Subtemporal Approach Research Articles

V-4-51 - A combined trans-sylvian and subtemporal approach for basilar bifurcation aneurysms

V-4-51 - A combined trans-sylvian and subtemporal approach for basilar bifurcation aneurysms

Transmaxillary approach to the anterior cavernous sinus: a microanatomic study.

Several approaches to expose the anterior cavernous sinus have been used, such as frontotemporal, orbitofrontal, anterior subtemporal, and various transfacial approaches. In an effort to gain exposure to the anterior cavernous sinus without necessitating a craniotomy or wide transfacial exposure, the authors in the present study have developed a transmaxillary approach to the cavernous sinus. The approach was developed using data obtained by performing 24 cadaveric dissections. Using a sublabial incision to expose the maxilla, maxillotomy is performed and the course of the infraorbital nerve is identified as a guide to the maxillary branch of the trigeminal nerve. After an osteotomy of the posterior sinus wall and pterygoid plate, the foramen rotundum is identified, which lies a mean of 10 mm from the posterior wall of the maxilla. A superomedial enlargement of the foramen rotundum is then undertaken to ultimately expose the anterior cavernous sinus. This technique offers access to all cavernous cranial nerves, as well as the entire course of the anterior loop of the internal carotid artery to the origin of the ophthalmic artery. With a mean operative range of 38 mm from the posterior wall of the maxilla to the anterior loop of the internal carotid artery, this approach offers adequate exposure with a short operative distance. The approach may be useful in limited exposure of tumors of the anterior cavernous sinus and some intracavernous vascular lesions.

Commentary

As a variant of the classic pterional approach, the pretemporal approach aims to combine the advantages of the pterional, temporopolar, and subtemporal approaches, offering enhanced angles of the view and the action of the surgeon: whether the straight downward view of the pterional approach, the anterolateral temporopolar view obtained by pulling back the temporal pole, or the lateral view offered by the subtemporal approach. This enhanced view is accomplished by adding a more extended and basal temporal exposure to the classic pterional craniotomy, as low as the floor of the middle fossa, and exposing completely the temporal pole. The sylvian fissure is split widely, the basal cisterns are opened widely, and the arachnoid adhesions among the frontal and the temporal lobes, tentorial edge, and cranial nerve III are sectioned completely. When necessary, the superficial sylvian vein or veins binding the temporal pole to the sphenoparietal sinus are sacrificed, allowing a posterior retraction (temporopolar exposure) or a superior retraction (subtemporal exposure) of the temporal lobe. The interpeduncular, upper petroclival, middle fossa, sellar and parasellar regions, and anterior portion of the tentorial incisura are within the reach of the pretemporal approach. The inclusion of an orbitozygomatic osteotomy to the pretemporal approach can greatly improve the surgical exposure of such areas. The more basal exposure of the anterior and middle cranial fossae provided by the orbitozygomatic craniotomy allows the treatment of lesions that either arise or extend to the extradural compartment of these regions. The sphenoid, frontal and ethmoidal sinuses, components of the orbit, cavernous sinus, infratemporal fossa, petrous apex, intrapetrous internal carotid artery, and remainder of the middle cranial fossa can be accessed with this approach.

Surgical extirpation of the posterior hippocampal arteriovenous malformation

Surgical extirpation of medial temporal (AVMs) arteriovenous malformations has been one of the most challenging issues in neurosurgery. Yaşargil classified mediobasal AVM into four subtypes: amygdala, anterior hippocampal, middle hippocampal, and posterior hippocampal lesions. The lesions around the trigone extending forward to the temporal horn, and medially adjacent to the midbrain, can be referred to as posterior hippocampal AVMs. The therapeutic indications and operative approaches for these lesions remain controversial. Nine patients underwent surgical resection for AVMs of the posterior hippocampus using a laterobasal approach. In four patients, AVMs were located chiefly within the lateral ventricle, and the lesions were resected using a laterobasal approach through the occipitotemporal sulcus, or through a hematoma cavity within the fusiform gyrus. Clinical improvement followed the procedure in three of four patients. In the remaining five patients, the nidi were located chiefly within the ambient cistern, extending upward to the basal ganglia. Contralateral hemiparesis occurred in three patients. Two patients showed marked improvement following an initial decline in neurologic status. A laterobasal transventricular approach is suitable for ventricular AVMs, whereas only limited exposure can be afforded through a transventricular, transchoroidal fissure route for the AVMs within the ambient cistern. For these lesions, a conventional subtemporal approach to the tentorial incisura is preferable.

Splitting of temporalis muscle for basal exposure--technical note.

Splitting of the temporalis muscle to increase the basal exposure in subtemporal approaches is discussed. The temporalis muscle is split vertically in the direction of its insertion at the coronoid process of the mandible up to the zygomatic arch and the split components of the muscle are retracted apart. This simple procedure significantly reduces the obstruction caused by the temporalis muscle during subtemporal surgery. The procedure was employed in six patients with tumors located in the basal temporal, posterior cavernous sinus, and petrous apex region. Zygomatic osteotomy could be avoided in selected patients and the exposure of the infratemporal fossa region could be widened by employing this technique. The function and bulk of the temporalis muscle were effectively preserved.

脳底動脈末梢部動脈瘤に対するreversed posterolateral subtemporal approach

We describe our modified subtemporal approach for basilar terminal aneurysms. We have modified the conventional subtemporal approach to diminish temporal lobe retraction and the risk of damage to the temporal lobe. The surgeon stands at the dorsocaudal side of the patient's head and the operative microscope is introduced posterolaterally to the patient's head. The posterior part of the temporal lobe is slightly retracted upward anterior to the vein of Labbé. The tentorium and arachnoid are cut, and the cerebrospinal fluid is aspirated as much as possible. Thus the brain becomes slack at the initial stage of the operation. The operative microscope is positioned parallel to the inclination of the tentorium or temporal base. The basilar terminal vasculatures can be examined upward from below with minimal temporal lobe retraction and the aneurysm is clipped. The perforating arteries arising from the terminal portion of the basilar artery are well recognized in this modified approach.

後大脳動脈末梢部動脈瘤 (P3segment) の1手術例-Posterior subtemporal approachの有用性-

後大脳動脈末梢部動脈瘤 (P<SUB>3</SUB>segment) の1手術例-Posterior subtemporal approachの有用性-

Biportal neuroendoscopic microsurgical approaches to the subarachnoid cisterns. A cadaver study.

A preclinical cadaver study was performed to develop the technique of biportal neuroendoscopic dissection in the subarachnoid space of the basal cisterns and to test the feasibility, utility, and safety of this new technique. In 23 fresh post-mortem adult human cadavers and 2 formalin-fixed adult human head specimen a total of 33 biportal endomicrosurgical dissections into and within the basal cisterns were carried out. Following suction of cerebrospinal fluid from the subarachnoid space 0 degree-, 30 degrees-, and 70 degrees-lens-scopes (Aesculap AG, Tuttlingen, Germany) with outer diameters of 4.2 mm and trochars with outer diameters of 5 to 6.5 mm were introduced into the surgical field. 6 different endoscopic routes to the basal cisterns and a total of 10 different combinations of these approaches for biportal endoneurosurgery could be described, but it was found that not all of them were useful and safe. The transventricular approach to the prepontine cisterns through the foramen of Monro and the floor of the third ventricle, biportally combined with a subfrontal or a subtemporal approach, turned out to be not safe enough as it was accompanied by traumatization of the fornix at the interventricular foramen and of the hypothalamus at the level of the tuber cinereum due to relaxation and caudal shift of the brain following suction of cerebrospinal fluid to clear the basal cisterns for the subfrontal or subtemporal approaches. Useful and safe endomicrosurgical approaches to the basal cisterns were: 1st subfrontal, either epidural or intradural, 2nd subtemporal, either anterior or posterior, and 3rd frontal interhemispheric. Various biportal combinations of these approaches are estimated to be feasible, useful, and safe enough to be performed during microsurgical procedures in the operating room. The biportal endomicrosurgical strategy allows for effective and safe dissections within the subarachnoid spaces of the basal cisterns. The tip of the microinstruments as well as the neighboring anatomical structures can be nicely controlled at angles of about 60 degrees to 180 degrees depending on the viewing angles of the scopes used and depending on the individual shape of the head. A variety of microsurgical instruments has been tested. A number of these will have to be redesigned for this new technique. Regions suitable for biportal neuroendoscopic subarachnoid preparations are the olfactory groove, the prechiasmatic cistern, the region of the optic chiasm, the entire suprasellar area, parts of the parasellar area, the pre- and perimesencephalic cisterns, and the prepontine cistern.

Cholesterol granulomas of the petrous apex: combined neurosurgical and otological management.

Cholesterol granulomas of the head are relatively rare. Isolated lesions of the cerebellopontine angle are even more uncommon. In this report, 17 cases of petrous apex cholesterol granulomas are presented and management is discussed. Symptoms at presentation included dizziness (14 patients), pressure (nine patients), tinnitus (eight patients), hearing loss (eight patients), otalgia (six patients), headache (six patients), nausea (three patients), drainage from ear (two patients), facial pain (two patients), seizure (two patients), lightheadedness (one patient), hemifacial spasm (one patient), and facial numbness (one patient). Six cases were managed without surgery and 11 patients underwent operative procedures. The approaches used included the infralabyrinthine (eight patients), transcanal-infracochlear (two patients), and translabyrinthine (one patient). The mean follow-up period for all cases was 29.5 months. Of those patients managed without surgery, symptoms improved in all except one, whose tinnitus was slightly worse. Of surgically treated patients, symptoms improved or remained the same except in one with worsened dizziness. There were nine patients with hearing present presurgery and seven whose hearing was preserved postsurgery. The authors present a case that was managed at another center where an attempt at surgical resection through a subtemporal middle fossa approach was unsuccessful. This lesion was successfully treated using an infralabyrinthine approach with drainage into the mastoid cavity. Cholesterol granulomas of the petrous apex can be managed without surgery when symptoms are stable or improve. Otherwise, a transmastoid extradural approach with simple drainage into the mastoid sinus or middle ear produces symptomatic improvement with low morbidity. Resection of petrous apex cholesterol granulomas is not necessary.

Successful removal of cryptic arteriovenous malformation located at the upper ventral pons via subtemporal transtentorial approach

Lesions located at the ventral portion of the brain stem are still difficult to access surgically. We report herein a case of ventral pontine cryptic arteriovenous malformation that was successfully removed via a subtemporal-transtentorial approach. An 18-year-old female patient experienced repetitive hemorrhagic attacks leading to a massive pontine hemorrhage with several neurologic deficits. Since angiography and magnetic resonance imaging failed to delineate the hemorrhagic origin, a combination of multiple approaches was initially attempted. The subtemporal-transtentorial approach made it possible to obtain an adequate operative view in this case. An angioma observed at the septum of the multilocular hematoma was totally removed. Pathologic examination of the resected specimen revealed it to be an arteriovenous malformation. Postoperatively, the patient showed unexpectedly good recovery despite the original massive pontine hemorrhage. Several surgical approaches to the ventral pons have been proposed in the literature. While the subtemporal-transtentorial approach was useful in our patient, multiple routes should be considered to access a massive lesion of unknown extent at the ventral pons. The unexpected recovery observed in our patient suggests that surgery is an option in the treatment of this type of lesion.

Obituary: Professor A. Beller (1912–1996)

The improvement in the knowledge of the main anatomical landmarks permits an evolution in the safety of the surgical treatment and a conceptual development of the geometrical anatomicosurgical characteristics of the infratemporal fossa. This conceptual evolution determines surgical and oncological advantages : firstly, improved comprehension of the anatomico-surgical limits of the resection and secondly the safeguarding of the oncological en-bloc dissection. The lateral approach of the infratemporal fossa gives a wider exposure of the surgical field, a shorter depth of work, a good control over the vessels and the possibility of carry out a microsurgical transfer. The surgical approaches correspond to the topographical location and the biology of the neoplasm in cases with infratemporal fossa and inferior compartment location the lateral transfacial approach is indicated. In cases with involvement of the superior compartment a lateral transcraniofacial subtemporal approach is necessary in order to remove the skull base. In cases with a neoplastic invasion of the skull base where the dura mater is the anatomical plane free from disease it is necessary to utilize an intradural approach. In patients with a secondary spread into the inferior compartment from the maxilla a combined antero-lateral transfacial approach is indicated. Finally, an orbitomaxillary involvement with secondary spread in the upper compartment of the infratemporal fossa necessitates an antero-lateral transcraniofacial subtemporal subfrontal approach.

Infratemporal fossa surgery for malignant diseases.

The improvement in the knowledge of the main anatomical landmarks permits an evolution in the safety of the surgical treatment and a conceptual development of the geometrical anatomico-surgical characteristics of the infratemporal fossa. This conceptual evolution determines surgical and oncological advantages: firstly, improved comprehension of the anatomico-surgical limits of the resection and secondly the safeguarding of the oncological "en-bloc" dissection. The lateral approach of the infratemporal fossa gives a wider exposure of the surgical field, a shorter depth of work, a good control over the vessels and the possibility of carry out a microsurgical transfer. The surgical approaches correspond to the topographical location and the biology of the neoplasm in cases with infratemporal fossa and inferior compartment location the lateral transfacial approach is indicated. In cases with involvement of the superior compartment a lateral transcraniofacial subtemporal approach is necessary in order to remove the skull base. In cases with a neoplastic invasion of the skull base where the dura mater is the anatomical plane free from disease it is necessary to utilize an intradural approach. In patients with a secondary spread into the inferior compartment from the maxilla a combined antero-lateral transfacial approach is indicated. Finally, an orbitomaxillary involvement with secondary spread in the upper compartment of the infratemporal fossa necessitates an antero-lateral transcraniofacial subtemporal subfrontal approach.

Intramedullary epidermoid cyst in the brain stem: Case report

The incidence of intracranial epidermoid cysts is between 0.2% to 1.8% of all brain tumors. They usually occur in the cerebellopontine angle or parasellar region. Intramedullary epidermoid cyst is rare and only nine cases have been previously reported. A 69-year-old woman had progressive left hemiparesis for 2 years. Computed tomography scanning and magnetic resonance imaging (MRI) revealed that there was a cystic tumor in the pons that was compressing the brain stem. A part of the tumor cyst wall and the content of the cyst were surgically removed by right subtemporal transtentorial approach. The histologic diagnosis was epidermoid cyst. After the surgery, the left hemiparesis was improved and there was no sign of the tumor growth by MRI. The outcome of the previous cases with radical tumor resection was poor compared with the present case in which only a part of the cyst wall and the content were removed. Therefore, radical removal of the whole tumor may not be necessary for intramedullary epidermoid cyst of the brain stem.

Extradural Total Petrous Apex Resection With Trigeminal Translocation for Improved Exposure of the Posterior Cavernous Sinus and Petroclival Region

We have analyzed a strategy for improved exposure of the posterior cavernous sinus and petroclival region through an extradural subtemporal approach to be utilized in the removal of neoplastic processes with involvement of the apical petrous bone and posterior cavernous sinus. This surgical approach includes the following elements for improved exposure of the posterior cavernous sinus through the middle fossa corridor: (1) maximal extradural exposure and mobilization of the trigeminal nerve complex, allowing its elevation and anterior displacement, (2) complete extradural removal of the anterior petrous pyramid from the porus acousticus to the petrous apex under direct vision, (3) total exposure of the abducens nerve from the posterior fossa to its point of cross over the intracavernous carotid artery, and (4) wide extradural exposure of the cavernous carotid artery in the foramen lacerum region. This strategy can be combined with other related approaches; specifically, frontotemporal or posterior transpetrosal exposures for extensive lesions.Microsurgical dissection and morphometric analysis were performed in 20 fixed cadaver specimens for the purposes of validating the method for clinical application and determining the key elements to maximization of exposure. The trigeminal complex could be anteromedially retracted 4.8 mm +/- 1.3 (range = 3 to 6 mm) without skeletonization of V(2) and V(3). Liberating these two divisions from their bony canals to their first peripheral branch (10.4 mm +/- 2.5 and 5.4 mm +/- 1.1, respectively) resulted in increased mobilization an average of 9.1 mm +/- 1.7 (7 to 14 mm). Further mobilization is achieved by dividing the attachment between the trigeminal connective tissue sheath and the fibrous carotid ring at the foramen lacerum. An average of 13.0 mm +/- 3.1 (7 to 20 mm) of the posterior intracavernous carotid artery was exposed. Detailed microanatomic observations and a comprehensive morphometric analysis of the relevant anatomic relationships were made.

The orbitozygomatic infratemporal fossa approach: a quantitative anatomical study

Using detailed cadaveric dissections this study has demonstrated and quantified the increase in exposure and additional access gained by using the orbitozygomatic infratemporal fossa approach for neurosurgical access. The surgical window of exposure can be increased by up to 300% when this technique is utilised to facilitate access via either a subtemporal (to access the P2 segment of the posterior cerebral artery) or transsylvian (to access the basilar bifurcation) approach. In addition the distance between the surgeon and the operative field can be decreased by approximately 2-3 cm. The orbitozygomatic infratemporal fossa approach is a relatively simple technique which can readily increase neurosurgical exposure of the skull base. It also provides simultaneous access to the infratemporal fossa, pterygopalatine fossa and the orbit.

Meningiomas of the space of the cavernous sinus.

During the years 1985 to 1992, we encountered 59 patients with meningiomas involving the space of the cavernous sinus. In 29 of these patients, meningiomas were primarily located within the space of the cavernous sinus and were operated on without mortality and with low morbidity. A small subtemporal surgical approach was favored, which allowed initial tumor resection from the posterior aspect, where the Parkinson's triangle is wide, thus avoiding the additional morbidity of large-scale approaches. According to the relationships of the all-important cranial nerves passing within the lateral wall of the cavernous sinus, we divided the primary intracavernous meningiomas into four types, which reflected not only the preoperative cranial nerve deficit but also the feasibility of surgical resection. Cranial nerve function deteriorated after operations in 14% of oculomotor nerves, in one abducent nerve, in 58% of trochlear nerves, and in 21% of trigeminal nerves. We encountered improvement of function in 43% of oculomotor nerves, in 50% of abducent nerves, and in approximately 30% of the second and third but in only 7% of the first branches of trigeminal nerves. There was no improvement in trochlear nerve function. Improvement of oculomotor nerve function was observed only in moderately impaired nerves, which indicates that surgery should be undertaken early to preserve or improve oculomotor nerve function.

Meningiomas of the cerebellopontine angle.

Meningiomas of the cerebellopontine angle (CPA) represent a clinically and surgically interesting entity. The opportunity of complete surgical excision and the incidence of impairment of nerval structures largely depend on the tumour biology that either leads to displacement of surrounding structures by an expansive type of growth or to an enveloping of nerval and vascular structures by an en plaque type of growth. As the origin and the direction of growth are very variable, the exact tumour extension in relation to the nerval structures and the tumour origin can be identified sometimes only at the time of surgery. Out of a series of 230 meningiomas of the posterior skull base operated between 1978 and 1993, data of 134 meningiomas involving the cerebellopontine angle are presented. There were 20% male and 80% female patients, age at the time of surgery ranging from 18 to 76 years, on the average 51 years. The clinical presentation was characterized by a predominant disturbance of the cranial nerves V (19%), VII (11%), VIII (67%) and the caudal cranial nerves (6%) and signs of ataxia (28%). 80% of the meningiomas were larger than 30 mm in diameter, 53% led to evident brainstem compression or dislocation and 85% extended anteriorly to the internal auditory canal. Using the lateral suboccipital approach in the majority of cases and a combined presigmoidal or combined suboccipital and subtemporal approaches in either sequence in 5%, complete tumour removal (Simpson I and II) was accomplished in 95% and subtotal tumour removal in 5%. Histologically the meningiotheliomatous type was most common (49%) followed by the mixed type (19%), fibroblastic (16%), psammomatous (7%), hemangioblastic (7%) and anaplastic (2%) types. Major post-operative complications were CSF leakage (8%) requiring surgical revision in 2% and hemorrhage (3%) requiring revision in 2%. While the majority of neurological disturbances showed signs of recovery, facial nerve paresis or paralysis was encountered in 17%, and facial nerve reconstruction was necessary in 7%. Hearing was preserved in 82% with improvement of hearing in 6%. The variability of tumour extension, the implications and limitations for complete surgical excision are discussed along with the experiences from the literature.

頭蓋底中央部病変に対するcombined subtemporal and orbitozygomatic approach

頭蓋底中央部病変に対しcombined subtemporal and orbitozygomatic approachを用い良好な結果を得たので,手術の実際を中心に報告した.本アプローチは,(1)各方向から頭蓋底中央部病変の観察が可能である,(2)十分な術野が比較的浅い位置として確保できる,(3)病変部周辺の重要な構造物を直視下に収めることができる,(4)髄液の十分な排液を加えることにより脳の牽引を最小に抑えることができる,などの利点がある.病変の前方,側方のみでなく,後方からも接近することが手術結果を左右すると思われる症例において有用なアプローチと考えられた.併せて本アプローチの問題点についても言及した.

Basal extension of craniotomy for subtemporal middle fossa approach.

Resection of the root of the zygomatic arch including the glenoid fossa, and the roof of the external ear and the superior third of the mastoid process was seen to improve the basal exposure of the lateral subtemporal middle fossa approach. The exposure was horizontally wide. The enhanced exposure helped in reducing the extent of brain retraction that was necessary and improved the working space for manipulation of the instruments.

The transzygomatic approach: a long-term clinical review.

The transzygomatic approach has been utilised to improve access to the skull base, infratemporal fossa and orbit for a number of years. It provides a low anterolateral approach to the skull base, along the floor of the middle fossa. It allows both a transsylvian and subtemporal approach with a reduction in brain retraction and better exposure of adjacent neurovasculature structures. A long term review of 53 patients is presented highlighting outcome at two years post surgery and morbidity of the approach. It is concluded that the technique is versatile and can be used to improve exposure of a variety of anatomical locations. There is minimal long term morbidity attributable to the surgery of access and the majority of patients have had good outcomes.