The Western giants of the neuroanatomical past: an ode to yesterday. Part II.

"The history of the world is the biography of the great man. And I said: the great man always acts like a thunder. He storms the skies, while others are waiting to be stormed," said Thomas Carlyle. In this historical vignette, we study the contribution to neuroanatomy, of greats from the past. What led them to find the basis of topography and anatomical localization? How did they unravel the pathways of cerebrospinal fluid and cortical structure of the human brain? To understand this, we study the paths of Pierre Paul Broca, Richard L. Heschl, Hubert von Luschka, Carl Wernicke, Hans Chiari, Ludwig Edinger, and Carl Westphal, Korbinian Brodmann, and Walter Dandy.

Does Small Aneurysm Size (<10 mm) Predict Complete Occlusion After Flow Diversion? A Surpass Evolve Single-Center Study.

BACKGROUND: Long-term safety and efficacy outcomes of Surpass Evolve flow diverter (SEFD) in treatment of intracranial aneurysms are lacking. Factors predicting complete aneurysm occlusion are elusive in literature. METHODS: A retrospective review of all consecutive aneurysms treated with SEFD from February 2020 to July 2022, at a single comprehensive stroke center. RESULTS: Fifty-one patients with 80 aneurysms were included. Mean target aneurysm size was 5.6 mm and mean neck-width 3.42 mm. Small aneurysms (<10 mm) were 75% (n=60), while 25% were >10 mm. Unruptured were 71 (88.7%), previously ruptured were 8 (10%), and partially thrombosed 2.3% (n=1). Mean SEFDs used per patient were 1.07 and 40% (n=22) procedures were performed transradially. Mean procedure time was 59.1 minutes. The technical success rate for device deployment was 100%. Raymond Roy (RR) class I occlusion at 6 month (n=73) was seen among 56.2% (n=41), at 1 year (n=35) among 85.7% (n=30) and at 2 year (n=18) among 88.8% (n=16) aneurysms. Aneurysm size <10 mm significantly predicted RR-I occlusion outcome (odds ratio [OR]: 2.16; confidence interval [CI]: 0.02-4.29) at 6 months. Age, gender, smoking status, hypertension, location of aneurysm, and rupture status did not predict RR-I occlusion outcome. No mortality or permanent neurological morbidity was observed in the cohort. Major complications seen in 7.2% (n=4) patients were stent thrombosis (n=1, 1.8%), carotid-cavernous fistula (n=1, 1.8%) and transient ischemia in 2 (3.6%). Non-flow limiting stenosis was observed in 3 (5.4%) patients. CONCLUSION: SEFD gives good aneurysm occlusion rates with favorable long-term safety profile and low rate of thromboembolic complications. Small aneurysm size (<10 mm) was associated with complete aneurysm occlusion at 6-month angiographic follow-up. CLINICAL IMPACT: As Surpass Evolve is a newer generation Flow diverter of the Stryker Surpass FDs, with its improved design and applicability in intracranial aneurysms, we believe that more physicians will be encouraged to use this device worldwide.

The western giants of neuroanatomical past: an ode to yesterday - Part I.

"The only history is a mere question of one's struggle inside oneself. But that is the joy of it. One need neither discover Americas nor conquer nations, and yet one has as great a work as Columbus or Alexander to do," said David H. Lawrence. In this historical vignette, we look at the lives of certain western giants of neuroanatomy from the past. To understand the origin of today's advancements and successes in neurosurgery, a strong foothold on the path taken by anatomical greats is necessary. What curiosity inspired them to search the meaning of the human nervous system? Learning this from the paths of Herophilus, Galen, Franciscus Sylvius, Thomas Willis, Alexander Monro secundus, Luigi Rolando, François Magendie, and Martin Rathke, will propel us to create a better future for our successors.

Exoscope-assisted resection of a recurrent left frontal pilocytic astrocytoma.

An exoscope strengthens the armamentarium of a neurosurgeon by improving visualization and surgeon ergonomics, reducing surgeon discomfort, and improving coordination among the surgical team. A 23-year-old male patient developed focal seizures and weakness affecting his right arm that was attributable to a recurrent left frontal lesion. Despite two craniotomies at an 8-year interval, chemotherapy, and radiation, the tumor continued to progress. In this video, the authors demonstrate resection of a recurrent left frontal pilocytic astrocytoma with the assistance of an exoscope, neuronavigation, and neuromonitoring. The exoscope can enhance surgical resectability while smoothening the surgical workflow. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23158.

Radially adjustable stent retriever for mechanical thrombectomy in acute ischemic stroke: Improved first-pass effect with rapid-inflation deflation technique.

INTRODUCTION: Evidence for improved first-pass effect with the novel radially adjustable radio-opaque stent retriever Tigertriever is lacking. OBJECTIVE: To compare improvement in first pass success with Tigertriever using two different techniques-rapid inflation deflation (RID) and suction thrombectomy (ST). METHODS: Retrospective analysis of patients with acute ischemic stroke who underwent mechanical thrombectomy with Tigertriever at a single comprehensive stroke center. RESULTS: Thirty patients were included. Mean age was 72.8 years. Twelve patients (48%) experienced successful first passes with Tigertriever. Successful revascularization (modified thrombolysis in cerebral infarction (mTICI) 2b/3) was achieved in all (100%) patients who received RID or ST technique for thrombectomy. Good clinical outcome (modified Rankin score = 0-2) was noted in 40% (n = 10). Total mortality in the cohort was 8% (n = 2). RID and ST groups comprised of 10 and 15 patients, respectively. Five patients underwent MT with Tigertriever as a rescue device. RID VS ST: No difference was noted in mean age (p = 0.27), gender (p = 0.29), location of occlusion (p = 0.46), and device used for first pass (p = 0.57). A 70% first-pass success rate in RID group and 37.5% in ST group was noticed (p = 0.06). Mean time from groin puncture to reperfusion (TICI 2b//3) was statistically similar (p = 0.29, RID: 19.9 min vs ST: 25 min). Both groups noted a 100% complete recanalization rate. The rate of mortality between the two groups were not statistically different (p = 0.46). CONCLUSION: The preliminary first-pass success rates of RID technique with Tigertriever compared to ST technique, are encouraging. Longitudinal studies with longer follow up are needed to elucidate the smaller learning curve with this device.

Flow Diversion for Treatment of Anterior Inferior Cerebellar Artery Aneurysms: Mechanism and Pitfalls from a Novel Management Strategy.

BACKGROUND: Anterior inferior cerebellar artery (AICA) aneurysms present a challenge for neurosurgeons and neurointerventionalists alike. METHODS: Cases of AICA aneurysms managed with endovascular flow diversion at our institute are reviewed with their angiographic outcomes. RESULTS: Both direct and indirect flow diversion provide complete aneurysm occlusion at follow-up. We propose a stratified method of approaching AICA aneurysms based on location, rupture status, and neck size. CONCLUSIONS: Careful evaluation of preoperative parameters is paramount in deciding between a surgical or a neuroendovascular approach. Low-profile stents in the future may assist in direct flow diversion of AICA trunk aneurysms. In addition, neurosurgeons need to be well versed in endovascular approaches.

Management Strategies of Plasma Cell Granuloma Involving the Central Nervous System: A Systematic Review of the Literature.

BACKGROUND: Plasma cell granuloma (PCG) is a rare clinical entity seen in the neurosurgical literature. It has often been referred to as inflammatory myofibroblastic tumor or inflammatory pseudotumor. No well-defined management guidelines exist in the literature. METHODS: Using PRISMA guidelines, we systematically reviewed the literature in PubMed and Google Scholar using MeSH terms: intracranial plasma cell granuloma, myofibroblastic tumor, intracranial pseudotumor, spinal plasma cell granuloma. We analyzed the clinical presentation, treatment strategies, clinical outcomes, and follow-up across different studies. RESULTS: Eighty-three studies were included presenting 108 cases. Primary extracranial disease was seen in 4 patients and primary central nervous system (CNS) disease in 104. In the combined cohort, multicompartmental disease was seen in 22 (20.8%) patients. Headache (n=40, 42.59%) was the most common clinical symptom. Surgical excision (n=86, 79.6%) was the most common primary treatment used. Radiation therapy, steroids, and chemotherapy (methotrexate/6-mercaptopurine/rituximab) were also used. Disease recurrence was noted in 25 (33.3%) patients and residual disease in 33 (30.5%). Mortality was seen in 4 (3.7%) patients. In the cranial PCG subgroup (n=87), 81 (93.1%) patients had solitary lesions, and 6 (6.8%) had multiple lesions. Recurrence after primary surgery was noted in 27.58% (n=24). In the spinal PCG subgroup (n=17), the thoracic spine was the most common location (n=9, 52.9%) and recurrence was seen in 5.84% (n=1). CONCLUSIONS: Combination of multiple treatment modalities is needed when approaching this complex disease. Spinal PCGs respond favorably to gross total excision, with a low recurrence rate. Cranial PCGs warrant intense follow-up with secondary chemotherapy/radiation/steroids in recurrent cases.

Surpass embolization of intracranial aneurysms: Perspective from a 2-year longitudinal follow-up study across high volume comprehensive stroke centers.

BACKGROUND: Surpass Streamline (SS; Stryker©) is an over-the-wire first-generation flow diverter (FD). There is a scarcity of data on real-world outcomes and complications of this FD. METHODS: A retrospective review of consecutive cases between January 2019 and July 2021 at two high-volume comprehensive stroke centers, involving SS was conducted. RESULTS: Fifty-five patients harbored 69 treated aneurysms, of which 96% were in the internal carotid petrous to terminus segments and 88% were <10 mm in size, and 12% measuring 10-24 mm. Raymond Roy Grade 1 occlusion was noted in 55 aneurysms (79.7%) at 1 year. Median follow-up duration was 26 months (mean = 26.06). Major complications were seen in eight patients (14.5%; 95% CI 6.5-26.7) and mortality attributable to SS stenting complications occurred in two (4.3%) patients. Four (7.2%) had ophthalmologic thromboembolic complications and two had (3.6%) ischemic complications. Procedural complications occurred in 10 patients (18.18%; 95% CI 9.1-30.9). Technical complications during procedure (n = 3, 5.3%) were: "confirmed" distal middle cerebral artery (MCA) guidewire perforation; "suspected" distal MCA guidewire perforation causing post-procedural subarachnoid hemorrhage and internal carotid artery dissection causing ischemic stroke. Seizures were seen in 5 (9.09%) and carotid-cavernous fistula in 1 (1.8%). Multivariate regression analysis showed technical challenges significantly predicted occurrence of major complications (p = 0.001; R2 = 0.39, F(13,43) = 2.15, p = 0.029). Univariate analysis showed technical challenges significantly predicted ophthalmological complications (R2 = 0.06, F(1,55) = 4.04, p = 0.049) and major complications (R2 = 0.21, F(1,55) = 15.11, p = 0.0002). CONCLUSION: Large-scale future registry should focus on national data regarding SS safety, technical challenges, and procedural complications. We present one of the longest follow-ups for SS in literature.

Network analysis of neurosurgical literature: an increased focus on training during the COVID-19 pandemic.

The COVID-19 pandemic led to stringent guidelines to restrict the conduct of non-emergent surgical procedures. Consequently, neurosurgery departments experienced a decline in case volumes and greater educational time being spent on virtual research projects. In our report, we reveal how neurosurgical research has changed during the pandemic compared to the pre-pandemic phase. The WebOfScience database was searched for neurosurgical articles published between 2012-2019 (pre-pandemic) and 2020-2022 (pandemic). From this data, the keywords, terms, and countries were analyzed using networks formed by the VOS Viewer software. In addition, the analysis was repeated for neurosurgical articles specific to COVID-19. Network analyses of terms and keywords revealed an increased popularity of virtual research projects, including case reports, meta-analyses, reviews, surveys, and database studies. Additionally, there was increased interest in research pertaining to neurosurgical education during the post-pandemic era, including topics regarding virtual training modalities, mental health, and telemedicine. Our bibliometrics analysis suggests that the impact of COVID-19 restrictions on hospital systems affected neurosurgical training programs. Future investigations should explore the effects of the trainee experience during the COVID-19 pandemic on the outlook for neurosurgical education.

Trends in Global Research for Treating Intracranial Aneurysms: A Bibliometric Analysis.

OBJECTIVE: Although significant advancements have been made in the detection, surveillance, and treatment of intracranial aneurysms, research and care can differ vastly based on location. Currently, there is lack of knowledge regarding the trends in literature and how the field is evolving with new technology. Here, we use bibliometric analysis to visualize the knowledge structure of the field and identify global research trends in intracranial aneurysm treatment. METHODS: The Web of Science Core Collection was queried for primary research and review articles related to intracranial aneurysm treatment. Four thousand seven hundred and 2 relevant documents were collected and publications over time on different treatment types and publications and citations of journals were collected. VOS viewer was used for the following: 1) identify relationships between keywords, 2) identify co-authorship patterns among organizations and countries, and 3) analyze citation patterns of countries, organizations, and journals. RESULTS: Our results show that research in flow diversion increased at a rapid rate but tended to have low link strength with keywords related to evaluating patient risk and mortality. The highest publication producing countries were the United States of America, Japan, and China, although China had fewer citations relative to its peers. Korean organizations showed less international collaboration. The USA has been the leader in terms of productivity and collaboration in the field, as have several US-based journals such as Journal of Neurosurgery, Neurosurgery, and World Neurosurgery. CONCLUSIONS: Evaluating the safety of flow diversion treatment remains a pressing area of research. Chinese and Korean organizations may be of interest for global collaborations.

Tension Pneumocranium Following Transsphenoidal Surgeries-A Case Report and Systematic Review of Literature with Analysis of Predisposing Factors and Treatment Regimens: Is Early Skull Base Repair Better than Conservative Treatment?

BACKGROUND: Conclusive evidence describing the outcomes following different treatment strategies for tension pneumocranium (TP) is lacking. Impact of predisposing conditions like multiple transnasal transsphenoidal (TNTS) procedures, intraoperative cerebrospinal fluid leak, obstructive sleep apnea, continuous positive airway pressure, violent coughing, nose blowing, positive pressure ventilation on TP outcomes is also unknown. METHODS: PubMed, Embase, Cochrane, and Google Scholar were searched for articles using Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Multivariate logistic regression analysis was done using STATA/ BE ver 17.0. RESULTS: Thirty-five studies with 49 cases of endoscopic TNTS surgeries were included. Tension pneumocephalus was seen in 77.5% (n = 38), tension pneumosella in 7 (14.28%), and tension pneumoventricle in 4 (8.16%). Nonfunctional pituitary adenomas (40.81%) were most common lesions associated with TP. The need of mechanical ventilation was significantly higher in patients who received conservative management (odds ratio, 1.34; confidence interval, 0.65-2.74) (P < 0.01). However, incidence of meningitis or mortality were not influenced by factors like age, gender, pathological diagnosis, initial conservative management or early skull base repair, use of adjuvant radiation, intraoperative cerebrospinal fluid leak, multiple TNTS explorations, or presence of precipitating factors. CONCLUSIONS: Nonfunctional pituitary adenomas were the most common lesions associated with TP. Multiple TNTS procedures did not increase incidence of meningitis or mortality. Conservative management increased the need for mechanical ventilation but did not worsen the mortality outcomes.

Hypo-fractionated Gamma Knife Radiosurgery for Intra-cranial Pathologies: A Single-Center Prospective Analysis of Feasibility, Safety, Efficacy, and Complication Profile.

Background: Single-session stereotactic radiosurgery (SRS) is a proven and effective treatment modality for various benign, malignant, and functional intra-cranial pathologies. In certain situations, single-fraction SRS is limited because of lesion size and location. Hypo-fractionated gamma knife radiosurgery (hfGKRS) is an alternative approach for such unconventional indications. Objective: To evaluate the feasibility, efficacy, safety, and complication profile of hfGKRS with evaluation of different fractionation schemes and dosing patterns. Methodology: The authors prospectively evaluated 202 patients treated with frame-based hfGKRS over a 9-year period. GKRS was administered fractionated because of either a large volume (>14 cc) or an inability to spare neighboring organs at risk from permissible radiation in single-session GKRS. The inter-fraction interval was kept at 24 hours, and the dose calculation was performed with linear quadratic equations. Patients with more than 3 years of clinical and radiological follow-up were included in prospective analysis. At pre-decided follow-up criteria, treatment effects and side effects were documented on objective scales. Results: A total of 169/202 patients met inclusion criteria. 41% patients received treatment in three fractions, whereas 59% received two-fraction GKRS. Two patients of giant cavernous sinus hemangiomas were treated with 5 Gy in the five-fraction regimen. In patients with more than 3 years of follow-up, the obliteration rate was 88% for complex arteriovenous malformations (AVMs) treated with hfGKRS because of eloquent locations, whereas it was 62% for Spetzler-Martin grade 4-5 AVMs. For non-AVM pathologies (meningiomas, schwannomas, pituitary adenomas, paragangliomas, hypothalamic hamartomas, etc.), the 5-year progression free survival was 95%. Tumor failure was noted in 0.05% patient population. Radiation necrosis developed in 8.1% patients, and radiation-induced brain edema developed in 12% patients. It was resistant to treatment in 4% patients. No patient developed radiation-induced malignancy. Hypo-fractionation did not provide any hearing improvement in giant vestibular schwannomas. Conclusion: hfGKRS is a valuable standalone treatment option for candidates unsuitable for single-session GKRS. The dosing parameters need to be tailored as per the pathology and neighboring structures. It provides comparable results to single-session GKRS with an acceptable safety and complication profile.

Gearing Up for the U.S. Medical Licensing Examination Step 1 Pass/Fail Transition, Evaluating the Role of Research Productivity as an Alternative During the Neurosurgical Residency Selection Process: An Overview.

Neurosurgery residency programs are the most competitive among the surgical specialties for applicants to match into. U.S. Medical Licensing Examination (USMLE) step 1 scores are staple and pivotal in narrowing down applicants for granting interviews and ranking in the match process. The upcoming transition from a numeric to binary step 1 scoring shifts the emphasis on using the status quo Step 2 Clinical Knowledge numeric scoring as the only objective measure. It can prove insubstantial for accurate assessment of competencies, further urging residency programs to widen their selection protocols to allow multiple assessments of competency. Research experience has consistently proved to result in higher successful match rates, and a positive correlation is seen with the number of research publications and Hirsch indices. However, with a predicted emphasis on research with the shift in scoring practices, these tools provide inadequate insight into authorship, contributions, type of publications, and community impact, warranting the need to include supplementary modifications, surrogates, or alternatives to such tools for a more comprehensive and equitable assessment of research. This study summarizes the role of research in the neurosurgical match process, describes nuances in research evaluation, and introduces novel Hirsch indices and additional strategies to address these nuances for equitable evaluation of research productions.

Management paradigms of persistent primitive trigeminal artery aneurysms: A systematic review and analysis of techniques and complications from 1960s to 2022: From conservative to surgical to endovascular, how far along the right path are we?

INTRODUCTION: Aneurysms of persistent primitive trigeminal artery (PPTAAs) are increasingly reported and commonly managed by endovascular (EN) techniques. There are no systematic reviews or meta-analyses which analyse outcomes and complications of treatment modalities for PPTAAs. We aim to highlight the change in trend of management of PPTAAs and to identify clinical and radiological parameters which may influence management paradigms. METHODOLOGY: A systematic search of literature was done in PubMed, Embase, Google Scholar, Cochrane library and Medline using keywords 'persistent primitive trigeminal artery', 'aneurysms', 'embolization', 'surgical clipping', etc. Only cases reporting aneurysms of PPTA were included. Three subgroups, such as conservative, open surgical (OS) and EN interventional, were studied for outcome evaluation. In the EN subgroup, relation of clinical and radiological parameters with outcome (complete/partial occlusion) was analysed using Microsoft Excel Data Analysis ToolPak. RESULTS: Of the 101 articles found eligible for assessment, 54 were analysed quantitatively. Mortality in the conservative group was 12.5% and OS group was 9.09%. After EN treatment, complete angiographic occlusion was seen in 88.89% PPTAAs and 5.5% warranted retreatment. In the EN subgroup, location (p=0.17), shape (p=0.69), Saltzman circulation (p=0.26) or status of rupture (p=0.08) did not significantly impact angiographic occlusion outcome. Multivariate regression analysis showed 6.6% influence of independent variables, that is, age, gender, aneurysm location, side, shape (saccular/fusiform), rupture status and type of Saltzman circulation on aneurysm occlusion outcome [F(7,27) =1.34] (p=0.27). Total mortality reported in the EN group was 8.57%. CONCLUSION: Clinical or radiological parameters do not influence angiographic occlusion outcome. Although EN techniques are successful, meticulous reporting of outcomes and complications is important.

Sequential aneurysms with incidental persistent primitive trigeminal artery: Is this association purely coincidental? A case study and review of the literature in search for a pathobiological mechanism.

Background: The appearance of sequential bilateral aneurysms in patients with persistent primitive trigeminal artery (PTA) is not described in the literature. No clear guidelines on screening and follow-up of patients with incidental PTAs for the detection of associated lesions have been established. Case Description: A 55-year-old lady presented with occasional headaches. Detailed evaluation showed a left ophthalmic segment internal carotid artery (ICA) aneurysm measuring (11.2 × 5.5) mm. A bovine aortic arch configuration (type III) and a persistent left PTA were identified. A pipeline flex flow diverter was placed and aneurysm was coiled. Follow-up angiography after 6 months showed a completely occluded aneurysm with preserved PTA and a new aneurysm in the right ICA ophthalmic segment measuring 3.5 × 1.5 mm. It was followed up serially with angiography which revealed significant increase in 6 months. The base measured 5.4 mm and two blebs 3.1 mm and 2.5 mm had appeared on the dome. A SUPRASS flow diverter was placed across this aneurysm. Serial follow-up showed complete occlusion of the left aneurysm and significant reduction in filling of the right aneurysm. A review of the literature identified 34 cases of incidental PTAs associated with 50 aneurysms with increased prevalence of anterior circulation aneurysms in patients with incidental PTA. Conclusion: Sequential angiography of a patient with incidental PTA and an ICA aneurysm shows presence of a new aneurysm in contralateral circulation and its progression in size and morphology. Detailed large-scale studies are needed to assess the impact of incidental PTA on aneurysm development and management.

Effect of Age, Stage, and Type of Surgical Revascularization on Clinical and Angiographic Outcome in Moyamoya Disease - Experience from a Case Series of 175 Revascularization Procedures.

Background: There is dearth of literature on impact of age - pediatric versus adult, Suzuki staging - early versus late, and revascularization type - indirect versus direct on clinical and angiographic outcome in moyamoya disease (MMD). Hence, we intend to comprehensively evaluate factors influencing outcome in MMD following surgical revascularization. Methods: MMD patients operated at our institute from January 2011 to August 2018 were followed for an average 24 months. Primary outcomes were modified Rankin score (mRS) and stroke risk reduction. Secondary outcome was angiographic outcome score (AOS). Results: A total of 133 patients including 37.6% adults (>18 years; n = 50) underwent 175 revascularizations - 89 direct (DR) and 86 indirect (IR) subgroups. Mean mRS scores improved in pediatric DR (P < 0.001), IR (P < 0.001), adult IR (P = 0.10), and DR (P = 0.25) subgroups. Recurrent stroke rate was similar in pediatric-DR (2.7%) and IR (7.6%, P = 0.61), and adult-DR (0%) and IR (4.1%) subgroups (P = 1.00). AOS scores improved in pediatric DR (P = 0.002) and IR (P = 0.01), and adult-DR (P = 0.02) and IR (P = 0.06) subgroups. Late-stage MMD (Suzuki IV-VI) showed better improvement in mRS scores than early-stage-Suzuki (I-III; P < 0.001). Recurrent stroke rates were similar (P = 0.26) and AOS scores improved significantly in early- and late-stage MMD (P < 0.001). Conclusions: In pediatrics, clinical and angiographic outcome significantly improved after revascularization procedure, and in adults, angiographic improvement was more evident than clinical recovery. Late-stage Suzuki MMD patients demonstrated significantly better clinical improvement than early stage. The angiographic improvement was equivalent to early stage, irrespective of age and type of revascularization.

Aberrant drainage of posterior condylar emissary vein and abnormal orifice of hypoglossal canal: surgical implications in the transcondylar fossa approach for VA-PICA junction aneurysm.

BACKGROUND: The posterior condylar emissary vein (PCEV) and posterior condylar canal (PCC) are anatomical landmarks for identifying important structures like jugular tubercle and occipital condyle in surgical approach to the foramen magnum and condylar fossa. Several anatomical variations have been described. Drainage into the jugular bulb is found to be commonest. METHOD: A 70-year-old patient with unruptured vertebral artery-posterior inferior cerebellar artery (PICA) junction aneurysm-underwent surgical clipping via transcondylar fossa approach. RESULT: Preoperative computed tomography demonstrated an abnormal communication existed between the left-sided PCC and hypoglossal canal (HC). The PCEV was identified draining into a dilated venous channel/pouch at the "hip" of sigmoid sinus (junction of sigmoid sinus and jugular bulb). Intra-operatively, an occipital artery-PICA bypass was performed. The PCEV was skeletonized, coagulated, and divided to achieve hemostasis. The lateral and cranial drilling around PCC was successful at safeguarding the underlying contents of HC (in medial and caudal extent). CONCLUSION: Preoperative angiography and detailed morphometric analysis of the PCC were helpful in planning surgical approach-identifying and controlling the PCEV, and skeletonization of the PCC without compromising the hypoglossal nerve and anterior condylar emissary vein.