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

Obliteration of the Superior Petrosal Vein During Cerebellopontine Angle-Surgery: More Cons than Pros?

A profound knowledge of the anatomy and surgical management of the superior petrosal vein (SPV) is vital during neurosurgical procedures in the posterior fossa. The debate on preserving the SPV or whether it can be duly obliterated is still ongoing. This review provides an update on all historical articles pertaining to the risk profile of superior petrosal sacrifice since Walter Dandy. Not only were the heterogenous methods but also the respective authors' conclusions analyzed. In light of the collected evidence, we come to the conclusion that occluding the SPV poses an ineligible risk to patient safety and should be considered obsolete.

Comparative Analysis of Patients Undergoing Microvascular Decompression for Trigeminal Neuralgia Caused by Solely Arterial or Solely Venous Compression

OBJECTIVE

Trigeminal neuralgia (TN) due to venous compression is far less common than that due to arterial compression, and its pathogenesis is less clear. We investigated the clinical and imaging features of TN caused by solely venous compression by measuring the morphologies of the posterior cranial fossa (PCF) and the trigeminal nerve.

METHODS

We retrospectively reviewed records of TN patients who underwent microvascular decompression at our institution and extracted cases with solely arterial or solely venous compression. Preoperative magnetic resonance imaging was used to find the length (Y), width (X), height (Z), and volume (V) of the PCF, the angle between the trigeminal nerve and pons, and the distance between Meckel's cave and the root entry zone of the trigeminal nerve.

RESULTS

Of 152 patients, 24 had TN caused solely by venous compression. The value of Y was significantly smaller in the venous group than the arterial group (P < 0.01). The trigeminal nerve and pons was significantly smaller in the venous group (P < 0.01). We hypothesized that TN patients with solely venous compression had a characteristic PCF morphology with a short anteroposterior diameter (Y), such that age-related changes in brain morphology could alter the course of the trigeminal nerve and cause compression by a vein.

CONCLUSIONS

The morphological features of the PCF differed between patients with TN of venous and those with TN of arterial etiology. Age-related changes in brain morphology and changes of course of the trigeminal nerve may also add to the possibility of developing TN, especially of venous etiology.

Standard operating procedure and surgical technique innovation in fully endoscopic microvascular decompression for trigeminal neuralgia: technical note on 189 patients

BACKGROUND

Microvascular decompression (MVD) is a well-established and effective treatment for primary trigeminal neuralgia (TN). Endoscopy has been implemented to provide a comprehensive view of neurovascular conflict and minimizes the damages of brain retraction during MVD.

OBJECTIVES

To preliminarily evaluate the surgical safety and efficacy of fully endoscopic microvascular decompression (EMVD) for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope.

METHODS

Retrospective clinical analysis of 189 patients with primary TN underwent EMVD between June 2019 and August 2022 was performed. By analyzing the intraoperative situation, the outcomes of postoperative symptoms and the main complications, we evaluated the reliability and effectivity of the operative technique in the treatment of primary TN.

RESULTS

We summarized the standard operating procedure of EMVD for primary TN with surgeon performing two-hand manipulation and assistant holding endoscope. In addition, acicular bipolar electrocoagulation technique was developed to handle venous compression. During the follow-up period, good pain relief was achieved in 178 patients (94.2%) and recurrence of pain was observed in 4 patients (2.1%). Postoperative temporary complications included trigeminal dysesthesias (7 patients, 4.8%), cerebrospinal fluid leak (2 patients, 1.1%), hearing difficulty (3 patient, 1.6%), facial paresis (2 patients, 1.1%) and vertigo (5 patients, 2.7%). There were no cases of intracranial hemorrhage, cerebellar swelling and death.

CONCLUSION

This EMVD technique is reliable and effective, and can be used as a routine surgical procedure for primary TN.

Hemifacial Spasm Associated With the Specific Offending Vein

BACKGROUND AND OBJECTIVES

Hemifacial spasm (HFS) caused by venous compression is a rare occurrence. Currently, there is no relevant research on the venous characteristics and potential pathogenic mechanisms causing venous HFS. Exploring the venous characteristics in venous-type HFS may reduce the likelihood of repeated surgery.

METHODS

The authors presented 4 cases of HFS caused by veins of middle cerebellar peduncle (V. of Mid.Cer.Ped) successfully treated with microvascular decompression.

RESULTS

Based on intraoperative observations and abnormal muscle response (AMR) monitoring, it was determined that V. of Mid.Cer.Ped were offending vessels in these patients. Moreover, veins crossed between the facial and vestibulocochlear nerves, and then surrounded the ventral aspect of the facial nerve root. Microvascular decompression for the offending vessel was successfully performed, and AMR disappeared for each patient. These patients were discharged without any complications and involuntary contractions or twitching of facial muscles.

CONCLUSION

The study demonstrated that veins can indeed induce HFS. The characteristic of the V. of Mid.Cer.Ped that leads to HFS is that these veins traverse between the facial nerve and the vestibulocochlear nerve, and then surround the ventral aspect of the facial nerve root. The dynamic influence of cerebrospinal fluid leads to pulsatile impingement of the facial nerve on the vein, resulting in facial nerve bending and deformation at the location of the vein. Significantly, in the context of surgery, if it is noticed that the V. of Mid.Cer.Ped surrounds the ventral aspect of the facial nerve root and the facial nerve is compressed and deformed, when AMR disappears after decompression of the artery, it may be necessary to perform vein decompression.

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.

The Visualization of Intraneural Venous Compression in Trigeminal Neuralgia by Using Advanced Three-Dimensional Computer Graphics: An Illustrative Case Report

Trigeminal neuralgia (TN) caused by venous compression presents challenges in surgical management, unlike the arterial type. Preoperative diagnostic certainty regarding venous etiology and anatomical relationships is crucial for surgical success. We discuss a case of TN caused by a vein passing through the nerve that was challenging to visualize on conventional MRI and was treated successfully by leveraging information from modern surgical simulation technology with 3D computer graphics. We recognized a potentially troublesome anatomical feature in advance and mitigated the risk by identifying a collateral drainage route for the causative vein, making it feasible to be sacrificed while ensuring treatment efficacy.

A novel non-segmented inverted water outline rendering method can improve the tracking of responsible blood vessels for hemifacial spasm

This study aimed to explore a novel, non-segmented based on inverted water outline, and rapid 3D rendering method for identifying the responsible blood vessels for hemifacial spasm. First, the software was developed using the free and open-source 3D Slicer to process magnetic resonance images. Outlines of the water region were extracted and rendered in a three-dimensional space. The traditional image re-slicing technique (IMRT) was used for the control group, while non-segmented inverted water outline rendering (NSIWR) was used to observe the relevant blood vessels in the root entry/exit zone (REZ) of patients with hemifacial spasm. The intraoperative exploration results were considered the gold standard for comparing the differences in identifying relevant blood vessels between the two methods. Twenty-five patients were included, and the reconstruction effect evaluation suggested that NSIWR could effectively reconstruct the responsible blood vessels of the cochlea, facial nerve, and REZ. Compared with IMRT, NSIWR effectively improved the diagnosis of the responsible blood vessels in the REZ, clarified their sources and directions, and was consistent with intraoperative results. This study introduced a novel rapid rendering method based on NSIWR, which was successfully applied for hemifacial spasm. The method enhances accuracy in identifying responsible blood vessels in the REZ without needing multi-modal techniques. It has the potential to improve surgical effectiveness and reduce exploration time in treating hemifacial spasm.

Prevention of Superior Petrosal Vein Injury during Microvascular Decompression for Trigeminal Neuralgia: Operative Nuances

Background The superior petrosal vein (SPV) often obscures the surgical field or bleeds during microvascular decompression (MVD) for the treatment of trigeminal neuralgia. Although SPV sacrifice has been proposed, it is associated with multiple complications. We have performed more than 4,500 MVDs, including approximately 400 cases involving trigeminal neuralgia. We aimed to describe our operative technique and nuances to avoid SPV injury.

Methods We have provided a detailed description of our institutional protocol, including the anesthesia technique, neurophysiologic monitoring, patient positioning, surgical approach, and SPV management. The surgical outcomes and treatment-related complications were retrospectively analyzed.

Results No SPVs were sacrificed intentionally or accidentally during our MVD protocol for trigeminal neuralgia. In the 344 operations performed during 2006 to 2020, 269 (78.2%) patients did not require medication postoperatively, 58 (16.9%) tolerated the procedure with adequate medication, and 17 (4.9%) did not respond to MVD. Postoperatively, 35 (10.2%), 1 (0.3%), and 0 patients showed permanent trigeminal, facial, or vestibulocochlear nerve dysfunction, respectively. Wound infection occurred in five (1.5%) patients, while cerebrospinal fluid leaks occurred in three (0.9%) patients. Hemorrhagic complications appeared in four (1.2%) patients but these were unrelated to SPV injury. No surgery-related mortalities were reported.

Conclusion MVD for the treatment of trigeminal neuralgia can be achieved safely without sacrificing the SPV. A key step is positioning the patient's vertex at a 10-degree elevation from the floor, which can ease venous return and loosen the SPV, making it less fragile to manipulation and providing a wider surgical corridor.

Cerebrovascular Complications of Vestibular Schwannoma Surgery

Objective Cerebrovascular complications (CVC) are rare consequences of vestibular schwannoma (VS) surgery. Our objective was to assess incidences of findings suggestive of postoperative CVC in a large single surgeon cohort, as well as potential risk factors, and implications.

Study Design A cohort of 591 patients was retrospectively reviewed. Postoperative magnetic resonance images were screened for findings suggestive of stroke, T2 hyperintensity in the cerebellopontine angle structures or new encephalomalacia. Clinical records were queried for findings consistent with postoperative CVC.

Results In total, 61 patients had radiographic findings consistent with possible postoperative CVC (10%); of them, eight had documented intraoperative vascular injury (1.4%), and four had postoperative clinical exam changes indicative of CVC (0.7%). Clinically manifest intraoperative vascular injuries occurred in four patients and involved the petrosal venous complex (n = 3, 5%) or anterior inferior cerebellar artery (n = 1, 2%); clinical deficits included hemiparesis (n = 1, 2%), facial anesthesia (n = 2, 4%), dysphagia (n = 2, 2%), and unfavorable facial nerve function in two (50%). Three out of four patients in this group required out-of-home placement (75%). Clinical CVCs (n = 4) were not significantly associated with tumor size, tumor cyst, gross total resection, or length of stay. Patients with clinical CVC were significantly more likely to require posthospitalization rehabilitation (19 vs. 75%, p = 0.02; 14 vs. 100%, p = 0.0002).

Conclusion Although radiographic findings suggestive of CVC were unexpectedly common in this cohort, intraoperative vascular injury and postoperative clinical CVC were exceedingly rare. The association between unfavorable facial nerve outcome and clinical CVC is likely a marker for more difficult operations, predisposing to higher risk of complications.

Classification and Management of Pontecerebellar-Petrosal Bridging Veins

INTRODUCTION

The risks and benefits of coagulating intradural venous elements during a retrosigmoid approach for trigeminal neurovascular decompression has not been accurately established. The objectives of this study are to identify the veins that drain into the superior petrosal sinus, classify them in relation to the suprameatal tubercle and determine the implication of their coagulation.

MATERIAL AND METHODS

A retrospective study of 3D surgical videos of retrosigmoid approaches for trigeminal neurovascular decompression from the LINT (Laboratory of Neurosurgical Innovations of Tucumán) digital archive was carried out. The veins encountered were classified into 3 groups: retromeatal, meatal and premeatal. The neurosurgical postoperative complication scale proposed by Landriel et al. was utilized to assess complications from venous coagulation. A Grade 0 was added for patients without complications. The STATA 14 program was utilized for statistical analysis.

RESULTS

The pontocerebellar-petrosal veins of 28 patients who underwent trigeminal decompressive surgery were analyzed. In 7 cases these were found in the retromeatal region; 100% were sacrificed. 11 cases revealed veins within the meatal region; 90,91% were coagulated. Veins in the premeatal region were found in 14 cases; 57,14% were sacrificed. In the postoperative follow-up, 27 patients were grade 0 and 1 patient developed postoperative meningitis (grade Ib complication). No patient suffered vascular complications.

CONCLUSION

The venous elements identified in trigeminal neurovascular decompressive surgery are variable. We propose classifying them into retromeatal, metal and premeatal groups. Retromeatal and meatal veins can be safely sacrificed for appropriate visualization of the neurovascular conflict. The premeatal venous elements should be coagulated only in justified cases.

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.

Petrosal Vein Involvement in Neurovascular Conflict in Trigeminal Neuralgia: Surgical Technique and Clinical Outcomes

BACKGROUND

Contact of the main stem of the petrosal vein (PV) to the nerve root is a rare cause of trigeminal neuralgia (TGN). The implication of the PV in relation with neurovascular contact (NVC) is not fully understood.

OBJECTIVE

To assess the operative procedures in microvascular decompression (MVD) in patients with PV involvement in the long-term.

METHODS

We retrospectively reviewed 34 cases (7.0%) in 485 consecutive MVDs for TGN, whose PV main stem had contact with the trigeminal nerve root (PV-NVC). PV-NVCs were divided into 2 groups: concomitant arterial contact or no concomitant arterial contact. Surgical techniques, outcomes, complications, and recurrence were assessed.

RESULTS

The anatomical relationship of the PV with the trigeminal nerve root was consistent with preoperative 3-dimensional imaging in all patients. Pain relief was obtained in most patients immediately after surgery (97.1%) by separating the PV from the nerve root. Postoperative facial numbness was noted in 9 patients (26.5%). Symptomatic venous infarctions occurred in 2 patients (5.9%). Recurrence of facial pain occurred in 3 patients (8.8%) with a median 48 mo follow-up period. Re-exploration surgery revealed adhesion being the cause of recurrence. The statistical analyses showed no difference in the surgical outcomes of the 2 groups.

CONCLUSION

Separating the PV from the nerve root contributes to pain relief in patients with PV conflict regardless of concomitant arteries. Preserving venous flow is crucial to avoid postoperative venous insufficiency.

A Novel Technical Refinement of Microvascular Decompression: Pain Relief and Complication Rate in a Consecutive Series of Patients With Trigeminal Neuralgia

BACKGROUND

Microvascular decompression (MVD) represents a milestone for the treatment of trigeminal neuralgia (TN). Nevertheless, several complications still occur and may negatively affect the outcome. We recently proposed some technical nuances for complication avoidance related to MVD.

OBJECTIVE

To verify the efficacy of the proposed refinement of the standard MVD technique in terms of resolution of the pain and reduction of complication rates.

METHODS

We analyzed surgical and outcome data of patients with TN using a novel surgical refinement to MVD, over the last 4 yr. Outcome variables included pain relief, facial numbness, muscular atrophy, local cutaneous occipital and temporal pain or numbness, cerebellar injury, hearing loss, cranial nerve deficits, wound infection, and cerebrospinal fluid (CSF) leak. Overall complication rate was defined as the occurrence of any of the aforementioned items.

RESULTS

A total of 72 consecutive patients were enrolled in the study. Pain relief was achieved in 91.6% and 88.8% of patients at 1- and 4-yr follow-up, respectively. No patient reported postoperative facial numbness during the entire follow-up period. The incidence of CSF leak was 1.4%. One patient developed a complete hearing loss and another a minor cerebellar ischemia. There was no mortality. The overall complication rate was 5.6%, but only 1.4% of patients experienced permanent sequelae.

CONCLUSION

The proposed refinement of the standard MVD technique has proved effective in maintaining excellent results in terms of pain relief while minimizing the overall complication rate associated with this surgical approach.

Comparative Analysis of Trigeminal Neuralgia Caused by Sole Arterial and Venous Compression: Clinical Features and Surgical Outcomes From 222 Cases

Background: Compared with trigeminal neuralgia (TN) caused by arterial neurovascular conflict (NVC), the clinical characteristics and managements for TN with venous NVC are not well-established. This study aims to comparatively summarize the clinical features and surgical outcomes of microvascular decompression (MVD) for patients with TN caused by sole arterial and venous compression, with a particular focus on the morphological features of posterior cranial fossa (PCF).

Methods: A total of 222 patients with TN caused by sole arterial NVC (188/84.7%) and venous NVC (34/15.3%) underwent MVD in our department from January 2014 to December 2018. The patient data were analyzed retrospectively. Particularly, we focused on the potential impact of PCF on surgical outcomes.

Results: Compared with arterial NVC, V3 branch of the trigeminal nerve was more frequently involved in venous NVC (p = 0.009). The most common compression site was root entry zone for arterial NVC (68.6%) and midcisternal segment for venous NVC (76.5%) (p < 0.001). No serious post-operative complication was observed in the two groups. Both short- and long-term outcomes were relatively worse in venous NVC cases compared with arterial NVC cases (p = 0.001 and p = 0.030, respectively); and a dominantly higher rate of delayed cure was demonstrated in venous NVC cases (p < 0.001). TN patients with venous NVC revealed a more flat-shaped PCF than those with arterial NVC. Moreover, flat-shaped PCF morphometry was negatively correlated with surgical outcomes of TN patients with arterial NVC, but not with those of venous NVC cases.

Conclusions: MVD is an effective and safe treatment for patients with TN caused by either arterial or venous NVC. Patients with a more flat-shaped PCF might be vulnerable to venous compression. Our study demonstrated that PCF morphometry only affected the surgical outcomes of patients with TN caused by arterial NVC, but not the outcomes of those with venous NVC.

Virtual reality-based evaluation of neurovascular conflict for the surgical planning of microvascular decompression in trigeminal neuralgia patients

OBJECTIVE

Trigeminal neuralgia (TN) is a lightning bolt of violent, electrifying, and stinging pain, often secondary to the neurovascular conflict (NVC). The vessels involved in NVC are mostly arteries and rarely veins. Evaluation of NVC in the deep infratentorial region is inseparably connected with cranial imaging. We retrospectively analyzed the potential influence of three-dimensional (3D) virtual reality (VR) reconstructions compared to conventional magnetic resonance imaging (MRI) scans on the evaluation of NVC for the surgical planning of microvascular decompression in patients with TN.

METHODS

Medical files were retrospectively analyzed regarding patient- and disease-related data. Preoperative MRI scans were retrospectively visualized via VR software to detect the characteristics of NVC. A questionnaire of experienced neurosurgeons evaluated the influence of VR visualization technique on identification of anatomical structures involved in NVC and on surgical strategy.

RESULTS

Twenty-four patients were included and 480 answer sheets were evaluated. Compared to conventional MRI, image presentation using 3D-VR modality significantly influenced the identification of the affected trigeminal nerve (p = 0.004), the vascular structure involved in the NVC (p = 0.0002), and the affected side of the trigeminal nerve (p = 0.005).

CONCLUSIONS

In patients with TN caused by NVC, the reconstruction of conventional preoperative MRI scans and the spatial and anatomical presentation in 3D-VR models offers the possibility of increased understanding of the anatomy and even more the underlying pathology, and thus influences operation planning and strategy.

Characteristics and management of the offending veins in microvascular decompression surgery for trigeminal neuralgia

The optimal technique of microvascular decompression (MVD) for trigeminal neuralgia (TN) caused by venous conflict remains unclear. The objectives of this study are to characterize the offending veins identified during MVD for TN and to evaluate intraoperative technique applied for their management. From 2007 till 2019, 308 MVD surgeries were performed in 288 consecutive patients with TN, and in 58 of them, pure venous conflict was identified. In 44 patients, the offending vein was interrupted, as was done for small veins arising from the cisternal trigeminal nerve (CN V) or its root entry zone (REZ) causing their stretching (19 cases), small veins on the surface of REZ (9 cases), transverse pontine vein (TPV) compressing REZ or distal CN V (12 cases), and superior petrosal vein (SPV) using flow conversion technique (4 cases). In 14 other cases, the offending vein was relocated, as was done for the SPV or the vein of cerebellopontine fissure (8 cases), TPV (3 cases), and the vein of middle cerebellar peduncle (3 cases). Complete pain relief after surgery was noted in 49 patients (84%). No one patient experienced major neurological deterioration. Postoperative facial numbness developed in 14 patients (24%), and in 8 of them, it was permanent. In 14 patients, MRI demonstrated venous infarction of the middle cerebellar peduncle, which was associated with the presence of any (P = 0.0180) and permanent (P = 0.0002) facial numbness. Ten patients experienced pain recurrence. Thus, 39 patients (67%) sustained complete pain relief at the last follow-up (median, 48 months), which was significantly associated with the presence of any (P = 0.0228) and permanent (P = 0.0427) postoperative facial numbness. In conclusion, in cases of TN, small offending veins arising from REZ and/or distal CN V and causing their stretching may be coagulated and cut. In many cases, TPV can be also interrupted safely or considered as collateral way for blood outflow. The main complication of such procedures is facial numbness, which is associated with the venous infarction of middle cerebellar peduncle and long-term complete pain relief.

Use of Superior Petrosal Venous Complex to Transpose the Superior Cerebellar Artery in Microvascular Decompression for Trigeminal Neuralgia: 2-Dimensional Operative Video

Trigeminal neuralgia is a cause of severe facial pain, usually provoked by a neurovascular conflict, commonly involving the superior cerebellar artery (SCA).¹ The superior petrosal venous complex is in the way toward the nerve through a retrosigmoid approach and can narrow the working area around trigeminal nerve.^2-4 Nonetheless, instead an obstacle it can be faced in selected cases as an adjunct to help to transpose the offending arterial loop, avoiding undesired venous sacrifice. We present a case of a 64-year-old man with left-sided severe shock-like pain in the V3 territory suggestive of trigeminal neuralgia (Video 1). Preoperative imaging depicted a neurovascular conflict between SCA and trigeminal nerve root. A retrosigmoid approach was implemented, and stimulation of the compression point was consistent with the preoperative referred pain.⁵ Considering the thick superior petrosal vein (SPV), we transposed the offending artery and anchored it over a SPV tributary.⁶ In this way no prosthetic material was placed in contact with trigeminal nerve, minimizing chance of recurrence.^7-9 No abnormality on neurophysiological monitoring was reported, and postoperative imaging demonstrated no edema or hemorrhage, as well successful displacement of SCA. Patient presented complete resolution of pain and no new neurological deficit after 1 year of follow-up. This case is an uncommon report depicting a helpful intraoperative decision to be considered in selected cases to avoid venous sacrifice and preclude prosthetic material in contact with the nerve. Anatomical pictures courtesy of the Rhoton Collection, American Association of Neurological Surgeons (AANS)/Neurosurgical Research and Educational Foundation (NREF).

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.

Arachnoid bands and venous compression as rare causes of hemifacial spasm: analysis of etiology in 353 patients

BACKGROUND

Hemifacial spasm is usually caused by arterial compression at the root exit zone of the facial nerve. However, other etiologies have been reported. The aim of this study was to analyze the frequency of other causes of hemifacial spasm.

METHODS

Our prospectively maintained hemifacial spasm database containing all patients who underwent microvascular decompression (MVD) for hemifacial spasm from 2002 to 2018 was reviewed. All offending structures were identified and recorded by the surgeon at the time of surgery. Additionally, the operative videos were analyzed retrospectively.

RESULTS

MVD was performed in 353 patients. Arterial compression was the main cause of hemifacial spasm in 341 (96.9%) patients. Combined venous-arterial compression was seen in 7 (2.0%) patients. In one patient, the compression was from a large vein. In two patients, no compression was found. One patient who suffered from Bell's palsy many years previously had severe synkinesis and the other had facial tics. In two patients, the spasm was caused due to strangulation of the facial nerve by arachnoid bands. Long-term follow-up of more than 18 months was available in 249 patients with total resolution or near total resolution of spasms in 89.96% of patients.

CONCLUSIONS

In most patients with hemifacial spasm, arterial vessels are involved in compressing the facial nerve. Purely venous compression is rarely encountered. We report for the very first time arachnoid bands strangulating the nerve as a cause for hemifacial spasm without involvement of any vessel.

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.

Trigeminal root massage in microsurgical treatment of trigeminal neuralgia patients without arterial compression: When, how and why

BACKGROUND

During the microsurgical exploration of trigeminal root in the pontocerebellar angle in patients with primary trigeminal neuralgia (TN) without an evident arterial compression, the surgeon is in an engaged situation because there are not well-established surgical strategies. The aim of this study is to describe in these cases the surgical maneuver we call "trigeminal root massage" (TRM).

METHODS

52 consecutive patients with primary trigeminal neuralgia who had undergone a microsurgical suboccipital retrosigmoid exploration of trigeminal root were reviewed. Among them we found 10 patients without an evident arterial compression after a thorough microsurgical exploration. In the great majority of these 10 cases, we noticed a venous contact to the trigeminal root along this cisternal trajectory, in most cases we have had to coagulate the compressive vein/s and then cut. All underwent a simple trigeminal root massage, without interposition of any material implant.

RESULTS

All 10 patients experienced immediate pain disappearance and the postoperative course was uneventful except one case with a severe complication: cerebellar swelling, meningitis and hydrocephaly. The recurrence rate was 40%. Six patients achieved pain relief without specific medication with an average follow-up period of 5 years. There have been no mortalities nor any postoperative anesthesia dolorosa.

CONCLUSIONS

The described maneuver provides an easy and simple alternative way in cases where during a microsurgical exploration of trigeminal root, where we don't find a clear arterial compression, with similar results than other possibilities such as partial sensory rhizotomy or more complicated and time consuming surgery as "nerve combing". Nevertheless, a 40% of pain recurrence after an average follow-up of 5 years means that is a good alternative, but not a definitive technique at the moment for permanent cure of trigeminal neuralgia without arterial compression.

Treatment of Venous Hemorrhage Between Vestibulocochlear Nerve and Hypertrophic Flocculus During Microvascular Decompression Procedure for Hemifacial Spasm

Hemifacial spasm is a kind of painless, intermittent, involuntary, and irregular unilateral facial muscles convulsion. Microvascular decompression has become the standard surgical procedure for hemifacial spasm after years of popularization and development. In the article, the authors described in detail a therapeutic strategy for rapid intracranial venous bleeding between vestibulocochlear nerve and hypertrophic flocculus. When simple compression hemostasis failed, the authors applied fibrin glue and gelatin sponges for hemostasis and finally successfully controlled venous bleeding. The patient's symptoms were completely relieved after operation. Routine postoperative examination of head computed tomography revealed no intracranial hemorrhage. The combination of fibrin glue and gelatin sponges may be a possible solution for complicated and intractable venous hemorrhage during microvascular decompression procedure in some patients with hemifacial spasm.

Vascular Complications in Microvascular Decompression: A Survey of 4000 Operations

BACKGROUND

Vascular complications in posterior fossa surgery, even in microvascular decompression (MVD) involving a small cranial opening, can have catastrophic consequences. We analyzed these complications to determine the incidence, risk factors, prognosis, and preventive measures involved.

METHODS

Between April 1997 and March 2018, 4000 consecutive patients with neurovascular compression syndrome were admitted and underwent MVD. We reviewed the medical records of patients who developed vascular complications after MVD, focusing on their past medical history, perioperative laboratory findings and images, surgical findings, and postoperative progress.

RESULTS

Vascular complications developed in 28 patients (0.7%), including 24 with hemifacial spasm and 4 with trigeminal neuralgia. Twenty-two hemorrhagic (78.6%) and 6 ischemic (21.4%) complications occurred, with epidural hematoma the most frequent type identified. Ten patients (35.7%) patients were asymptomatic and 18 (64.3%) were symptomatic. Six patients (21.4%) underwent revision surgery, such as hematoma removal, craniectomy, or extraventricular drainage insertion. At the last follow-up, dizziness was the most commonly reported sequela from vascular complications. No deaths had occurred.

CONCLUSIONS

Vascular complications are rare, but can be the most devastating adverse outcome of MVD surgery. Unusual signs and symptoms after MVD should prompt special attention to early management and patient safety.

Combined Hyperactive Dysfunction Syndrome of the Cranial Nerves: Analysis of 37 Cases and Literature Review

BACKGROUND

Hyperactive dysfunction syndrome (HDS) of the cranial nerves, such as trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia (GPN), is commonly managed by microsurgical treatment. However, certain patients may present a combination of these syndromes in the neurosurgery department. Here, we aimed to retrospectively assess patients with combined HDS from a single center.

METHOD

Of 1275 consecutive patients with HDS treated at our center between 2007 and 2017, 37 patients with combined HDS were enrolled, and their medical and surgical records were analyzed.

RESULTS

The patients with combined HDS, accounting for 2.9% of all patients with HDS, included 22 patients with bilateral TN, 5 patients with TN-HFS, 8 patients with TN-GPN, and 2 patients with GPN-HFS. A comparison of patients with single and combined HDS indicated a significant difference in the mean age at initial diagnosis (63.57 vs. 56.18 years, P = 0.000) but no such difference in the sex ratio (0.54 vs. 0.59, P = 0.865) or incidence of hypertension (32.43% vs. 24.56%, P = 0.274). In total, 32 microvascular decompression (MVD) procedures were performed in the 27 patients with combined HDS, and repeated MVD was required in 5 patients with bilateral TN. Of the 27 patients who underwent MVD, 25 (92.6%) experienced clinical cure or obvious alleviation.

CONCLUSIONS

Combined HDS involves a group of functional disturbance disorders affecting specific cranial nerves, and it may include TN, HFS, and GPN. In addition to gender and incidence of hypertension, age appeared to be a vital indicator for the development of combined HDS, although this finding was inconsistent in previous studies. MVD appears to be a safe and effective treatment for combined HDS, with a high rate of long-term success.