Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

Microsurgical treatment for superior petrosal sinus dural arteriovenous fistulas

Superior petrosal sinus (SPS) dural arteriovenous fistulas (DAVFs) are a commonly encountered type of tentorial DAVF that occasionally requires microsurgical intervention. This study aims to analyze the tributaries of the superior petrosal vein (SPV) observed intraoperatively, their association with clinical symptoms, and venous drainage patterns. This retrospective study reviewed 34 consecutive patients with SPS DAVFs who underwent microsurgical treatment at a single institution between 2014 and 2022. The cohort had a mean age of 52.8 ± 11.8 years, with 85.3% (29/34) being male. Predominant symptoms included venous hypertensive myelopathy (VHM) (55.9%) and intraparenchymal or subarachnoid hemorrhage (23.5%). Standard retrosigmoid approach was used to ligate 94.1% (32/34) of the lesions, resulting in immediate complete fistula occlusion for all patients. Supratentorial venous drainage patterns were associated with a higher incidence of intracranial hemorrhage and venous varix (P = 0.047). Infratentorial drainage patterns were more frequently linked with VHM-related symptoms (P<0.001). Patients presenting VHM-related symptoms showed a higher prevalence of drainage through the vein of the cerebellopontine fissure (VCPF) (P = 0.01), while those with intracranial hemorrhage symptoms exhibited a higher prevalence of pontotrigeminal vein (PTV) drainage (P = 0.033) in their DAVFs. Endovascular management of SPS DAVFs carries inherent risks. Surgical treatment via standard retrosigmoid craniotomy offers favorable clinical outcomes with high rates of cure. In cases featuring infratentorial venous drainage, the predominant arterialized tributary of the SPV was the VCPF, commonly associated with VHM-related symptoms. Conversely, in cases with supratentorial venous drainage, the predominant arterialized SPV tributary was the PTV, often associated with intracranial hemorrhage symptoms.

Hemorrhagic cerebral venous infarction after vein injury during intraoperative lesion resection: incidence, hemorrhagic stages, risk factors and prognosis

Objective

Cerebral venous infarction (CVI) after vein injury during intraoperative lesion resection is associated with intracranial hemorrhage. We conducted this study to identify the incidence, clinical and imaging features, and prognosis of hemorrhage CVI.

Methods

We performed a retrospective analysis of patients with confirmed CVI after vein injury who underwent craniotomy in our hospital. Postoperative clinical symptoms were observed, and imaging features were compared between patients with and without intracranial hemorrhages through CT examination. Variables were analyzed using univariate and multivariate regression analyses.

Results

Among 2,767 patients who underwent craniotomy, 93 cases of injured veins were identified intraoperatively. Hemorrhagic CVI was found in 38% (35/93). Multivariate analysis revealed that midline approach, meningioma, postoperative seizures, disorders of consciousness and interval in hours < 72 h were identified as predictors of hemorrhagic CVI. After 3 months of follow-up, the prognosis was poor in 15 cases (16%, 15/93), including death (two cases), vegetative survival (four cases), and severe disability (nine cases).

Conclusions

Hemorrhagic CVI, as a critical complication after venous injury, can have disastrous consequences. Do not injure known veins intraoperatively. In case of injury, requisite remedial measures should be adopted during and after surgery.

Preoperative assessment of the individual anatomy of the superior petrosal vein complex using balanced fast field echo magnetic resonance imaging

BACKGROUND

Here, we sought to examine the validity and reproducibility of balanced fast field echo (bFFE) for assessing superior petrosal vein (SPV) complex (SPVC) anatomy.

METHODS

Preoperative bFFE or equivalent scans and operative videos were studied and directly compared with regard to the individual anatomical features of SPVCs and their relation to the operative field. The anatomical details of the bFFE findings of the non-operated side (group 2) of all 50 patients were then reviewed, including the presence of petrosal-galenic anastomosis, and finally compared to the operated SPVCs (group 1).

RESULTS

A complete correlation between bFFE and intraoperative findings was observed in 62% of cases and had a significant correlation with 3 Tesla magnet strength and higher pixel bandwidth (rbis = - 0.47; p = 0.005). The sensitivity and specificity of bFFE magnetic resonance imaging were 93.7 and 95.2%, respectively, for detecting an SPV disturbing the operative field, and 97.3% and 95% for a disturbing tributary, respectively. Each group had 50 SPVCs, with a total of 70 and 64 SPVs, 10 and 11 general SPVC configurations, as well as 29 and 28 different individual anatomical variations in groups 1 and 2, respectively. Both groups had 1-3 SPVs with a similar distribution of frequencies [Chi-square (4) = 27.56; p = 0.0145 (Fisher's exact test)]. The similarity of the general configurations was not statistically significant. The same four predominant configurations constituted 80% of the SPVCs in each group. The vein of the cerebellopontine fissure was most frequently found in 86% and 88% of cases, and a petrosal-galenic anastomosis was seen in 38% and 40% of groups 1 and 2, respectively.

CONCLUSIONS

Individual SPVC variations are extensive. Good quality bFFE or equivalents are feasible for preoperative SPVC assessments. However, methods improving vascular visualization are recommended.

Deadly complication of sacrificing superior petrosal vein during cerebellopontine angle tumor resection: A case report and literature review

Background:

Tumors of the cerebellopontine angle (CPA) are challenging to resect and have been proven difficult for neurosurgeons to manage optimally. Superior petrosal vein complex (SPVC) as the main drainage system and close proximity to CPA could be an obstacle during operation. There is an incidence ranging from 55% to 84% of injury to one part of the SPVC during CPA tumor surgery.

Case Description:

We report a case of 65-year-old woman with CPA tumor, who complained of unilateral hearing loss, dizziness, and facial pain. During tumor resection, one part of SPV complex was injured, then cerebellar edema develops.

Conclusion:

This case provides an overview of surgical complication associated with venous sacrifice. This would support the agreement to preserve SPV regarding risks and improve the quality of surgical decision making.

Absence of Ischemic Injury after Sacrificing the Superior Petrosal Vein during Microvascular Decompression

BACKGROUND

Sacrificing the superior petrosal vein (SPV) is controversial during a microvascular decompression (MVD). There have been multiple reports of complications including life-threatening brainstem infarction and cerebellar edema.

OBJECTIVE

To analyze the potential for vascular complications when the SPV is sacrificed during an MVD.

METHODS

Retrospective chart review was performed to identify all MVDs for trigeminal neuralgia and hemifacial spasm from 2007 to 2018 at 1 institution. Cases with ≥1 mo of follow-up were included and SPV sacrifice was noted. The primary outcome was complications related to SPV sacrifice including sinus thrombosis, cerebellar edema, and midbrain or pontine infarction. Imaging was used to confirm all potential vascular complications noted in medical records. Fisher's exact test and unpaired t-tests were used to compare between groups.

RESULTS

A total of 732 MVD cases were identified and 592 met inclusion criteria with an average follow-up of 11.8 ± 16.4 mo and a male-to-female ratio of 1:2.2. The SPV was sacrificed in 217 cases and retained in 375 cases. No SPV-related vascular complications were found in this study. Two unrelated cases of vascular complications were identified and both were in the nonsacrificed group. One case involved cerebellar bleeding while the other was an ipsilateral transverse sinus thrombosis that was present preoperatively.

CONCLUSION

In MVDs, there is no difference in the rate of vascular complications when the SPV is sacrificed compared to preserved. To best visualize a cranial nerve and optimize safe decompression, surgeons should feel free to sacrifice the SPV.

Anatomy of petrous face

The anatomy of the petrous face of the temporal bone, also known as the petrous pyramid, should be carefully examined to understand the location of, blood supply to, and venous drainage of meningiomas in this area (42%-59% of posterior fossa meningiomas). The petrous face is located in the skull base between the sphenoid and occipital bones. It consists of a base that joins the mastoid laterally and an apex that extends anteromedially to form the foramen lacerum. The anatomy can be divided into three surfaces: anterior/superior, posterior, and inferior. The anterior/superior surface is a continuation of the posteromedial portion of the middle cranial fossa with boundaries extending from the arcuate eminence to the petrous apex. The posterior surface is a continuation of the front part of the posterior cranial fossa with the internal auditory meatus at its center. The inferior surface contains foramina that transmit important vessels and cranial nerves. The vascular anatomy of the petrous face is also described, including branches of the carotid artery and vertebrobasilar systems. It is imperative to understand potential anastomotic routes between extracranial and intracranial arteries, as well as arterial supply to cranial nerves, to facilitate preoperative transarterial embolization of meningiomas and avoid neurologic complications during surgery.

Venous anatomy of the infratentorial compartment

Approximately 7%-12% of all intracranial meningiomas are located in the posterior fossa (PF), a region which contains-among many other critical neurovascular structures-numerous major veins and sinuses draining blood away from the PF structures. There is a growing body of evidence indicating that venous sacrifice or injury during surgery are linked to serious postoperative complications-which may lead to significant morbidity and mortality. Thus, it is of paramount importance that clinicians charged with the preoperative, surgical, and postoperative care of patients undergoing treatment for meningioma are familiar with the general anatomy of the PF veins, as well as their structural nuances and drainage variations. The present chapter surveys the relevant anatomy in a manner that aims to be useful for an interdisciplinary team of clinicians and concludes with a discussion of emerging imaging technologies that may assist them in their clinical decision-making.

The Inferolateral Surgical Triangle of the Cavernous Sinus: A Cadaveric and MRI Study with Neurosurgical Significance

BACKGROUND

The inferolateral triangle is a surgical skull base triangle used as a neurosurgical landmark. There are few reports of its measurements with little attention paid to anatomic variations.

METHODS

The inferolateral triangle was measured in 10 adult human cadaveric heads via dissection then direct measurement and 5 participants undergoing neuroimaging using tracing features.

RESULTS

In the cadavers, mean lengths (mm) of the superior, anterior, and posterior borders were 17.0 (±5.5), 12.9 (±1.7), and 17.8 (±3.3), respectively, with mean area of 97.85 (±28.17) mm². In the participants, mean lengths (mm) of the superior, anterior, and posterior borders were 17.35 (±4.01), 14.36 (±1.36), and 18.01 (±2.43), respectively, with mean area of 113.6 (±25.46) mm². No statistical difference in triangle areas between groups was found.

CONCLUSIONS

Intimate understanding of the inferolateral triangle is essential to skull-based surgery; knowing its anatomy and variations aids in surgical planning and understanding of regional pathology.

Life-threatening complications after microvascular decompression procedure: Lessons from a consecutive series of 596 patients

The microvascular decompression procedure (MVD) is widely utilized on patients with neurovascular compression syndromes, such as trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia, which have failed medical therapy. However, surgical complications are an ongoing problem. We retrospectively reviewed a total of 596 patients undergoing MVD in the Affiliated Hospital of Qingdao University from January 2008 to December 2018. Furthermore, we discussed the cases with life-threatening complications to determine the potential causes, aiming to achieve the goal of safer microvascular decompression. There were seven cases with life-threatening complications. Of those complications, one was cerebellar infarction with acute hydrocephalus, one was infarction of the cerebellum and the brain stem with acute hydrocephalus and serious intracranial infection, two were cerebellar haematoma, one was multiple haemorrhage with acute hydrocephalus, one was supratentorial subdural haematoma, and one was cerebellar swelling with acute hydrocephalus. After therapy, one patient died, one was in a persistent vegetative state, and five were discharged from the hospital upon recovery. In brief, MVD is a safe operation, and life-threatening complications accompanying MVD are rare, but require attention. The causes of some life-threatening complications are still not completely clear. Surgeons should continuously improve surgical techniques and perioperative care to reduce potential risks.

Conquering the Rock-A Retrospective Single-Center Experience of the Transapical Petrosal Transtentorial (Kawase) Approach: Operative Technique and Impact on Cranial Nerve Function

Since its description in 1985, the transapical petrosal transtentorial or Kawase approach has become a viable option of approaching lesions located in and around the apex of the petrous bone, Meckel's cave, and the anterolateral surface of the brain stem while preserving cranial nerve function. At the Brain Tumor Center, Erasmus MC, 25 patients were treated using the Kawase approach between 2004 and 2018 for various indications, including petroclival meningiomas, chondrosarcomas, pontine cavernomas, trigeminal schwannomas, and posterior circulation aneurysms. Hearing preservation was achieved in all patients; new abducens nerve and trochlear nerve palsies were present in three and six patients, respectively, of which a total of eight required ophthalmological correction. Seven patients experienced a cerebrospinal fluid fistula postoperatively, but this complication appeared self-limiting in all cases, with one patient experiencing secondary meningitis. After modifying our closure technique, the rate of fistulas dropped to zero. The observed direct postoperative mortality was 4% (one patient), although not related to the approach itself. In conclusion, the Kawase approach is a highly complex, but essential middle fossa approach, extremely robust, and able to serve a wide array of pathologies together with its extensions. It is very accurate for performing hearing preservation surgery, but not without caveats and inherent risk of complications.

Surgeons' experience of venous risk with CPA surgery

The study aims to systematize neurosurgeons' practical knowledge of venous sacrifice as applied to the posterior fossa region and to analyze the collected data to present and preserve relevant experience and expert knowledge for current and future practicing neurosurgeons. The venous structures assessed were the superior petrosal vein (SPV), sigmoid sinus (SS), and the tentorial veins (TV). The survey is constructed to obtain surgeons' idea of assessed risk when sacrificing specific venous structures during posterior fossa surgery. They were asked how they prep for surgery, number of operations conducted, and their basis of knowledge. Collected data were mainly qualitative and analyzed with a mixed-method approach. A mean absolute deviation was calculated measuring rate of disagreement for a given substructure. Consensus existed among the participating surgeons that sacrificing the SPV and the TV was considered safe. Although, the risk of death when occluding major structures like the main trunk of the SPV, one of the SS' and or a total occlusion of all TV yielded high risk of death. The risk of infarction was often too apparent to discredit even with low risk of death among an experienced class of surgeons. Our findings provide an overview of surgical risk associated with venous sacrifice. This will minimize cases where indispensable practical knowledge on safe handling veins in the cerebellopontine angle is either to be lost or taught among few when the neurosurgeons retire. This will lower the disagreement regarding risks and increase the quality of surgical decision-making.

Preservation of Coexisting Normal Superior Petrosal Vein in the Microsurgical Treatment of Superior Petrosal Sinus Dural Arteriovenous Fistulas Assisted by Indocyanine Green Video Angiography

BACKGROUND

Superior petrosal sinus (SPS) dural arteriovenous fistulas (DAVFs) are a common subtype of tentorial DAVFs that often require microsurgical treatment. We have noted a rare condition involving the presence of a coexisting normal superior petrosal vein (SPV) during surgery for SPS DAVFs; this condition has not been reported in the literature. Identification and preservation of coexisting normal veins are crucial to prevent venous complications.

METHODS

We reviewed data of 12 patients with SPS DAVFs who underwent microsurgical treatment. Intraoperative indocyanine green video angiography was used to confirm the location of the fistula and identify the normal SPV. Postoperative radiologic examination was performed, and the clinical outcome was evaluated with the modified Rankin Scale.

RESULTS

A coexisting normal functional SPV was found in 6 cases. Analysis of the tributaries of the SPV showed the vein of the cerebellopontine fissure was the most frequent arterialized drainage vein (66.7%), while the pontotrigeminal vein was the most frequent normal drainage vein (45.5%). The DAVFs were easily identified and disrupted using intraoperative indocyanine green video angiography. The normal SPV was also successfully preserved. All 6 patients experienced good clinical and radiologic outcomes.

CONCLUSIONS

An SPS DAVF can coexist with a normal functional SPV, which should be preserved. Use of indocyanine green video angiography is an efficient way to identify the normal SPV.

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.

Safe handling of veins in the pineal region-a mixed method study

Surgical experience in pineal surgery is largely confined to a few experienced surgeons and may be lost when they stop their practice. The objective of this study is to systematically preserve and analyze valuable practical knowledge of pineal region surgical venous anatomy. A survey was constructed to obtain experienced surgeons' perception of estimated risks and individual experience following occlusion of veins during pineal surgery. Data were qualitative and analyzed with a mixed methods approach. Of the 126 invited neurosurgeons, 40 submitted completed questionnaires. General agreement existed of which veins were associated with high and low risks following occlusion. The risk of death was estimated to be high with sacrifice of the vein of Galen (83%), both internal cerebral veins (69%) and the basal veins (58%). The risk of death was estimated to be lower with the sacrifice of both superior vermian veins (13%) and one internal occipital vein (10%). Importantly, a sub-group of experienced surgeons reported substantial risk of death and consequences with the sacrifice of cerebellar bridging veins (8-13%). Our findings provide a coherent picture of surgical risk with venous sacrifice, which can inform the surgical community of systematically gathered views from aggregated surgeries of a very large cohort of patients. Extensive presurgical radiological workup and anatomical studies seemed to correlate more cautious risk estimations. Our findings increase available knowledge of risks of venous complications.

Safety profile of superior petrosal vein (the vein of Dandy) sacrifice in neurosurgical procedures: a systematic review

OBJECTIVE Walter E. Dandy described for the first time the anatomical course of the superior petrosal vein (SPV) and its significance during surgery for trigeminal neuralgia. The patient's safety after sacrifice of this vein is a challenging question, with conflicting views in current literature. The aim of this systematic review was to analyze the current surgical considerations regarding Dandy's vein, as well as provide a concise review of the complications after its obliteration. METHODS A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A thorough literature search was conducted on PubMed, Web of Science, and the Cochrane database; articles were selected systematically based on the PRISMA protocol and reviewed completely, and then relevant data were summarized and discussed. RESULTS A total of 35 publications pertaining to the SPV were included and reviewed. Although certain studies report almost negligible complications of SPV sectioning, there are reports demonstrating the deleterious effects of SPV obliteration when achieving adequate exposure in surgical pathologies like trigeminal neuralgia, vestibular schwannoma, and petroclival meningioma. The incidence of complications after SPV sacrifice (32/50 cases in the authors' series) is 2/32 (6.2%), and that reported in various case series varies from 0.01% to 31%. It includes hemorrhagic and nonhemorrhagic venous infarction of the cerebellum, sigmoid thrombosis, cerebellar hemorrhage, midbrain and pontine infarct, intracerebral hematoma, cerebellar and brainstem edema, acute hydrocephalus, peduncular hallucinosis, hearing loss, facial nerve palsy, coma, and even death. In many studies, the difference in incidence of complications between the SPV-sacrificed group and the SPV-preserved group was significant. CONCLUSIONS The preservation of Dandy's vein is a neurosurgical dilemma. Literature review and experiences from large series suggest that obliterating the vein of Dandy while approaching the superior cerebellopontine angle corridor may be associated with negligible complications. However, the counterview cannot be neglected in light of some series showing an up to 30% complication rate from SPV sacrifice. This review provides the insight that although the incidence of complications due to SPV obliteration is low, they can happen, and the sequelae might be worse than the natural history of the existing pathology. Therefore, SPV preservation should be attempted to optimize patient outcome.

Surgical and Functional Outcome after Resection of 57 Tentorial Meningiomas

Tentorial meningiomas (TMs) may challenge the surgeon with their close association to neurovascular structures. We analyzed a consecutive series with regard to surgical and functional outcome following microsurgical resection. We retrospectively reviewed patient charts and imaging data of every patient with a TM resected at a single institution and compared surgical and functional outcomes between groups stratified by choice of approach. 57 consecutive patients from October 2006 to September 2017 were included, of which 75.4% were female; mean age was 60 years (range 31–90), follow-up data was available for 85.4% and reached a mean of 18.3 (range 2–119) months with a median of 14.5 months. 54.4% of TMs were located at the medial compartments of the tentorium, 45.6% at the lateral edges. Complete resection defined as Simpson grades I and II was achieved in 72% of all cases, without statistically significant differences for both subgroups (p = 0.532). 9 patients (15.8%) developed a new cranial nerve palsy postoperatively with the vestibulocochlear nerve affected exclusively in the lateral subgroup (8.8% of total), followed by disturbances of oculomotion (5.4%). After 12 months, 93.0% of patients with available follow-up after 12 months retained fully independent functional status without deficit. Despite providing a surgical challenge due to potentially complicated anatomical relations, the choice of an appropriate surgical strategy overall results in favourable oncological and functional outcome after resection of TMs.

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.

Pathophysiological changes in the cerebellum and brain stem in a rabbit model after superior petrosal vein sacrifice

In certain surgical procedures, sacrificing the superior petrosal vein (SPV) is required. Previous studies have reported transient cerebellar edema, venous infarction, or hemorrhage that might occur after sectioning of the SPV. The present study investigated the pathophysiological changes in cerebellum and brain stem after SPV sacrifice. Rabbits were divided into the operation group where the SPV was sacrificed and the control group where the SPV remained intact. Each group was further subdivided into 4, 8, 12, 24, 48, and 72 h groups which represented the time period from sacrificing of the SPV to killing of the rabbits. The water content (WC), Na⁺ content, K⁺ content, and pathophysiological changes in cerebellum and brain stem tissue were measured. In comparison with the control, the WC and Na⁺ content of cerebellar tissue were increased in the 4, 8, 12, and 24 h operation subgroups (P<0.05), but only increased in the 4-h subgroup of the brain stem tissue (P<0.05). The K⁺ content of the cerebellar tissue decreased in the 4, 8, 12, and 24 h operation subgroups (P<0.05) but only decreased in the 4-h subgroup of brain stem tissue (P<0.05). Nissl staining and TEM demonstrated that cerebellar edema occurred in the 4, 8, 12, and 24 h operation subgroups but not in the 48- and 72-h subgroups. Brain stem edema occurred in the 4-h operation subgroup. In summary, cerebellum and brain stem edema can be observed at different time points after sacrificing of the SPV in the rabbit model.

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.

The Analysis of the Petrosal Vein to Prevent Venous Complications During the Anterior Transpetrosal Approach in the Resection of Petroclival Meningioma

BACKGROUND

The anterior transpetrosal approach (ATPA) has been used in the resection of petroclival meningioma (PCM) for more than 20 years. Although PCM sometimes involves the petrosal vein and its preservation has been an important issue, the precise risk of petrosal vein sacrifice and subsequent venous complications associated with the use of the ATPA in patients with PCM has not yet been elucidated.

METHODS

We used computed tomographic (CT) digital subtraction venography (DSV) in the retrospective analysis of the petrosal vein and its tributaries in patients with PCM before and after surgery. We also examined the incidence of postoperative venous complications in each of the patients.

RESULTS

The detection rate of the petrosal vein and some of its tributaries on CT-DSV in patients with PCM was significantly lower than that in controls. Preoperatively, CT-DSV detected the petrosal vein in 71.8% of patients with PCM. The detected petrosal veins were preserved after the operation in 64.3% of these patients. No venous complications involving petrosal vein were observed in any of the patients. Anastomosis between the petrosal vein and the basal vein via the pontotrigeminal vein was found to be significantly more developed in the patients with PCM compared with the controls.

CONCLUSIONS

Our study demonstrated that the ATPA could be performed safely on patients with PCM from the viewpoint of venous preservation. Preoperative CT-DSV is important for assessing the petrosal vein and its tributaries to facilitate a safer operation.

Sacrificing the superior petrosal vein during microvascular decompression. Is it safe? Learning the hard way. Case report and review of literature

BACKGROUND

Venous infarction as a complication of microvascular decompression (MVD) is a recognized but extremely rare occurrence in an otherwise standard neurosurgical procedure. Sacrificing one or more veins is considered safe by majority of experienced surgeons and authors. However, in the recent years, there has been growing debate about the management of venous trigeminal compression and/or superior petrosal complex (separation vs. coagulation and cutting of the vein), with few papers describing mild to severe complications related to venous sacrifice.

CASE DESCRIPTION

We report our dramatic experience during re-exploration for MVD on a male who developed massive cerebellar, brainstem, and brain infarction. Extensive analysis of surgical planning and literature debate about this topic is also reported.

CONCLUSION

Despite rare, venous infarction after venous sacrifice in MVD is possible and can have catastrophic consequences. We would advise: (1) To try preserving the vein anytime this is possible, especially if it is large in size; (2) if it is decided to sacrifice the vein temporary occlusion while observing changed in the neurophysiology might be safer; (3) when planning an MVD for suspected venous compression, possible alternative forms of treatment should also be considered.

Study of Changing Intracranial Venous Drainage Patterns in Petroclival Meningioma

OBJECTIVE

To elucidate venous drainage patterns to avoid damage to the venous drainage route in the middle cranial fossa and superior petrosal sinus when employing the transpetrosal approach.

METHODS

Venous drainage patterns were assessed using three-dimensional computed tomography venography in 22 hemispheres of petroclival meningioma (PCM) cases from patients who underwent primary surgery and 40 hemispheres of control cases. Intracranial venous drainage patterns were compared between control cases and PCM cases.

RESULTS

The proportion of hemispheres with complete and medial superior petrosal sinus drainage patterns was lower in PCM cases. With regard to the superficial middle cerebral vein drainage pattern, the proportion of hemispheres with the cavernous sinus capture type was lower and the proportion with the emissary type was higher in PCM cases. The proportion of hemispheres with multiple greater anastomoses of the superficial middle cerebral vein was higher in PCM cases without the emissary-type and cavernous sinus capture-type patterns. When the venous drainage route of the cavernous sinus capture type and/or emissary type was disturbed, in particular, greater anastomosis via the vein of Labbè and the vein of Trolard was needed to control venous drainage flow.

CONCLUSIONS

In cases of venous drainage impairment secondary to PCM progression, the drainage route changed to the pterygoid plexus route through the emissary foramen and/or superior sagittal sinus and to the transverse sinus route through the greater anastomosis of the superficial middle cerebral vein. In the anterior transpetrosal approach, peeling off the dura propria of the trigeminal nerve of the foramen rotundum for petrous apex exposure may be associated with the potential risk of pterygoid plexus drainage route impairment.

Intrapetrous Anastomosis between the Internal Jugular Vein and the Superior Petrosal Sinus: Cone Beam Computed Tomography Incidental Finding

This is a case report of a 62-year-old male who presented to the Ear, Nose, and Throat clinic for a follow-up exam for hearing loss stemming from a fall from a horse in his infancy. A Cone Beam Computed Tomography (CBCT) examination revealed an intrapetrous communication between the internal jugular vein bulb and the superior petrosal sinus. Three-dimensional bone and soft tissues volume renderings were generated to demonstrate this incidental anatomical variant.

Short-term therapeutic effects of low-dose cytarabine plus surgical resection on elderly patients with trigeminal nerve tumor and safety observation

OBJECTIVE

To evaluate the short-term therapeutic effects of low-dose cytarabine plus surgical resection on elderly patients with trigeminal nerve tumor and to observe the safety.

METHODS

A total of 120 elderly patients with trigeminal nerve tumor were divided into a treatment group and a control group by random draw (n=60), and both groups were subjected to resection by stereotactic image-guided endoscopic nasal surgery. Afterwards, the control group was administered with high-dose cytarabine while the treatment group was given low-dose cytarabine for 14 days.

RESULTS

Both groups completed treatment, but the effective rate of the treatment group (96.7%) was significantly higher than that of the control group (83.3%) (P < 0.05). The pain scores of the two groups were similar at T0, T1 and T2, but the score of the treatment group at T2 was significantly different from those at T0 and T1 (P < 0.05). During treatment, the treatment group was significantly less prone to complications such as headache, vomiting, vision impairment, nausea and local swelling than the control group (P < 0.05). During three months of follow-up, the appetite, sleep and daily living scores were significantly higher than those of the control group (P < 0.05).

CONCLUSION

Stereotactic image-guided surgery was able to treat trigeminal nerve tumor well, and the effect was enhanced by low-dose cytarabine that improved postoperative outcomes and quality of life by dramatically decreasing complications.

Anterior Transpetrosal Approach Combined with Partial Posterior Petrosectomy for Petroclival Meningiomas with Posterior Extension

BACKGROUND

An anterior transpetrosal approach (ATPA) is suitable for treating upper petroclival lesions. However, the limit of the ATPA is reached when the tumor extends posterolaterally over the internal auditory canal (IAC) along the petrous edge. In such cases, ligation of the posterior part of the superior petrosal sinus (SPS) is necessary. To overcome this limitation, we combined the ATPA with a partial posterior petrosectomy in 8 patients who had petroclival meningiomas extending posterolaterally over the IAC.

METHODS

We resected only the Trautmann triangle in addition to the Kawase triangle to secure the space to ligate the posterior portion of the SPS. Because the tympanic cavity and bony labyrinth of the ear were not exposed, we were able to preserve hearing function and lower the risk of cerebrospinal fluid leakage. Furthermore, this approach enables easy ligation of the SPS and the tentorium posterior to the tumor attachment. This combined technique also allows visualization of the petrosal vein, which is important for surgery of the posterior fossa.

RESULTS

Total and near-total tumor removal was achieved in 6 patients (75%) with no permanent complications and no cerebrospinal fluid leakage. Postoperative hearing impairment was not found in any of the patients who underwent this surgery.

CONCLUSIONS

The ATPA combined with partial posterior petrosectomy is an effective method for removal of complicated petroclival meningiomas that extend posterolaterally over the IAC along the petrous edge.

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.