Sylvian Fissure Dissection Research Articles

Human placenta in vascular neurosurgery training: a comprehensive review of laboratory models, possible exercises, and assessments for skills improvement.

Simulation is increasingly recognized as an important tool to enhance neurosurgical education. In this field, especially in neurovascular surgery, human placenta (hPl) is being recognized as a valuable training model because of its abundant availability, ethical acceptance, and analogous vasculature with other vessels of the human body. Nevertheless, although a rising body of literature is witnessing a renovated interest toward this "old" model, to date no comprehensive reviews on the topics are available. Main objective of this paper is to comprehensively review hPl use in neurovascular surgery training, focusing on model preparation, type of possible exercises along with assessment tools which can be used to check for trainees learning. A systematic review of the pertinent literature was performed, following PRISMA guidelines, searching the following key words in "title/abstract" fields in only English-written works: "placenta and neurosurgery." We focused on preclinical works concerning use of hPl models in neurovascular surgery training. We included studies published in the last 40 years, till December 31st, 2023. A total of 950 scientific publications were initially screened, and 23 papers met the inclusion and exclusion criteria. In summary, the chorionic surface of hPl may be used as a neurovascular gym where different exercises can be performed. Placenta models can be produced with or without the use of intravascular dyes and or/pumping systems to resemble a beating-heart vascular system. The three main neurovascular surgical fields where hPl is being considered to be highly simulative are: 1) Sylvian fissure dissection; 2) aneurysm dissection and clipping; 3) bypass training. Considering the simulative purpose, face, content and construct validify of hPl model have been tested and verified by many authors, although still few data are available regarding transfer/predictive validity. This systematic review highlighted the easiness of preparation and availability along with the strong didactical meaning that the use of hPl-based models may have in the field of neurovascular surgery training. In view of current progressive lowering of surgical vascular cases and increasing technical demand related to their management, further studies aimed to assess if this simulator could be able to produce a learning effect and improve performance with continued use are strongly needed.

Basal vein of Rosenthal classification: the key to venous outflow of the deep sylvian fissure.

Mastery of sylvian fissure dissection is essential to access lesions within the deep basal cisterns. The deep sylvian vein and its tributaries play a major role during access to and beyond the carotid cistern through the sylvian fissure and determine the complexity of microdissection. Preserving the venous outflow during sylvian fissure dissection is the best reliable strategy to prevent postoperative venous strokes or venous hypertension. The authors report the role of the basal vein of Rosenthal (BVR) in the venous outflow pattern of the deep sylvian cistern. The authors analyzed 262 consecutive surgical cases involving sylvian fissure dissection from 2015 to 2017. Inclusion criteria were complete sylvian fissure dissection for the treatment of intracranial aneurysms. Exclusion criteria were giant size (aneurysm diameter > 24 mm), meningitis, subarachnoid hemorrhage within the sylvian cistern, absence of 4D CT angiography, and previous surgery. Retrospective radiological and operative video reviews were carried out to assess the association between the superficial sylvian vein and the BVR. The authors analyzed the course of the BVR and the patterns of venous drainage of the sylvian cistern. The surgical difficulty of sylvian fissure dissection was rated by the authors to study the operative significance of the venous patterns encountered. Two clinical cases are described to illustrate the proposed BVR classification. A total of 97 patients met the selection criteria. The most frequent type of BVR was immature (diameter < 0.5 mm, 68%). When the BVR was incompletely developed or absent (immature type), the deep sylvian veins drained through a middle sylvian vein in 70% of cases, requiring advanced sylvian fissure dissection techniques. However, when the BVR was completely developed (32%), the middle sylvian vein was found in a minority of cases (6%), which allowed for an unobstructed transsylvian corridor. Interrater and test-retest reliability of the surgical difficulty was greater than 0.9. Preoperative assessment of the BVR anatomy is key to predict the deep sylvian venous pattern. The authors provide objective evidence supporting the reciprocal relationship between the type of BVR and the presence of a middle sylvian vein and the deep sylvian venous outflow. An immature BVR should alert the neurosurgeon of the high likelihood of finding a complex deep venous pattern, which may drive surgical planning.

Intrasylvian Retraction Technique to Facilitate the Sylvian Fissure Dissection: A Clinical Study of 125 Cases.

Although many authors have recommended the retractorless technique to avoid retractor-induced brain injury, others usually use brain retractors with a meticulous technique to facilitate the surgery, especially for sylvian fissure dissection. The intrasylvian retraction technique was described for sylvian fissure opening, but no clinical evidence was found. We evaluate the efficacy and safety of this technique for the distal transsylvian approach. We reviewed the video records of clinical cases where the distal transsylvian approach was performed using the intrasylvian retraction technique for aneurysm treatment and middle cerebral artery (MCA) bypass between September 2018 and August 2022. Operative techniques are described. The efficacy and safety of the technique were assessed by full exposure of the sylvian fissure and new postoperative perisylvian hematoma, respectively. One hundred twenty-five cases were included and had an average age of 53.5 (range 16-85) years. Women comprised 73.6%. Aneurysm surgery, pure MCA revascularization, and aneurysm surgery with MCA revascularization were 106 (84.8%), 12 (9.6%), and 7 cases (5.6%), respectively. The most common aneurysm location was the internal carotid artery-posterior communicating artery junction in 37 cases (34.9%), followed by the anterior communicating artery in 27 (25.5%). Full exposure of the Sylvian fissure was achieved in all cases. No perisylvian hematoma was detected by immediate postoperative computed tomography in any patient. Using an appropriate technique for brain retractor application, sylvian fissure dissection was safely performed. The intrasylvian retraction technique effectively facilitated sylvian fissure dissection and provided wide exposure for the distal transsylvian approach.

Training in Sylvian Arachnoid Dissection: The Art of Using Kamiyama Scissors and a Simple Novel Model for Practice Sylvian Arachnoid Dissection Using Cotton Fiber with Brain Model.

Background Transsylvian approach is one of the main approaches for a variety of vascular, tumor, and skull-base lesions. Sylvian fissure harbors a lot of critical structures including the middle cerebral artery and many venous structures. If not done properly, the transsylvian approach could cause several complications. Up to now, there is no simple training model for practicing Sylvian fissure dissection. In this article, we describe the technique of using microscissors for the sharp dissection of arachnoid trabeculae. We also propose a new model for practicing Sylvian arachnoid dissection using a three-dimensional (3D) brain model with cotton fiber. Materials and Method We inserted cotton fiber into the Sylvian fissure of the brain model (aneurysm box from UpsurgeOn) and covered the Sylvian fissure with a cotton sheet, then sprayed the water over it. We dissected this model under a microscope by using Kamiyama scissors in the right hand and suction in the left hand. Result Under the microscope, our model appears comparable with the real Sylvian fissure. We can use this model for practicing arachnoid dissection with Kamiyama scissors. Conclusion The arachnoid dissection model by using a 3D brain model with cotton fiber is a simplified and novel approach for practicing the Sylvian fissure dissection.

Bypass-Assisted Microsurgical Clipping for an Endovascular Treatment-Resistant Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm, Recurring Two Decades Postinitial Clipping: 2-Dimensional Operative Video.

Salvage treatment of postclipping recurrent aneurysms remains challenging.1,2 The salvage microsurgical clipping is a possible intervention but sometimes difficult because of tissue adhesions around the aneurysm and previously installed clips; therefore, salvage coil embolization may have certain advantages.1-5 However, when coil embolization is not applicable,6 microsurgical clipping is a stand-alone curative treatment, requiring proficient and reliable microsurgical techniques. This article describes a unique case of a 70-year-old female patient complaining of a severe headache with subarachnoid hemorrhage due to a recurrent ruptured left internal carotid-posterior communicating artery aneurysm after microsurgical clipping 23 years ago. An initial attempt at coil embolization proved unsuccessful because of the aneurysm shape. Consequently, the salvage microsurgical clipping was planned. Given the additional time for trapping the internal carotid artery for the old clip removal, a superficial temporal artery-middle cerebral artery bypass was also planned. The operation entailed a superficial temporal artery-middle cerebral artery bypass, a Sylvian fissure dissection, the old clip removal, and aneurysm clipping. Intraoperatively, the complete aneurysm neck clipping was successfully performed without any complication, and patient postoperative course was uneventful. A wide surgical field should be obtained to be able to manipulate the aneurysm and old clip safely under a microscope. It is also important to temporarily trap the main artery to ensure removal of old clips and to prepare for intraprocedural ischemia using bypass after a precise assessment of hemodynamics before surgery. The patient provided informed consent for the procedure and the publication of the case along with its pertinent imaging, and this report was approved by the institutional review board at our hospital.

A realistic aneurysm clipping simulation combining 3D-printed and placenta-based models-how I do it.

Neurovascular surgery, particularly aneurysm clipping, is a critical skill for aspiring neurosurgeons. However, hands-on training opportunities are limited, especially with the growing popularity of endovascular techniques. To address this challenge, we present a novel neurovascular surgical training station that combines synthetic 3D-printed models with placental vascular structures to create a semi-realistic surgical field. Our model consists of three components: a 3D-printed skull replica with anatomical landmarks, a malleable silicone parenchyma with a Sylvian fissure, and vascular layers (placenta). The placental vascular layer is catheterized and perfused to replicate pulsatile flow, offering a realistic aneurysm simulation. This innovative training station provides a cost-effective solution (approximately 200 USD once) without ethical constraints. Surgeons can practice essential skills such as Sylvian fissure dissection, managing anatomical constraints like bone, and achieving proximal vascular control. The model's realism allows for training in various scenarios, including clipping with different hand orientations and handling ruptures realistically. Our neurovascular surgical station bridges the gap between existing training models, offering affordability, ecological considerations, and minimal ethical concerns. It empowers neurosurgery residents to refine their skills in handling both emergencies and elective cases under close-to-real surgical conditions, with the potential for independent practice and senior supervision.

Posterior Fossa Anatomy for Microvascular Decompression Surgery

In most microvascular decompression surgeries, surgical maneuvers are performed within normal anatomical structures without any neoplasms. Thus, detailed anatomical knowledge is essential to perform safe and efficient procedures. "Rule of 3" by Rhoton AL Jr. is helpful for understanding not only the anatomy of the posterior fossa but also the three neurovascular compression syndromes. The cerebellar arteries and posterior fossa veins have substantial variability, but a basic understanding of their typical patterns is useful to explore individual cases. To use adequate surgical approaches through the cerebellar tentorial or petrosal surface in individual trigeminal neuralgia surgeries, anatomical knowledge of the bridging veins on the tentorial(the bridging veins into the tentorial sinus)and petrosal surfaces(the superior petrosal vein)is crucial. Fissure openings help to minimize cerebellar retraction, similarly to the sylvian fissure dissection in supratentorial surgeries.

Safety around Sylvian Fissure: Technical Note

ABSTRACT Background: Sylvian fissure dissection is one of the most important neurosurgical procedures for a number of vascular, neoplastic and other (epilepsy) neurological ailments. Safe dissection in this region is of utmost importance, especially for trainees and young Neurosurgeons. The authors highlight some of the important and basic safety tips so that surgery is without unwarranted complications. Material and Methods: Technical difficulties, most commonly faced by trainees and young neurosurgeons during Microneurosurgery around the sylvian fissure, were identified based on experiences of senior authors and were related to: Surgical Planning, Head positioning, Dural opening, use of Macro and Microinstruments, Microdissection and closure. Technical details of steps which are safe and easy to address above mentioned difficulties were outlined. Results: Safe and easy technique to perform Microneurosurgery around sylvian fissure have been mentioned with special attention to the difficulties faced by trainees and young neurosurgeons. It includes all technical aspects starting from planning the surgery to closure of the wound. Conclusion: Microneurosurgery around sylvian fissure is the most important expertise to address variety of vascular and neoplastic lesions in neurosurgery. Sound concepts of basic neuroanatomy and basic principles of physics help in planning and performing Microneurosurgery safely in the region of sylvian fissure.

Usefulness of the Multimodal Fusion Image for Visualization of Deep Sylvian Veins.

The preoperative assessment of cerebral veins is important to avoid unexpected cerebral venous infarction in the neurosurgical setting. However, information is particularly limited regarding deep Sylvian veins, which occasionally disturb surgical procedures for cerebral anterior circulation aneurysms. The predictability of detecting deep Sylvian veins and their tributaries using a modern multimodal fusion image was aimed to be evaluated. Moreover, 51 patients who underwent microsurgery for unruptured cerebral aneurysms with Sylvian fissure dissection were retrospectively reviewed. The visualization of the four components of the deep Sylvian veins in conventional computed tomography (CT) venography and multimodal fusion images was evaluated. To compare the detection accuracy among these radiological images, the sensitivity and specificity for the detection of each of the four venous structures were calculated in comparison with those of intraoperative inspections. The kappa coefficients were also measured and the inter-rater agreement for each venous structure in each radiological image was examined. In all veins, the multimodal fusion image exhibited a high detection rate without statistical difference from intraoperative inspections (P = 1.0). However, CT venography exhibited a low detection rate with a significant difference from intraoperative inspections in the common vertical trunk (P = 0.006) and attached vein (P = 0.008). The kappa coefficients of the fusion image ranged from 0.73 to 0.91 and were superior to those of CT venography for all venous structures. This is the first report to indicate the usefulness of a multimodal fusion image in evaluating deep Sylvian veins, especially for the detection of nontypical, relatively small veins with large individual variability.

Impact of dome projection on operative steps during clipping of a ruptured pure posteriorly directed posterior communicating artery aneurysms

Background: Ruptured posterior communicating artery (PCoA) aneurysms are common; they usually present with subarachnoid haemorrhage (SAH) and oculomotor nerve palsy. The aneurysmal dome projection may influence the safety access and aneurysmal neck clipping. Here, we discuss additional intraoperative steps that may be required to widen the surgical field to ensure safe surgical clipping of a rupture pure posteriorly directed PCoA aneurysm. Case description: A previously healthy 38-year-old male reported sudden severe headache and disturbed level of consciousness with a Glasgow coma scale (GCS) of 13. His initial computed tomography (CT) scan of the head showed SAH in the basal cistern. 3D-constructed CT angiography (CTA) revealed a left pure posteriorly directed PCoA aneurysm. In the surgery, through the left pterional approach, all intraoperative steps were carried out. Additional steps were performed as well. Three additional intraoperative steps were contemplated because a pure posteriorly directed PCoA aneurysm is not well appreciated and is often hidden behind the supra cliniold internal carotid artery (ICA). First, the extension of Sylvian fissure dissection to include the distal part and the proximal. Second, temporal pole mobilization is performed by cutting small anterior temporal veins. Third, a brain retractor is placed on the temporal lobe to gently tract the superficial part of the lobe. All these steps widened the surgical corridor to ensure the aneurysm's safe clipping. Conclusion: Surgical clipping is influenced by the aneurysmal dome projection. In a ruptured pure posteriorly directed PCoA aneurysm, further intraoperative steps may facilitate complete access and safe clipping of the aneurysm.

A Low Subfrontal Dural Opening for Operative Management of Anterior Skull Base Lesions.

Introduction A low subfrontal dural opening technique that limits brain manipulation was assessed in patients who underwent frontotemporal approaches for anterior fossa lesions. Methods A retrospective review was performed for cases using a low subfrontal dural opening including characterization of demographics, lesion size and location, neurological and ophthalmological assessments, clinical course, and imaging findings. Results A low subfrontal dural opening was performed in 23 patients (17F, 6M), median age of 53 years (range 23-81) with a median follow-up duration of 21.9 months (range 6.2-67.1). Lesions included 22 meningiomas (nine anterior clinoid, 12 tuberculum sellae, and one sphenoid wing), one unruptured internal carotid artery aneurysm clipped during a meningioma resection, and one optic nerve cavernous malformation. Maximal possible resection was achieved in all cases including gross total resection in 16/22 (72.7%), near total in 1/22 (4.5%), and subtotal in 5/22 (22.7%) in which tumor involvement of critical structures limited complete resection. Eighteen patients presented with vision loss; 11 (61%) improved postoperatively, three (17%) were stable, and four (22%) worsened. The mean ICU stay and time to discharge were 1.3 days (range 0-3) and 3.8 days (range 2-8). Conclusion A low sub-frontal dural opening for approaches to the anterior fossa can be performed with minimal brain exposure, early visualization of the optico-carotid cistern for cerebrospinal fluid release, minimizing need for fixed brain retraction, and Sylvian fissure dissection. This technique can potentially reduce surgical risk and provide excellent exposure for anterior skull base lesions with favorable extent of resection, visual recovery, and complication rates.

Early Exposure of the Dorsal Surface of M1 Segment via the Distal Transsylvian Approach for Clipping of Anteroinferior-Projecting Middle Cerebral Artery Bifurcation Aneurysms.

Background Middle cerebral artery bifurcation (MCAB) aneurysms are common intracranial aneurysms. Anteroinferior-projecting MCAB aneurysms, with M1 segment usually embedded into the deep part of the Sylvian fissure, cause some surgical challenges. The distal transsylvian approach (DTSA) allows M1 exposure from the dorsal surface for proximal control in the early step. Therefore, this study aimed to demonstrate the efficacy and safety of DTSA for clipping anteroinferior-projecting MCAB aneurysms. Methods Among 97 patients with MCA aneurysms, 13 with anteroinferior-projecting MCAB aneurysms who underwent aneurysm clipping via the DTSA between June 2018 and January 2021 were retrospectively evaluated for the aneurysm obliteration rate, surgical complications, and outcomes. Results Ten patients (76.9%) had ruptured MCAB aneurysms and three (23.1%) had incidentally discovered unruptured MCAB aneurysms. Favorable outcome was achieved in 100% of patients with good grade. The complete aneurysm obliteration rate was 100% without intraoperative lenticulostriate artery injury. Twelve (92.3%) patients had early identified distal M1 segment for proximal control, and one (7.7%) patient had premature rupture of aneurysm that achieved favorable outcome at 3 months postoperatively. Difficult M1 exposure and premature rupture occurred in the patient with MCAB located above the Sylvian fissure line. Permanent postoperative neurological deficit was detected in one patient due to severe vasospasm. Conclusion DTSA, which simplify the early exposure of the dorsal surface of distal M1, is safe and effective for clipping anteroinferior-projecting MCAB aneurysms without extensive Sylvian fissure dissection. High-positioned MCAB requires careful dissection of the aneurysm neck with consideration of tentative clipping preparation.

Early Exposure of the Dorsal Surface of M1 Segment via the Distal Transsylvian Approach for Clipping of Anteroinferior-Projecting Middle Cerebral Artery Bifurcation Aneurysms.

Background:Middle cerebral artery bifurcation (MCAB) aneurysms are common intracranial aneurysms. Anteroinferior-projecting MCAB aneurysms, with the M1 segment usually embedded into the deep part of the Sylvian fissure, cause some surgical challenges. The distal transsylvian approach (DTSA) allows M1 exposure from the dorsal surface for proximal control in the early step. Therefore, this study aimed to demonstrate the efficacy and safety of DTSA for clipping anteroinferior-projecting MCAB aneurysms.Materials and Methods:Among 97 patients with MCA aneurysms, 13 with anteroinferior-projecting MCAB aneurysms who underwent aneurysm clipping via the DTSA between June 2018 and January 2021 were retrospectively evaluated for the aneurysm obliteration rate, surgical complications, and outcomes.Results:Ten patients (76.9%) had ruptured MCAB aneurysms and three (23.1%) had incidentally discovered unruptured MCAB aneurysms. Favorable outcome was achieved in 100% of patients with good grade. The complete aneurysm obliteration rate was 100% without intraoperative lenticulostriate artery injury. Twelve (92.3%) patients had early identified distal M1 segment for proximal control, and one (7.7%) patient had premature rupture of aneurysm that achieved favorable outcome at 3 months postoperatively. Difficult M1 exposure and premature rupture occurred in the patient with MCAB located above the Sylvian fissure line. Permanent postoperative neurological deficit was detected in one patient due to severe vasospasm.Conclusions:DTSA, which simplify the early exposure of the dorsal surface of distal M1, is safe and effective for clipping anteroinferior-projecting MCAB aneurysms without extensive Sylvian fissure dissection. High-positioned MCAB requires careful dissection of the aneurysm neck with consideration of tentative clipping preparation.

Microsurgical Management of the Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Feasibility Study

Background: The proper head positioning decreases the surgical complications by enabling a better surgical maneuverability. Middle cerebral artery (MCA) bifurcation aneurysms have been classified by Dashti et al. [Surg Neurol. 2007 May;67(5):441–56] as the intertruncal, inferior, lateral, insular, and complex types based on dome projection. Our aim was to identify the optimum head positions and to explain the anatomic variables, which may affect the surgical strategy of MCA bifurcation aneurysms. Methods: The lateral supraorbital approach bilaterally was performed in the 4 cadaveric heads. All steps of the dissection were recorded using digital camera. Results: The distal Sylvian fissure (SF) dissection may be preferred for insular type and the proximal SF dissection may be preferred for all other types. Fifteen degrees head rotation was found as the most suitable position for the intertruncal, lateral type and subtype of complex aneurysms related with superior trunk. Thirty degrees head rotation was found the most suitable position for the inferior type, insular type, and subtype of complex aneurysms related with inferior trunk. Conclusions: The head positioning in middle cerebral bifurcation aneurysms surgery is a critical step. It should be tailored according to the projection and its relationship with the parent vessels of the middle cerebral bifurcation.

Anterior transperiinsular approach to the head of the caudate nucleus and mediobasal frontal lobe

The head of the caudate nucleus and adjacent mediobasal frontal lobe are deeply localized and have complex anatomical and topographic relationships with surrounding functionally significant cerebral structures. These aspects determine difficult surgical treatment of pathology in this zone. To propose a new anterior transperiinsular approach for optimizing surgical access to the head of the caudate nucleus and mediobasal frontal lobe. Two patients with cavernoma of the head of the caudate nucleus and oligodendroglioma of the head of the caudate nucleus and mediobasal frontal lobe underwent resection via transsylvian anterior transperiinsular approach in 2018. In both cases, tumors were localized in dominant hemisphere. Standard MRI was performed before and after surgery. Luria's neurological and neuropsychological examination was carried out before surgery, in 7 days after surgery and then every 3 months. Surgical access was performed via stage-by-stage proximal dissection of Sylvian fissure with visualization of anterior and superior periinsular grooves. After that, periinsular groove was dissected at the base of anterior short gyrus. Then, we moved apart white matter using microinstruments and approached the area of interest. In case of this trajectory, surgical approach was performed at the level of the upper parts of inferior frontooccipital fascicle under the arcuate fascicle. Both patients underwent total resection of tumors that was confirmed by MRI. No pre- and postoperative neurological or neuropsychological abnormalities were observed. Anterior transperiinsular approach provides minimally invasive access to the head of the caudate nucleus and mediobasal frontal lobe. It can be used on dominant hemisphere without significant risk of speech or other cognitive impairments. The advantages of this approach are minimal damage to associative pathways and small distance between periinsular groove and zone of interest. Dissection of commissural fibers of the corpus callosum is not required compared to conventional transcallosal approach.

Comparison Between Minipterional Craniotomy Associated With Focused Sylvian Fissure Opening and Standard Pterional Approach With Extended Sylvian Fissure Dissection for Treatment of Unruptured Middle Cerebral Artery Aneurysms

In our institution, standard pterional craniotomy (PC) with an extended Sylvian fissure opening (ESFO) represented the standard approach for unruptured middle cerebral artery (MCA) aneurysm clipping until 2014, when we progressively started to prefer minipterional craniotomy (MPC) associated with a focused Sylvian fissure opening (FSFO). In the present study, we compared our results in terms of the efficacy of clipping and the rate of complications with these 2 different techniques. We included patients with small- and medium-size unruptured MCA aneurysms from January 2008 to December 2018 with follow-up of >12 months. The clinical and radiologic data were reviewed from the medical records. The outcomes were measured in terms of efficacy (aneurysmal exclusion rate) and safety (intracranial complication rate). Overall, 134 patients who had presented with unruptured MCA aneurysms <1.5 cm were treated at our institution from January 2007 to December 2018: PC and ESFO were used in 73 patients and MPC and FSFO in 61. The demographics and angioarchitectural features were comparable between the 2 groups, except for age, which was older in the FSFO group. The aneurysm exclusion rate was not different between the 2 groups. The intracranial complication rate was, overall, significantly lower in the FSFO group (P < 0.001), especially for the rate of postoperative seizures. Finally, the FSFO group had had shorter postoperative hospitalization and better short- and long-term clinical outcomes. The association between MPC and FSFO should represent the standard of treatment of unruptured MCA aneurysms in all referral cerebrovascular centers, allowing for the achievement of the same efficacy of standard PC with ESFO and minimizing the complications.

Changing Hands: A Rising Role of the Tumor Surgeon in Teaching Sylvian Fissure Dissection

The landscape of microneurosurgery has changed considerably over the past 2 decades, with a decline in indications for open surgery on cerebrovascular pathology and ever-increasing indications for open resection of brain tumors. This study investigated how these trends in case volume affected residents' training experiences in microsurgery and, specifically, Sylvian fissure dissection. Resident case logs were reviewed, identifying open cerebrovascular operations and craniotomies for tumor. Operations involving Sylvian fissure dissection were identified through operative reports. Changes in case number by resident were plotted over time, and linear regression was applied. Among 23 chief residents, 3045 operations were identified, 1071 of which were for cerebrovascular pathology and 1974 for tumor. Open cerebrovascular experience decreased (P < 0.0001) while tumor volume remained unchanged (P= 0.221). The number of Sylvian fissure dissections per resident did not change over time overall (P= 0.583) or within cerebrovascular operations (P= 0.071). The number of Sylvian fissure dissections in tumor operations increased (P= 0.004). This effect was predominated by an increase in intraaxial tumors approached via Sylvian fissure dissection (P= 0.003). The proportion of Sylvian fissure dissections in tumor surgery increased from 15% in 2009 to 34% by 2019 (P= 0.003). Residents are seeing an increasing proportion of their Sylvian fissure dissection experience during tumor operations. The distribution of this experience will continue to evolve as surgical indications change but suggests a growing role for tumor surgeons in resident training in microsurgery.

Orbitozygomatic Craniotomy for Clipping a Complex Middle Cerebral Artery Aneurysm: 2-Dimensional Operative Video.

Middle cerebral artery (MCA) aneurysms pose a surgical challenge because of the large caliber of the parent artery and the common need to dissect the sylvian fissure to permit access to the proximal and distal control. The neck of the aneurysm should be generously dissected to permit visualization of any adjacent lenticulostriate perforators. This patient demonstrated a left-sided wide-necked bilobed MCA aneurysm at the M1 bifurcation. The aneurysm was approached using a left orbitozygomatic craniotomy with distal sylvian fissure dissection. A single curved clip was applied for aneurysm occlusion, and postoperative angiography demonstrated aneurysm obliteration with parent vessel patency. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Surgical Techniques and Prevention of Complications in the Treatment of Basal Ganglia Hemorrhage Through the Distal Transsylvian Approach.

Basal ganglia hemorrhage can damage the internal capsule and lead to high rates of disability and mortality. The distal transsylvian approach is a validated approach in the treatment of basal ganglia hemorrhage. However, this approach is difficult and prone to complications. The present study was performed to investigate the surgical techniques and prevention of complications of basal ganglia hemorrhage through the distal transsylvian approach. From January 2015 to January 2018, the authors treated 40 cases of basal ganglia hemorrhage using the distal transsylvian approach. The surgical video recordings and the patients' clinical data were retrospectively analyzed. The authors discussed the surgical techniques and prevention of complications through the distal transsylvian approach. Thirty-eight cases of basal ganglia hemorrhage were successfully treated through the distal transsylvian approach. The other 2 cases were converted to the transcortical transtemporal approach. In the early cases, complications occurred in 3 stages: sylvian fissure dissection, insula lobectomy, and hematoma removal. In the subsequent cases, the authors implemented appropriate surgical techniques to prevent complications. Basal ganglia hemorrhage can be treated through the distal transsylvian approach, but not in all patients. The distal transsylvian approach is highly technical and more problematic than the transcortical transtemporal approach. Mastering certain operative skills can reduce the surgical complications.

Transsylvian, Carotid-Oculomotor Triangle Approach for Resection of a Rapidly Enlarging Midbrain-Pontine Cavernous Malformation: 3-Dimensional Operative Video.

Cavernous malformations (CM) of the anterior midbrain are best reached through an orbitozygomatic (OZ) approach with removal of the orbital rim and wide Sylvian fissure dissection. Our surgical video demonstrates this approach to resect a ruptured CM in a 36-yr-old woman who presented with headaches, left face and left arm paresthesias/weakness, and right-sided partial oculomotor nerve (CN III) palsy. Initial magnetic resonance imaging (MRI) showed a midbrain CM, and the patient was managed conservatively. However, 1 wk later, she presented again with worsened left arm and leg weakness and complete CN III palsy. Seven Tesla MRI demonstrated a larger hematoma, and the CM with new mass effect and upper pons extension. The patient underwent a right modified OZ craniotomy and Sylvian fissure split under guidance of intraoperative neuronavigation and with neuromonitoring. The carotid-oculomotor triangle and the Liliequist membrane were dissected to access the midbrain, and CN III was identified and followed posteriorly to the midbrain. Confirmed with neuronavigation, a longitudinal incision of the midbrain was performed, and the CM was encountered. The hematoma and CM were debulked and removed in a piece-meal fashion, leaving hemosiderin-stained brain intact to prevent unnecessary additional damage to the midbrain. Postoperative MRI confirmed gross-total resection, and the patient's weakness recovered substantially. In this video, we demonstrate that the brainstem is no longer forbidden surgical territory, and show how the use of neuronavigation for surgical planning, positioning, and approach, in addition to the understanding of safe entry zones and meticulous microsurgical technique have made safe and effective surgery on the brainstem possible.