Subtemporal Approach Research Articles

Dual-Port 2D and 3D Endoscopy: Expanding the Limits of the Endonasal Approaches to Midline Skull Base Lesions with Lateral Extension.

Objective To investigate a novel dual-port endonasal and subtemporal endoscopic approach targeting midline lesions with lateral extension beyond the intracavernous carotid artery anteriorly and the Dorello canal posteriorly. Methods Ten dual-port approaches were performed on five cadaveric heads. All specimens underwent an endoscopic endonasal approach from the sella to middle clivus. The endonasal port was combined with an anterior or posterior endoscopic extradural subtemporal approach. The anterior subtemporal port was placed directly above the middle third of the zygomatic arch, and the posterior port was placed at its posterior root. The extradural space was explored using two-dimensional and three-dimensional endoscopes. Results The anterior subtemporal port complemented the endonasal port with direct access to the Meckel cave, lateral sphenoid sinus, superior orbital fissure, and lateral and posterosuperior compartments of the cavernous sinus; the posterior subtemporal port enhanced access to the petrous apex. Endoscopic dissection and instrument maneuverability were feasible and performed without difficulty in both the anterior and posterior subtemporal ports. Conclusion The anterior and posterior subtemporal ports enhanced exposure and control of the region lateral to the carotid artery and Dorello canal. Dual-port neuroendoscopy is still minimally invasive yet dramatically increases surgical maneuverability while enhancing visualization and control of anatomical structures.

Sub-Temporal Approach to Suprasellar Retrochiasmatic Tumors: Case Series and Anatomic Cadaveric Correlation

Sub-Temporal Approach to Suprasellar Retrochiasmatic Tumors: Case Series and Anatomic Cadaveric Correlation

Operability score: An innovative tool for quantitative assessment of operability in comparative studies on surgical anatomy

ObjectivesComparative anatomical studies have proved to be invaluable in the evaluation of advantages and drawbacks of single approaches to access established target areas. Approach-related exposed areas do not necessarily represent useful areas when performing surgical manoeuvres. Accordingly the concept of “operability” has recently been introduced as a qualitative assessment of the ability to execute surgical manoeuvres. The authors propose an innovative model for the quantitative assessment of the operability, defined as “operability score” (OS), which can be effectively and easily applied to comparative studies on surgical anatomy. MethodsA microanatomical study was conducted on six cadaveric heads. ResultsMorphometric measurements were collected and operability scores in selected target points of the surgical field were calculated. As illustrative example, the operability score was applied to the extradural subtemporal transzygomatic approach (ESTZ). ConclusionThe operability score is effective in grading system of surgical operability, and instruments manipulation capability. It is a useful tool to evaluate, in a single approach, areas that can be exposed, and to quantify how those areas are suitable for surgical manoeuvres.

Successful excision of a pontomesencephalic cavernoma through anterior subtemporal route without mapping: Anatomical landmarks as a road map

Successful excision of a pontomesencephalic cavernoma through anterior subtemporal route without mapping: Anatomical landmarks as a road map

Microsurgical Resection of Petroclival Tumors via the Subtemporal Transtentorial Approach.

To study and summarize our experience with the subtemporal transtentorial approach for resection of petroclival tumors. Twenty-eight patients who suffered from petroclival tumors and underwent tumor resection via a subtemporal transtentorial approach between October 2010 and July 2013 were retrospectively reviewed. Total resection was performed in 22 cases, at a rate of 78.57%, subtotal resection in 5 cases, and large portion resection in 1 case. 13 patients who suffered from varying degrees of postoperative nerve dysfunction all improved or recovered, during the 6 to 24 month post-operative follow up. The subtemporal transtentorial approach is one of the best approaches for resection of petroclival tumors, especially for a tumor at the petrosal apex and upper-middle clival region, and has the advantages of less trauma, easy procedure of craniotomy, and also a good surgical exposure.

Simultaneous Discovery of Cranial and Spinal Intradural Chordomas: Case Report

The present case illustrates the unexpected occurrence of intradural chordomas that were simultaneously discovered in cranial and spinal locations. A 63-year-old female presented with weakness in the left upper extremity. The patient visited a local doctor and underwent brain computerized tomography (CT). CT revealed a brain tumor, and she was referred to our hospital. Brain magnetic resonance imaging (MRI) demonstrated a midline intradural retroclival tumor in addition to an intradural extramedullary mass lesion at the level of C1–C2. The patient developed a spastic gait disturbance that forced her to use a cane. She underwent laminectomy at C1–C2 along with total removal of the tumor and showed no remarkable symptoms after surgery. Histopathological examination confirmed the diagnosis of chordoma. One month after the cervical surgery, the intracranial tumor was subtotally removed in intracranial surgery via the right subtemporal approach. Histopathological data were identical to that of the cervical tumor. The patient consulted another hospital and underwent gamma-knife surgery. Her neurological examination is relatively unchanged 20 months after the cervical surgery. This case suggests that neuroradiological evaluation should also be performed for an intradural spinal chordoma when an intracranial chordoma is detected. Careful determination of the tumor responsible for the symptoms is necessary if an intradural spinal chordoma is simultaneously detected with an intracranial chordoma.

Aneurysms of the P2P Segment of Posterior Cerebral Artery: Case Report and Surgical Steps.

The posterior cerebral artery (PCA) is divided into 4 segments: precommunicating segment (P1), postcommunicating segment (P2), quadrigeminal segment (P3), and calcarine segment (P4). Small aneurysms are more prevalent than large aneurysms in patients with ruptured aneurysms. P2 and P3 aneurysms are usually managed by the subtemporal approach. This is a case report of rupture saccular aneurysm of posterior cerebral artery on P2P segment. The authors show the surgical steps of these rare aneurysms with an illustrative case.

A case of giant skull base chondroma.

Intracranial chondroma is a rare benign tumor. Here, we present the case of a 29-year-old female who was afflicted with left eye blindness and ptosis. Brain computerized tomography and magnetic resonance imaging revealed the presence of a giant calcified mass accompanied by a solid mass in the middle and posterior fossa. A differential diagnosis regarding chordoma, chondrosarcoma, and other chondroid tumors based on radiologic information was inconclusive. The lesion was resected completely under a microscope using a combined pterional and subtemporal approach. The pathologic report confirmed the diagnosis of chondroma. No evidence of neurological worsening was observed. The tumor had a calcified mass with mature hyaline cartilage surrounded by a thick fibrous capsule. We dissected the periphery of the tumor mass and removed it via aspiration. It was readily distinguished from normal brain parenchymal tissue. The large calcified mass at the center of the tumor had relatively high vascularity, and a high-speed drill and various rongeurs were used to remove the tumor.

Treatment of Meningoencephalocele of Temporal Bone Occurred after Open Cavity Mastoidectomy

Meningoenceophalic herniation into the external auditory canal is a rare and potentially life threatening condition that needs a surgical treatment. It can lead to potential infectious sequelae including meningitis, encephalitis, otologic brain abscess and dysfunctional herniated brain tissue can trigger epilepsy. It is caused by chronic otitis media, cholesteatoma, middle ear surgery, trauma, congenital skull base defect and irradiation. We present a case of meningoencephalic herniation into the external auditory canal that had occurred 8 years after open cavity tympanomastoidectomy, which was treated with subtemporal middle cranial fossa approach.

The subtemporal preauricular infratemporal fossa approach

The subtemporal preauricular approach to the infratemporal fossa (ITF) is ideal in the surgical exposure and resection of any lesion, benign or malignant, which involves the ITF and adjacent regions. This approach to the ITF affords access to this area without loss of conductive hearing. The indications, technique and its modifications, as well as the potential complications of this approach are discussed.

Magnetic resonance imaging diagnosis and microsurgical treatment of cavernous sinus hemangiomas

To summarize the magnetic resonance imaging(MRI)features and microsurgical treatment of cavernous sinus hemangiomas(CSH). Twenty-three patients with surgically and pathologically verified CSH were reviewed. All patients underwent computed tomography(CT)and MR scan, 19 cases underwent MR diffusion-weighted imaging(DWI)and 7 underwent single voxel (1)H magnetic resonance spectroscopy((1)HMRS)before operation. The microsurgery through modified pterional approach was performed in 11 cases and 12 cases removal was achieved in combined fronto-temporal preauricular subtemporal approach. Nineteen cases with large tumors were treated by Leksell Gamma knife(LGK)before operation. CSHs were single, large, and spherical/lie gourd-shaped tumors across the inside and outside the sella. CSH showed equal or slightly low signal on T1WI, high signal on T2WI and FLAIR, homogeneous or heterogeneous great enhancement on MR enhancement scan 19 cases showed equal or slightly low signal on DWI, 7 cases showed no NAA, Cr, and Cho peak, and 6 cases showed Lip peak on (1)HMRS. In 23 cases, the tumors were totally removed in 18, subtotally removed in 3, and partially removed in 2. No perioperative death was reported. The postoperative symptoms were improved in 17 cases but remained unchanged in 4 cases two patients suffered from new nervous symptoms after the surgery, which were improved or cured after three weeks of treatment. In 5 patients who had received subtotal or partial removal of the lesions, LGK was performed postoperatively, which resulted in smaller residual tumors in 4 cases and unchanged tumor in one patient. CONCLUSIONS CSH has some unique MRI features, and therefore MRI is helpful to improve the preoperative localization and qualitative diagnosis. The microsurgery through modified pterional approach combined with fronto-temporal preauricular subtemporal approach is an effective procedure for CSH.

Surgical Anatomy of Endoscope-Assisted Approaches to Common Aneurysm Sites

The endoscope is being introduced as an adjuvant to improve visualization of certain areas in open cranial surgery. To describe the endoscopic anatomy of common aneurysm sites and to compare it with the microsurgical anatomy. Pterional, anterior interhemispheric, and subtemporal approaches to the most common aneurysm sites were examined in cadaveric heads under the surgical microscope and with the endoscope. The endoscopic view, particularly with the angled endoscopes, provides a significant improvement compared with the microscopic view, especially for poorly visualized sites such as the medial aspect of the supraclinoid carotid artery and its branches, the area below the anterior perforated substance and optic tract, and the carotid and basilar bifurcations. The endoscope aided in the early visualization of perforating branches at each aneurysm site except the middle cerebral artery. Small-diameter optics (2.7 mm) provided greater space for dissection and less potential for tissue damage in narrow places, whereas the larger 4-mm diameter optics provided better visualization and less panoramic distortion. The positioning of the endoscope for each aneurysm site is reviewed. The endoscope provides views that complement or improve the microscopic view at each aneurysm site except the middle cerebral artery. Endoscopy training and a thorough knowledge of endoscopic vascular anatomy are essential to safely introduce endoscopic assistance in vascular surgery.

Brainstem Gliomas: Surgical indications and technical considerations in a series of 58 cases

Objectives. To analyze the indications of surgical treatment, surgical management strategies and post-surgical outcome in patients with brainstem glioma (BSG). Methods. In this retrospective study conducted from 1998 to 2012, 58 patients of surgically treated intrinsic BSG, meeting the inclusion criterion were enrolled. There were 40 males and 18 females, with age range varying from 3 to 55 years. The most common presentation was gait disturbances, either due to cerebellar involvement or motor weakness, followed by motor weakness, ocular involvement and headache. The posteriorly located tumors were operated by midline suboccipital approach (42 patients) and supracerebellar–infratentorial approach (4 patients). Posterolaterally located tumors were operated by retromastoid (10 patients) and all the ventrolateral tumors by subtemporal approach (4 patients). Results. Above 90% patients improved in their neurological status, while 5% deteriorated. Pilocytic astrocytoma was the most common histopathology (41.4%), followed by Grade II astrocytoma (34.5%) and Grade III astrocytoma (24.1%). Overall, 19% patients had postoperative complications and three patients (5%) died in the perioperative period. Conclusions. Surgery is advocated for patients with well delineated, posteriorly, posterolaterally and ventrolaterally located tumors having slow progression and relative preservation of motor power. BSG can have excellent surgical results with surgeon's experience and modern surgical facilities.

Extended Subtemporal Transtentorial Approach to the Anterior Incisural Space and Upper Clival Region

Although most posterior circulation aneurysms are currently treated by endovascular means, some are not amenable to this treatment modality. The narrow working window afforded by the anterolateral and lateral surgical approaches often translates into suboptimal visualization and limited maneuverability. We present a modified technique of tentorial incision and reflection that optimizes the exposure achieved with the traditional subtemporal approach and report our clinical experience in a series of posterior circulation aneurysms. Retrospective review of patients operated via an extended subtemporal transtentorial approach for posterior circulation aneurysms. The modified tentorial incision implies dissection of the trochlear nerve along its dural canal up to its entrance into the cavernous sinus and incision of a tentorial flap that extends up to Meckel cave, which is then reflected far anterolaterally. Clinical and radiological data were reviewed. This series comprises 18 patients (21 procedures). Ten patients presented (56%) with a subarachnoid hemorrhage. Aneurysms most frequently arose from the basilar tip (61%) and were of small size (50%) and saccular morphology (72%). Two patients underwent surgery following unsuccessful endovascular treatment. Aneurysm treatment was successful on the first attempt in 90% (19/21) and after a second attempt in 10% (2/21). Documented postoperative palsies of the oculomotor (n = 3) and trochlear (n = 1) nerves were all transient. No procedure-related mortality occurred. This modified technique of tentorial incision and reflection optimizes visibility, anatomic orientation, and maneuverability by increasing the rostrocaudal and anterolateral exposure obtained via the extended subtemporal transtentorial route without permanent postoperative trochlear nerve deficit.

Editorial: Medial temporal epilepsy

In their article, Hu et al.3 have provided interesting data on the results of the 2 most commonly used approaches for treating medial temporal lobe epilepsy. They performed a meta-analysis comparing the seizure-free and memory (IQ) outcomes after anterior temporal lobectomy (ATL) versus selective amygdalohippocampectomy (SelAH). They found that ATL was more likely to result in seizure freedom than SelAH, although the percentages were similar (71% vs 66%). Fewer studies were available to compare memory outcomes, and there was no difference between the types of surgery in that important outcome measure. Hu and colleagues correctly describe the limitations of this evaluation, including the paucity of data from prospective studies, especially with respect to memory outcomes. Nevertheless, this analysis confirms in a meta-analysis what many epilepsy surgeons have understood: the most commonly performed selective resections of the medial temporal lobes are slightly less likely to result in seizure freedom and do not spare memory function. It should not be surprising that anterior lobectomy should result in somewhat improved seizure-free outcomes compared with the more selective resections. When electrocorticography is used to define the amount of tissue to be resected (so-called tailored approach), it is common to see combined medial and neocortical epileptiform activity.1 Anterior temporal neocortical resection may include some or all of these areas. What is not obvious is why selective resections do not confer an advantage with respect to verbal memory function. It is possible that the track taken through the brain to the medial temporal structures results in as much disruption of memory networks as tissue removal. Recent attempts to avoid damage to the neocortex have focused on the subtemporal approach.2,4 While early reports with small numbers of patients have been encouraging, subsequent evaluations have shown results similar to what is shown in this metaanalysis: that memory deficits may not be spared when direct comparisons are made with other techniques.7 Similarly, preliminary evidence from radiosurgical treatment of the medial temporal lobe indicates that there is a relative sparing of verbal memory.6 A larger series that randomizes patients between standard lobectomy and radiosurgery is underway. Given these results, it is difficult to understand why so many epilepsy surgeons seem to prefer the SelAH procedure. Perhaps it is the seeming elegance of the selective approach, using available technology (frameless stereotactic guidance and microsurgical technique) that is attractive. As the most important determinant of quality of life after epilepsy surgery is seizure freedom,5 the decision on the type of surgery to perform should be based on the best available evidence. As Hu et al. stated in their conclusions, further studies are needed to properly compare these techniques. However, until better data are available, appropriately directed, larger resections seem to have an advantage in the most important aspect of epilepsy surgery, seizure control. (http://thejns.org/doi/abs/10.3171/2013.5.JNS13704)

How I do it – selective amygdalohippocampectomy via subtemporal approach

Surgery is superior over medicamentous treatment of pharmacoresistant mesial temporal lobe epilepsy caused by hippocampal sclerosis. The armamentarium of surgical procedures comprises standard temporal lobectomy and more selective procedures. Selective amygdalohippocampectomy can be performed via transcortical, transsylvian or subtemporal approach. Describe the selective amygdalohippocampectomy through the subtemporal approach After the detailed preoperative epilepsy evaluation, surgery can be offered to pharmacoresistant epilepsy patient with hippocampal sclerosis. Selective amygdalohippocampectomy can be safely performed through the subtemporal approach. The good knowledge of the mesial temporal lobe anatomy is necessary when performing this procedure.

Microsurgical anatomic study of subtemporal approach using a minimal access

Objective To investigate the surgical exposure of the subtemporal approach and explore clinical indications using a minimal-access.Methods Ten adult cadaveric heads fixed with formalin were used in this study.The holes with 3.0 cm × 2.5 cm of zygomatic arch vertically were operated on each head with subtemporal approach.During the anatomical procedures,measured the maximal exposure lengths of tentorial margin,posterior cerebral artery,and anterior border of brain stem,vertical distances between highest structure in the field of view and posterior clinoid process,the shortest distances form the zygomatic arch 1/3 to tentorial edge,sulcus lateralis mesencephali and anterior clinoid process; After tentorium of cerebellum was cut,measured the straight distance form the internal carotid artery to the optic nerve and form the posterior communicating artery to the tentorial edge.Results Oculomotor,trochlear nerve,tentorial edge,superior cerebllar artery.,P1-P2 segment of posterior cerebral artery,ventrolateral surface of mesencephalon and pon higher than root of trigeminal nerve,anterior and posterior clinoid process,posterior communicating artery and anterior choroidal artery,and superior portion of pituitary stalk could be observed via subtemporal approach using a minimal-access.Conclusion 1.The subtemporal approach using a minimal-access can protect the superficial temporal artery and the facial nerve branches especially in the process of the flap formation.It does little damage to the temporallis,reduces the invalid exposure of brain tissue,farthest lowers the damage to the scalp,skull and adjacent tissue ; 2.The subtemporal approach using a minimal-access can obtain the exposure rang.It can see the upper pons,petroclival region,tentorial notch area,ventrolateral brain stem. Key words: Subtemporal approach; Superficial temporal artery; Facial nerve; Tentorial notch area; Microanatomy

Temporal lobe arteriovenous malformations: anatomical subtypes, surgical strategy, and outcomes

Descriptions of temporal lobe arteriovenous malformations (AVMs) are inconsistent. To standardize reporting, the authors blended existing descriptions in the literature into an intuitive classification with 5 anatomical subtypes: lateral, medial, basal, sylvian, and ventricular. The authors' surgical experience with temporal lobe AVMs was reviewed according to these subtypes. Eighty-eight patients with temporal lobe AVMs were treated surgically. Lateral temporal lobe AVMs were the most common (58 AVMs, 66%). Thirteen AVMs (15%) were medial, 9 (10%) were basal, and 5 (6%) were sylvian. Ventricular AVMs were least common (3 AVMs, 3%). A temporal craniotomy based over the ear was used in 64%. Complete AVM resection was achieved in 82 patients (93%). Four patients (5%) died in the perioperative period (6 in all were lost to follow-up); 71 (87%) of the remaining 82 patients had good outcomes (modified Rankin Scale scores 0-2); and 68 (83%) were unchanged or improved after surgery. Categorization of temporal AVMs into subtypes can assist with surgical planning and also standardize reporting. Lateral AVMs are the easiest to expose surgically, with circumferential access to feeding arteries and draining veins at the AVM margins. Basal AVMs require a subtemporal approach, often with some transcortical dissection through the inferior temporal gyrus. Medial AVMs are exposed tangentially with an orbitozygomatic craniotomy and transsylvian dissection of anterior choroidal artery and posterior cerebral artery feeders in the medial cisterns. Medial AVMs posterior to the cerebral peduncle require transcortical approaches through the temporo-occipital gyrus. Sylvian AVMs require a wide sylvian fissure split and differentiation of normal arteries, terminal feeding arteries, and transit arteries. Ventricular AVMs require a transcortical approach through the inferior temporal gyrus that avoids the Meyer loop. Surgical results with temporal lobe AVMs are generally good, and classifying them does not offer any prediction of surgical risk.

Microsurgical resection of petroclival meningiomas by subtemporal transpetrosal-transtentorial approach assisted with neuroendoscopy

Objective To study the removal technique and operative experiences in the microsurgical resection of petroclival meningiomas with the subtemporal transpetrosal-transtentorial approach assisted with neuroendoscopy,and to improve the rate of total resection of tumors and the postoperative results.Methods Consecutive 21 cases of petroclival meningiomas treated from Jan.2002 to Jun.2012 by microsurgical technique using the subtemporal transpetrosal-transtentorial approach were reviewed retrospectively.Among the 21 cases,11 patients were operated with an assistance of neuroendoscopy.The tumor control rate,postoperative neurological deficit,and functional status were assessed by the Karnofsky Performance Score (KPS),and to evaluate the indications,advantages and disadvantages of this approach in assistance with neuroendoscopy.Results Gross total tumor resection was achieved in 10 patients,subtotal resection in 8 cases,and partial resection in 3 cases.New developed cranial nerves dysfunction and deterioration of original symptom after the operation were found in 7 patients.There were no deaths and longterm coma.The surgical results of patients assisted with neuroendoscopy were better than only using microscope,P ＜ 0.05.Conclusions The subtemporal transpetrosal-transtentorial approach in assistance with neuroendoscopy is suitable for petroclival meningiomas mainly in the middle fossa with extension to the posterior fossa (type Ⅰ).By resecting the petroal bone,this approach can improve the rate of total resection of tumors and the postoperative results,while decreasing the postoperative functional deficit of the cranial nerves. Key words: Petroclival meningioma ; Neuroendoscopy; Microsurgery ; Subtemporal transpetrosal-transtentorial approach

The extended subtemporal transtentorial approach: The impact of trochlear nerve dissection and tentorial incision

The subtemporal transtentorial approach provides excellent exposure of the incisural space. Incision of the tentorium improves access to the interpeduncular cistern, basilar artery, and rostral ventral pons. Description of the starting and termination points of the tentorial incision has varied greatly. We assessed the impact on surgical exposure of freeing the trochlear nerve (TN) from its dural canal (DC) in addition to dividing and retracting the tentorium. A subtemporal approach was performed on 10 hemispheres of cadaveric specimens. Following exposure of the middle tentorial incisura, the TN is dissected from its DC over a few millimeters. Two retraction sutures are placed along the tentorial edge, posterior to the TN entrance in its DC. The tentorial incision is started between the sutures. Dissection of TN from its DC continues for a short distance. The tentorial incision is extended straight up towards the superior petrosal sinus. Dissection of the TN DC continues anteriorly, up to its entry into the cavernous sinus. The tentorial incision can then be extended, just over the entrance to Meckel’s cave, and the flap reflected far anterolateraly. Using this technique, the exposure of the interpeduncular cistern and its content increased by a mean of 8.2mm (standard deviation [SD] 3.9mm) in the anteroposterior axis and by 5.5mm (SD 1.9mm) in the rostrocaudal axis. Tentorial incision following dissection of the TN from its DC optimizes reflection of the tentorium flap anterolateraly, maximizes the exposure, and improves lighting and visibility as well as maneuverability within the interpeduncular and rostral pre-pontine cisterns.