Roberto Rodriguez Rubio

Internal Maxillary Artery to Upper Posterior Circulation Bypass Using a Superficial Temporal Artery Graft: Surgical Anatomy and Feasibility Assessment

BACKGROUND Revascularization of the upper posterior circulation (UPC), including the superior cerebellar artery (SCA) and posterior cerebral artery (PCA), may be necessary as part of the surgical treatment of complex UPC aneurysms or vertebrobasilar insufficiency. The existing bypass options have relative advantages and disadvantages. However, the use of a superficial temporal artery graft (STAg) in a bypass from the internal maxillary artery (IMA) to the UPC has not been previously assessed. We studied the surgical anatomy and assessed the technical feasibility of the IMA-STAg-UPC bypass. METHODS Fourteen cadaver heads were studied. The STAg was harvested proximally from about 15 mm below the zygomatic arch. The IMA was exposed through the lateral triangle of the middle fossa. The IMA-STAg-UPC bypass was completed using a subtemporal approach. RESULTS The bypass was successfully performed in all specimens. The average length of the STAg from the donor to the recipient was 46.4 mm for the s2 SCA, and 49.5 mm for the P2 PCA. The average distal diameter of the STAg was 2.3 mm. More than 83% of STAgs had a diameter of ≥2 mm distally. At the point of anastomosis, the average diameter of the SCA was 1.9 mm, and the average diameter of the PCA was 3.0 mm. CONCLUSIONS The proposed bypass is anatomically feasible and provides a suitable caliber match between the bypass components. Our results provide the anatomic basis for clinical assessment of the bypass in tackling complex lesions of the vertebrobasilar system requiring revascularization.

Internal Maxillary Artery to Anterior Circulation Bypass with Local Interposition Grafts Using a Minimally Invasive Approach: Surgical Anatomy and Technical Feasibility

BACKGROUND The internal maxillary artery (IMA) is a reliable donor for extracranial-intracranial high-flow bypasses. However, previously described landmarks and techniques to harvest the IMA are complex and confusing and require extensive bone drilling, carrying significant neurovascular risk. The objective of our study was to describe a minimally invasive technique for exposing the IMA and to assess the feasibility of using the IMA as a donor for anterior-circulation recipient vessels using 2 different local interposition vessels. METHODS Via a minimally invasive technique, the IMA was harvested in 10 cadaveric specimens and a pterional craniotomy was performed. Two interposition grafts-the superficial temporal artery (STA) and middle temporal artery-were evaluated individually. Transsylvian exposure of the second segment of middle cerebral artery (M2), the supraclinoid internal carotid artery, and the proximal postcommunicating anterior cerebral artery segment was completed. Relevant vessel calibers and graft lengths were measured for each bypass model. RESULTS The mean caliber of the IMA was 2.7 ± 0.5 mm. Of all 3 recipients, the shortest graft length was seen in the IMA-STA-M2 bypass, measuring 42.0 ± 8.4 mm. There was a good caliber match between the M2 (2.4 ± 0.4 mm) and STA (2.3 ± 0.4 mm) at the anastomotic site. The harvested middle temporal artery was sufficient in length in only 30% cases, with a mean distal caliber of 2.0 ± 0.7 mm. CONCLUSIONS This study confirmed the technical feasibility of IMA as a donor for an extracranial-intracranial bypass to the second segment of the anterior cerebral artery, M2, and the supraclinoid internal carotid artery. However, IMA-STA-M2 was observed to be the most suitable bypass model.

Contralateral Approach to Middle Cerebral Artery Aneurysms: An Anatomical-Clinical Analysis to Improve Patient Selection

BACKGROUND A contralateral approach to aneurysm clipping in cases of bilateral middle cerebral artery (MCA) aneurysms reduces surgical time and cost. However, there is a lack of evidence for objective patient selection. In this study, we assessed the change in surgical freedom along the contralateral MCA to provide objective evidence for patient selection. METHODS Sixteen cadaveric specimens were studied. Through a pterional approach, the surgical freedom was calculated moving distally along the contralateral MCA in 5-mm increments. In addition, in a series of 19 MCA aneurysms clipped contralaterally by the senior author, the average length of the MCA from its origin to the aneurysm neck was measured on angiography. RESULTS In these patients treated via a contralateral approach, the average length of the MCA segment from its origin to the aneurysm neck was 12.4 mm. Starting at the MCA origin, surgical freedom decreased significantly between all adjacent target points except at 5-10 mm from the MCA origin. CONCLUSIONS After the proximal 5 mm, there is no significant decrease in surgical maneuverability within the proximal 10 mm of MCA when approached contralaterally. When compared to the average length of the MCA from its origin to the aneurysm neck in the clinical series, it can be concluded that the first 10 mm (average, 12.4 mm) of the contralateral MCA may be considered a surgical comfort zone for a contralateral approach. This criterion may be useful for patient selection for a contralateral approach in cases of multiple bilateral intracranial aneurysms.

Intradural and Extradural Ligation of a Left Dural Arteriovenous Fistula of the Sigmoid Sinus Using a Retrosigmoid Approach: 3-Dimensional Operative Video

Dural arteriovenous fistulas (dAVFs) are acquired dural shunts between an artery and a vein without parenchymal nidus. DAVFs represent 10%-15% of intracranial arteriovenous malformations, and their manifestations vary from asymptomatic to devastating intracranial hemorrhage.1 They are classified according to their drainage and presence/absence of cortical venous reflux (CVR).2,3 The junction between transverse and sigmoid sinus (SS) is the most common location, and their treatment in case of CVR can involve the sacrifice of the sinus. DAVF occlusion may be achieved with both endovascular and surgical technique and frequently with combined techniques. This video demonstrates the management of a left dAVF of the SS in a 54-yr-old male with recent onset of diplopia and imbalance with venous congestion seen in the left cerebellum on T2 sequence MRI. Angiography revealed a Borden grade 2, Cognard grade IIa + b left SS dAVF supplied by the jugular and hypoglossal branches of the neuromeningeal trunk with retrograde filling of the partially thrombosed SS and drainage to the superior petrosal sinus and multiple cerebellar veins. Endovascular repair was not feasible due to high risk of postoperative cranial neuropathy. The patient consented to surgery. A left retrosigmoid craniotomy was performed to achieve intradural ligation of the fistula at the dural edge along the inferior aspect of the tentorium. After drainage occlusion and cauterization of the transmastoid extradural feeders (via mastoidectomy), the SS was entirely exposed and clipped to prevent any further retrograde arteriovenous shunting. The postoperative course was without complication and angiography showed complete occlusion of the dAVF.

Comprehensive Anatomic Assessment of the Pterional, Orbitopterional, and Orbitozygomatic Approaches for Basilar Apex Aneurysm Clipping

BACKGROUND The pterional approach, along with its orbitopterional and orbitozygomatic extensions, is among the most common surgical approaches for tackling challenging aneurysms of the basilar artery apex (BAX). There is general consensus that the orbitozygomatic approach provides the best exposure for these lesions. However, there is little objective evidence to support approach selection for surgical treatment of BAX aneurysms. OBJECTIVE To compare different features regarding surgical treatment of BAX aneurysms between the pterional, orbitopterional, and orbitozygomatic approaches. METHODS The pterional, orbitopterional, and orbitozygomatic approaches were sequentially completed on 10 cadaveric specimens. The visibility of perforators, lengths of exposure, and safe clipping for major BAX branches, surgical area of exposure, and the surgical freedom for the BAX target were assessed. RESULTS The orbitopterional approach provided significantly greater values than the pterional approach in all variables, except for exposure of the bilateral P1 posterior cerebral artery (PCA) perforators. When compared to the orbitopterional approach, the orbitozygomatic approach did not provide a statistically significant increase in (1) surgical freedom through the carotid-oculomotor triangle, (2) area of exposure, (3) ipsilateral, and (4) contralateral P1 PCA perforator visibility, and (5) ipsilateral PCA exposure and (6) clipping lengths. CONCLUSION The orbitopterional approach provides significantly greater surgical exposure to BAX than the pterional approach. The orbitopterional approach is less invasive while providing similar surgical access to the BAX compared to the orbitozygomatic. The results of this study show that the orbitopterional approach may be optimal for the treatment of most BAX aneurysms, particularly to reduce morbidity resulting from the full orbitozygomatic approach.

Right Retrosigmoid Approach for In Situ Occlusion of Brainstem Arteriovenous Malformation Surrounding the Trigeminal Nerve: 3-Dimensional Operative Video

Arteriovenous malformations (AVMs) of the trigeminal root entry zone are rare and can be associated with neurovascular compression syndromes as well as intracranial hemorrhage.1 They generally have a small nidus located on and around the pial surface of the brainstem; thus, they are feasible for surgery. Nevertheless, they represent a challenge given the vicinity and involvement of cranial nerves and brainstem perforators.2-4This video demonstrates the case of a 57-yr-old man with new onset of a severe headache without neurological deficit associated with MRI evidence of a vascular malformation around the cisternal right trigeminal nerve. The nerve showed an altered signal on the MRI. Angiography revealed a Spetzler-Martin grade II AVM with a 16-mm nidus supplied by basilar artery perforators, right anterior inferior cerebellar artery, and the superior cerebellar artery (SCA), with drainage into the superior petrosal vein and sigmoid sinus. After an unsuccessful attempted embolization, the patient was referred for and elected microsurgical treatment. With the patient in a lateral position, a right retrosigmoid approach was performed. After cisternal dissection and identification of the nidus, the feeders were occluded by alternating cauterization and clipping to avoid damage to the critical surrounding structures. The AVM in-situ occlusion was carried on without resection, given the involvement of the trigeminal nerve. The intraoperative indocyanine green angiography allowed recognition of the venous drainage and helped to localize and differentiate the feeders from normal perforators. In the immediate postoperative course, the patient suffered from mild numbness with a V2-V3 distribution that progressively improved. Angiography showed no residual AVM.

Assessment of the endoscopic endonasal approach to the basilar apex region for aneurysm clipping

OBJECTIVEThe expanded endoscopic endonasal approach (EEA) has shown promising results in treatment of midline skull base lesions. Several case reports exist on the utilization of the EEA for treatment of aneurysms. However, a comparison of this approach with the classic transcranial orbitozygomatic approach to the basilar apex (BAX) region is missing.The present study summarizes the results of a series of cadaveric surgical simulations for assessment of the EEA to the BAX region for aneurysm clipping and its comparison with the transcranial orbitozygomatic approach as one of the most common approaches used to treat BAX aneurysms.METHODSFifteen cadaveric specimens underwent bilateral orbitozygomatic craniotomies as well as an EEA (first without a pituitary transposition [PT] and then with a PT) to expose the BAX. The following variables were measured, recorded, and compared between the orbitozygomatic approach and the EEA: 1) number of perforating arteries counted on bilateral posterior cerebral arteries (PCAs); 2) exposure and clipping lengths of the PCAs, superior cerebellar arteries (SCAs), and proximal basilar artery; and 3) surgical area of exposure in the BAX region.RESULTSExcept for the proximal basilar artery exposure and clipping, the orbitozygomatic approach provided statistically significantly greater values for vascular exposure and control in the BAX region (i.e., exposure and clipping of ipsilateral and contralateral SCAs and PCAs). The EEA with PT was significantly better in exposing and clipping bilateral PCAs compared to EEA without a PT, but not in terms of other measured variables. The surgical area of exposure and PCA perforator counts were not significantly different between the 3 approaches. The EEA provided better exposure and control if the BAX was located ≥ 4 mm inferior to the dorsum sellae.CONCLUSIONSFor BAX aneurysms located in the retrosellar area, PT is usually required to obtain improved exposure and control for the bilateral PCAs. However, the transcranial approach is generally superior to both endoscopic approaches for accessing the BAX region. Considering the superior exposure of the proximal basilar artery obtained with the EEA, it could be a viable option when surgical treatment is considered for a low-lying BAX or mid-basilar trunk aneurysms (≥ 4 mm inferior to dorsum sellae).

A mini-open transspinous approach for resection of intramedullary spinal cavernous malformations

BACKGROUND AND IMPORTANCE Advances in minimally invasive (MIS) and mini-open surgical approaches have led to reductions in perioperative morbidity without compromising rates of resection of non-degenerative intradural spinal pathologies. Whether these approaches may be adapted for the surgical resection for intramedullary vascular malformations - such as cavernous malformations (CMs) - has yet to be reported. The authors describe a mini-open transspinous approach to resect a ruptured intramedullary CM of the conus medullaris. CLINICAL PRESENTATION A 28-year-old man presented with sudden onset of bilateral lower extremity weakness, urinary retention and saddle anesthesia. Magnetic resonance imaging demonstrated a ruptured CM within the conus medullaris with pronounced extralesional hemorrhage. A mini-open transspinous approach with an expandable tubular retractor was successfully applied to facilitate microsurgical resection of the CM and evacuation of the associated hematoma. The patient made a good neurologic recovery, and postoperative imaging confirmed a gross total resection of the CM. CONCLUSION A mini-open transspinous approach utilizing an expandable tubular retractor offers feasible less invasive alternative to provide dorsal midline access for the microsurgical resection of intramedullary spinal CMs. Larger case series or future randomized prospective trials are warranted to fully explore suitability of MIS techniques for the surgical management of intradural spinal cord vascular pathologies - such as CMs.