Pterional Transsylvian Approach Research Articles

Small Sphenoid Ridge as a Factor Associated with Laterally Deviated Proximal Sylvian Fissure in Patients Undergoing Pterional Craniotomy

During the pterional-transsylvian approach, we sometimes encounter the proximal Sylvian fissure (SF) deviating laterally beyond the fold of the sphenoidal ridge (SR) and experience difficulty dissecting the SF due to the deep and oblique dissection plane. In the present study, we explored the association between the height of the SR and lateral deviation of the SF during the pterional-transsylvian approach. The association between the height of the SR on axial computed tomography and the presence of a laterally deviated SF was evaluated by reviewing patients who had undergone pterional craniotomy. Among the 52 patients included, lateral deviation of the SF was observed in 8 patients (13.4%). The median height of the SR was significantly smaller in patients with laterally deviated SF (6.0mm) than in patients with non-deviating SF (13.4mm; P<0.0001). The oculomotor nerves and middle fossa were observed at the edge of the dissection plane of the SF in all patients with a laterally deviating SF, while medial structures such as the internal carotid artery or optic nerve were observed in patients with non-deviating SF. Small SR was associated with lateral deviation of the proximal SF.

Dual approach for Difficult Intracranial Lesions and their Outcome in BSMMU: Experience of Two Cases

Some lesions in the brain are difficult to approach through a single common route / trajectory. For those, dual approach combined together may ensure easier safe removal with better outcome as we had lesions like left petroclival meningioma &amp; large craniopharyngioma. Methods Two patients, one left petroclival meningioma and one suprasellar craniopharyngioma with intraventricular extension underwent surgery with dual approach at the Neurosurgery department, BSMMU. After detailed clinical and radiological evaluation, the left petroclival meningioma patient was planned for a combined pre and post sigmoid petrosectomy and retromastoid retrosigmoid route. These were accomplished in two stages, three months apart. The craniopharyngioma patient with intraventricular extension underwent surgery through pterional transsylvian and frontal anterior trans-callosal approach in a single sitting.&#x0D; Bang. J Neurosurgery 2020; 10(1): 111-118

A technical note

The Liliequist membrane is a critical membrane located at the base of the brain separating the supratentorial from the infratentorial cisterns. The advantages of Liliequist membrane fenestration as a critical part of the pterional trans-Sylvian approach for ruptured anterior circulation aneurysm clipping is not well established. We demonstrated that the fundamental role of Liliequist membrane fenestration is brain relaxation through the egress of CSF that is not usually gained from other modalities (e.g., placement of a lumbar drain, fenestration of lamina terminalis) in this specific setting.

Hemorrhagic presentation of intracranial pilocytic astrocytomas: literature review.

Pilocytic astrocytomas (PAs) are seemingly innocuous and benign tumors. However, in recent times, many case series have documented high rates of hemorrhage in these neoplasms. We hereby provide a detailed analysis on hemorrhagic pilocytic astrocytomas (HPA) in adults and report one such case managed at our institute. In addition, salient differences between adult and pediatric hemorrhagic PA have been briefed. Hospital records were retrieved for our case. Literature review was conducted by searching online databases for the following keywords-pilocytic astrocytoma, hemorrhage, cranial, pediatric, and adults. A 22-year-old male with neurofibromatosis-1 presented with sudden onset headache and vomiting of 3-day duration. Imaging revealed a lobulated suprasellar lesion with obstructive hydrocephalus. Pterional transsylvian approach and subtotal resection were performed. Histopathology showed features of PA with bleed. Including current report, a total of 26 cases have been reported. Mean age was 37years (21-75years) and they are mostly found in the third decade. The male:female ratio was 2.1:1. Sudden headache with vomiting was the most common symptoms. Tumors were mostly located in cerebral hemispheres (n=9/34.6%), hypothalamus/suprasellar region (n=7/27%), and cerebellum (n=6/23%). Two-thirds underwent gross total excision. There were two deaths and except one case, no recurrences were reported in those with available follow-ups. Hemorrhagic presentation of a PA is rare, although more commonly seen in adults and most commonly located in cerebral hemispheres. Maximal safe resection is the standard treatment and recurrences are rare.

Intraoperative nursing cooperation for micro-surgical clipping of middle cerebral artery aneurysms

Objective To investigate the importance of nursing cooperation in the operation of middle cerebral artery aneurysm (MCAA) microsurgical clipping. Methods We retrospectively analyzed 202 cases (male 103 cases, female 99 cases) of MCAA patients who were underwent microsurgical clipping surgery (from January 1997 to December 2013), and the importance of nursing cooperation in the process were analyzed. A total of 242 aneurysms were found during surgery of 212 cases underwent craniotomy clipping, in which 215 cases were MCAA, and 2 cases underwent autologous dura wrapping, except one unbroken MCAA case was embolism. Results All patients in this group underwent Yasargil′s pterional trans-sylvian approach, 212 MCAA surgery were successfully clipped. 174 cases were clipped without rupture (81.3%), while rupture (18.7%) occurred in 40 patients during surgery. All patients had been treated with controlled hypotension and intracranial hypotension, through timely blood transfusion, infusion and other response measures to ensure the successful completion of surgery. Conclusions It can help will the operation completed smoothly and improve surgical effects by personalized utilizing of controlled hypotension, brain tissue relaxation techniques and other measures in microsurgical clipping of MCAA, as well as good nursing cooperation during the process of aneurysms rupture. Key words: Middle cerebral artery aneurysms; Microsurgical clipping; Intraoperative nursing

The Pterional-Transsylvian Approach for Tumor in the Temporal Horn: A Case Report.

A variety of surgical approaches to temporal horn tumors of the lateral ventricle have been described. Magnetic resonance imaging (MRI) and angiography are the preferred modalities for preoperative evaluation and provide important information for the choice of surgical approach. A 59-year-old man was referred to our hospital due to confusion and gait disturbance. On enhanced MRI, a homogeneous enhanced solitary mass was observed within the temporal horn of the left lateral ventricle with transependymal extension. The lesion was accompanied by increased hypervascular tumor blush on preoperative cerebral angiography. Subtotal removal of the temporal horn tumor was performed because the lesion was identified as lymphoma during surgery. The postoperative course was un-eventful. The patient was referred to the oncology department for conventional chemotherapy. Adjuvant chemotherapy improved the clinical outcome. The pterional-transsylvian approach was beneficial for partial removal of the tumor and tissue diagnosis in this case.

Yasargil Higway in Neurosurgery (For the nineteen years old of my teacher Mahmut Gazi YASARGIL)

My Teacher Professor Yasargil is very famous doctor, mentor, surgeon, lider, scientist, researcher, inventor and teacher of last Century, not only in Neurosurgery, but also in Neuroscience of the World. His very important Neurosurgical Way and thecniques, the pterional trans Sylvian approach, I called as “Yasargil Higway” is commonly employed in surgery of the anterior circulation and upper basilar artery aneurysms, as well as for the tumors of orbital, retroorbital, sellar, chiasmatic, sub frontal and prepontine areas and lesions around the sella especially for lesions behind the clivus. Also tumors arising from the medial sphenoid ridge, the superior orbital fissure, the anteromedial temporal surface, or the cavernous sinus region are approached through a pterional exposure. The modification of surgical technique is based on the experience, training and observation of the neurosurgeon. One technique is not necessarily better than the another. Regardless of the surgical technique, the end results depend on a rigorous, methodical, systematic, and step by-step approach to the target, securing it with minimal injury to surrounding structures.

Entry Point to the Sylvian Fissure for the Pterional Transsylvian Approach

Although the anatomy of the Sylvian fissure is understood, there is little information on where to start its dissection in the pterional transsylvian (PT-TS) approach. At small craniotomy using the PT-TS approach, we set the entry point to the Sylvian fissure at 15 mm behind the anterior edge of the craniotomy along the Sylvian fissure and designated this site "point 15." Here we compared the utility of "point 15" with the Sylvian point (point on the Sylvian fissure giving rise to the horizontal and anterior ascending rami) that had been recommended earlier as the entry site for opening the Sylvian fissure. This study includes 16 patients with 7 ruptured and 9 unruptured anterior circulation aneurysms. We evaluated the usefulness of "point 15" in the PT-TS approach for aneurysmal neck clipping with respect to the adequacy of anatomical exposure and low invasiveness. In 12 patients "point 15" provided for excellent anatomical exposure of the Sylvian fissure; complete neck clipping was possible with minimal brain retraction and damage. In two patients with ruptured aneurysms and thick subarachnoid hemorrhage and in two patients with unruptured aneurysms, the dissection had to be enlarged 3 to 4 mm distally without reaching the Sylvian point. In the latter two patients the Sylvian veins were tethered to frontal and temporal lobes. The "point 15" was an easily set entry point to the Sylvian fissure. It provided for sufficient anatomical exposure at surgery for anterior circulation aneurysms; additional posterior dissection was required in rare cases. We found that "point 15" was useful in small craniotomies using the PT-TS approach.

Anatomical configuration of the Sylvian fissure and its influence on outcome after pterional approach for microsurgical aneurysm clipping

Background:The sylvian fissure (SF) is the anatomical pathway used in a pterional approach, which leads to most aneurysms. There are four different anatomical variants of the SF described. In the present retrospective study the four different categories of the SF were studied in order to evaluate any correlation of these variants to surgical outcome.Methods:Patients treated for intracranial aneurysms by a pterional transsylvian approach during 2003-2012 (N = 237) were included in the study. The SF category was determined by analysis of preoperative computed tomography (CT) scanning. Patients were grouped into unruptured intracranial aneurysms (UIA) and ruptured intracranial aneurysms with subarachnoid hemorrhage (SAH) according to the Hunt and Hess grades. Brain edema, vasospasms, ischemic lesion rate, and outcome were evaluated for possible correlation with SF anatomical variants.Results:Postsurgically brain edema formation correlated significantly with more complex anatomical variants of the SF in patients with UIAs and in patients with Hunt and Hess 1 and 2. Ischemia rate, vasospasms, or clinical outcome was not negatively affected though.Conclusion:The classification of the SF as proposed by Yasargil is more than a pure anatomical observation. In this retrospective study, we show that the anatomical variants of the SF can be associated to postoperative complications like formation of brain edema or ischemic lesions Preoperative knowledge of the SF anatomy and possibly consecutive adapted extend of the surgical approach can decrease procedure-related morbidity.

Immediate results of microsurgical clipping of posterior communicating artery aneurysms using the pretemporal transclinoidal approach

BackgroundWe evaluated adverse ischemic events as early surgical results of microsurgical clipping of 44 and 34 posterior communicating artery (PComA) aneurysms through the pterional transsylvian and pretemporal transclinoidal approach, respectively, between January 2007 and October 2010. MethodsPatients undergoing PComA aneurysm clipping were divided into two groups, and their immediate surgical results were compared and analyzed. Those who underwent the pterional transsylvian approach (group A) comprised 42 patients with 44 PComA aneurysms (24 ruptured and 20 unruptured). Those who underwent the pretemporal transclinoidal approach (group B) comprised 32 patients with 34 PComA aneurysms (20 ruptured and 14 unruptured). ResultsThe immediate postoperative total occlusion rates were 97.7% in group A and 100% in group B. The pretemporal transclinoidal approach significantly reduced the overall risk of silent and symptomatic ischemic strokes (p = 0.04) in ruptured PComA clippings and tended to lower the incidence of intraoperative aneurysm rupture (p = 0.07) as well as the overall ischemic events (p = 0.06) in a total of 78 aneurysm clippings, as compared with the pterional transsylvian approach. Although not significantly, the pretemporal transclinoidal approach also tended to have a lower incidence of intraoperative aneurysm rupture in ruptured aneurysm clippings (p = 0.11), which were mainly responsible for the symptomatic ischemia. The pretemporal transclinoidal approach had no additional advantage over the traditional pterional transsylvian approach in unruptured PComA aneurysm clippings in the present study. ConclusionThe pretemporal transclinoidal approach achieved better visualization of the vital neurovascular structures surrounding PComA aneurysms, which might be a key improvement in lowering the risk of intraoperative aneurysm rupture and obtaining significantly satisfactory immediate surgical results in the microsurgical clipping of PComA aneurysms, especially ruptured ones.

Should patients be routinely assessed for cerebral vasospasm after temporal lobe epilepsy surgery?

Temporal lobe epilepsy (TLE) is the most common form of epilepsy that is resistant to antiepileptic drug treatment. Resective epilepsy surgery offers a substantially greater prospect of achieving seizure control than continued medical therapy, and is associated with better quality of life outcomes.1 The nature of the resection performed in patients undergoing epilepsy surgery for drug-resistant TLE varies among centers and surgeons. The most common type of resection is an “anterior temporal lobectomy” based on the procedure developed by Falconer and colleagues in the 1960s.2 This involves the excision of the mesial temporal structures, the anterior temporal pole, and 3–6.5 cm of the lateral temporal neocortex (usually sparing the superior temporal gyrus). More recently, some surgeons have adopted the “selective amygdalohippocampectomy” approach, first described by Wieser and Yasargil.3 This procedure attempts to restrict the resection to the mesial temporal structures, via a pterional craniotomy and transsylvian approach, while minimizing the possibility of reduced function due to resection of anterior and lateral temporal structures,3 especially neurocognitive deficits, as compared to the standard anterior temporal lobectomy procedure.4 However, performing a selective amygdalohippocampectomy is …

Surgical excision of hypothalamic hamartoma in a twenty months old boy with precocious puberty

A twenty months old boy presented to our department with true precocious puberty due to hypothalamic hamartoma. Total surgical excision of pedunculated hypothalamic hamartoma was done successfully by the pterional trans-sylvian approach as he could not afford medical management. Patient had uneventful post-operative course with normalization of serum testosterone levels and regression of secondary sexual characters.

Microsurgical management of large and giant paraclinoid aneurysms

Background Because of the complex topographic anatomical relationship between vascular, dural and bone structures, paraclinoid aneurysms, especially those of larger size, remain a great challenge for vascular neurosurgeons. We present our microneurosurgical experience of 51 consecutive patients with large and giant paraclinoid aneurysms to scrutinize our personal strategies related to surgical treatment. Methods Fifty-one patients with large or giant paraclinoid underwent micorneurosurgical aneurysm treatment. Operative strategies were planned according to preoperative state-of-the-art imaging studies, and a pterional-transsylvian approach was routinely used. Proximal control of the internal carotid artery (ICA) was achieved by exposure of the cervical portion of the vessel. Intraoperative electroencephalogram and somatosensory evoked potential monitoring, indocyanine green (ICG) videoangiography and/or microvascular Doppler ultrasonography (MDU) were regularly used. A postoperative digital subtraction angiography or computed tomography angiography was performed to verify the efficacy of treatment. Results Forty-three large and giant paraclinoid aneurysm necks (84%) were directly clipped, seven unclippable aneurysms (14%) were trapped with extra-intracranial high-flow revascularization, and one aneurysm (2%) was treated with only ICA proximal Hunterian ligation. Two patients (4%) died in the early postoperative period. In 84% of the patients, the Glasgow Outcome Scale score was 4 or 5 at discharge. At the 6-month follow-up examination, the Rankin Outcome Scale score was 0-2 in 90% of patients. Conclusions Temporary parent vessel occlusion, retrograde suction decompression, endoaneurysmectomy, parent vessel clip reconstruction, and bypass vascular anastomosis are essential techniques to treat complex paraclinoid aneurysms. The combined use of electrophysiological monitoring, MDU, intraoperative ICG videoangiography, and endoscopy can substantially improve microsurgical outcome.

Hemiparkinsonism due to a pontomesencephalic cavernoma: improvement after resection

Cavernous angiomas of the upper brainstem causing hemiparkinsonism are very rare. Due to their difficult-to-reach localization, brainstem cavernomas, in particular those in anterior locations, continue to present a therapeutic challenge. The authors report on a 16-year-old boy with a pontomesencephalic cavernoma who developed hemiparkinsonism and hemiparesis after hemorrhage. After complete surgical removal of the pontomesencephalic cavernoma via a pterional transsylvian approach, his symptoms resolved. Although pontomesencephalic cavernomas occupying the ventral portion of the brainstem are regarded as problematic for resection, the pterional transsylvian approach provides an excellent route for removal of cavernomas that are in contact with the ventral surface of the midbrain in the interpeduncular cistern. Surgical removal of this type of lesion is recommended because resolution of clinical symptoms, including hemiparkinsonism, can be achieved.

The Minimally Invasive Supraorbital Subfrontal Key-Hole Approach for Surgical Treatment of Temporomesial Lesions of the Dominant Hemisphere

Surgery in the temporomesial region is generally performed using a subtemporal, transtemporal, or pterional-transsylvian approach. However, these approaches may lead to approach-related trauma of the temporal lobe and frontotemporal operculum with subsequent postoperative neurological deficits. Iatrogenic traumatisation is especially significant if surgery is performed in the dominant hemisphere. During a five-year period between January 2003 and December 2007, we have approached the temporomesial region in 21 cases via the supraorbital approach. In 15 cases, the lesion was located within the dominant hemisphere, all lesions had space-occupying effects. In all cases, meticulous approach planning was performed, demonstrating a close proximity of the lesion to the pial surface on the upper anterior mesial aspect of the temporal lobe. An extension within the parahippocampal gyrus or with deep temporobasal tumor growth below the sphenoid wing were considered as exclusion criteria for using the supraorbital approach. In all cases surgery was performed without intraoperative complications. Pathological investigation showed 7 low-grade astrocytomas, 4 high-grade astrocytomas, 2 gangliogliomas and 2 cavernomas. Early postoperative MRI scans confirmed a complete removal of the lesion in 14 cases. In one case of a subtotal resection, the residual tumor was removed through a posterior subtemporal approach. The postoperative neurological examination was unchanged in 14 cases. In one case a transient hemiparesis was observed. In patients with dominant-sided lesions no speech or mental deficits were present. In selected cases, the minimally invasive supraorbital craniotomy offers excellent surgical efficiency in the temporomesial region with no approach-related morbidity compared to a standard transtemporal or pterional-transsylvian approach.

Colloid-like cyst located in the prepontine region

Background The term “colloid cysts” refers to nonneoplastic lesions located in the anterior part of the third ventricle. However, cysts morphologically identical to colloid cysts are found, albeit extremely rarely, through the neuraxis. Case description We report a case of a 44-year-old man with a short history of headache and 5 years of bilateral hearing loss. Computed tomography (CT) and magnetic resonance imaging (MRI) scans showed an oval lesion located at the anterior surface of the pons. The tumor was excised through a right pterional transsylvian approach. Postoperatively, the hearing deficit remained unchanged. Otherwise, the patient made an excellent recovery. Histopathological examination showed a colloid-like cyst. Conclusions Colloid-like cysts growing in the prepontine region are extremely rare. To date, only two similar cases have been reported in the literature. Patients present with headaches, hearing loss, or blurred vision.

Totally thrombosed giant P2 aneurysm: a case report and review of literature

The diagnosis and treatment of intracranial saccular giant aneurysms is still difficult despite developments in neuroradiology, neuroanesthesiology and micro-neurosurgery. These aneurysms are usually located on major intracranial arteries and are rarely on distal branches of these arteries. An extra-axial 4×5 cm mass lesion in the left mediobasal temporal region was detected on the CT and MRI examinations of a 37 year old male patient who was admitted to our institution with headache and slight right-sided hemiparesis lasting for 2 months. The lesion was avascular on angiography. Surgery proved that the lesion was a totally thrombosed giant aneurysm of the P2 segment of posterior cerebral artery (PCA). The P2 segment was clipped proximal to the aneurysm with pterional-transsylvian approach and the aneurysm was totally excised. Giant aneurysms of the P2 segment are rare and 15 cases have been reported in the literature. This report presents a rarely seen totally thrombosed giant P2 aneurysms and discusses the difficulties in diagnosis and treatment.

The trans-supraorbital approach.

The trans-supraorbital approach represents the advantage of combining the keyhole principle and skull base surgery. In cadaveric work the author shows the anatomic fields visualized with this procedure, advantages and potential surgical applications. The experimental surgical procedure was performed on 8 adult skulls and on 3 cadavers with intact cerebral structures. First, a 2 cm supraorbital approach for endoscopic exploration was used. The basic anatomic landmarks and corresponding dimensions of the microsurgical field were recorded and then compared with those from the trans-supraorbital approach, after removing the orbital arch and other parts of the orbital ceiling. This technique offers a 0.5 cm average increase in surgical field from the craniotomy. The surgical distance that results is shorter (about 2 cm), as well as the length of the surgical instruments required. A better microscope illumination in the deep fields, and the possibility of access to the intraorbital region, the superior orbital fissure, the optic foramen, and the cavernous sinus through the clinoid space are also obtained, with minimal cerebral retraction and similar advantages as through the pterional trans-sylvian approach. The author concludes that by extending the craniotomy and decreasing the surgical distance, the microsurgical field is more convenient for microscope-assisted surgery without totally relying on the endoscope, and with minimal brain retraction. It also provides multiple options to approach vascular and tumor lesions found in these microsurgical corridors, combining principles of minimal invasion and skull-base surgery.

Giant Olfactory Meningiomas: The Pterional Approach and Its Relevance for Minimizing Surgical Morbidity

Olfactory groove meningiomas may attain surprisingly large size. The subfrontal approach is currently the route preferred by most neurosurgeons for their excision. The pterional-transsylvian route represents an alternate exposure for microsurgery of frontobasal tumors. Although this approach has been already described for olfactory meningiomas, tumors of giant size were not specifically addressed in the literature. We report the application of the pterional-transsylvian approach in six patients with giant olfactory meningiomas. This series is unique because it includes only patients with tumors exceeding 6 cm in diameter with bilateral symmetrical development. A radical removal was achieved in all patients and all of them made a full recovery. To investigate the relevance of the pterional-transsylvian approach for minimizing surgical morbidity, a magnetic resonance imaging protocol was designed to characterize even subtle postoperative frontal lobe structural changes. These changes, limited to the frontal lobe ipsilateral to exposure and localized in specific anatomical domains of the prefrontal area, included cystic degenerative alterations, parenchymal gliosis, and associated persistent white matter edema. Results from the present series strengthen the usefulness of the pterional-transsylvian approach as a safe surgical route for lesions affecting the anterior skull base, even with huge bilateral symmetrical expansion, such as giant olfactory meningiomas.

Combined infratemporal epidural and medial triangle approachによる脳底動脈先端部動脈瘤の手術

Surgical techniques for a combined infratemporal epidural and medial triangle approach to basilar tip aneurysms consists of 1) an orbitozygomatic frontotemporal craniotomy, 2) an infratemporal epidural approach in order to expose the nerve sheathes of the IInd and Ist divisions of the trigeminal nerve and the medial half of the gasserian ganglion, 3) a pterional transsylvian approach for opening the superior wall of the cavernous sinus via the medial triangle and 4) unveiling the cavernous sinus medial to the IInd division of the trigeminal nerve.Seventeen cases of ruptured basilar tip aneurysms which were operated on via this orbitozygomatic infratemporal transcavernous approach were divided into three groups and the clinical features were reviewed. The fact that out of 4 cases in the early-operation group only one case showed good operative result seems to be attributed to the serious original Hunt and Kosnik Grade of the patients. All 3 cases with Hunt and Kosnik Grades I and II in the relatively early-stage operation group (operated on between Day 6 and Day 10) were good postoperatively. The operative result of 6 out of 8 cases with Grade I or II in the delayed-operation group was good. Conclusion: 1. This transcavernous approach seems to be the preferable approach to the basilar tip aneurysm in the early stage, with several advantages such as 1) wide exposure of the operative field, 2) the shortest possible distance with only slight retraction of the temporal tip with its dura mater, and 3) no division of the Sylvian vein and the spheno-parietal sinus running within the temporal dura propria. 2. Clipping of the basilar tip aneurysm being located either in higher or lower position can be performed successfully without retracting the carotid artery and its tributaries.