Angiographic measurement of the superficial temporal artery for potential use in cerebral bypass surgery: a combined radiological and cadaveric study

PURPOSE

This study aims to investigate the microsurgical anatomy of the superficial temporal artery (STA), explore the relationship between STA length and lumen diameter, and develop a reliable radiologic method for selecting STA segments for bypass surgery.

METHODS

This study used 10 cadaveric dissections (20 STAs, both sides) and 20 retrospective radiological examinations (40 STAs, both sides), employing curved multiplanar reformation and flow color lookup table (CLUT) DICOM processing. Measurements included vessel lumen diameters and luminal cross-sectional thicknesses 3 mm proximal to the STA bifurcation, 3 mm distal to the frontal branch, 5 cm distal to the frontal branch, 3 mm distal to the parietal branch, and 5 cm distal to the parietal branch. The distance between the STA bifurcation and the superior zygomatic border (SZB) was also measured. In our analysis, descriptive statistics encompassed mean, standard deviation (SD), standard error, minimum and maximum values, and distributions. Comparative statistics were performed using Student's t-test, with statistical significance set at p < 0.05.

RESULTS

There were no statistically significant differences between STA measurements of bifurcation distances (p = 0.88) and lumen diameters (p = 0.46) between cadavers and radiological measures. However, lumen thicknesses were larger in frontal branches than parietal branches at the seventh and eighth centimeter (p = 0.012, p = 0.039). Branches became thinner distally from the zygoma in both cadavers and radiological image measurements.

CONCLUSION

The CLUT DICOM processing radiological measures provided the high-precision required to enable pre-surgical vessel selection for extracranial-intracranial bypass. The results show that STA vessel luminal diameters are sufficient (> 1 mm) for bypass surgery in the first 9 cm but gradually decrease after that. Also shown is that the choice of frontal versus parietal branches depends on individual anatomical features; therefore, careful preoperative radiological examination is critical.

Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle

PURPOSE

Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes.

METHODS

In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor.

RESULTS

The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission.

CONCLUSION

The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.

Comparative Anatomic Analysis of Neuronavigated Transmastoid-Infralabyrinthine Approaches for Jugular Fossa Pathologies: Short Anterior Rerouting Versus Nonrerouting and Tailored Nonrerouting Techniques

BACKGROUND AND OBJECTIVES

Access to the jugular fossa pathologies (JFPs) via the transmastoid infralabyrinthine approach (TI-A) using the nonrerouting technique (removing the bone anterior and posterior to the facial nerve while leaving the nerve protected within the fallopian canal) or with the short-rerouting technique (rerouting the mastoid segment of the facial nerve anteriorly) has been described in previous studies. The objective of this study is to compare the access to Fisch class C lesions (JFPs extending or destroying the infralabyrinthine and apical compartment of the temporal bone with or without involving the carotid canal) between the nonrerouting and the short-rerouting techniques. Also, some tailored steps to the nonrerouting technique (NR-T) were outlined to enhance access to the jugular fossa (JF) as an alternative to the short-rerouting technique.

METHODS

Neuronavigated TI-A was performed using the nonrerouting, tailored nonrerouting, and short-rerouting techniques on both sides of 10 human head specimens. Exposed area, horizontal distance, surgical freedom, and horizontal angle were calculated using vector coordinates for nonrerouting and short-rerouting techniques.

RESULTS

The short-rerouting technique had significantly higher values than the NR-T ( P < .01) for the exposed area (169.1 ± SD 11.5 mm 2 vs 151.0 ± SD 12.4 mm 2 ), horizontal distance (15.9 ± SD 0.6 mm vs 10.6 ± SD 0.5 mm 2 ), surgical freedom (19 650.2 ± SD 722.5 mm 2 vs 17 233.8 ± SD 631.7 mm 2 ), and horizontal angle (75.2 ± SD 5.1° vs 61.7 ± SD 4.6°). However, adding some tailored steps to the NR-T permitted comparable access to the JF.

CONCLUSION

Neuronavigated TI-A with the short-rerouting technique permits wider access to the JF compared with the NR-T. However, the tailored NR-T provides comparable access to the JF and may be a better option for class C1 and selected class C2 and C3 JFPs.

Subcutaneous preservation versus cryopreservation of autologous bone grafts for cranioplasty: A systematic review and meta-analysis

BACKGROUND

Cranioplasty corrects cranial bone defects using various bone substitutes or autologous bone flaps created during a previous craniectomy surgery. These autologous bone flaps can be preserved through subcutaneous preservation (SP) or cryopreservation (CP).

AIM

We aim to compare outcomes and complications for both SP and CP techniques to enhance the current evidence about autologous bone flap preservation.

METHODS

Five electronic databases were searched to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. We categorized surgical site infection (SSI) as either due to Traumatic brain injury (TBI) or not to reveal potential variations in SSI incidence. The double-arm meta-analysis utilized risk ratios (RR) and mean differences (MD) with corresponding confidence intervals (CI) to pool categorical and continuous outcomes, respectively. Proportions with their respective 95% CIs were pooled for single-arm meta-analyses to determine outcomes related to SP technique.

RESULTS

Seventeen studies involving 1169 patients were analyzed. No significant difference in SSI rates was observed between SP and CP methods in patients with or without TBI. SP was linked to shorter hospital stays in two studies (194 patients). Single-arm analysis showed a 17% revision surgery rate across five studies (375 patients) and infection rates in 17 studies for SP. New bone formation occurred in 13.2% of patients, with 19.9% showing resorption.

CONCLUSION

SP and CP methods showed similar SSI rates post-craniectomy in TBI and non-TBI patients. SP was associated with reduced hospitalization time, low infection rates, and a moderate need for revision surgery.

The importance of considering competing risks in recurrence analysis of intracranial meningioma

BACKGROUND

The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated.

METHODS

We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions.

RESULTS

Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions).

CONCLUSION

The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions.

A new classification of parasagittal bridging veins based on their configurations and drainage routes pertinent to interhemispheric approaches: a surgical anatomical study

OBJECTIVE

Opening the roof of the interhemispheric microsurgical corridor to access various neurooncological or neurovascular lesions can be demanding because of the multiple bridging veins that drain into the sinus with their highly variable, location-specific anatomy. The objective of this study was to propose a new classification system for these parasagittal bridging veins, which are herein described as being arranged in 3 configurations with 4 drainage routes.

METHODS

Twenty adult cadaveric heads (40 hemispheres) were examined. From this examination, the authors describe 3 types of configurations of the parasagittal bridging veins relative to specific anatomical landmarks (coronal suture, postcentral sulcus) and their drainage routes into the superior sagittal sinus, convexity dura, lacunae, and falx. They also quantify the relative incidence and extension of these anatomical variations and provide several preoperative, postoperative, and microneurosurgical clinical case study examples.

RESULTS

The authors describe 3 anatomical configurations for venous drainage, which improves on the 2 types that have been previously described. In type 1, a single vein joins; in type 2, 2 or more contiguous veins join; and in type 3, a venous complex joins at the same point. Anterior to the coronal suture, the most common configuration was type 1 dural drainage, occurring in 57% of hemispheres. Between the coronal suture and the postcentral sulcus, most veins (including 73% of superior anastomotic veins of Trolard) drain first into a venous lacuna, which are larger and more numerous in this region. Posterior to the postcentral sulcus, the most common drainage route was through the falx.

CONCLUSIONS

The authors propose a systematic classification for the parasagittal venous network. Using anatomical landmarks, they define 3 venous configurations and 4 drainage routes. Analysis of these configurations with respect to surgical routes indicates 2 highly risky interhemispheric surgical fissure routes. The risks are attributable to the presence of large lacunae that receive multiple veins (type 2) or venous complex (type 3) configurations that negatively impact a surgeon's working space and degree of movement and thus are predisposed to inadvertent avulsions, bleeding, and venous thrombosis.

Two-Stage Surgical Management for Acutely Presented Large Vestibular Schwannomas: Report of Two Cases

The surgical management of vestibular schwannomas should be based on their presentation, neuro-imaging findings, surgeons' expertise, and logistics. Multi-stage surgery can be beneficial for large-sized lesions with acute presentations. Herein, we highlighted the indications for two cases managed initially through the retrosigmoid and, subsequently, translabyrinthine approaches. The first case presented with acute balance and gait issues and a long history of hearing loss and blurred vision. Neuroimaging findings revealed a cerebellopontine angle lesion, resembling a vestibular schwannoma, with significant brainstem compression and hydrocephalus. Due to the rapidly deteriorating clinical status and large-sized tumor, we first proceeded with urgent decompression via a retrosigmoid approach, followed by gross total resection via a translabyrinthine approach two weeks later. The second case presented with gradually worsening dizziness and hemifacial numbness accompanied by acute onset severe headaches and hearing loss. Neuroimaging findings showed a large cerebellopontine angle lesion suggestive of a vestibular schwannoma with acute intratumoral hemorrhage. Given the acute clinical deterioration and large size of the tumor, we performed urgent decompression with a retrosigmoid approach followed by gross total resection through a translabyrinthine approach a week later. Post-surgery, both patients showed excellent recovery. When managing acutely presented large-sized vestibular schwannomas, immediate surgical decompression is vital to avoid permanent neurological deficits.

A rapid clinical deterioration of a cervical exophytic intradural intramedullary sporadic hemangioblastoma diagnosed during pregnancy

Hemangioblastomas are benign CNS tumors that can occur sporadically or in conjunction with von Hippel-Lindau disease. While 2% of spinal cord tumors are hemangioblastomas, combined cervical hemangioblastomas and pregnancy is rare. Some reports suggest that hemodynamic and hormonal changes in pregnancy might increase hemangioblastoma growth and aggravate symptoms. Urgent tumor removal is required when neurological problems deteriorate after failed symptomatic treatment. Neurosurgeons should collaborate with anesthesiologists and obstetricians in such cases. Herein, the authors present the first known video case of a sporadic cervical hemangioblastoma diagnosed during pregnancy that required urgent surgery due to failed symptomatic treatment and progressive clinical deterioration.

Human ventromedial prefrontal cortex lesions enhance the effect of expectations on pain perception

Pain is strongly modulated by expectations and beliefs. Across species, subregions of ventromedial prefrontal cortex (VMPFC) are implicated in a variety of functions germane to pain, predictions, and learning. Human fMRI studies show that VMPFC activity tracks expectations about pain and mediates expectancy effects on pain-related activity in other brain regions. Prior lesion studies suggest that VMPFC may instead play a more general role in generating affective responses to painful stimuli. To test whether VMPFC is required to generate affective responses to pain or is more specifically involved in expectancy-based pain modulation, we studied responses to heat stimuli in five adults with bilateral surgical lesions of VMPFC and twenty healthy adults without brain damage. All participants underwent a quantitative sensory testing procedure followed by a pain expectancy task in which cues predicting either low or high pain were followed by intermittent medium intensity heat stimuli. Compared to adults without brain damage, individuals with VMPFC lesions reported larger differences in expected pain based on predictive cues and failed to update expectations following the covert introduction of unexpected medium temperature stimuli. Consistent with observed expectancy differences, subjective pain unpleasantness ratings in the VMPFC lesion group were more strongly modulated by cue during thermal stimulation. We found no group differences in overall pain sensitivity, nor in relationships between pain and autonomic arousal, suggesting that VMPFC damage specifically enhances the effect of expectations on pain processing, likely driven by impaired integration of new sensory feedback to update expectations about pain. These results provide essential new data regarding the specific functional contribution of VMPFC to pain modulation.

Microneurosurgical treatment of a small perimesencephalic pure pial arterial malformation: an under-recognized etiology of angiographically occult subarachnoid hemorrhage. Illustrative case

BACKGROUND

Pial arterial malformations (PAMs) are rare vascular lesions consisting of dilated tortuous arteries without venous drainage. Current PAM understanding is limited by the lesion's rarity, limited anatomopathological studies, and frequent misclassifications.

OBSERVATIONS

A 23-year-old male experienced two spontaneous subarachnoid hemorrhages (SAHs) over 6 months with initially unremarkable diagnostic cerebral angiograms. Magnetic resonance imaging (MRI) and angiography after the second SAH revealed a small perimesencephalic ovoid lesion within the left crural cistern, between the left superior and posterior cerebral arteries, appearing to be an exophytic cavernoma, a thrombosed aneurysm, or a hemorrhagic tumor. Microsurgical resection was achieved with a pterional craniotomy and anterior clinoidectomy. The resected lesion was characteristic of a pure PAM arising from superior cerebellar arterial branches.

LESSONS

Small pure PAMs can be deceitfully dynamic lesions causing episodes of hemorrhage, complete thrombosis (angiographically occult), recanalization, and rehemorrhage. Small thrombosed vascular malformations or aneurysms should be included in differential diagnoses of angiographically occult SAH. MRI can be diagnostic, but the true angioarchitecture can only be elucidated with microneurosurgery. The only definitive cure is removal. The microneurosurgical strategy should account for worst-case scenarios, provide adequate skull base exposures, and include bypass revascularization options when thrombosed aneurysms are encountered.

A Neuroenteric Cyst of the Cavernous Sinus: A Case Report

Background  Neuroenteric cysts (NECs) are benign lesions mostly found as intradural extramedullary lesions in the cervicothoracic spinal cord. NECs in the cavernous sinus are very rare. To the best of our knowledge, this is only the second reported case and the first in an adult. Presentation  We present a left cavernous sinus NEC in a 75-year-old female with gradually worsening headache and facial pain unresponsive to medical treatment. Imaging revealed a cystic mass lesion in the left cavernous sinus encasing the distal petrosal and cavernous segment of the internal carotid artery. Initial differential diagnoses included more common pathologies located near the cavernous sinus, including cystic schwannoma, craniopharyngioma, and dermoid and epidermoid tumors. The patient underwent a left pterional craniotomy with an extradural transcavernous approach for surgical exploration and possible resection of this mass lesion. Histopathology revealed an NEC lined with benign respiratory-type epithelium. Postoperative imaging revealed gross total tumor resection. The patient remained neurologically intact with complete resolution of facial pain. Conclusion  We present a rare pathology that can easily be misinterpreted as other types of lesions. NECs should be kept in mind for differential diagnosis of cavernous sinus cystic lesions. The surgical aim should be maximal safe excision.

Microsurgical Obliteration of Craniocervical Junction Dural Arteriovenous Fistulas: Multicenter Experience

BACKGROUND

Dural arteriovenous fistulas (dAVFs) located at craniocervical junction are extremely rare (1%-2% of intracranial/spinal dAVFs). Their angio-architectural complexity renders endovascular embolization to be challenging given multiple small feeders with risk of embolysate reflux into vertebral artery and limited transvenous access. The available literature discussing microsurgery for these lesions is limited to few case reports.

OBJECTIVE

To report a multicenter experience assessing microsurgery safety/efficacy.

METHODS

Prospectively maintained registries at 13 North American centers were queried to identify craniocervical junction dAVFs treated with microsurgery (2006-2021).

RESULTS

Thirty-eight patients (median age 59.5 years, 44.7% female patients) were included. The most common presentation was subarachnoid/intracranial hemorrhage (47.4%) and myelopathy (36.8%) (92.1% of lesions Cognard type III-V). Direct meningeal branches from V3/4 vertebral artery segments supplied 84.2% of lesions. All lesions failed (n = 5, 13.2%) or were deemed inaccessible/unsafe to endovascular treatment. Far lateral craniotomy was the most used approach (94.7%). Intraoperative angiogram was performed in 39.5% of the cases, with angiographic cure in 94.7% of cases (median imaging follow-up of 9.2 months) and retreatment rate of 5.3%. Favorable last follow-up modified Rankin Scale of 0 to 2 was recorded in 81.6% of the patients with procedural complications of 2.6%.

CONCLUSION

Craniocervical dAVFs represent rare entity of lesions presenting most commonly with hemorrhage or myelopathy because of venous congestion. Microsurgery using a far lateral approach provides robust exposure and visualization for these lesions and allows obliteration of the arterialized draining vein intradurally as close as possible to the fistula point. This approach was associated with a high rate of angiographic cure and favorable clinical outcomes.

An interdisciplinary consensus on the management of brain metastases in patients with renal cell carcinoma

Brain metastases are a challenging manifestation of renal cell carcinoma. We have a limited understanding of brain metastasis tumor and immune biology, drivers of resistance to systemic treatment, and their overall poor prognosis. Current data support a multimodal treatment strategy with radiation treatment and/or surgery. Nonetheless, the optimal approach for the management of brain metastases from renal cell carcinoma remains unclear. To improve patient care, the authors sought to standardize practical management strategies. They performed an unstructured literature review and elaborated on the current management strategies through an international group of experts from different disciplines assembled via the network of the International Kidney Cancer Coalition. Experts from different disciplines were administered a survey to answer questions related to current challenges and unmet patient needs. On the basis of the integrated approach of literature review and survey study results, the authors built algorithms for the management of single and multiple brain metastases in patients with renal cell carcinoma. The literature review, consensus statements, and algorithms presented in this report can serve as a framework guiding treatment decisions for patients. CA Cancer J Clin. 2022;72:454-489.

Transcavernous Resection of a Giant Extensive Chondrosarcoma with Endoscopic Assistance

Chondrosarcomas are one of the major malignant neoplasms which occur at the skull base. These tumors are locally invasive. Gross total resection of chondrosarcomas is associated with longer progression-free survival rates. The patient is a 55-year-old man with a history of dysphagia, left eye dryness, hearing loss, and left-sided facial pain. Magnetic resonance imaging (MRI) showed a giant heterogeneously enhancing left-sided skull base mass within the cavernous sinus and the petrous apex with extension into the sphenoid bone, clivus, and the cerebellopontine angle, with associated displacement of the brainstem (Fig. 1). An endoscopic endonasal biopsy revealed a grade-II chondrosarcoma. The patient was then referred for surgical resection. Computed tomography (CT) scan and CT angiogram of the head and neck showed a left-sided skull base mass, partial destruction of the petrous apex, and complete or near-complete occlusion of the left internal carotid artery. Digital subtraction angiography confirmed complete occlusion of the left internal carotid artery with cortical, vertebrobasilar, and leptomeningeal collateral development. The decision was made to proceed with a left-sided transcavernous approach with possible petrous apex drilling. During surgery, minimal petrous apex drilling was necessary due to autopetrosectomy by the tumor. Endoscopy was used to assist achieving gross total resection (Fig. 2). Surgery and postoperative course were uneventful. MRI confirmed gross total resection of the tumor. The histopathology was a grade-II chondrosarcoma. The patient received proton therapy and continues to do well without recurrence at 4-year follow-up. This video demonstrates steps of the combined microsurgical skull base approaches for resection of these challenging tumors.

The link to the video can be found at: https://youtu.be/WlmCP_-i57s.

A Posterior Communicating Segment Aneurysm of the Supraclinoid Internal Carotid Artery Treated with an Extracranial to Intracranial Bypass and Trapping

Surgical treatment of giant aneurysms often poses significant challenges. Endovascular techniques have evolved exponentially over the last decades, and most of these complex aneurysms can be treated with flow-diverting techniques; however, successful obliteration of all giant aneurysms is not always possible with endovascular flow-diverting techniques. Although the need for microsurgical intervention has undoubtedly diminished, a versatile-thinking surgeon should keep in mind that obliteration of these aneurysms combined with revascularizing the distal circulation via extracranial–intracranial bypass techniques can provide a potentially life-long durable solution. The key to curing these pathologies is to utilize interdisciplinary decision making with a robust knowledge of the pros and cons of different treatment approaches. Herein, we present a case of a giant posterior communicating segment aneurysm of the left supraclinoid internal carotid artery (ICA), which was treated by obliteration ( Fig. 1 ). Extradural anterior clinoidectomy was used to provide exposure of the supraclinoidal ICA proximal to the aneurysm, and revascularization of the distal circulation was achieved with a common carotid artery to M2-superior trunk bypass using a radial artery interposition graft ( Fig. 2 ). The patient was a 62-year-old female who presented with vision loss in her left eye but was otherwise neurologically intact. She had a history of two unsuccessful flow-diverting stent placement attempts 2 months prior to this surgery. Postoperatively, the patient woke up without any deficits, with her left eye vision partially recovered and ultimately returning to normal at 1-year follow-up. Computed tomography (CT) angiography at a 1-year follow-up showed complete obliteration of the aneurysm and successful revascularization of the distal circulation.

The link to the video can be found at: https://youtu.be/DsIuIJJj1l4 .

Clip Reconstruction of a Previously Leaked Large Complex Posterior Communicating Segment Aneurysm with Extradural Anterior Clinoidectomy

Fusiform or near-fusiform aneurysms that involve the long segment of the supraclinoid internal carotid artery (ICA) pose significant challenges to neurovascular surgeons. Involvement of the origin of vital branching arteries in this segment may preclude safe treatment with flow diverting stents. In addition, clip reconstruction may also not be possible in this region due to entire or near-entire involvement of the circumference of the ICA ( Fig. 1 ). In this video article, we present a case of a complex and previously leaked, (visualized with hemosiderin) aneurysm of the posterior communicating segment of the ICA, in a 60-year-old female. Multiple complexities made this aneurysm challenging to treat. These included (1) a 270-degree encirclement of the ICA with multiple lobulations that left only a small section of nondiseased vessel wall, (2) a relatively short segment of the supraclinoidal ICA that made proximal control challenging thus requiring an extradural anterior clinoidectomy, (3) a fetal posterior communicating artery that originated immediately proximal to the beginning of the aneurysm, and lastly, (4) an anterior choroidal artery that was firmly adherent over the aneurysm dome. In this video, we present the microsurgical steps for dealing with this complex aneurysm, including extradural clinoidectomy and clip reconstruction ( Fig. 2 ). Postoperatively, the patient woke up without any deficits. Angiography showed complete obliteration of the aneurysm.

The link to the video can be found at: https://youtu.be/3Zz-ecvlDIc .

Combined Transcavernous and Kawase's Approach for Gross Total Resection of a Cavernous Sinus Meningioma

Microsurgery of cavernous sinus (CS) lesions is generally considered to be associated with a high rate of morbidity and cranial nerve deficits. The success for surgical removal of CS meningiomas is debatable and achieving a good functional outcome with preservation of the cranial nerves is the goal. Surgery of these lesions is challenging, recurrence rates are high, and therapeutic strategies remain controversial. In this video, we present a case of a CS meningioma that extended to Meckel's cave and the posterior fossa in a 46-year-old woman with history of a left-sided cerebellopontine angle World Health Organization (WHO) grade-I meningioma with extension to the left CS. Seven years ago, she had a microsurgical resection of a Cerebellopontine angle (CPA) meningioma. She later received radiotherapy for the slowly growing meningioma of the posterior CS. The patient presented with newly onset headache and facial pain. Magnetic resonance imaging (MRI) showed a meningioma of the left CS and Meckel's cave extending into the ambient cistern, with a mild mass effect on the pons, and a size increase compared with prior imaging. Since this area previously received radiotherapy, and the patient was symptomatic from trigeminal compression, the decision was made to proceed with surgical resection of the tumor via combined transcavernous and anterior petrosectomy. Postoperatively, the patient woke up with the same neurological status. MRI confirmed gross total resection of the tumor. The histopathology was a WHO grade-II chordoid meningioma. The patient is currently receiving radiotherapy. This video demonstrates the surgical approach and the resection steps of this pathology.

The link to the video can be found at: https://youtu.be/HrU1VOzUGWU .

What you need to know about: arterial cerebrovascular syndromes caused by static or dynamic musculoskeletal compression

Compressive syndromes of the cervical arteries caused by musculoskeletal structures include bow hunter's syndrome, beauty parlour stroke syndrome, carotid compression by the hyoid bone, carotid compression by the digastric muscle and Eagle syndrome. They are a rare but increasingly recognised group of syndromes, so a high level of suspicion is needed so the diagnosis is not missed. The diagnosis is typically based on a combination of clinical history and advanced imaging investigations. Compression of the arteries may be static (only provoked by compression) or dynamic (exaggerated by movement), and this should be considered when selecting imaging studies. Symptoms resulting from vertebrobasilar insufficiency or ischaemia of areas supplied by the internal carotid artery are caused by compression of the vertebral artery and the internal carotid artery respectively. Surgical procedures are the preferred treatment for most of these syndromes.

The role of microsurgery for poor-grade aneurysmal subarachnoid hemorrhages in the endovascular era

BACKGROUND

Poor-grade aneurysmal subarachnoid hemorrhage (PGASAH) is associated with high mortality and morbidity regardless of treatment. Herein, we re-evaluate the safety and efficacy of microsurgical treatment for managing PGASAH patients in the current endovascular era.

METHODS

We retrospectively reviewed 141 consecutive patient records in a single institution who underwent microsurgical (n = 80) or endovascular (n = 61) treatment for PGASAH.

RESULTS

Baseline characteristics were similar, except for more intracerebral hematomas (46.3% vs 24.6%, p = 0.009), fewer intraventricular hemorrhages (26.3% vs 59%, p < 0.001), and fewer posterior circulation aneurysms (5.1% vs 44.3%, p < 0.001) in the microsurgery group. Decompressive craniectomy (58.5% vs 24.6%, p < 0.001) and shunt-dependent hydrocephalus (63.7% vs 41%, p = 0.01) were more common for microsurgery, while procedural ischemic complications were less common (5% vs 24.6%, p = 0.001). Both early (12.5% vs 32.8%, p = 0.006) and late mortality rates (22.5% vs 39.3%, p = 0.041) were lower for microsurgery, and favorable 12-month outcomes (modified Rankin scale = 0-2) were better (62.5% vs 42.6%, p = 0.026). Multivariate analysis revealed that advanced age, neurological grade, modified Fisher grade, larger aneurysm size, rebleeding, and cerebral infarctions were independent predictors of poor outcome. Microsurgery fared marginally better than endovascular treatment (OR: 2.630, 95% CI: [0.991-6.981], p = 0.052).

CONCLUSIONS

Timely and efficient treatment, either via open microsurgery or endovascular surgery, provided favorable outcomes for over half of PGASAH patients in this series. Therefore, early treatment should be offered to all PGASAH patients regardless of clinical and/or radiological factors. Microsurgery remains an effective treatment modality for selected PGASAH patients in the endovascular era.

Posterior Circulation Aneurysms

Posterior circulation aneurysms have a higher tendency to rupture and become symptomatic in comparison to anterior circulation aneurysms. Current treatment modalities for aneurysms in these locations vary widely including microsurgical clipping, trapping with bypass, wrapping, and various endovascular methods such as coiling, balloon or stent-assisted coiling, flow diversion, and vessel sacrifice, among others.Overall, surgical versus endovascular treatment of posterior circulation aneurysms continue to be a controversial topic in cerebrovascular neurosurgery. At our center, multi-disciplinary assessments including surgeons capable of both endovascular and microsurgical treatments of these aneurysms are employed to guide the treatment strategies. As advancements in both fields are made, this will continue to be a topic for debate. Anatomy and individual patient's characteristics will dictate the correct approach and therefore proficiency in the microsurgical techniques required to treat these aneurysms will continue to be both relevant and important.

Brainatomy-Demystifying the Temporal Bone, Rule of 3-2-1

BACKGROUND

The temporal bone is difficult to comprehend in three-dimensional (3D) space. We provide a novel 3D mental model of the temporal bone which helps clinicians and surgeons dealing with it in teaching, diagnosing, conservative managements, and preoperative and intraoperative orientation. This study is part of the scientific project Brainatomy.

OBJECTIVE

To analyze and simplify the temporal bone anatomy to enhance its comprehension and long-term retention.

METHODS

The study was conducted at the Neurosurgical Department of the University Hospital of Bochum, Germany. We retrospectively analyzed data sets of 221 adult patients who underwent computed tomography (CT) of the skull (n = 167) and magnetic resonance imaging (MRI) of the brain (n = 54). A total of 142 patients with their respective imaging scans remained in our pool of interest after excluding 79 scans. The raw digital imaging and communications in medicine scans were transformed into 3D objects. Spatial analyses were then conducted, and all collected data were used to create our own 3D model of the temporal bone.

RESULTS

We define the temporal bone as a prism-shaped model and divide it into 6 compartments: apex, neurovascular, mastoid, blank, tympanic, and temporomandibular compartments. The division into compartments has been achieved with the "Rule of 3-2-1." Finally, the 3D model has been used to record a video (Video), using a novel and "easy-to-follow" didactic approach.

CONCLUSION

This simplified 3D model along with the corresponding video (Video) potentially enhances the efficiency of studying temporal none anatomy with a novel "easy-to-follow" approach.

Ovoid Foramen Magnum Shape is Associated with Increased Complications and Decreased Extent of Resection for Anterolateral Foramen Magnum Meningiomas

Background  Antero-laterally located meningiomas of the foramen magnum (FM) pose significant surgical resection challenges. The effect of FM shape on surgical resection of FM meningiomas has not been previously studied. The present study investigates how FM shape effects the extent of tumor resection and complication rates in antero-lateral FM meningiomas. Materials and Methods  This retrospective study included 16 consecutive patients with antero-lateral FM meningiomas operated on by a single surgeon. FMs were classified as ovoid ( n  = 8) and nonovoid ( n  = 8) using radiographic evaluation. Results  Sixteen patients were examined: seven males and nine females (mean age of 58.5, and range of 29 to 81 years). Gross total resection was achieved in 81% of patients, with tumor encased vertebral arteries in 44%. Patient characteristics were similar including age, sex, preoperative tumor volume, relationship of vertebral artery with tumor, preoperative Karnofsky performance score (KPS), symptom duration, and presence of lower cranial nerve symptoms. The ovoid FM group had lower volumetric extents of resection without statistical significance (93 ± 10 vs. 100 ± 0%, p  = 0.069), more intraoperative blood loss (319 ± 75 vs. 219 ± 75 mL, p  = 0.019), more complications per patient (1.9 ± 1.8 vs. 0.3 ± 0.4, p  = 0.039), and poorer postoperative KPS (80 ± 21 vs. 96 ± 5, p  = 0.007). Hypoglossal nerve palsy was more frequent in the ovoid FM group (38 vs. 13%). Conclusion  This is the first study demonstrating that ovoid FMs may pose surgical challenges, poorer operative outcomes, and lower rates of extent of resection. Preoperative radiological investigation including morphometric FM measurement to determine if FMs are ovoid or nonovoid can improve surgical planning and complication avoidance.

The Suprasellar Meningioma Patient-Reported Outcome Survey: a disease-specific patient-reported outcome measure for resection of suprasellar meningioma

OBJECTIVE

Suprasellar meningioma resection via either the transcranial approach (TCA) or the endoscopic endonasal approach (EEA) is an area of controversy and active evaluation. Skull base surgeons increasingly consider patient-reported outcomes (PROs) when choosing an approach. No PRO measure currently exists to assess quality of life for suprasellar meningiomas.

METHODS

Adult patients undergoing suprasellar meningioma resection between 2013 and 2019 via EEA (n = 14) or TCA (n = 14) underwent semistructured interviews. Transcripts were coded using a grounded theory approach to identify themes as the basis for a PRO measure that includes all uniquely reported symptoms. To assess content validity, 32 patients and 15 surgeons used a Likert scale to rate the relevance of items on the resulting questionnaire and the general Patient-Reported Outcomes Measurement Information System-29 (PROMIS29). The mean scores were calculated for all items and compared for TCA versus EEA patient cohorts by using unpaired t-tests. Items on either questionnaire with mean scores ≥ 2.0 from patients were considered meaningful and were aggregated to form the novel Suprasellar Meningioma Patient-Reported Outcome Survey (SMPRO) instrument.

RESULTS

Qualitative analyses resulted in 55 candidate items. Relative to patients who underwent the EEA, those who underwent the TCA reported significantly worse future outlook before surgery (p = 0.01), tiredness from medications 2 weeks after surgery (p = 0.001), and word-finding and memory difficulties 3 months after surgery (p = 0.05 and < 0.001, respectively). The items that patients who received a TCA were most concerned about included medication-induced lethargy after surgery (2.9 ± 1.3), blurry vision before surgery (2.7 ± 1.5), and difficulty reading due to blurry vision before surgery (2.7 ± 2.7). Items that patients who received an EEA were most concerned about included blurry vision before surgery (3.5 ± 1.3), difficulty reading due to blurry vision before surgery (2.4 ± 1.3), and problems with smell postsurgery (2.9 ± 1.3). Although surgeons overall overestimated how concerned patients were about questionnaire items (p < 0.0005), the greatest discrepancies between patient and surgeon relevance scores were for blurry vision pre- and postoperatively (p < 0.001 and < 0.001, respectively) and problems with taste postoperatively (p < 0.001). Seventeen meningioma-specific items were considered meaningful, supplementing 8 significant PROMIS29 items to create the novel 25-item SMPRO.

CONCLUSIONS

The authors developed a disease- and approach-specific measure for suprasellar meningiomas to compare quality of life by operative approach. If demonstrated to be reliable and valid in future studies, this instrument may assist patients and providers in choosing a personalized surgical approach.

ABBREVIATIONS

EEA = endoscopic endonasal approach; GTR = gross-total resection; PRO = patient-reported outcome; PROMIS29 = Patient-Reported Outcomes Measurement Information System-29; QOL = quality of life; SMPRO = Suprasellar Meningioma Patient-Reported Outcome Survey; TCA = transcranial approach.

Navigating a Carotico-Clinoid Foramen and an Interclinoidal Bridge in the Endonasal Endoscopic Approach: An Anatomical and Technical Note

Objective  The carotico-clinoid foramen and interclinoid bridge are two anatomical variants of the sellar region. If these anatomical variants go unrecognized and are not managed safely by the surgeon during expanded endoscopic endonasal surgery for a posterior clinoidectomy, a carotid artery injury may occur. We summarize a method to safely navigate in the presence of the carotico-clinoid foramen and interclinoid bridge in an endoscopic endonasal approach. Study Design  The study involves cadaveric dissection and management of the anatomical variants. Setting  The study took place in a cadaveric dissection laboratory. Participants  The object of study is one cadaveric head. Main Outcome Measures  After discovering the two variants in both cavernous sinuses of a cadaveric head, we established a stepwise coping strategy to avoid carotid artery injury while performing an endoscopic endonasal bilateral interdural pituitary transposition, and we report the final view after endoscopic management. Results  Debulking of the middle clinoid process can decrease the obstacle effect, and the pituitary transposition can be performed medial to the ossified carotico-clinoid ligament. Disconnection of the interclinoid bridge is the prerequisite to an effective posterior clinoidectomy, and distinguishing the transition between the sellar diaphragm and the interclinoid bridge is essential. Conclusion  In the presence of both the carotico-clinoid foramen and the interclinoid bridge, a bilateral interdural pituitary transposition can still be performed, although preoperative strategic preparation, full inspection, and stepwise disconnections are of paramount importance in such a scenario to avoid cavernous carotid artery injury.

Meningioma of posterolateral tentorial incisura: a case demonstration of paramedian supracerebellar transtentorial approach

The paramedian supracerebellar transtentorial approach allows unobstructed exposure to the quadrigeminal cistern, tectal plate, pineal region, tentorial incisura, medial basal temporal lobe, and posterior ambient cistern. The authors present a meningioma of the posterolateral tentorial incisura case in a 62-year-old male who presented with a long history of upper-extremity tremors and walking difficulties. MRI revealed supra- and infratentorial tumor extension and hydrocephalus. This approach enabled us to achieve gross-total resection without causing neurovascular injury or any postoperative neurological deficits. For each pathology, the pros and cons of various approaches should be considered based on the anatomy, vasculature, and any surrounding structures.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2138.

Surgical approaches for resection of third ventricle colloid cysts: meta-analysis

Although outcome studies and systematic reviews have been published on the surgical treatment of third ventricle colloid cysts (TVCC), there are no meta-analyses that compare the outcomes for various surgical approaches. This meta-analysis assesses the outcomes and complications for transcortical, transcallosal, and endoscopic surgical approaches used to excise TVCCs. A meta-analysis of surgically excised TVCCs was performed with an assessment of outcome for transcortical, transcallosal, and endoscopic approaches. A random-effects model analyzed the extent of surgical excision. The analysis included reports that compared at least two of these surgical approaches, for a total of 11 studies comprising a population of 301 patients. The transcortical approach was associated with a higher incidence of complete excision compared to the endoscopic approach (OR = 0.137, p = 0.041), with no significant differences observed between transcortical and transcallosal approaches, and between transcallosal and endoscopic approaches. Comparison between endoscopic and pooled microsurgical approaches was also insignificant (OR = 0.22, p = 1). The risk of motor weakness was increased with the transcortical approach compared to the endoscopic approach (OR = 6.10, p = 0.018). There were no significant differences between transcortical and transcallosal approaches regarding newly onset seizures, and no significant mortality differences between all three approaches. This study demonstrates that microsurgical approaches are associated with a greater extent of resection compared to endoscopic approaches; however, best results are likely achieved based on the surgeon's expertise, flexibility, and case review.

Intraoperative application of a new-generation 3D IV-DSA technology in resection of a hemorrhagic cerebellar AVM

Although intravenous digital subtraction angiography (IV-DSA), cone-beam CT, and rotational angiography are well-established technologies, using them in a single system in the hybrid operating room to acquire high-quality noninvasive 3D images is a recent development. This video demonstrates microsurgical excision of a ruptured cerebellar arteriovenous malformation (AVM) in a 66-year-old male followed by intraoperative IV-DSA acquisition using a new-generation system (Artis Icono). IV-DSA confirmed in real time that no residual remained following excision without the need to reposition the patient. To the best of the authors’ knowledge, this is the first surgical video to demonstrate the simplified workflow and application of this technology in neurovascular surgery.

The video can be found here: https://youtu.be/bo5ya9DQQPw

Demonstration of Microsurgical Technique and Nuances for the Obliteration of Complex Intracranial Dural Arteriovenous Fistulas in Three Consecutive Cases: Operative Video

An intracranial dural arteriovenous fistula (DAVF) is an uncommon acquired dural shunt between an artery and a vein without a parenchymal nidus. DAVF occlusion may be achieved using either endovascular or open surgical means. Combining both techniques is also frequently used in clinical practice. In this video, we present 3 patients with Borden type III, complex intracranial DAVFs. The first patient presented with intracranial hemorrhage and underwent a successful microsurgical obliteration of the fistula in the tentorium. Two other patients had DAVFs that were incidentally found. Both underwent embolization procedures, which did not result in complete DAVF obliteration. Both patients then subsequently underwent microsurgical obliteration of these DAVFs. All 3 patients had very good outcomes. In 2 of these cases, we performed indocyanine green video angiography to identify fistulous connections. As demonstrated in this Video 1, microsurgical obliteration of DAVFs is relatively straightforward. This provides a valuable treatment option of some selected DAVFs and should be considered as a primary initial treatment option of complex DAVFs in certain locations. Open surgical obliteration is the best possible, most durable, and most effective therapeutic option when there are failures or shortcomings with endovascular management.

Trigeminal Neuralgia Caused by Vascular Compression from the Petrous Carotid Artery with Bony Erosion and Meckel Cave Encephalocele: Clinical Imaging with Surgical Video

Trigeminal neuralgia (TN) is most commonly caused by neurovascular compression of the superior cerebellar artery. We present the first reported TN case where nerve compression was caused by the petrous internal carotid artery in the vicinity of a Meckel cave (MC) encephalocele. The patient underwent a pterional craniotomy for decompression of the gasserian ganglion and trigeminal nerve branches. All symptoms were resolved post surgery. We surmise that the principal cause of the TN was vascular compression from an exposed petrous internal carotid artery in the presence of an encephalocele. Causation was irrespective of whether the dehiscence in the petrous apex was a congenital defect or associated with destruction from the encephalocele. Based on this observation, we recommend that surgeons carefully consider all possible causes of patient symptoms as they prepare a meticulous dissection plan to avoid damage to surrounding neurovascular structures.

Identification of the Distal Dural Ring and Definition of Paraclinoid Aneurysms According to Bony Landmarks on 3-Dimensional Computed Tomography Angiography: A Cadaveric and Radiological Study

BACKGROUND

Determining if paraclinoid aneurysms are intradural or extradural is critical for surgical planning.

OBJECTIVE

To create an easily reproducible diagnostic method based on bony anatomy that precisely locates the distal dural ring (DDR) to determine the position of paraclinoid aneurysms as intradural, transitional, or extradural.

METHODS

Bilateral anatomic dissections of 10 cadaveric heads (20 sides) were performed to evaluate DDR anatomy. We observed a plane that reflects the position of the DDR passes through 4 bony landmarks: 1) The anterior clinoid-internal carotid artery intersection, 2) the optic strut, 3) the optico-carotid elevation, and 4) the base of the posterior clinoid process. This landmark-based plane can thus define the location of the DDR using 3-dimensional computed tomography angiography (CTA). This was confirmed in 27 surgical patients with intradural/transitional aneurysms and 7 patients with extradural aneurysms confirmed with magnetic resonance imaging (MRI). The DDR plane method easily classified aneurysm locations as intradural (above the DDR plane), extradural (below the DDR plane), or transitional (the DDR plane crosses the aneurysm). The aneurysm's location was subsequently confirmed intraoperatively or with MRI.

RESULTS

The DDR plane method determined if paraclinoid aneurysms were intradural, transitional, or extradural in all 34 cases examined. The visibility of the anatomic features that define the DDR plane was also verified in 82% to 89% of CTA images from 100 patients.

CONCLUSION

The DDR plane method provides a useful diagnostic tool to evaluate the position of the DDR and determine the anatomic location of paraclinoid aneurysms.

Surgical Strategies for Cerebral Revascularization in Patients with Limited Bypass Conduit Options and Unexpected Intraoperative Difficulties

BACKGROUND

Cerebral bypass procedures are complex and require substantial experience and skills and thorough preoperative planning. Cerebrovascular surgeons face increasingly complex bypass cases because most routine cases are managed by endovascular means, and because increasing numbers of patients have complex medical problems that affect available and suitable bypass conduit options. We report the cases of several patients undergoing cerebral bypass with limited bypass conduit alternatives, in whom there were unexpected intraoperative difficulties requiring complex solutions.

METHODS

The neurological surgery department database was reviewed to identify patients who had undergone cerebral bypass procedures during a 13-year period in whom there were limited available bypass conduits, and in whom unexpected intraoperative difficulties were encountered during cerebral bypass.

RESULTS

Patient outcomes and graft patency were evaluated for 13 patients including 6 with ischemia, 3 with giant aneurysms, 2 with mycotic aneurysms, 1 with dissecting aneurysm, and 1 with gunshot-induced pseudoaneurysm. Median duration of follow-up was 43 months. In 12 of 13 patients, bypass graft/grafts were patent on the last computed tomography angiogram. In 1 patient, a prophylactic bypass procedure, the graft was not filling, probably because of lack of demand. Two patients died during follow-up of unrelated causes.

CONCLUSIONS

Cerebrovascular surgeons should be versatile in dealing with patients with complex bypass. When there are limited available conduit options, we find that collaboration with other surgical specialties (e.g., plastics and vascular) is helpful. In patients in whom extreme intraoperative difficulties are expected, thorough preoperative planning with multiple backup plans should be exercised, as described in this report.

Intraoperative Shortening of Aneurysm Clips: Revisiting an Old Technique in a New Era

BACKGROUND

It can sometimes be challenging to find a suitable clip to treat an unusual aneurysm, or when the surrounding anatomy is unusual, especially in resource-limited environments. We describe a method to modify aneurysm clips based on the method originated by Sugita et al in 1985. Herein clip modification (Clip-Mod) is used to treat anatomically difficult anterior communicating artery aneurysms.

METHODS

The Department of Neurological Surgery database was reviewed to find aneurysm patients treated using modified aneurysm clips. Clip-Mod was performed during surgery by shortening the tines of titanium aneurysm clips by abrasion applied from the side of a standard 3-mm surgical diamond drill bit under constant irrigation. Note that the thickness of the tines and the clip spring were not modified or contacted by the drill.

RESULTS

Four cases used modified aneurysm clips, from 648 total clip-treated aneurysms (0.6%) by 2 surgeons over a 14-year period. Three patients presented with subarachnoid hemorrhages that were determined to be due to anterior communicating artery aneurysms. One patient presented with an incidental unruptured anterior communicating artery aneurysm. All 4 patients were treated with 3-mm titanium clips shortened intraoperatively to 1- to 2-mm lengths, to achieve aneurysm obliteration without stenosing parent or perforating vessels.

CONCLUSIONS

All 4 patients have done well clinically with no reoccurrences after 2-6 years' follow-up, which included angiographic evaluation. The use of this "Clip-Mod" technique thus appears useful for anterior communicating artery aneurysms. Clip-Mod could also be considered for treating other aneurysms when the "perfect" length clip is not available.

Gross Total Resection of a Grade IV Astrocytoma Adjacent to the Precentral Gyrus With Nonawake Motor Mapping and Motor-Evoked Potential Monitoring: 3-Dimensional Operative Video

Surgical treatment of the gliomas located in or adjacent to the eloquent areas poses significant challenge to neurosurgeons. The main goal of the surgery is to achieve maximal safe resection while preserving the neurological function. This might be possible with utilizing pre- and intraoperative adjuncts such as functional magnetic resonance imaging (MRI), image guidance, mapping of the function of interest, intraoperative MRI, and neurophysiological monitoring. In this video, we demonstrate the utilization of nonawake mapping and motor-evoked potential (MEP) monitoring for the resection of a right-sided posterior superior frontal gyrus grade IV astrocytoma adjacent to the primary motor cortex. The patient is a 69-yr-old woman presented with multiple episodes of simple partial seizures involving her left leg and spreading to the left arm. MRI and functional MRI examinations showed a heterogeneously enhancing mass with peritumoral edema adjacent to the primary motor cortex. Because the patient did not want to undergo an awake craniotomy, a decision was made to perform the resection of the tumor with nonawake motor mapping and continuous MEP monitoring. Nonawake motor mapping and MEP monitoring enabled us to perform gross total resection. Because it has been shown that supratotal resection may provide improved survival outcome,1,2 we extended the white matter resection beyond the contrast enhancing area in noneloquent parts of the tumor. Surgical steps in dealing with vascular anatomy as well as utilizing intraoperative adjuncts such as motor mapping and MEP monitoring to enhance the extent of resection while preserving the function are demonstrated in this 3-dimensional surgical video.  The patient consented to publication of her operative video.

Spontaneous Subarachnoid Hemorrhage From a Pure Pial Arterial Malformation in the Lateral Cerebellomedullary Junction: Clinical Images with a Surgical Video

Pure pial arterial malformations (PAMs) are poorly understood owing to the limited number of reported cases. Because PAMs have been thought to have a benign natural history, they have generally been managed conservatively, unlike arteriovenous malformations or arteriovenous fistulas. In the present report, we have described a spontaneous subarachnoid hemorrhage from the rupture of a PAM at the cerebellomedullary junction. This hemorrhage was surgically treated using clip trapping.

Hydrocephalus Following Giant Transosseous Vertex Meningioma Resection

Introduction  Meningiomas are among the most common primary intracranial tumors. While well-described, there is limited information on the outcomes and consequences following treatment of giant-sized vertex-based meningiomas. These meningiomas have specific risks and potential complications due to their size, location, and involvement with extracalvarial soft tissue and dural sinuses. Herein, we present four giant-sized vertex transosseous meningioma cases with involvement and occlusion of the sagittal sinus, that postoperatively developed external hydrocephalus and ultimately required shunting. Methods  A retrospective chart review identified patients with large vertex meningiomas that were: (1) large (>6 cm) with hemispheric (no skull base) location, (2) involvement of the superior sagittal sinus resulting in complete sinus occlusion, (3) involvement of dura resulting in a large duraplasty area, (4) transosseous involvement requiring a 5 cm or larger craniectomy for resection of invaded calvarial bone. Results  Tumors were resected in all four cases, with all patients subsequently developing external hydrocephalus which required shunting within 2 weeks to 6 months postsurgery. Conclusion  We believe this may be the first report of the development of hydrocephalus following surgical resection of these large lesions. Based on our observations, we propose that a combination of superior sagittal sinus occlusion and changes in brain elasticity and compliance affect the brain's CSF absorptive capacity, which ultimately lead to hydrocephalus development. We suggest that neurosurgeons be aware that postoperative hydrocephalus can quickly develop following treatment of giant-sized vertex-based meningiomas, and that correction of hydrocephalus with shunting can readily be achieved.

Delayed Onset Abducens Nerve Palsy following Uncomplicated Large Cystic Vestibular Schwannoma Resection: Case Report

Although delayed facial palsy after vestibular schwannoma (VS) surgery is a poorly understood but a well-known phenomenon, other delayed cranial nerve palsies in the cerebellopontine angle have not been reported after VS surgery. In this report, we describe a 54-year-old woman with a large cystic VS who experienced double vision and a new delayed onset right abducens nerve (AbN) palsy, 3 weeks after gross total resection of VS via a translabyrinthine approach. To the best of our knowledge, this is the first report describing delayed isolated AbN palsy after uncomplicated VS surgery. Magnetic resonance imaging findings and the management of this complication following VS surgery are discussed in this case report.

Minimizing Retraction by Pia-Arachnoidal 10-0 Sutures in Intrasulcal Dissection

BACKGROUND

In contemporary microneurosurgery reducing retraction-induced injury to the brain is essential. Self-retaining retractor systems are commonly used to improve visualization and decrease the repetitive microtrauma, but sometimes self-retaining retractor systems can be cumbersome and the force applied can cause focal ischemia or contusions. This may increase the morbidity and mortality. Here, we describe a technique of retraction using 10-0 sutures in the arachnoid.

OBJECTIVE

To evaluate the imaging and clinical results in patients where 10-0 suture retraction was used to aid the surgical procedure.

METHODS

Adjacent cortex was retracted by placing 10-0 nylon suture in the arachnoid of the bank or banks of the sulcus. The suture was secured to the adjacent dural edge by using aneurysm clips, allowing for easy adjustability of the amount of retraction. We retrospectively analyzed the neurological outcome, signal changes in postoperative imaging, and ease of performing surgery in 31 patients with various intracranial lesions including intracranial aneurysms, intra- and extra-axial tumors, and cerebral ischemia requiring arterial bypass.

RESULTS

Clinically, there were no injuries, vascular events, or neurological deficits referable to the relevant cortex. Postoperative imaging did not show changes consistent with ischemia or contusion due to the retraction. This technique improved the visualization and illumination of the surgical field in all cases.

CONCLUSION

Retraction of the arachnoid can be used safely in cases where trans-sulcal dissection is required. This technique may improve initial visualization and decrease the need for dynamic or static retraction.

Revascularization for Cerebral Ischemia, Step-by-Step Demonstration of Bonnet Bypass: 3-Dimensional Operative Video

The superficial temporal artery (STA) to the middle cerebral artery (MCA) bypass is the most common bypass type for revascularization to treat cerebral ischemia. If the ipsilateral STA is not available for anastomosis, various options for bypass conduits can be exercised. When the entire ipsilateral external carotid and its branches are not available, the contralateral STA may be used as a donor artery through an interposition graft. This technique is known as a "bonnet bypass." In this video, we demonstrate the utilization of a bonnet bypass in a 48-yr-old man with protein S deficiency, and right carotid artery occlusion with recurrent strokes and transient ischemic attacks (TIA). After exhausting nonsurgical options by treating with 2 antiplatelet drugs and supportive lifestyle changes, the patient continued to experience TIAs and watershed strokes in the right hemisphere. Angiography showed that the right anterior artery and the MCA were filled through the Circle of Willis, but the ipsilateral STA and entire external and common carotid arteries were not patent for potential use as a bypass donor. Since the ipsilateral bypass options were not available, we elected to perform a bypass from the contralateral STA trunk to the ipsilateral M2 with a saphenous vein interposition graft, for a so-called bonnet bypass. The patient did well after surgery and has remained symptom-free for 19 mo post bypass. The surgical technique and each step in performing this bonnet bypass are demonstrated in this 3-dimensional video. The patient consented to the publication of his operative video.