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.

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.

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 Novel Surgical Classification of the Sylvian Fissure and Its Implications on the Clinical and Radiological Outcomes of Patients Undergoing Clipping for Unruptured Middle Cerebral Artery Aneurysms.

BACKGROUND: The main access route for middle cerebral artery (MCA) aneurysms is the transsylvian approach. Although Sylvian fissure (SF) variations have been assessed, none have examined how this affects MCA aneurysm surgery. The objective of this study is to investigate how SF variants affect clinical and radiological outcomes for surgically-treated unruptured MCA aneurysms. METHODS: This retrospective study examined consecutive unruptured MCA aneurysms in 101 patients undergoing SF dissection and aneurysm clipping. SF anatomical variants were categorized using a novel functional anatomical classification: Type I: Wide straight, Type II: Wide with frontal and/or temporal opercula herniation, Type III: Narrow straight, and Type IV: Narrow with frontal and/or temporal opercula herniation. The relationships between SF variants and postoperative edema, ischemia, hemorrhage, vasospasm, and Glasgow Outcome Scale (GOS) were analyzed. RESULTS: Study included 101 patients (53.5% women), 60.9 ± 9.4 (range 24-78) years. SF types were 29.7% Type I, 19.8% Type II, 35.6% Type III, and 14.9% Type IV. The SF type with the highest proportion of females was Type IV (n = 11, 73.3%), while it was Type III for males (n = 23, 63.9%) (P = 0.03). There were significant differences between SF types, ischemia, and edema (P < 0.001, P = 0.008, respectively). Although narrow SF types had poorer GOS scores (P = 0.055), there were no significant differences between SF types and GOS, postoperative hemorrhage, vasospasm, or hospital stay. CONCLUSIONS: Sylvian fissure variants may impact intraoperative complications during aneurysm surgery. Thus, presurgical determination of SF variants can predict surgical difficulties, thereby potentially reducing morbidity for patients with MCA aneurysms and other pathologies requiring SF dissection.

Safety and efficacy of microsurgery for complex cranial pathologies in the ultra-geriatric population.

OBJECTIVE: The global increase in the "ultra-geriatric" population (aged 80 years and older) has led to higher demand for neurosurgical procedures in this vulnerable population. The objective was to evaluate the safety and efficacy of advanced microsurgical procedures on ultra-geriatric patients, in our modern era of neurosurgery, anesthesiology, and advanced medical care. METHODS: The study examined 66 complex cranial procedures, performed on 65 ultra-geriatric patients, who constituted 3.8% of the 4461 consecutive neurosurgical procedures performed by a single neurosurgeon over 14-years in a tertiary care university hospital. Excluded from this study were intra- or extra-axial spontaneous hematomas or traumatic brain injuries, infections, biopsy-only cases and carotid endarterectomies. RESULTS: The most common indication for surgery for the 66 complex cranial procedures were meningiomas (23.9%), followed by gliomas (17.9%), and metastatic brain tumors (17.9%). Postoperative complications occurred in seven procedures (10.60%). No patient deaths were directly caused by intra- or postoperative events, and only one 30-day mortality occurred. All deceased patients had a statistically significant higher American Society of Anesthesiologists (ASA) class (p = 0.024). However, there was no significant correlation between ASA class and modified Rankin scale at discharge (p = 0.238). CONCLUSION: With the aging global population and increasing life expectancy, the number of ultra-geriatric patients with complex pathologies seeking advanced microsurgical treatment is growing. Therefore, neurosurgeons are confronting a growing number and variety of complex pathologies in ultra-geriatric patients in their daily practice. Regardless of advanced age, microsurgery provides safe and effective treatment, with age alone not being a barrier to proper neurosurgical treatment when other risk factors are adequately modified.

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 .

An Unusual Bifurcated Proximal Facial Nerve Found During Excision of a Vestibular Schwannoma: Clinical Imaging with a Surgical Video.

Carefully preserving facial nerve function is crucial when using the translabyrinthine approach for vestibular schwannoma surgery. Nerve preservation can only be accomplished by employing rigorous surgical methods and having a thorough understanding of the relevant anatomy, including any variations. Anatomical variations in the path of the facial nerve are infrequent but are most commonly encountered in association with congenital abnormalities of the temporal bone or ossicles. We present a rare case of vestibular schwannoma with a bifurcated facial nerve having 2 origins at the brainstem. The patient underwent a right-sided microsurgical excision using the right translabyrinthine approach. Postoperative recovery went smoothly, resulting in a House-Brackmann scale of Grade I. This case emphasizes the importance of identifying and preserving the facial nerve during vestibular schwannoma resection. To avoid injury, intraoperative neurostimulation should be used to positively identify the facial nerve and its anatomical variations along its entire course.

How I do it: management of M2 tear injury caused by drilling during intradural anterior clinoidectomy for microsurgical clipping of intracranial aneurysms.

BACKGROUND: High-speed drilling is associated with potential injury to neurovascular structures, particularly during intradural drilling of the anterior clinoid process. METHOD: During an anterior clinoidectomy, a cotton patty and middle cerebral artery branches became inadvertently wrapped around the bit, causing a tear on the inferior M2 trunk. Following temporary clipping of the internal carotid artery, the tear was identified. Temporary clips were placed proximally and distally. The tear was then repaired with interrupted microsutures. CONCLUSION: Extreme care should be exercised during clinoidectomy. Should small vascular injury occur, direct microsuturing can be a good alternative to sacrificing or implantation anastomosis repair.

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.

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.

Neurotoxic Effects of Ammonia in a Patient With Ornithine Transcarbamylase Deficiency and Bilateral Brain Abscesses: Case Report.

Brain abscesses are a rare complication of dental procedures. High concentrations of ammonia in brain abscesses may increase vasogenic edema and other brain abscess symptoms. Ornithine transcarbamylase deficiency (OTCD) is an x-linked genetic disorder of the urea cycle associated with an increased risk of brain damage due to hyperammonia. During acute metabolic decompensations, due to stresses such as infection in OTCD patients, blood ammonia levels become moderately high. This, in turn, causes cerebral glutamine levels to increase and exacerbate cerebral edema and neurological symptoms. In this report, we present a 25-year-old woman with known partial OTCD who presented with bilateral brain abscesses 2 weeks after a wisdom tooth extraction. Neurotoxic effects of ammonia, from local ammonia formation in brain abscesses positive for streptococcus intermedius, or due to her OTCD, may have exacerbated the cerebral edema, which resulted in irreversible encephalopathy that lead to her death.

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.

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.

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.

Surgical anatomy of the presacral area.

OBJECTIVE: L5-S1 instabilities can be fixated using minimally invasive presacral approach. The close relationship between the sacrum and neurovascular as well as intestinal structures may complicate the procedure during this approach. This requires knowledge regarding the normal anatomy of the presacral area to avoid the iatrogenic injuries. The aim of this study was to measure the distance between the sacrum and the structures anterior to it. MATERIALS AND METHODS: The measurements were performed on ten cadavers fixed with formaldehyde and ten MR imaging studies on individuals without any pathology in the presacral area. The distances between the sacrum and the presacral structures (i.e., middle and lateral sacral arteries, sympathetic trunks, internal iliac arteries and veins, and colon/rectum) were measured. RESULTS: Cadaver study showed that the middle sacral artery was located on the right side in 55.0%, on the left side in 31.7%, and on the midline in the 13.3% of cases. The distance between the sacral midline and middle sacral artery was found to be 8.0 +/- 5.4, 9.0 +/- 4.9, 8.7 +/- 6.0, 8.6 +/- 6.4, and 4.7 +/- 5.0 mm at the levels of S1-2, S2-3, S3-4, S4-5, and S5-coccyx, respectively. The distance between the sacral midline and the sympathetic trunk ranged between 22.4 +/- 5.8 and 9.5 +/- 3.2 mm in different levels between S1 and coccygeal level. The study also showed that the distance between the posterior wall of the intestine (colon/rectum) and the ventral surface of the sacrum can be as close as 11.44 +/- 7.69 mm on MR images. CONCLUSION: This study showed that there was close distance between the sacral midline and the structures anterior to it. The close relationships, as well as the potential for anatomical variations, require the use of sacral and presacral imaging before presacral approach.