Subtemporal Keyhole Approach Research Articles

Minimally Invasive Approaches to the Lateral Cavernous Sinus and Meckel's Cave: Comparison of Transorbital and Subtemporal Endoscopic Techniques

Transorbital and subtemporal keyhole approaches have recently been proposed to approach lesions in the lateral wall of the cavernous sinus (CS) and Meckel's cave (MC). Our goal was to compare these approaches and suggest indications for each of them. Five cadaver heads (10 sides, 40 procedures) were used. The lateral transorbital approaches were carried out without and with the removal of the lateral orbital rim, herein referred to as the lateral transorbital approach (LTOA) and the lateral orbital wall approach (LOWA). The subtemporal approaches were performed without and with the removal of the zygomatic arch, referred to as the subtemporal approach (STA) and the subtemporozygomatic approach (STZA). Five targets were chosen and 2 triangles were created representing thelateral wall of the CS and MC. Stereotactic measurements were quantified to calculate angles of attack, surgical freedom, and temporal lobe retraction for each approach. LTOA presented the smaller horizontal angles of attack. LOWA increased the angles to the same level of STA and STZA. STA and STZA presented larger vertical angles of attack. The surgical freedom presented gradual increase from LTOA to LOWA, STA, and STZA. STA and STZA needed greater temporal lobe retraction for most targets. LTOA is a good option to biopsy a lesion in the lateral wall of the CS and LOWA increased the surgical corridor to work with microsurgical techniques. STA and STZA could be better options when wide exposure is necessary, but temporal lobe retraction should be taken into consideration.

Pure Endoscopic Surgery via Subtemporal Extradural Keyhole Approach for Middle Cranial Fossa Tumors

Extradural subtemporal keyhole approach could provide adequate removal for some specific middle skull base tumors. The combination of endoscopy and keyhole technique might further help to minimize the complications and provide optimal surgical visualization. Here, a series of attempts with endoscopy by mini-invasive subtemporal extradural approach for 5 middle skull base tumors were successfully achieved. From November 2015 to November 2018, resections of 5 cases of middle cranial fossa tumors were performed with pure endoscopy via subtemporal extradural keyhole approach. Patient medical records, imaging data, surgical procedures, pathology results, and follow-up outcomes were collected and analyzed. Adequate extradural subtemporal space was successfully established for endoscopy, and tumor resection was performed. Postoperative pathology confirmed cholesteatoma, cholesterol granuloma, schwannoma, granuloma, and osteoblastoma, respectively. Two patients with osteoblastoma and granuloma received subtotal resection, and the other 3 achieved total resection. One patient suffered from brain edema and was relieved after systematic mannitol treatment. No other complications were observed, and no progression was found during follow-up. This exploratory series demonstrated the safety and effectiveness of pure endoscopic surgery via subtemporal extradural route for satisfactory middle cranial base tumor resection.

Intradural Subtemporal Keyhole Approach with Neuronavigational Assistance to the Petroclival and Ventrolateral Brainstem Regions: Quantitative Analysis of Anatomic Exposure and Surgical Freedom

The purpose of this study was to evaluate the advantages of endoscopy and navigational assistance in the intradural subtemporal keyhole approach and the intradural Kawase approach by studying anatomic exposure and surgical freedom in the posterior cranial fossa. Twenty endoscopic intradural subtemporal keyhole approaches (EISKA) were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through a 0° endoscope and a microscope. Anatomic exposure and surgical freedom were measured by transparent graph paper and analyzed. Compared with the microsurgical technique, the superior, inferior, and medial limits of the endoscopic anatomic exposure increased by 2.9, 15.65, and 10.2 mm, whereas the surgical freedom increased by 2.9, 7.55, and 6 mm (P < 0.05) in the intradural subtemporal keyhole approach. In the intradural Kawase approach and the navigation-assisted intradural Kawase approach, the endoscopic anatomic exposure and surgical freedom also increased (P < 0.05). Using a frameless navigational device, the inferior limit of the anatomic exposure increased 3.8 mm by endoscopy and 3.5 mm by microscopy, whereas the surgical freedom increased by 2.7 and 2.2 mm, respectively (P < 0.05). The EISKA provides greater anatomic exposure and surgical freedom primarily in the superior, inferior, and medial directions of the brainstem region. Maximum anatomic exposure and surgical freedom of the posterior cranial fossa was obtained by navigational assistance with fewer complications.

Endoscopic intradural subtemporal keyhole approach with neuronavigational assistance: An anatomic study

Objective To evaluate the feasibility of a purely endoscopic intradural approach to the suprasellar, petroclival and ventrolateral brainstem regions through a subtemporal keyhole and to assess the value of neuronavigational assistance in the Kawase approach. Methods Twenty operations through endoscopic intradural subtemporal keyhole approach were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through endoscopes. Two types of the milled Kawase rhombus ranges and the thicknesses of residual bones were compared. Results Through the keyhole endoscopic technique, anatomic structures in the suprasellar, petroclival and ventrolateral brainstem regions were clearly visualized via an intradural subtemporal route. Most structures in the suprasellar region could be observed in the oculomotor nerve-posterior communicating artery space. Using a frameless navigational device, the mean area of milled Kawase rhombus was larger than that in the intradural Kawase approach (276.8±14.6 mm2vs. 244.8±12.6 mm2,P<0.05), and the thicknesses of residual bones including the superior wall of internal acoustic meatus (1.0±0.2 mm vs. 2.5±0.4 mm), the medial superior wall of cochlear (1.0±0.2 mm vs. 3.0±0.4 mm) and the superior wall of petrous segment of internal carotid artery (1.2±0.2 mm vs. 3.4±0.4 mm) were all thinner than those in the intradural Kawase approach (all P<0.05). Conclusions The endoscopic intradural subtemporal keyhole approach could facilitate excellent observation of the suprasellar, petroclival and ventrolateral brainstem regions with less invasiveness. More anatomic exposure and surgical freedom could be achieved via neuronavigational assistance. Key words: Neuroanatomy; Neuronavigation; Neuroendoscopy; Subtemporal approach; Keyhole; Kawase approach

Endoscope-Assisted Microsurgical Subtemporal Keyhole Approach to the Posterolateral Suprasellar Region and Basal Cisterns.

Refinements in optics and instrumentation have enabled surgeons to approach deep-seated intracranial diseases with reduced exposure and brain retraction. The anterior subtemporal keyhole approach is a minimally invasive route to the posterolateral aspect of the suprasellar area and petroclival region. In this cadaveric study, we show the benefits of endoscope-assisted microsurgical techniques in the anterior subtemporal keyhole approach. The anterior subtemporal keyhole approach was performed bilaterally on 5 formalin-fixed human specimens using standard microneurosurgical methods. Dissections compared the exposure afforded by the microsurgical route with the endoscope-assisted technique, using 0° and30° angled rod-lenses. Anatomic relationships among the surgical target and the surrounding neurovascular structures were described. Endoscope-assisted maneuvers enhanced the operative view afforded by the microscope and helped to minimize parenchymal retraction and neurovascular injury. Endoscope-assisted microsurgery provides a panoramic picture of the surgical target and its surroundings. It enables the operator to see into hidden corners beyond the microsurgical view. The endoscope provides enhanced visualization of the neurovascular structures located in the posterolateral suprasellar region, basal cisterns, upper clivus and midclivus, and interpeduncular region. Endoscope-assisted microsurgery provides a means to approach selected lesions located in the posterolateral suprasellar region, perimesencephalic cisterns, and upper clivus and midclivus. The operative view can be maximized by introducing the 0° and 30° angled endoscopes. Minimally invasive techniques help to optimize surgical exposure and lessen parenchymal retraction, thus improving control of the surrounding neurovascular structures.

Endoscopic Intradural Subtemporal Keyhole Approach with Neuronavigational Assistance to the Suprasellar, Petroclival, and Ventrolateral Brainstem Regions: An Anatomic Study

The purposes of this study were to evaluate the feasibility of a purely endoscopic intradural approach to the suprasellar, petroclival, and ventrolateral brainstem regions through a subtemporal keyhole and to assess the value of neuronavigational assistance in the Kawase approach. Twenty endoscopic intradural subtemporal keyhole approaches were performed on 10 cadaveric heads. An intradural Kawase approach and a navigation-assisted intradural Kawase approach were then carried out on a random side of each specimen. Related anatomic structures were observed through 4-mm 0° and 30° endoscopes; data were measured by a frameless navigational device. In addition, 2 types of the milled Kawase rhombus ranges and the thicknesses of the residual bones were compared. This keyhole endoscopic technique clearly visualized the anatomic structures in the suprasellar, petroclival, and ventrolateral brainstem regions via an intradural subtemporal route. Most of the structures in the suprasellar region were observed by the oculomotor nerve-posterior communicating artery space. Using a frameless navigational device, the mean area of the milled Kawase rhombus increased by 32.04 mm2 (P < 0.05), and the thicknesses of the residual bones including the superior wall of the internal acoustic meatus, the medial superior wall of the cochlea, and the superior wall of the petrous segment of the internal carotid artery reduced by 1.55, 2.03, and 2.19 mm on average, respectively (P < 0.05). The endoscopic intradural subtemporal keyhole approach could facilitate excellent observation of the suprasellar, petroclival, and ventrolateral brainstem regions with less invasiveness. More anatomic exposure and surgical freedom could be achieved via neuronavigational assistance with fewer complications.

Subtemporal keyhole approach to Meckel’s cave epidermoid cyst: Case report and review of literature

We report the first case of subtemporal keyhole surgery approach with neuronavigation and endoscopy, for total resection of an uncommon case of epidermoid cyst of the Meckel’s cave in a 43‑year‑old woman who presented with paroxysmal headache and diplopia. Magnetic resonance imagines revealed the tumor location on the right area of the cavernous sinus. Postoperative examinations showed complete recovery of symptoms.

Microsurgical Treatment of Posterior Cerebral Circulation Aneurysms Via Keyhole Approaches

To explore the techniques of microsurgical treatment for posterior cerebral circulation aneurysms via keyhole approaches and assess its feasibility. A total of 27 patients with 28 posterior cerebral circulation aneurysms were treated surgically by keyhole approaches; 24 patients presented with subarachnoid hemorrhage and 3 with headache. Of these 27 patients, 15 patients were treated via the supraorbital keyhole approach, 6 via the retrosigmoid keyhole approach, 3 via the subtemporal keyhole approach, 2 via median suboccipital approach, and 1 via the pterional keyhole approach. Of the 28 posterior cerebral circulation aneurysms, 24 aneurysms were clipped and 4 trapped; 23 aneurysms clipped completely, and 1 had residual aneurysm. Glasgow Outcome Scores at discharge revealed 25 patients had a good recovery; 1 patient was slightly disabled, and 1 patient was severely disabled. Of 15 patients treated via the supraorbital keyhole approach, to make a wider operative space, drilling of anterior clinoid process (2 patients) and posterior clinoid process (3 patients) was performed; posterior communicating artery was cut off (1 patient). For 3 patients with multiple aneurysms, complete occlusion was achieved via the same approach at one-stage. Individualized keyhole approaches for posterior cerebral circulation artery aneurysms are safe and effective. The anterior clinoid process or posterior clinoid process could be drilled to offer a wide operative space for clipping. The use of multiple working windows is very helpful for controlling the parent artery and clipping the aneurysm.

Anterior Clinoidectomy to Anterior Petrosectomy through Modified Subtemporal Pterional Keyhole Approach

Anterior Clinoidectomy to Anterior Petrosectomy through Modified Subtemporal Pterional Keyhole Approach

The posterior subtemporal keyhole approach combined with the transchoroidal approach to the ambient cistern: microsurgical anatomy and image-guided quantitative analysis

The aim of this study is to describe microsurgical anatomy and to quantitatively analyze exposure using the posterior subtemporal keyhole (PSK) approach combined with the transchoroidal keyhole (TCK) approach to the ambient cistern. We determined the proper location of craniotomy of such combined keyhole approach on 16 sides of cadaver heads. The PSK approach and the TCK approach were performed in the same minicraniotomy to observe microanatomic features and to quantitatively measure exposure limits of the ambient cistern and related structures using image-guided system. Some superficial and bone landmarks could be used to find the proper location of such combined minicraniotomy. In the PSK approach, the exposure distances of the trigeminal nerve and the anterior portion of the P2 segment (P2a) were 10.02 ± 0.76mm and 16.32 ± 2.02mm, respectively. The superior, inferior, anterior, and posterior exposure limit of brainstem from the intersection point of the lateral mesencephalic sulcus and pontomesencephalic sulcus was 7.5 ± 0.19mm, 11.04 ± 0.27mm, 15.72 ± 0.52mm, and 10.16 ± 0.38mm, respectively. In the TCK approach, the vertical distances between the taenia fimbriae and the lateral geniculate body without and with mild caudal retraction of the hippocampus were 5.28 ± 0.46mm and 11.18 ± 0.57mm, respectively. The linear exposure distances of the posterior portion of the P2 segment (P2p) or P3 segment were 12.14 ± 1.88mm. Except of one case, the P2p could be exposed using the TCK approach. The midpoint of the medial edge of the parahippocampal gyrus on the coronal magnetic resonance images provides landmark to choose the appropriate approach. The PSK combined with the TCK approach can simultaneously expose the lower and upper ambient cistern in a proper minicraniotomy.

Combined endoscope-assisted translabyrinthine subtemporal keyhole approach for vestibular Schwannoma and auditory midbrain implantation: Cadaveric study

Conclusions: The combined endoscope-assisted translabyrinthine subtemporal keyhole approach can expose the internal auditory canal, cerebellopontine, and inferior colliculus satisfactorily in the same surgical setting. As a minimally invasive approach, this can be considered an effective method for removal of vestibular schwannoma and auditory midbrain implantation in the same surgical setting, while avoiding retraction of the cerebellum and serious adverse events and complications. Objectives: Patients with neurofibromatosis type II are the initial candidates for auditory midbrain implantation; the appropriate surgical approach should allow for tumor removal and electrode implantation in the same surgical setting. Here, we demonstrate the possibility of the combined endoscope-assisted translabyrinthine subtemporal keyhole approach to achieve this aim. Methods: Five formalin-fixed cadaver heads were used to simulate surgical procedures in 10 sides, by means of microscopy and endoscopy. The relationship between concerned structures was identified. Results: With the help of an endoscope, we exposed the internal auditory canal and cerebellopontine through a translabyrinthine approach and the inferior colliculus through a subtemporal keyhole approach. This double approach can be combined to expose the internal auditory canal and cerebellopontine and inferior colliculus satisfactorily in the same surgical setting. This combined approach can avoid retraction of the cerebellum and reduce serious adverse events and complications.

Opening cranial cisterns in anterior subtemporal keyhole approach to superior petroclival region:anatomic study and comparative analysis

Objective To quantitatively compare the exposure areas and angles in anterior subtemporal keyhole approach to superior petroclival region before and after cranial cisterns opening. Methods The study was carried out on 20 sides of cadaver heads. With application of a navigation system, the exposure area in superior clivus, the ventrolateral area in brain stem around BA, the linear exposure of the posterior petroclinoid fold and BA trunk, and the approach angles to BA tip were evaluated. Results The exposure area in superior clivus （ 136. 7 ± 19. 8 ） mm^2, the ventrolateral area in brain stem （ 222. 8 ± 25.8 ） mm^2, the linear exposure of the posterior petroclinoid fold （ 11.5 ±0. 6 ） mm, and BA trunk （10. 3± 2.0 ）mm, and the approach angles in the vertical axis to BA tip（ 13.7 ± 1.7 ）°were significantly greater after opening cranial nerve cisterns. But the approach angles in the horizontal axis to BA tip were indifferent. Conclusions The exposure areas and angles of anterior subtemporal keyhole approach to superior petroclival region can be increased after opening cranial nerve cisterns. Key words: Subtemporal; Keyhole approach; Cranial nerve cisterns ; Superior petroclival region

Opening cranial cisterns by the anterior subtemporal keyhole approach to the superior petroclival region: anatomical study and comparative analysis

Background Without drilling the bony structures, simple incision of the tentorium dorsal to the porus of trochlear nerve by the anterior subtemporal keyhole approach provides narrow exposure in the superior petroclival region. This study was designed to measure and compare the areas of exposure, linear distances, and angles of approach in the superior petroclival region before and after opening cranial cisterns. Methods The study was carried out on 20 sides of cadaver heads. With the use of a navigation system, the area of exposure in the dorsum sella and clivus, the ventrolateral area of exposure in brainstem around the BA, the linear exposure of the posterior petroclinoid fold and BA trunk, and the angles of approach to BA tip were evaluated. The length of oculomotor cistern and trochlear cistern, the distance of oculomotor porus between trochlear porus, the linear exposure of the trigeminal nerve, and the angle to the most inferior medial point in clivus were also measured. Results The area of exposure in the dorsum sella and clivus (157.6 ± 27.2mm 2), the ventrolateral area of exposure in brainstem around BA (249.5 ± 29.7mm 2), the linear exposure of the posterior petroclinoid fold (11.5 ± 0.6 mm) and BA trunk (10.3 ± 2.0 mm), and the angle of approach in the vertical axis to the BA tip (13.7° ± 1.7°) were significantly greater after opening cisterns. The angles of approach in the horizontal axis to the BA tip (24.5° ± 1.1° vs 24.7° ± 0.8°) were not statistically different. The length of oculomotor cistern and trochlear cistern, the distance of oculomotor porus and trochlear porus, the linear exposure of the trigeminal nerve, and the angle of approach to the most inferior medial point in clivus were 6.7 ± 1.3 mm, 10.7 ± 2.4 mm, 9.6 ± 2.3 mm, 15.8 ± 1.4 mm, and 13.0° ± 1.5°, respectively. Conclusion The areas of exposure, linear distances, and the angles of approach in the superior petroclival region can be increased after opening cranial cisterns by the anterior subtemporal keyhole approach.

Microsurgical experience with keyhole operations on intracranial aneurysms

Background We report our experience with keyhole approaches as favorable treatments for various intracranial aneurysms including multiple aneurysms and giant aneurysms. Methods According to the different locations of 105 aneurysms harbored in 100 patients, different keyhole approaches were designed elaborately, among which a supraorbital keyhole approach was used in 91 cases, a pterional keyhole approach in 5 cases, a subtemporal keyhole approach in 3 cases, a retromastoid keyhole approach in 2 cases, and a unifrontal interhemispheric keyhole approach in 1 case. Results Among those 105 aneurysms, 99 were clipped successfully, including 4 that were resected after clipping. One mini-aneurysm was wrapped. The other aneurysms were trapped, including 1 VA aneurysm, 1 giant ICA aneurysm, 1 giant PCoA aneurysm, and 2 giant aneurysms in the PCAs (P2-P3 segment). Multiple aneurysms in 5 cases were treated in 1 surgical session, including 3 cases via unilateral approaches and 2 cases via bilateral approaches. There were no severe keyhole approach–related complications in this present series. Conclusion The keyhole approaches, based on improvements in diagnostic imaging, advanced surgical instruments, and microsurgical skills, are effective and ideal craniotomy techniques in the hands of experienced neurosurgeons for the treatment of intracranial aneurysms, including multiple and giant aneurysms, in patients without diffuse SAH, severe cerebral vasospasm, and severe brain edema or brain swelling.

The extradural subtemporal keyhole approach to the sphenocavernous region: anatomic considerations.

Fourteen cadaver specimens (28 sides) and twelve dry human skulls (24 sides) were used to study the anatomic relationships between bony, neurovascular and foraminal landmarks in the floor of the middle fossa in preparation for performing the extradural subtemporal keyhole approach to the sphenocavernous region. The interforaminal distance was largest between the foramina rotundum (FR) and ovale (FO) and was smallest between the FO and foramen spinosum (FS). The largest angle between exit foramen was the FR to FO. The greater superficial petrosal nerve (GSPN) was always found to overlie and run parallel to the petrous internal carotid artery, however, its location over the artery and its separation from it by bone was variable. With a subtemporal "keyhole" placed above the posterior zygomatic root (PZR), a 0 degrees endoscope allowed easy visualization of the middle meningeal artery (MMA) and the mandibular nerve (V 3 ) however, a 30 degrees endoscope was more useful for visualizing the maxillary nerve (V 2 ) and the ophthalmic nerve (V 2 ). With a sphenoidotomy performed between V 1 and V 2, the 30 degrees endoscope was found to be the most useful for visualizing the carotid siphon and the contralateral wall of the sphenoid sinus, while the 70 degrees endoscope was the most useful for visualizing of the floor of the sella and the walls of the sphenoid sinus. Two venous concerns with respect to performing endoscopic approaches to the region were identified: a fibrous layer overlies a heavy venous plexus that encircles the petrous carotid artery, and the foramen Vesalius, which transmits a large emissary vein draining the cavernous sinus, was identified medial to the FO in 30 % of our dissected sides.

Subtemporal keyhole approach to the suprasellar and petroclival region: microanatomic considerations and clinical application.

To minimize surgical invasiveness, the keyhole concept is applied to the subtemporal approach. Anatomic features were studied in 14 sides of adult cadaver heads, and the technique was used in 162 interventions. Although most of the lesions treated were 3 cm in size or smaller, larger lesions were also treated using this technique. In some cases, if needed, an endoscope-assisted microsurgical technique was used. The cadaveric study provided intimate experience with the microsurgical anatomy of the approach. The 162 consecutive patients who were operated on harbored various types of lesions; the most recent 43 consecutive interventions were investigated in detail. The complications encountered included five cases of permanent cranial nerve palsy, two cases of cerebrospinal leakage, two cases of short memory disturbance, two cases of seizure, and one case each of hemiplegia and incoordination, transient hearing loss and tinnitus, and consciousness deterioration and hemiplegia. With careful patient selection, the subtemporal keyhole approach diminishes tissue traumatization considerably and has proven to provide sufficient operating space in the suprasellar area. When this approach is combined with the cranial base technique, the petroclival region can also be treated. However, the subtemporal keyhole approach requires deliberate preoperative planning for each patient, as well as for each surgeon.

Subtemporal Keyhole Approach to the Suprasellar and Petroclival Region: Microanatomic Considerations and Clinical Application

Subtemporal Keyhole Approach to the Suprasellar and Petroclival Region: Microanatomic Considerations and Clinical Application