Minimally Invasive Posterolateral Transcavernous Transtentorial Approach: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND EXPOSURE: MIPLATTA uses a "key-exposure" concept aligning a small minipterional craniotomy with variations of extradural transcavernous transtentorial corridors to access the skull base. ANATOMIC ESSENTIALS FOR PREOPERATIVE PLANNING: Safety and efficiency depend on mastery of the anterior clinoid process (ACP) and cavernous sinus (CS). Preoperative planning includes assessment of ACP pneumatization; tumor epicenter relative to the CS, ACP, and tentorium; and pattern of venous drainage (role of vein of Labbé). ESSENTIAL SURGICAL STEPS: 1. Interfascial flap for facial nerve preservation.2. Minipterional craniotomy with extradural anterior clinoidectomy.3. Variable Transcavernous dissection according to the Hakuba method4. Dural opening parallel to the Sylvian fissure.5. Transtentorial with possible Kawase.6. Closure with autologous graft into the clinoidal triangle and water-tight dural closure. PITFALLS: Incomplete release of the optic and oculomotor nerves during anterior clinoidectomy may lead to deficits. Insufficient caudal extent of the craniotomy may cause undue retraction on Labbé and a temporal lobe infarct. Thorough anatomic knowledge of the CS is a key for catastrophe prevention. VARIANTS AND THEIR INDICATIONS: 1. Basic MIPLATTA with minipterional and extradural anterior clinoidectomy (Hakuba approach) for optic nerve decompression and parasellar lesions.2. Extended MIPLATTA adds oculomotor nerve transposition and cavernous sinus peeling for middle fossa, sphenoid ridge, and giant clinoid tumors.3. Full MIPLATTA adds Kawase and internal auditory canal exposure with endoscopic-assisted microsurgery for tumors invading the posterior fossa.The patients consented to both surgery and publication of their images. Permission was obtained appropriately for the publication of the cadaveric images. The anatomic images and animations in the surgical anatomy section of the video are sole property of www.neurosurgicalanatomy.com and Neurosurgical Anatomy by Arnau Benet, MD, who shall retain copyright, and used with permission.

Minipterional Approach for Middle Fossa Skull Base Lesions: Technical Note.

Surgical access to the middle fossa can be technically challenging. As neurosurgery evolves to minimally invasive approaches, the objective of this study is to demonstrate the extension of the Minipterional approach to access the middle fossa. We present a new surgical approach to the middle fossa for the treatment of secondary trigeminal neuralgia. Three cases are reported to illustrate the following techniques: a patient with petrotentorial meningioma and trigeminal neuralgia, a patient with an arachnoid cyst compressing the fifth nerve, and a patient with a middle cerebral artery aneurysm and a long history of TN (trigeminal neuralgia) refractory to medical and surgical treatments. All three experienced full symptom controls with no permanent neurological deficits. Therefore, the Minipterional technique might represent a feasible, effective, and safe option to treat refractory secondary TN. It also allows approaching these lesions when the posterior fossa approach is compromised by anatomical distortion and enables the simultaneous treatment of secondary trigeminal neuralgia and other lesions, such as aneurysms and meningiomas.

Impact of the Extent of Microsurgical Resection in Sphenopetro-clival Meningiomas Trough a Multistaged Approach: A Volumetric Analysis.

Objective Sphenopetroclival meningiomas (SPCMs) represent a challenge for surgical treatment. The authors used an objective volumetric analysis to assess the effect of the grade of resection and different surgical strategies that may affect the outcome of this tumors. Methods Over a period of 4 years, patients with SPCMs were treated using a middle versus posterior fossa approach, or a two-stage surgery combining both approaches, based on the tumor location in relation to the petrous ridge and tumor volume. Retrospectively, all cases were analyzed with regard to tumor volume, extent of resection (EOR), functional outcome, and complications. Results Twenty-seven patients with SPCMs met the inclusion criteria, and the mean follow-up was 24.8 months. Eleven patients underwent a two-stage surgery, while 16 patients had their SPCMs resected via a single craniotomy. Mean EOR was 87.6% and gross total resection was achieved in 48% of patients. Patients with greater EOR had better functional outcomes ( r = 0.81, p < 0.01). Greater EOR was not accompanied by a significant increase in surgical complications. There was a trend toward lower postoperative volumes and better EOR with our two-stage approach (2.2 vs. 3.2 cm 3 , p = 0.09; and 94.1 vs. 91.2%, p = 0.49, respectively), without an increase in the rate of complications (18.7 vs. 18.2%, p = 0.5). Conclusion Staging of the surgical resection of larger tumors may lead to greater EOR, and this strategy should be considered for larger tumors.

The Minimally Invasive Posterolateral Transcavernous-Transtentorial Approach. Technical Nuances, Proof of Feasibility, and Surgical Outcomes Throughout a Case Series of Sphenopetroclival Meningiomas.

OBJECTIVE: Sphenopetroclival (SPC) meningiomas are considered among the most complex skull-base neoplasms to approach surgically. We aim to determine whether some SPC meningiomas can be safely and effectively treated using a modified minimally invasive pterional posterolateral transcavernous-transtentorial approach (MIPLATTA). METHODS: Fourteen patients harboring SPC meningiomas were surgically treated through a MIPLATTA. MIPLATTA includes a minipterional craniotomy, anterior extradural clinoidectomy, peeling of the temporal fossa, decompression of cranial nerves (CNs) in the cavernous sinus, and sectioning of the tentorium to reach the upper part of the posterior fossa. RESULTS: Gross total resection was achieved in 11 of 14 patients (78%), whereas near-total resection was accomplished in the other 3 patients (22%), each of whom underwent a further complementary retrosigmoid approach for gross total tumor resection. There were no deaths, and 13 of 14 patients were independent at 6 months follow-up (modified Rankin Scale score ≤2). One patient had pontine infarction after the procedure and experienced moderate disability at follow-up (modified Rankin Scale score 3). All patients had some degree of CN impairment. Of 38 cranial neuropathies, 15 (39%) improved, 20 (53%) remained stable, and 3 (8%) worsened postoperatively. Four new CN deficits were observed postoperatively in 3 patients (fourth CN, 2 patients; third CN, 1; fifth CN, 1). CONCLUSIONS: MIPLATTA is a useful and safe treatment alternative that allows resection of large SPC tumors with dominant invasion of cavernous sinus and middle fossa, preserves hearing and facial motor function, and provides good chances of recovery of visual and oculomotor deficits.

Microsurgical Anatomy of the Anterior Circulation of the Brain Adjusted to the Neurosurgeon's Daily Practice.

The study of cerebrovascular anatomy can be difficult and may take time due to its intrinsic complexity. However, it can also be difficult for the following reasons: the excessive description of neuroanatomy making articles hard to read, the unclear clinical application of what is written, the use of simplified or intricate schematic drawings that are not always appropriate for effective teaching, the poor quality of neuroanatomy dissections and the use of unusual views of figures that are not strictly related to the most frequent neuroimages to be interpreted in daily practice. Because of this, we designed an article that incorporates original and accurate anatomical dissections in an attempt to improve its comprehensibility. Five formalin-fixed adult cadaveric heads, whose vessels were injected with a colored silicone mixture (red for arteries and blue for veins), were dissected and examined under a microscope with magnifications from 3× to 40×. Special emphasis has been placed on correlating topographic anatomy with routine neuroimaging studies from computed tomographic angiography (CTA) and digital subtraction angiography (DSA). The essential surgical anatomy in a neurosurgeon's daily practice is also described. The cadaveric dissections included in this study contribute to the understanding of the cerebrovascular anatomy necessary for the neurosurgeon's daily practice.

Management of Giant Thrombosed MCA Aneurysm: Double STA-MCA Revascularization.

Giant middle cerebral artery (MCA) aneurysms are rare complex cerebrovascular lesions to treat.1 The management of those aneurysms may be very challenging, despite the introduction of refined microsurgical techniques and the rapid progress in endovascular methods, which often require bypass surgery as part of the strategy.2-4 This approach is particularly relevant to giant, dolichoectatic, and thrombotic aneurysms.5,6 This video shows the surgical strategy and stepwise depiction of the surgical treatment of a complex giant thrombosed aneurysm using a double-barrel superficial temporal artery (STA) to MCA bypass (Video 1). Informed written consent was obtained from the patient and his family. The patient was a 50-year-old man, previously healthy, who presented with headache, memory difficulty, and left-sided involuntary movements for 2 months. Computed tomography scan showed a giant round calcified and heterogeneous lesion compatible with a thrombosed MCA aneurysm. Brain magnetic resonance imaging showed the same lesion with a flow void signal inside in a serpentine fashion and a complete hemosiderin halo. Conventional angiography showed the false lumen and the filling of the distal MCA branches with a certain degree of arterial delay. The lesion was located between M1 and M3 segments of MCA. Extracranial-intracranial STA-MCA bypass was performed. Then we opened the aneurysm sac for decompression and observed the lenticulostriate artery branches arising away from the aneurysm sac. The complete clipping and patency of the anastomosis was validated during surgery by indocyanine green angiography. Postoperative cerebral computed tomography angiography revealed good patency from the STA to the MCA. The patient was neurologically intact without complains.

Microsurgical clipping of multiple cerebral aneurysms in the acute phase of aneurysmal subarachnoid hemorrhage through a minipterional approach: The Chilean experience.

OBJECTIVE: The minipterional craniotomy (MPTc) has been widely accepted as a minimally invasive alternative to the pterional approach for the treatment of certain small non-ruptured anterior circulation aneurysms. The aim of this study was to determine the effectiveness and safety of the MPTc in the context of a complex and potentially harmful scenario: acute onset of subarachnoid hemorrhage (SAH) in patients harboring multiple intracranial aneurysms (MIA). METHODS: Patients harboring MIA clipped through a unilateral MPTc were selected from four retrospective databases of four high-volume neurosurgical centers. Patients with a Hunt & Hess score 4 or 5 were not considered candidates for clipping through a MPTc. Medical records and radiological images were retrospectively reviewed. Epidemiological, clinical and radiological data, as well as short-term outcome (modified Rankin scale at 6 month-follow-up) were analyzed. RESULTS: 16 patients harboring 33 aneurysms (16 ruptured, 17 non ruptured) met the inclusion criteria. Each aneurysm size was 5.7 ± 2.1 mm (range 3-11). 12 out of 33 aneurysms were located in the middle cerebral artery (MCA). Anterior communicating (ACom) and MCA aneurysms were the aneurysm locations most commonly ruptured (5 each, 62 %). Complete occlusion was achieved in 32 aneurysms (97 %) and near-complete occlusion in 1 (3%). 13 patients (93 %) were independent at 6 month-follow-up. Mortality rate was 0%. Complications included 1 cerebrospinal-fluid leakage. CONCLUSION: When indicated (Hunt Hess < 4), performing a MPTc is safe and effective in aSAH cases with multiple aneurysms.

Extradural minipterional approach: Evolving indications of the minipterional craniotomy.

BACKGROUND: In this paper, we report a clinical series of skull base lesions operated on trough the MiniPT, extending its application to skull base lesions, either using the classical minipterional or a variant, we call extradural minipterional approach (MiniPTEx). METHODS: We describe our surgical technique of operating on complex skull base lesions using a minipterional extradural approach. Anterior clinoidectomy, middle fossa peeling, transcavernous, and Kawase approaches were performed as needed. In total, we carried out 24 surgeries: three skull base tumors, 1 Moyamoya case, and 20 giant/complex intracranial aneurysms. All the patients present good neurological result (mRs < 3). Only two patients had paralysis of any cranial nerve and only one patient had a mild hemiparesis. RESULTS: This surgery series there are 24 cases, 10 patients were treated with exclusive MiniPT. MiniPT extradural approach was made in 14 patients. Twelve were treated using pure MiniPTEx approach, 1 patient using transcavernous approach, and in 1 patient, the anterior clinoid was resected with the combination of a MiniPT, a medium fossa peeling, and the Kawase anterior petrosectomy for skull base surgery. CONCLUSION: We further advance the indications of the MiniPT by extending it to operate on the cranial base tumors or complex vascular lesions without additional morbidity. MiniPT approach may be safely associated with skull base techniques, including anterior and posterior clinoidectomies, peeling of the middle fossa, transcavernous approach, and anterior petrosectomy. The versatility of the MiniPT craniotomy and the feasibility of performing skull base surgery through the MiniPT technique have been demonstrated in this paper.

Surgical clipping of a non-ruptured ophthalmic aneurysm through an extradural micropterional keyhole approach.

BACKGROUND: Clipping continues to be one of the treatment strategies for ophthalmic artery aneurysms not amenable for stenting or coiling, or when long-term treatment durability is a concern. However, crescent development of endovascular techniques demands minimal invasiveness in the transcranial approaches while ensuring satisfactory results. METHODS: We describe an extradural micropterional keyhole approach (eMKA) to the paraclinoid region and highlight the key anatomical elements of this surgical approach. CONCLUSION: The eMKA is a minimally invasive approach that provides access to the paraclinoid region using an extradural corridor. Therefore, it is suitable for clipping of ophthalmic artery aneurysms and other paraclinoid aneurysms.

Extradural minipterional approach for giant intracranial aneurysms.

BACKGROUND: The clinical applicability of the minipterional (MPT) craniotomy is still limited to small and superficial anterior circulation aneurysms. We discuss the technical nuances of a modified MPT approach, the extradural MPT approach (eMPTa), for the treatment of a giant intracranial aneurysm (GIA) arising from the paraclinoid carotid artery. CASE DESCRIPTION: A 44-year-old female presented with facial hypoesthesia and third cranial nerve palsy. Further investigations revealed the presence of a 27 mm aneurysm arising from the communicating segment of the internal carotid artery. The patient underwent surgical clipping through an extradural MPT craniotomy and combined anterior clinoidectomy. Postoperative angio-computed tomography demonstrated complete aneurysm occlusion and patency of the parent vessels. The patient recovered fully from her previous deficits. CONCLUSION: The skull base drilling, interdural dissection, and anterior clinoidectomy are key steps during the eMPTa that optimizes the use of the extradural corridor. Such adaptations are enough to improve the surgical maneuverability along the paraclinoid region and adapt the MPT suitability for the treatment of complex GIA.

The extradural minipterional approach for the treatment of paraclinoid aneurysms: a cadaver stepwise dissection and clinical case series.

Minipterional (MPT) craniotomy has recently been added to the neurosurgical armamentarium as a less invasive alternative to the pterional craniotomy for the treatment of parasellar lesions. However, its clinical applicability in the treatment of certain complex aneurysms, such as those arising in the paraclinoid region, remains unclear. To illustrate the microsurgical anatomy of a modified extradural MPT approach, which combines a classic MPT craniotomy with an extradural anterior clinoidectomy, and to demonstrate its clinical applicability in the treatment of complex paraclinoid aneurysms. A stepwise extradural MPT approach is illustrated in a cadaver study. Clinical outcome data from a series of 19 patients with 20 paraclinoid aneurysms treated surgically using the extradural MPT approach between 2016 and 2018 were retrospectively collected. In 95% of the cases, complete aneurysm occlusion was achieved. No aneurysm recurrences were seen during follow-up with a median length of 21 months. The outcome, according to the modified Rankin Scale, was 0 points in 12 patients (63%), 1 point in 6 patients (32%), and 2 points in 1 patient (5%). Four out of 6 patients (67%) with initial visual symptoms showed improvement following treatment, whereas in two (11%), vision became worse. The extradural MPT approach ensures a sufficiently large exposure of the paraclinoid region that is comparable with conventional approaches with the advantage of being minimally invasive. Our case series demonstrates the feasibility of this approach for the treatment of complex paraclinoid aneurysms.

The extradural minipterional pretemporal approach for the treatment of spheno-petro-clival meningiomas.

BACKGROUND: Cavernous sinus and petroclival region is an anatomically complex region in close relationship with important neurovascular structures. As such, the surgical treatment of spheno-petro-clival (SPC) meningiomas represents an operative challenge, in which several routes and its combinations might be used. METHODS: We describe in detail the surgical technique of the extradural minipterional pretemporal approach (eMPT-P) to the SPC region and highlight the main anatomical key elements involved in this approach as well as the technical aspects for avoiding surgical complications. CONCLUSION: The eMPT-P is a versatile approach that uses the extradural route, and thereby reduces brain retraction, while provides a good angle of exposure of the SPC region.

Angiographic Findings in Refractory Delayed Cerebral Ischemia

Background Delayed cerebral ischemia (DCI) follows a refractory course in a subgroup of patients with aneurysmal subarachnoid hemorrhage (SAH), leading to diffuse ischemic injury. The role of angiographic vasospasm (AV) is unknown. Our goal is to study the angiographic alterations and the clinical profile of refractory DCI patients. Methods Retrospective study of patients with SAH who presented with DCI treated with medical and endovascular therapy, with a refractory evolution, defined asmultiple ischemic infarction and brain death. Results Out of a cohort of 336 patients, 7 (2%) developed refractory DCI. The median age of the patients was 48 (38­60) years old. Five patients had ruptured anterior communicating artery (ACoA) aneurysms. Four patients were treated with coil embolization, and three with microsurgical clipping. Angiographic vasospasm was classified as severe in 5 cases. Compromise of bilateral circulation was detected in six patients. Distal circulation vasospasm occurred in five cases. Slow circulatory transit times were observed in three patients. Conclusion Angiographic findings such as bilateral circulatory compromise and distal vasospasm were frequent alterations. Further studies are required to establish the association of these findings with the clinical outcomes.

Technical Description of Minimally Invasive Extradural Anterior Clinoidectomy and Optic Nerve Decompression. Study of Feasibility and Proof of Concept.

BACKGROUND: Several diseases that involve the optic canal or its contained structures may cause visual impairment. Several techniques have been developed to decompress the optic nerve. OBJECTIVE: To describe minimally invasive extradural anterior clinoidectomy (MiniEx) for optic nerve decompression, detail its surgical anatomy, present clinical cases, and established a proof of concept. METHODS: Anatomic dissections were performed in cadaver heads to show the surgical anatomy and to show stepwise the MiniEx approach. In addition, these surgical concepts were applied to decompress the optic nerve in 6 clinical cases. RESULTS: The MiniEx approach allowed the extradural anterior clinoidectomy and a nearly 270° optic nerve decompression using the no-drill technique. In the MiniEx approach, the skin incision, dissection of the temporal muscle, and craniotomy were smaller and provided the same extent of exposure of the optic nerve, anterior clinoid process, and superior orbital fissure as that usually provided by standard techniques. All patients who underwent operation with this technique had improved visual status. CONCLUSIONS: The MiniEx approach is an excellent alternative to traditional approaches for extradural anterior clinoidectomy and optic nerve decompression. It may be used as a part of more complex surgery or as a single surgical procedure.

The "Brain Stress Timing" phenomenon and other misinterpretations of randomized clinical trial on aneurysmal subarachnoid hemorrhage.

Clipping and coiling are currently the two alternatives in treatment of ruptured cerebral aneurysms. In spite of some meritorious analysis, further discussion is helpful to understand the actual state of art. Retreatment and rebleeding rates clearly favors clipping, although short-term functional outcome seems to be beneficial for clipping, while this different is not such if we perform the comparison at a longer follow up. Long-term follow ups and cost analysis are mandatory to have a clear view of the current picture in treatment of subarachnoid hemorrhage. Treatment strategy should be made by a multi-disciplinary team in accredited centers with proficient experience in both techniques.