approach

Object

The petrosal approach is based on sectioning the superior petrosal sinus (SPS) and the tentorium. However, the venous anatomy in certain situations forbids this maneuver. The authors have derived a technique that enables the SPS to be spared during the performance of the petrosal approach. They describe the anatomical basis of this technique and report on 2 cases in which the technique was applied.

Methods

Five alcohol-preserved cadaveric heads injected with colored silicone were used for bilateral dissection and demonstration of the technique. The described method was thoroughly investigated in these cadavers to assess its advantages, variabilities, and limitations. Subsequently, the technique was applied during the resection of petroclival tumors in 2 patients.

Results

The authors were able to demonstrate that the approach provides good access to the petroclival area through both the middle and posterior fossa in cadavers. By deriving a new technique of applying the combined petrosal approach without cutting the SPS, the senior author (O.A.M.) managed to achieve total resection of a dumbbell-shaped trigeminal schwannoma in a 19-year-old woman and of a petroclival meningioma in a 49-year-old man.

Conclusions

This modification of the petrosal approach involving sparing of the SPS or cutting of the tentorium is an effective means for cases in which the venous anatomy mandates preservation of these structures.

Reconstruction of the vein of Labbé by using a short saphenous vein bypass graft. Technical note

Protection of the vein of Labbé is a significant concern during surgery that involves retraction of the temporal lobe. A cranial base surgical approach, especially one via the presigmoid-petrosal route, carries considerable risk to this venous complex. A case is presented in which a large dominant vein of Labbé was injured during resection of a petroclival meningioma. This vein drained all the sylvian venous circulation as well as the lateral temporal surface; no connection to another venous system was noted. The vein was successfully reconstructed using a short saphenous vein bypass graft. Significant complications could have occurred without this reconstruction. The technique and benefits of this type of reconstruction are discussed.