Clinical features of postoperative cerebral venous infarction

SupraPetrous InfraTemporal Approach: A Supplemental Approach to Supracerebellar Infratentorial for Inferior Amygdala and Hippocampal Head Access-A Cadaveric Study With Case Illustrations

BACKGROUND AND OBJECTIVES

Access to the amygdala and hippocampus (A/H) is complex. To address the limitations and invasiveness of traditional approaches, including the Transsylvian, Subtemporal, and Supracerebellar infratentorial approaches, we developed the suprapetrous infratemporal (SPIT) approach. This study describes the nuances of this approach in both cadaveric studies and clinical cases.

METHODS

Three unilateral exposures were performed using microscopic and endoscopic methodologies in the SPIT approach. After cadaveric investigation, this approach was successfully implemented in representative clinical cases.

RESULTS

The SPIT approach enabled direct access to the inferior A/H, circumventing the requirement for temporal lobe retraction and detachment of the temporal lobe from the dura through a subtemporal route by drilling the upper part of the mastoid, consequently mitigating tension on the vein of Labbé. This enabled a bottom-up view because one would gain with a zygomatic osteotomy and forward projection like a mini-posterior petrosal view by using a transmastoid view, without cutting down the zygomatic arch and opening the dura subtemporally, limiting patient pain and preventing case comorbidity. The SPIT approach was performed in 2 cases of mesial temporal cavernoma presenting with seizures. The lesion was visualized intraoperatively and was successfully removed in these cases. The postoperative course was excellent with no complications, and gross total resection was radiographically confirmed with Engel Class 1a seizure freedom.

CONCLUSION

The SPIT approach is a complementary approach for inferior A/H disease, combining the combined middle fossa approach modified for intradural pathology. Limited drilling of the upper aspect of the mastoid with a medial dural opening at the level of the arcuate eminence provides a direct trajectory with minimal brain retraction. Additional research encompassing a larger patient cohort and extended follow-up periods is required to substantiate the advantages of SPIT in the management of inferior A/H lesions.

Comparison of Postoperative Seizures Between Burr-Hole Evacuation and Craniotomy in Patients With Nonacute Subdural Hematomas: A Bi-Institutional Propensity Score-Matched Analysis

BACKGROUND AND OBJECTIVES

Postoperative seizures are a common complication after surgical drainage of nonacute chronic subdural hematomas (SDHs). The literature increasingly supports the use of prophylactic antiepileptic drugs for craniotomy, a procedure that is often associated with larger collections and worse clinical status at admission. This study aimed to compare the incidence of postoperative seizures in patients treated with burr-hole drainage and those treated with craniotomy through propensity score matching (PSM).

METHODS

A retrospective cohort analysis was conducted on patients with surgical drainage of nonacute SDHs (burr-holes and craniotomies) between January 2017 to December 2021 at 2 academic institutions in the United States. PSM was performed by controlling for age, subdural thickness, subacute component, and preoperative Glasgow Coma Scale. Seizure rates and accompanying abnormalities on electroencephalographic tracing were evaluated postmatching.

RESULTS

A total of 467 patients with 510 nonacute SDHs underwent 474 procedures, with 242 burr-hole evacuations (51.0%) and 232 craniotomies (49.0%). PSM resulted in 62 matched pairs. After matching, univariate analysis revealed that burr-hole evacuations exhibited lower rates of seizures (1.6% vs 11.3%; P = .03) and abnormal electroencephalographic findings (0.0% vs 4.8%; P = .03) compared with craniotomies. No significant differences were observed in postoperative Glasgow Coma Scale (P = .77) and length of hospital stay (P = .61).

CONCLUSION

Burr-hole evacuation demonstrated significantly lower seizure rates than craniotomy using a propensity score-matched analysis controlling for significant variables.

Handling Severe Intraoperative Hemorrhage and Avoiding Iatrogenic Stroke During Brain Tumor Surgery: Techniques for Prevention of Hemorrhagic and Ischemic Complications

BACKGROUND

Nationwide databases show that iatrogenic stroke and postoperative hematoma are among the commonest complications in brain tumor surgery, with a 10-year incidence of 16.3/1000 and 10.3/1000, respectively. However, techniques for handling severe intraoperative hemorrhage and dissecting, preserving, or selectively obliterating vessels traversing the tumor are sparse in the literature.

METHODS

Records of the senior author's intraoperative techniques during severe haemorrhage and vessel preservation were reviewed and analyzed. Intraoperative media demonstrations of key techniques were collected and edited. In parallel, a literature search investigating technique description in handling severe intraoperative hemorrhage and vessel preservation in tumor surgery was undertaken. Histologic, anesthetic, and pharmacologic prerequisites of significant hemorrhagic complications and hemostasis were analyzed.

RESULTS

The senior author's techniques for arterial and venous skeletonization, temporary clipping with cognitive or motor mapping, and ION monitoring were categorized. Vessels interfacing with tumor are labeled intraoperatively as supplying/draining the tumor, or traversing en passant, while supplying/draining functional neural tissue. Intraoperative techniques of differentiation were analyzed and illustrated. Literature search found 2 vascular-related complication domains in tumor surgery: perioperative management of excessively vascular intraparenchymal tumors and lack of intraoperative techniques and decision processes for dissecting and preserving vessels interfacing or traversing tumors.

CONCLUSIONS

Literature searches showed a dearth of complication-avoidance techniques in tumor-related iatrogenic stroke, despite its high prevalence. A detailed preoperative and intraoperative decision process was provided along with a series of case illustrations and intraoperative videos showing the techniques required to reduce intraoperative stroke and associated morbidity addressing a void in complication avoidance of tumor surgery.

Anatomical variations and flow alterations of the uncal vein and its clinical implications in petroclival meningiomas

BACKGROUND

The Uncal vein (UV), downstream of the deep middle cerebral vein (DMCV), has a similar drainage pattern to the superficial middle cerebral vein (SMCV) and may be involved in venous complications during the anterior transpetrosal approach (ATPA). However, in petroclival meningioma (PCM), where the ATPA is frequently used, there are no reports evaluating drainage patterns of the UV and the risk of venous complications associated with the UV during the ATPA.

METHODS

Forty-three patients with petroclival meningioma (PCM) and 20 with unruptured intracranial aneurysm (control group) were included. Preoperative digital subtraction angiography was used to evaluate UV and DMCV drainage patterns on the side of the tumor and bilaterally in patients with PCM and the control group, respectively.

RESULTS

In the control group, the DMCV drained to the UV, UV and BVR, and BVR in 24 (60.0%), eight (20.0%), and eight (20.0%) hemispheres, respectively. Conversely, the DMCV in the patients with PCM drained to the UV, UV and BVR, and BVR in 12 (27.9%), 19 (44.2%), and 12 (27.9%) patients, respectively. The DMCV was more likely to be drained to the BVR in the PCM group (p < 0.01). In three patients with PCM (7.0%), the DMCV drained only to the UV, and furthermore, the UV drained to the pterygoid plexus via the foramen ovale, posing a risk for venous complications during the ATPA.

CONCLUSIONS

In the patients with PCM, the BVR functioned as a collateral venous pathway of the UV. Preoperative evaluation of the UV drainage patterns is recommended to reduce venous complications during the ATPA.

Utility of MRI in surgical planning for parasagittal meningiomas

BACKGROUND

Surgical resection is the standard treatment for parasagittal meningioma (PSM), but complete resection may be challenging due to superior sagittal sinus (SSS) involvement. The SSS may be partially or completely obstructed, and collateral veins are commonly present. Thus, knowing the status of the SSS in PSM cases prior to treatment is essential to a successful outcome. MRI is utilized prior to surgery in order to determine SSS status and to check for presence of collateral veins. The objective of this study is to evaluate the reliability of MRI in predicting both SSS involvement and presence of collateral veins in subsequent comparison to actual intra-operative findings, and to report on complications and outcomes.

METHODS

27 patients were retrospectively analyzed for this study. A blinded radiologist reviewed all pre-operative images, noting SSS status and collateral vein presence. Intraoperative findings were obtained from hospital records to similarly categorize SSS status and collateral vein presence.

RESULTS

Sensitivity of the MRI to SSS status was found to be 100% and specificity was 93%. However, sensitivity and specificity of MRI to collateral vein presence was only 40% and 78.6%, respectively. Complications were experienced by 22% of patients, the majority neurologic in nature.

CONCLUSION

MRI accurately predicted SSS occlusion status, but was less consistent in identification of collateral veins. These findings suggest MRI should be used with caution prior to PSM resection surgery particularly with regards to the presence of collateral veins which may complicate resection.

Revisiting the Role of Surgical Resection for Brain Metastasis

Brain metastasis (BM) is the most common type of brain tumor in adults. The contemporary management of BM remains challenging. Advancements in systemic cancer treatment have increased the survival of patients with cancer. Although the treatment of BM is still complicated, advances in radiotherapy, including stereotactic radiosurgery and chemotherapy, have improved treatment outcomes. Surgical resection is the traditional treatment for BM and its role in the surgical resection of BM has been well established. However, refinement of the surgical resection technique and strategy for BM is needed. Herein, we discuss the evolving role of surgery in patients with BM and the future of BM treatment.

Surgical Strategy in Modification of the Transpetrosal Approach to Avoid Postoperative Venous Complications: A Report of 74 Consecutive Cases

BACKGROUND

The transpetrosal approach is a complex skull base procedure with a high risk of complications, particularly caused by injury of the venous system. It is in part related to variability of blood outflow pathways and their distinctive patterns in each individual patient.

OBJECTIVE

To evaluate outcomes and complications after skull base surgery with use of the petrosal approach modifications, which selection was based on the detailed preoperative assessment of venous drainage patterns.

METHODS

Overall, 74 patients, who underwent surgery via the transpetrosal approach at our institution between 2000 and 2017, were included in this study. In all cases, the venous drainage pattern was assessed preoperatively and categorized according to the predominant blood outflow pathway into four types as previously suggested by Hacker: (1) sphenoparietal sinus (SpPrt), (2) sphenobasal vein (SpB), (3) sphenopetrosal sinus (SpPS), and (4) cortical. The blood outflow through the bridging petrosal vein and the vein of Labbé was also taken into consideration. In patients with SpPrt- and a cortical-type venous drainage, the transpetrosal approach was used in a standard way. In patients with SpB-type venous drainage, limited extradural anterior petrosectomy was combined with intradural anterior petrosectomy after dural opening, superior petrosal sinus transection, tentorial cutting, Meckel's cave opening, and trigeminal nerve mobilization. In patients with SpPS-type venous drainage, after standard petrosectomy, dural opening, and tentorial cutting, SpPS ligation was done followed by 2-week interval before staged definitive tumor resection.

RESULTS

Gross total, near-total, and subtotal resection of the lesion (meningioma, 48 cases; retrochiasmatic craniopharyngioma, 11 cases; brain stem cavernoma, 7 cases; other tumors, 8 cases) was achieved in 30 (40.5%), 24 (32.4%), and 20 (27.0%) patients, respectively. Postoperative complications that were possibly related to venous compromise were noted in 18 patients (24.3%), but neither one was major. Of these 18 patients, 9 were symptomatic, but all symptoms-aphasia (4 cases), seizures (2 cases), and confusion (3 cases)-fully resolved after conservative treatment. Overall, 13 patients, including 4 symptomatic, had signal changes on T2-weighted brain MRI, which were permanent only in 3 cases (all asymptomatic).

CONCLUSION

Our suggested surgical strategy can be applied to any type of the venous drainage pattern. Preoperative evaluation and intraoperative preservation of the blood outflow pathways are crucial means for safe and effective application of the transpetrosal approach.

How do I: Venous reconstruction of accidentally injured superficial sylvian vein during the clipping of an unruptured cerebral aneurysm

BACKGROUND

The transsylvian approach is a versatile treatment method for aneurysms of the anterior circulatory system. Studies have shown that sylvian veins run in various patterns, suggesting the need for dissection between veins to obtain appropriate surgical corridor. In case of inadvertent sylvian vein injury, serious complications such as venous congestion may occur.

METHOD

We herein describe the "side-to-side anastomosis reconstruction technique" of the resected superficial sylvian vein.

CONCLUSION

This technique can be effective for the reconstruction of other cortical veins, and indocyanine green videoangiography was effective in determining the indications for venous reconstruction.

Risk factors influencing cerebral venous infarction after meningioma resection

BACKGROUND

Cerebral venous infarction (CVI) is a serious complication after meningioma resection. The risk factors of postoperative cerebral venous infarction after surgical resection of meningioma can be determined through large samples and this study can add evidence to the literature.

METHODS

The clinical and imaging data of 1127 patients with intracranial meningiomas who underwent resection in our hospital were retrospectively collected and analyzed. CVI was evaluated by postoperative imaging and clinical manifestations. Univariate and multivariate analyses were performed to identify risk factors associated with CVI.

RESULTS

Overall, 4.7% (53/1127) of patients experienced CVI after meningioma resection. Multivariate analysis revealed superficial meningioma, moderate to severe peritumoral edema, peritumoral critical vein and WHO grade II-III as independent predictors of a postoperative CVI. After timely intervention, the symptoms were clearly alleviated in one month, and the prognosis was good, but injury to key veins could cause irreversible neurological disorders.

CONCLUSIONS

Intraoperative protection of veins is the primary way to prevent CVI. The present study identified several significant and independent risk factors for postoperative venous infarction, thereby enabling the identification of high-risk patients who require special attention during clinical and surgical management.

Intraoperative risk factors for peritumoral infarctions following glioma surgery

Background

Surgical intraoperative risk factors for peritumoral infarctions are not much studied. In the present study, we explore the possible association between intraoperative factors and infarctions diagnosed from early postoperative MRIs.

Methods

We screened all adult patients operated for newly diagnosed or recurrent diffuse gliomas at out department from December 2015 to October 2020 with available postoperative MRI including DWI sequences. Patient data was prospectively collected in a local tumor registry. Immediately after surgery, the surgeon completed a questionnaire on tumor vascularization, tumor stiffness, delineation of tumor from normal brain tissue, which surgical tool(s) were used, and if they had sacrificed a functional artery or a significant vein.

Results

Data from 175 operations were included for analysis. Of these, 66 cases (38%) had postoperative peritumoral infarctions. 24 (36%) were rim-shaped and 42 (64%) infarctions were sector-shaped. The median infarction volume was 2.4 ​cm³. Surgeon reported sacrifice of a significant vein was associated with infarctions, but we found no clear “dose-response”, as “perhaps” was associated with fewer infarctions than “no”. None of the other studied factors reached statistical significance. However, there was a trend for more infarctions when an ultrasonic aspirator was used for tumor resection. Subgroup analyses were done for rim-shaped and sector-shaped infarctions, and ultrasonic aspirator was associated with sector-shaped infarctions (p ​= ​0.032). Infarction rates differed across surgeons (range 15%–67%), p ​= ​0.021).

Conclusion

In this single center study, no clear relationships between surgeon reported intraoperative factors and postoperative infarctions were observed. Still, risks seem to be surgeon dependent.

•

Data on intraoperative factors from 175 operations for diffuse gliomas were assessed.

•

No clear relationships between surgeon reported intraoperative factors and postoperative infarctions were observed.

•

Risks of infarctions seems to be surgeon dependent.

Interhemispheric Precuneus Retrosplenial Transfalcine Approach for Falcotentorial Meningiomas: Anatomic Study and Clinical Series

BACKGROUND

Falcotentorial meningiomas are surgically challenging. Currently accepted approaches include occipital interhemispheric and supracerebellar infratentorial approaches, which have documented drawbacks.

OBJECTIVE

To propose an alternative approach to the posterior tentorial incisural space, the interhemispheric precuneus retrosplenial transfalcine approach (IPRTA).

METHODS

A total of 6 colored-silicone-injected adult cadaveric heads were dissected. We measured the interval between bridging veins and studied computed tomography venography scans of 20 subjects to confirm the feasibility of the IPRTA. Bony landmarks, the region's bridging veins, and the anterior and posterior borders of the approach were identified. The surgical corridor widths (veins' interval) and lengths were compared between alternative midline approaches. We also reviewed 4 consecutive clinical cases using this approach.

RESULTS

The IPRTA provides the shortest distance to the anterior and posterior limits of the posterior tentorial incisura. Moreover, it is the only approach that provides direct visualization of the anterior and posterior limits of falcotentorial junction meningiomas. In all specimens and patients, a minimum 30-mm interval between the anterior and posterior parietal veins was found in at least one of the hemispheres. Tumor removal was successful in all 4 patients but resulted in mild paresthesia in the lower extremities of 2 patients and temporary foot drop in 1 patient.

CONCLUSION

The IPRTA offers the shortest and most direct corridor for falcotentorial meningiomas and provides excellent visualization of most of the critical structures in the region. Detailed preoperative evaluation of the deep and superficial venous structures is recommended.

Intraoperative utilization of Microvascular Doppler for the detection of intracranial venous structures during tumor resection - A technical note

BACKGROUND

Microvascular Doppler (MVD) has been widely used for the detection of arterial blood flow in the brain, especially during aneurysm clipping, vascular malformation resection, or bypass surgeries. However, the benefits obtained from early identification of intracranial sinuses and deep draining veins during tumor resection has not been reported.

METHODS

We reviewed the clinical data and imaging from our cases and conducted a systemic review of the medical literature using PubMed and keywords. Bibliographies of each result were evaluated to determine if additional reports describing the use of MVD during tumor resection could be found.

RESULTS

No reports were found in the literature where MVD was specifically used for venous identification during the resection of deep-seated brain tumors. In our patient cohort, MVD was used successfully to detect and ultimately allow immediate protection of large dural venous sinuses as well as smaller deep cerebral veins during tumor resection. Each patient developed no new venous infarcts and made a satisfactory recovery with no new postoperative neurological deficits.

CONCLUSION

MVD is a reliable tool for the intraoperative detection of intracranial venous blood flow to allow for quick identification and protection of venous structures. MVD is an additional safety measure for the patient as its accuracy in detecting venous structures is less susceptible to many of the inherent weaknesses of stereotactic neuro-navigation including the accompanying brain shift or anatomical distortion produced by long duration deep seated brain tumor resection.

Classification of Peritumoral Veins in Convexity and Parasagittal Meningiomas and Its Significance in Preventing Cerebral Venous Infarction

OBJECTIVE

The medium (2-4 cm) convexity located closer to the sinus and parasagittal meningiomas (Sindou type I-Ⅲ) without obvious invasion of the superior sagittal sinus are considered simple to operate on. However, the tumors are often accompanied by the cortical bridging vein. Because of lack of collateral vein circulation in cortical areas, the damage of peritumoral veins will subsequently lead to venous infarction. To avoid the serious complications caused by intraoperative injury of peritumoral veins, it is necessary to define the classification of the progression of peritumoral veins and tumors to guide surgical safety.

METHODS

The clinical information of 57 patients with convexity and parasagittal meningiomas was collected and retrospectively analyzed. All patients underwent preoperative magnetic resonance imaging and magnetic resonance venography scanning to observe the imaging characteristics of peritumoral veins and preoperative evaluation. The actual relationship between the tumor and peritumoral vein was observed intraoperatively. Postoperative computed tomography and magnetic resonance imaging were used to determine tumor resection and the presence of venous infarction.

RESULTS

According to preoperative magnetic resonance venography and intraoperative findings, we divided the peritumoral veins into 3 types: type A (n = 33, 57.9%), the vein surrounds the tumor; type B (n = 15, 26.3%), the vein is located on the ventral side of the tumor; and type C (n = 9, 15.8%), the vein is located on the dorsal side of the tumor. Peritumoral vein injury occurred in 6 cases followed by serious complications. Treatments were as follows: 4 cases underwent decompression and 2 cases were treated conservatively. The prognosis Glasgow Outcome Scale (GOS) scores were as follows: 3 cases were score 5 for injury of posterior frontal vein or middle frontal vein, 2 cases were score 3 for injury of the central vein, 1 case was score 1 for death due to injury of the central vein. All cases were followed up for 6 months.

CONCLUSIONS

Attention should be paid to the peritumoral vein of special meningiomas. Injured vein in the medial third of superior sagittal sinus carries a high rate of postoperative morbidity. Understanding the type of peritumoral veins preoperatively can be used as a guide in determining the corresponding protective strategy during surgery, which can significantly decrease postoperative disability and improve quality of life.

Case report of hyperacute edema and cavitation following deep brain stimulation lead implantation

Background:

Postoperative cerebral edema around a deep brain stimulation (DBS) electrode is an uncommonly reported complication of DBS surgery. The etiology of this remains unknown, and the presentation is highly variable; however, the patients generally report a good outcome.

Case Description:

Here, we report an unusual presentation of postoperative edema in a 66-year-old female who has bilateral dentatorubrothalamic tract (specifically, the ventral intermediate nucleus) DBS for a mixed type tremor disorder. Initial postoperative computed tomography (CT) was unremarkable and the patient was admitted for observation. She declined later on postoperative day (POD) 1 and became lethargic. Stat head CT scan performed revealed marked left-sided peri-lead edema extending into the centrum semiovale with cystic cavitation, and trace right-sided edema. On POD 2, the patient was alert, but with global aphasia, right-sided neglect, and a plegic right upper extremity. Corticosteroids were started and a complete infectious workup was unremarkable. She was intubated and ultimately required a tracheostomy and percutaneous gastrostomy tube. She returned to the clinic 3 months postoperatively completely recovered and ready for battery implantation.

Conclusion:

While this is an unusual presentation of cerebral edema following DBS placement, ultimately, the outcome was good similar to other reported cases. Supportive care and corticosteroids remain the treatment of choice for this phenomenon.

Postoperative Unilateral Internal Cerebral Vein Thrombosis with Venous Watershed Infarcts: Case Report and Review of the Literature

BACKGROUND

Cerebral venous complications related to neurosurgical interventions are only rarely reported in the literature. Internal cerebral veins (ICVs) are vulnerable to injury during neurosurgical approaches to the pineal and thalamic regions. The occurrence of unilateral postoperative ICV thrombosis in children is extremely rare, with only 2 such cases reported thus far.

CASE DESCRIPTION

A 15-year-old child presented to the emergency department with headache, persistent vomiting, and pronounced lethargy for 3 days. Magnetic resonance imaging of the brain was performed and showed a large solid-cystic mass at the pineal region, resulting in upstream hydrocephalus. Serum beta-human chorionic gonadotropin was elevated, and a diagnosis of germ cell tumor was made. Patient was started on neoadjuvant chemotherapy, with partial response on repeat imaging after 3 courses of chemotherapy. Decision was made to proceed with surgical resection of the residual tumor. Magnetic resonance imaging of the brain performed on postoperative day 1 showed multiple foci of restricted diffusion in the right cerebral deep white matter, giving rise to a "string of pearls" appearance. There is also absence of enhancement of the right ICV, suspicious for deep cerebral venous thrombosis. This was confirmed on subsequent computed tomography venogram.

CONCLUSIONS

Our reported case adds to the limited literature on postoperative ICV thrombosis in children and describes a unique imaging phenotype of venous watershed infarcts. Neurosurgeons and neuroradiologists should be aware of this unique imaging phenotype and have a high index of suspicion for deep cerebral venous thrombosis, especially in patients with prior neurosurgical intervention in the pineal or thalamic regions.

Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression

Background

We investigated the understudied anatomical variations of the superior petrosal vein (SPV) complex (SPVC), which may play some role in dictating the individual complication risk following SPVC injury.

Methods

Microvascular decompressions of the trigeminal nerve between September 2012 and July 2016. All operations utilized an SPVC preserving technique. Preoperative balanced fast field echo (bFFE) magnetic resonance imaging, or equivalent sequences, and operative videos were studied for individual SPVC anatomical features.

Results

Applied imaging and operative SPVC anatomy were described for fifty patients (mean age, 67.18 years; female sex and right-sided operations, 58% each). An SPVC component was sacrificed intentionally in 6 and unintentionally in only 7 cases. Twenty-nine different individual variations were observed; 80% of SPVCs had either 2 SPVs with 3 or 1 SPV with 2, 3, or 4 direct tributaries. Most SPVCs had 1 SPV (64%) and 2 SPVs (32%). The SPV drainage point into the superior petrosal sinus was predominantly between the internal auditory meatus and Meckel cave (85.7% of cases). The vein of the cerebellopontine fissure was the most frequent direct tributary (86%), followed by the pontotrigeminal vein in 80% of SPVCs. Petrosal-galenic anastomosis was detected in at least 38% of cases. At least 1 SPV in 54% of the cases and at least 1 direct tributary in 90% disturbed the operative field. The tributaries were more commonly sacrificed.

Conclusions

The extensive anatomical variation of SPVC is depicted. Most SPVCs fall into 4 common general configurations and can usually be preserved. BFFE or equivalent sequences remarkably facilitated the intraoperative understanding of the individual SPVC in most cases.

Planning of Endocranial Supratentorial Basal Cistern and Skull Base Approaches Depending on Venous Patterns Using a Topogram

BACKGROUND

Because damage or sacrifice of venous drainage during supratentorial basal cistern and skull base approaches may have severe and harmful consequences, methods to identify preoperatively veins at risk are of paramount importance. Among methods, a codified assessment with a venous topogram is helpful, with practical implications.

METHODS

This technical note describes how to construct an easy-to-use topogram. Three regions of interest are defined as triangles. The anterior triangle corresponds to the anterior frontal veins draining to the superior sagittal sinus at risk during anterior cerebral fossa surgery, the middle triangle corresponds to the anterior sylvian veins draining to the cavernous sinus at risk during pterional approaches, and the inferior triangle corresponds to the inferior cerebral veins draining to the transverse sinus at risk in subtemporal approaches and temporal lobe surgery.

RESULTS

Depending on predominance of the drainage, 4 situations were defined: an anterior, an inferior, and a middle predominance or equilibrium between the 3 triangles. These anatomic features have important practical implications in skull base and basal cistern approaches.

CONCLUSIONS

This is, to our knowledge, the only topogram described in the scientific literature. Any well-defined approach should be adapted to the individual patient according not only to location and type of lesion but also to the venous drainage to be encountered along the way.

Use of ICG videoangiography and FLOW 800 analysis to identify the patient-specific venous circulation and predict the effect of venous sacrifice: a retrospective study of 172 patients

OBJECTIVE The best management of veins encountered during the neurosurgical approach is still a matter of debate. Even if venous sacrifice were to lead to devastating consequences, under certain circumstances, it might prove to be desirable, enlarging the surgical field or increasing the extent of resection in tumor surgery. In this study, the authors present a large series of patients with vascular or oncological entities, in which they used indocyanine green videoangiography (ICG-VA) with FLOW 800 analysis to study the patient-specific venous flow characteristics and the management workflow in cases in which a venous sacrifice was necessary. METHODS Between May 2011 and December 2017, 1972 patients were admitted to the authors' division for tumor and/or neurovascular surgery. They retrospectively reviewed all cases in which ICG-VA and FLOW 800 were used intraoperatively with a specific target in the venous angiographic phase or for the management of venous sacrifice, and whose surgical videos and FLOW 800 analysis were available. RESULTS A total of 296 ICG-VA and FLOW 800 studies were performed intraoperatively. In all cases, the venous structures were clearly identifiable and were described according to the flow direction and speed. The authors therefore defined different patterns of presentation: arterialized veins, thrombosed veins, fast-draining veins with anterograde flow, slow-draining veins with anterograde flow, and slow-draining veins with retrograde flow. In 16 cases we also performed a temporary clipping test to predict the effect of the venous sacrifice by the identification of potential collateral circulation. CONCLUSIONS ICG-VA and FLOW 800 analysis can provide complete and real-time intraoperative information regarding patient-specific venous drainage pattern and can guide the decision-making process regarding venous sacrifice, with a possible impact on reduction of surgical complications.

Insufficient cerebral venous drainage predicts early edema in acute intracerebral hemorrhage

OBJECTIVES

To explore the relationship between insufficient ipsilateral cerebral venous drainage and the development of perihematomal edema (PHE) and functional outcome in patients with acute intracerebral hemorrhage (ICH).

METHODS

We retrospectively reviewed our prospectively collected database for patients with acute spontaneous supratentorial ICH and analyzed patients who underwent baseline CT perfusion (CTP) within 6 hours of onset and noncontrast CT at 24 hours. Absence of filling of 1 or more of the ipsilateral superficial middle cerebral vein, vein of Trolard, vein of Labbé, basal vein of Rosenthal, and internal cerebral vein, evaluated on venous maps generated from baseline CTP, was identified as absent ipsilateral venous filling (AIVF). Relative PHE (rPHE) was calculated as the ratio of PHE volume to hematoma volume on follow-up CT.

RESULTS

A total of 138 patients were included. Median absolute PHE volume on follow-up CT was 3.5 (1.0-9.3) mL and rPHE was 24.3% (9.0%-49.4%). One absent ipsilateral vein was observed in 38 (27.5%) patients, and 2 absent veins were observed in 5 (3.6%) patients. Multivariate analysis showed that AIVF was independently associated with large rPHE at 24 hours (odds ratio [OR] 4.032, 95% confidence interval [CI] 1.739-9.347, p < 0.001). Large PHE volume was independently associated with poor outcome (OR 1.109, 95% CI 1.009-1.218, p = 0.031).

CONCLUSION

AIVF was observed in about one-third of patients with acute ICH, which might be attributed to hypoperfusion after ICH and was strongly related to the development of PHE. Identification of cerebral venous filling status might be a promising imaging marker for PHE and a potential therapeutic target in ICH.

A novel protocol for three-dimensional rotational venography with low-dose contrast media in preoperative angiography of brain tumours

AIM

The most appropriate imaging protocol for three-dimensional rotational venography (3D RV) has not been established. The aim of this study was to optimise the protocol for 3D RV with low-dose contrast media using time-density curve analysis.

METHODS

Twenty-five consecutive patients with brain tumours who received preoperative assessment with 3D RV were retrospectively collected and included in this study. To optimise the imaging delay time of 3D RV with low-dose contrast media, time-density curve analysis was performed on two-dimensional conventional angiography. The image quality for depicting cortical veins and venous sinuses was compared to that of magnetic resonance (MR) venography in five cases.

RESULTS

A total of 27 3D RVs were performed in 25 patients. The time-density curves of cortical veins were different from those of cerebral arteries or sinuses. The mean time to peak of cortical veins was significantly longer than the time to peak of cerebral arteries (2.47 ± 0.35 seconds vs. 6.44 ± 1.14 seconds; p < 0.0001) and shorter than the time to peak of venous sinuses (6.44 ± 1.14 seconds vs. 8.18 ± 1.12 seconds; p < 0.0001). The optimal imaging delay time could be determined as the phases in which cortical arterial opacities disappeared and cortical veins started to appear. The mean dose of injected contrast media was 5.3 mL. The image quality of cortical veins in 3D RV was superior to that in MR venography in all cases.

CONCLUSIONS

Three-dimensional RV with low-dose contrast media was useful for the preoperative assessment of cortical veins in patients with brain tumours.

Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach

BACKGROUND

The bridging vein (BV) and the tentorial sinus (TenS) are important venous structures in neurological surgery. These venous structures during the anterior transpetrosal approach (ATPA) have not been reported. The objective of this study is to examine the BV and the TenS in the subtemporal corridor during the ATPA and propose a technique to identify the BV preoperatively.

METHODS

This study included 126 patients treated via the ATPA. The BV and the TenS located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius).

RESULTS

Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003).

CONCLUSIONS

We showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, we found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively.

Veins of the Cerebellopontine Angle and Specific Complications of Sacrifice, with Special Emphasis on Microvascular Decompression Surgery. A Review

Good knowledge of the anatomy of veins is of crucial importance for the functional surgery of cranial nerve (CN) disorders, especially microvascular decompression for trigeminal neuralgia (TN), hemifacial spasm (HFS), and vagoglossopharyngeal neuralgia (VGPN). Although controversial, veins may be involved in neurovascular conflicts and may constitute dangerous obstacles to access to the CNs. With the aim of estimating the implications of veins in those diseases and evaluating the linked surgical difficulties, we carried out a review of the literature from 2000 to the end of February 2018. For this review, articles found on PubMed that gave enough precision about veins were retained (39 articles on TN, 38 on HFS, 8 on VGPN, and 26 on complications related to venous sacrifices). Before this review, we described a simplified anatomic classification of veins, amenable to easing the surgical approach to CNs. Access to the trigeminal nerve, via the infratentorial-supracerebellar route, is almost always affected by the superficial superior petrosal venous system, whereas access to the facial and cochleovestibular complex as well as to the lower CNs, through the infrafloccular trajectory, is almost always exempt of important venous obstacles. Respective incidences of venous compression at the origin of hyperactive CN syndromes are given. The percentages of a venous conflict alone were calculated at 10.8% for TN, 0.1% for HFS, and 2.9% for VGPN. We review the complications considered in relation with venous sacrifices. Precautions to minimize these complications are given.

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.

Anatomic comparison of veins of Labbé between autopsy, digital subtraction angiography and computed tomographic venography

Objective

The drainage portion of the vein of Labbé varies, and it is difficult to predict whether the operation is likely to damage this vein. The aim of this study was to correlate the microanatomy of the vein of Labbé with digital subtraction angiography (DSA) and computed tomographic venography (CTV), in order to provide a basis for the preservation of the vein of Labbé during a supratentorial surgical approach.

Methods

A total of 30 human cadavers (60 sides) and 61 living patients (110 sides) were examined in this study. Each cadaver head was injected with blue latex via the superior sagittal sinus and the internal jugular veins. The venograms of each patient were obtained from the venous phases of DSA (60 sides for 36 patients) or CTV (50 sides for 25 patients).

Results

The patients were divided into four subgroups based on the location where a vein entered the dural sinus: the transverse sinus group, the tentorial group, the petrosal group, and the upper-transverse sinus group. The veins of Labbé in transverse sinus group and petrosal group directly entered dural sinus. The veins of Labbé in tentorial group and upper-transverse sinus group indirectly entered transverse sinus via the tentorium sinus or the upper-transverse sinus. These sinuses were meningeal veins running through two layers of the cerebral dura mater. The length of meningeal veins in these groups was 10.0 ± 7.2 mm. The veins of Labbé were mainly localized around the STP junction, which was the confluence of sigmoid sinus, transverse sinus, and superior petrosal sinus. The distance between the dural entrance of veins and the STP junction was 16.8 ± 10.2 mm. There was no significant difference in the results of the DSA and CTV examinations when compared to the observations in cadavers.

Conclusions

Preoperative venograms are useful to design an individualized surgical approach for the preservation of the vein of Labbé. In general, the supratentorial median approach has the least chance to damage this vein. However, when preoperative venograms show that the vein of Labbé is too close to the confluence of sinuses or the meningeal veins are too long, an alternative approach should be chosen.

Effect of Fibrin Glue Injection Into the Cavernous Sinus for Hemostasis During Transcavernous Surgery on the Cerebral Venous Draining System

BACKGROUND: The extradural temporopolar transcavernous approach can be used to treat central skull base pathologies, but control of bleeding from the opened cavernous sinus is essential. Oxidized cellulose cotton packing and fibrin glue injection can be used, but the effect on the postoperative venous draining pattern remains unclear.

OBJECTIVE: To investigate changes in the venous drainage pattern immediately after transcavernous surgery with and without fibrin glue injection into the bleeding cavernous sinus.

METHODS: A total of 82 patients treated via the transcavernous approach were retrospectively divided into 2 groups based on the hemostasis methods. Both pre- and postoperative angiography and/or 3-dimensional computed tomography venography were available for 24 patients in the cotton packing group and 12 patients in the fibrin glue group.

RESULTS: Postoperative change in the venous draining pattern was observed in 5 of the 24 patients in the cotton packing group and in 3 of the 12 patients in the fibrin glue group. One of the 82 patients showed postoperative brain swelling due to obstruction of the sphenoparietal sinus. The volume of injected fibrin glue ranged from 0.5 to 2.5 mL (mean, 1.1 ± 0.5 mL), but none of the patients had brain swelling.

CONCLUSION: Direct fibrin glue injection into the opened cavernous sinus is relatively safe, but a change in the venous draining pattern occurs in 25% of patients. The study indicates the potential danger of the change in the venous draining pattern and recommends limiting the injection volume of fibrin glue in transcavernous surgery to avoid complications related to venous congestion.

Absent Filling of Ipsilateral Superficial Middle Cerebral Vein Is Associated With Poor Outcome After Reperfusion Therapy

BACKGROUND AND PURPOSE

Our aim was to study the effect of drainage of cortical veins, including the superficial middle cerebral vein (SMCV), vein of Trolard, and vein of Labbé on neurological outcomes after reperfusion therapy.

METHODS

Consecutive ischemic stroke patients who underwent pretreatment computed tomographic perfusion and 24-hour computed tomographic perfusion or magnetic resonance perfusion after intravenous thrombolysis were included. We defined "absent filling of ipsilateral cortical vein" (eg, SMCV-) as no contrast filling of the vein across the whole venous phase on 4-dimensional computed tomographic angiography in the ischemic hemisphere.

RESULTS

Of 228 patients, SMCV-, vein of Trolard- and vein of Labbé- were observed in 50 (21.9%), 27 (11.8%), and 32 (14.0%) patients, respectively. Only SMCV- independently predicted poor outcome (3-month modified Rankin Scale score of >2; odds ratio, 2.710; P=0.040). No difference was found in reperfusion rate after treatment between patients with and without SMCV- (P>0.05). In patients achieving major reperfusion (≥80%), there was no difference in 24-hour infarct volume, or rate of poor outcome between patients with and without SMCV- (P>0.05). However, in those without major reperfusion, patients with SMCV- had larger 24-hour infarct volume (P=0.011), higher rate of poor outcome (P=0.012), and death (P=0.032) compared with those with SMCV filling. SMCV- was significantly associated with brain edema at 24 hours (P=0.037), which, in turn, was associated with poor 3-month outcome (P=0.002).

CONCLUSIONS

Lack of SMCV filling contributed to poor outcome after thrombolysis, especially when reperfusion was not achieved. The main deleterious effect of poor venous filling appears related to the development of brain edema.

Acute and Subacute Presentations of Cerebral Edema following Deep Brain Stimulation Lead Implantation

BACKGROUND/AIMS

Postoperative cerebral edema around a deep brain stimulation (DBS) electrode is an uncommon reported complication. The goal of this study was to identify instances of postoperative edema based on clinical presentation, and to remark on their management.

METHODS

A retrospective chart review was performed on all patients who underwent DBS electrode implantation over a 3-year period. Routine CT imaging on postoperative day (POD) 1 was negative. Patients were identified based on clinical neurological changes, leading to imaging and subsequent diagnosis.

RESULTS

Five of 145 patients (3.4%) presented with new neurological symptoms from POD 1 to 14, which were confirmed by CT imaging to show perilead and/or subcortical edema around 6 of 281 electrodes (2.1%). Four of 5 patients had unilateral edema despite bilateral implantation. Clinical presentations varied widely. Two patients presenting on POD 1 with deteriorating conditions required longer inpatient stays with supportive measures than those presenting later (p = 0.0002). All patients were treated with corticosteroids and returned to baseline by 3 months after surgery.

CONCLUSIONS

Acute instances of DBS lead edema may occur as early as POD 1 and can rapidly progress into profound deficits. Treatment with supportive care and corticosteroids is otherwise identical to those cases presenting later.

Frontotemporal epi- and subdural approach to a cavernous sinus tumor for sphenobasal vein preservation--technical case report

In cavernous sinus (CS) surgery, venous complication may occur in some types of venous drainage. The sphenobasal vein (SBV) drains from the superficial middle cerebral vein (SMCV) to the pterygoid venous plexus at the temporal skull base. A frontotemporal epi- and interdural approach (Dolenc approach), which is one of the CS approaches, may damage the SBV's route. We report a case of intracavernous trigeminal schwannoma that contained the SBV and discuss our modified surgical procedure that combined epi- and subdural approaches to preserve the SBV. A 64-year-old man complained of right progressive oculomotor palsy and was referred to our hospital for surgery. MR images revealed a hemorrhagic tumor in the right CS. Three-dimensional venography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. After identifying the first branch of the trigeminal nerve epidurally, we incised the dura linearly along the sylvian fissure and entered the subdural space to visualize the SBV. The incision was continued to the meningeal dura of the lateral wall of the CS along the superior margin of the first branch of the trigeminal nerve, and the Parkinson's triangle was opened from the subdural side. The tumor was grossly totally removed, and the SBV was preserved. In conclusion, a frontotemporal epi- and subdural approach to the intracavernous trigeminal schwannoma can effectively preserve the SBV.

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.

Postoperative cerebral venous infarction

Background:

Postoperative cerebral venous infarction (POCVI) is not an uncommon complication in cranial surgeries. However, literature is sparse on the epidemiology and management of postoperative venous infarcts.

Aims and Objectives:

The aim was to study the incidence and clinico-radiological course of POCVI in patients in a tertiary level neurosurgical unit and compare the outcome between pediatric and adult patients following POCVI.

Materials and Methods:

In this prospective study carried out over an 8 month period, consecutive patients undergoing elective major cranial surgeries were monitored neurologically and with serial computed tomography (CT) of the head for POCVI in the postoperative period. All patients had at least one CT head done within 24 hours of surgery. Diagnosis of hemorrhagic POCVI was based on the presence of subcortical, multifocal hyperdensities with irregular margins and or low density areas in the perioperative fields. Nonhemorrhagic POCVI was diagnosed if CT showed a localized hypodensity poorly demarcated in the subcortical white matter with/without mass effect, along with the presence of fresh neurological deficits.

Observations and Results:

A total of 376 patients were enrolled in the study period. Of these, 26 (7%) developed POCVI. The male: female ratio was 1.2:1 and age ranged from 6 to 68 years with 12 (46%) being under the age of 18 years. Sixteen (61%) patients developed hemorrhagic POCVI and 10 (39%) patients developed nonhemorrhagic POCVI. The mean time to POCVI detection was 72 hours (range 24–144 hours). Seventeen (66%) patients were managed conservatively, and nine (34%) patients underwent decompressive craniectomy as an additional procedure for management of POCVI. In five patients (all with hemorrhagic POCVI), the infarction was an incidental finding. Of the 21 patients with symptomatic POCVI, 13 (61.9%) patients improved neurologically and were discharged with residual deficits. Two (9.5%) showed no neurological improvement till discharge, and 6 (28.5%) died during the hospital stay following POCVI.

Conclusions:

Children constitute a significant population (46% in our study) of the patients who develop POCVI with poor outcome similar to that seen in adult patients.

Absence of the superior petrosal veins and sinus: Surgical considerations

Background:

The superior petrosal vein, one of the most constant and largest drainage pathways in the posterior fossa, may result in complications if occluded. This study calls attention to a unique variant in which the superior petrosal veins and sinus were absent unilaterally, and the venous drainage was through the galenic and tentorial drainage groups.

Methods:

This study examines one venogram and another anatomic specimen in which the superior petrosal vein and sinus were absent.

Results:

The superior petrosal veins, described as 1–3 bridging veins, emptying into the superior petrosal sinus, are the major drainage pathways of the petrosal group of posterior fossa veins. In the cases presented, the superior petrosal vein and sinus were absent and venous drainage was through the galenic and tentorial groups, including the lateral mesencephalic or bridging vein on the tentorial cerebellar surface.

Conclusions:

In cases in which the superior petrosal sinus and veins are absent, care should be directed to preserving the collateral drainage through the galenic and tentorial tributaries. Although surgical strategies for intraoperative management and preservation of venous structures are still controversial, knowledge of the possible anatomical variations is considered to be essential to improve surgical outcomes.

Classification of the superior petrosal veins and sinus based on drainage pattern

BACKGROUND

The increasing number of reports of complications after sacrificing the superior petrosal veins, the largest veins in the posterior fossa, has led to a need for an increased understanding of the anatomy of these veins and the superior petrosal sinus into which they empty.

OBJECTIVE

To examine the anatomy of the superior petrosal veins and their size, draining area, and tributaries, as well as the anatomic variations of the superior petrosal sinus.

METHOD

Injected cadaveric cerebellopontine angles and 3-dimensional multifusion angiography images were examined.

RESULTS

The 4 groups of the superior petrosal veins based on their tributaries, course, and draining areas are the petrosal, posterior mesencephalic, anterior pontomesencephalic, and tentorial groups. The largest group was the petrosal group. Its largest tributary, the vein of the cerebellopontine fissure, was usually identifiable in the suprafloccular cistern located above the flocculus on the lateral surface of the middle cerebellar peduncle. The medial or lateral segment of the superior petrosal sinus was absent in 40% of cerebellopontine angles studied with venography.

CONCLUSION

The superior petrosal veins and their largest tributaries, especially the vein of the cerebellopontine fissure, should be preserved if possible. Obliteration of superior petrosal sinuses in which either the lateral or medial portion is absent may result in loss of the drainage pathway of the superior petrosal veins. Preoperative assessment of the superior petrosal sinus should be considered before transpetrosal surgery in which the superior petrosal sinus may be obliterated.

Anatomy of the superior petrosal veins and their exposure and management during petrous apex meningioma surgery using the lateral suboccipital retrosigmoid approach

During surgeries in the upper cerebellopontine angle (CPA), the superior petrosal veins (SPVs) often act as obstacles; and their sectioning sometimes causes serious complications. In this study, we introduced a classification system for the SPVs wherein their tributaries were classified into four groups on the basis of their courses and draining areas. We furthermore explained the detailed anatomy of the vein of the cerebellopontine fissure, which is the largest tributary. In surgeries of petrous apex meningioma, the knowledge of the displacement pattern of the vein is very helpful for avoiding major venous complications. Therefore, we elucidated its anatomical situation in relation to the original portion of the meningioma and the natural draining point of the vein into the superior petrosal sinus (SPS) in each patient. In addition, we described the methods and techniques used to expose and manage the vein of the cerebellopontine fissure during surgery using the lateral suboccipital retrosigmoid approach. Presenting two illustrative cases, we recommend that the initial exposure of the tumor should be performed through the infratentorial lateral supracerebellar route and that the suprafloccular cistern is the best area to find the vein of the cerebellopontine fissure. We emphasized the importance of the preservation of the vein of the cerebellopontine fissure and also proposed the order for exposure of SPV tributaries during upper CPA surgery using the retrosigmoid approach.

Staged 'intentional' bridging vein ligation: a safe strategy in gaining wide access to skull base tumors

BACKGROUND

The venous drainage of the temporal lobe, through bridging veins to the middle cranial fossa, is pivotal in determining the surgical corridor for skull base lesions. In dealing with select cases, where venous drainage was an obstacle in the surgical approach, we hypothesized that staged 'intentional' ligation of the dominant pathway of venous drainage would provide a safer and wider access to skull base tumors. We study the indications and safety of this surgical strategy in the management of skull base lesions.

MATERIALS AND METHODS

From 1995 to 2012, 318 patients with skull base tumors were treated at our institute by the fronto-orbito-zygomatic (FOZ) or transpetrosal approaches, eight of whom we planned for staged 'intentional' bridging vein ligation. Seven patients underwent planned ligation of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage, followed by definitive surgery through the desired skull base approach, in the second stage, while in one patient the strategy was abandoned. These patients were evaluated with respect to their clinical presentation, pre- and post-operative radiology including venogram, intra-operative findings and post-operative course.

RESULTS

Seven patients, four males and three females, with ages ranging from 16 to 63 years, underwent staged 'intentional' bridging vein ligation. The diagnoses were recurrent craniopharyngioma in four, and petroclival meningioma, sphenopetroclival meningioma and spheno-orbital meningioma in one each. Six of these lesions were approached from the dominant (left) side, while one lesion was on the right side. Venograms done after the first-stage procedure showed obliteration of the dominant venous drainage with opening up of anastomotic venous channels in all patients. All patients tolerated the first-stage procedure well; only one patient showed asymptomatic mild temporal lobe edema on MRI, which resolved in 3 weeks. None of the patients had venous complications after definitive surgery. One patient with recurrent chordoma, who was planned for staged ligation, did not undergo ligation as, intra-operatively, the draining channel turned out to be a cortical vein, which could be mobilized without ligation.

CONCLUSION

In an attempt to detether the temporal lobe, the disconnection of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage may lead to re-direction of the venous outflow over time. This may allow skull base surgeons a better surgical corridor and ensure safety of venous structures during the definitive surgery.

Comparison of anticoagulation and thrombolysis treatments in a rat model of superior sagittal sinus thrombosis

Superior sagittal sinus thrombosis (SSST) is a form of cerebral venous sinus thrombosis (CVST) routinely treated with anticoagulation therapy. Anticoagulation and thrombolysis treatment effects on neurological function, venous recanalization and brain edema were compared after SSST in rats. Male Sprague-Dawley rats underwent non-fatal SSST induction and were divided into no treatment (control), anticoagulation (heparin), carotid artery thrombolysis and local thrombolysis groups (each n = 50). Within each group, an equal number of rats (n = 10) were treated with anticoagulation and thrombolysis at day 3 or weeks 1, 2, 3 or 4 following SSST. Magnetic resonance venography (MRV) was conducted within 24 h of anticoagulation and thrombolysis treatments to determine recanalization, structural abnormalities and cerebral edema quantitated by wet-dry methods. Neurological function (Rotarod test) and histological abnormalities were compared. Severe brain edema, flattened gyri and coronal swelling were observed following SSST. Recanalization rates in carotid artery and local thrombolysis were higher than in anticoagulation (both p < 0.001). Carotid artery and local thrombolysis brain water contents were 79.6±0.1% and 79.2±0.1%, respectively, significantly lower than 83.9±0.1% and 84±0.1% in anticoagulation and controls, respectively (all p < 0.05), after treatments at day 3 following SSST. Increasing SSST onset to treatment time worsened neurological function ( p < 0.05). Maximum treatment benefits were observed <2 weeks post-SSST using local thrombolysis and, to a lesser extent, carotid artery thrombolysis. Thrombolysis may produce better functional outcomes if employed early rather than as a second-line treatment following anticoagulant failure.

Pontine extension of a tentorial schwannoma without cranial nerve involvement: a case report

Introduction

Intracranial schwannomas unrelated to the cranial nerves are uncommon. We report a new case of tentorial schwannoma unrelated to the cranial nerves, with extension into the pons. A literature review with discussion of the most relevant pathogenetic aspects is also performed.

Case presentation

A 42-year-old Caucasian man was admitted with right-sided paresthesias and weakness of his upper and lower extremities. The neurological examination revealed right hemiparesis and hemi-hypoesthesia. A brain magnetic resonance imaging scan revealed a cerebellopontine lesion, arising from the left free edge of the tentorium, and extending into his pons. A piecemeal removal was performed through a retrosigmoid approach. The lesion was not found to be associated with any cranial nerves. The histological examination revealed a schwannoma Antoni type A. His postoperative course was uneventful. At one year follow-up, the patient was neurologically intact and the magnetic resonance imaging of his brain performed at that time showed complete removal without signs of recurrence.

Conclusion

Tentorial schwannomas are rare clinical entities. Knowledge of their clinical, radiological and anatomical characteristics is very important for the correct diagnosis and management.

The posterior subtemporal keyhole approach combined with the transchoroidal approach to the ambient cistern: microsurgical anatomy and image-guided quantitative analysis

PURPOSE

The aim of this study is to describe microsurgical anatomy and to quantitatively analyze exposure using the posterior subtemporal keyhole (PSK) approach combined with the transchoroidal keyhole (TCK) approach to the ambient cistern.

METHODS

We determined the proper location of craniotomy of such combined keyhole approach on 16 sides of cadaver heads. The PSK approach and the TCK approach were performed in the same minicraniotomy to observe microanatomic features and to quantitatively measure exposure limits of the ambient cistern and related structures using image-guided system.

RESULTS

Some superficial and bone landmarks could be used to find the proper location of such combined minicraniotomy. In the PSK approach, the exposure distances of the trigeminal nerve and the anterior portion of the P2 segment (P2a) were 10.02 ± 0.76 mm and 16.32 ± 2.02 mm, respectively. The superior, inferior, anterior, and posterior exposure limit of brainstem from the intersection point of the lateral mesencephalic sulcus and pontomesencephalic sulcus was 7.5 ± 0.19 mm, 11.04 ± 0.27 mm, 15.72 ± 0.52 mm, and 10.16 ± 0.38 mm, respectively. In the TCK approach, the vertical distances between the taenia fimbriae and the lateral geniculate body without and with mild caudal retraction of the hippocampus were 5.28 ± 0.46 mm and 11.18 ± 0.57 mm, respectively. The linear exposure distances of the posterior portion of the P2 segment (P2p) or P3 segment were 12.14 ± 1.88 mm. Except of one case, the P2p could be exposed using the TCK approach. The midpoint of the medial edge of the parahippocampal gyrus on the coronal magnetic resonance images provides landmark to choose the appropriate approach.

CONCLUSIONS

The PSK combined with the TCK approach can simultaneously expose the lower and upper ambient cistern in a proper minicraniotomy.