Technical aspects and operative nuances using a high-definition 4K-3-dimensional exoscope for carotid endarterectomy surgery.

PURPOSE: Carotid endarterectomy (CEA) is effective in treating carotid artery stenosis to prevent stroke. Historically, this operation has been performed utilizing loupe magnification with or without the operating microscope (OM). However, there remains a need for continued improvement in operative visualization and surgical ergonomics. Recently, newly developed digital 'exoscope' has provided the surgeon with unique lighting and magnification as well as improvements in surgical ergonomics and working angle. We sought to review our cumulative experience using a novel 4K high-definition (4K-HD) 3-dimensional (3D) exoscope (EX) for CEA surgery. METHODS: All CEA surgery cases at our institution between 2013 and 2019 using the 4K-HD 3D EX were reviewed. Operative parameters, patient outcome and operator's assessment of the EX compared to OM-assisted cases was conducted. RESULTS: 28 patients were treated, 10 of which were operated using the EX. All procedures were performed without perioperative complications, or significant differences in operative parameters (blood loss <20 cm3 and 164 ± 49.5 minutes) compared to OM-assisted cases. Operators reported improved level of comfort performing 'high' bifurcation surgery and improved visualization and posture during inspection of the distal ICA lumen as primary advantages of EX-assisted CEA over OM-assisted CEA. CONCLUSIONS: The ORBEYE EX, albeit a learning curve necessitating a short period of the OR team, provided safety and outcome comparable to OM-assisted surgery. Potential advantages noted were improved visualization and ergonomics specifically for when extreme working angles were required. Our experience suggests that the exoscope may become a valuable alternative to standard magnification tools in CEA surgery.

N-Butyl Cyanoacrylate Transvenous Arteriovenous Malformation Embolization with Arterial Balloon Assistance: Defining Parameters for a Transvenous Approach as a Potential Upfront Treatment Option in Managing Cerebral Arteriovenous Malformations.

Complete obliteration of arteriovenous malformations (AVMs) using a transvenous approach as the primary and stand-alone treatment modality has been increasingly considered as a useful endovascular approach in the treatment of AVMs. AVMs are typically treated with microsurgery, stereotactic radiosurgery, endovascular embolization, or some combination of the three methods. Preservation of the draining vein is a key requisite common to all treatment modalities. Transvenous embolization (TVE) is conventionally not recommended as a stand-alone treatment for the vast majority of AVMs and has been thought to be best indicated when traditional approaches are considered less safe and when specific evaluation criteria are met. We report a case of a 35-year-old asymptomatic male diagnosed with a small intracranial AVM adjacent to the right motor strip which was managed utilizing this approach. We employed endovascular embolization via a transvenous approach with arterial balloon assistance due to the small size of the nidus, eloquent location, en passage arterial supply proximal to the venous varix, and a single draining vein from the fistula. This case illustrates the selective indications and technical nuances of TVE approach in managing AVMs as a potential upfront treatment option. When patients harbor AVMs with specific angio-architectural findings as outlined, TVE utilizing Onyx or N-butyl cyanoacrylate can be safely performed as a primary treatment modality.

Excision of a Retrochiasmatic Craniopharyngioma by Transcallosal, Interforniceal Approach With Exoscope Assistance: 2-Dimensional Operative Video.

Retrochiasmatic craniopharyngiomas are difficult to treat due to their close proximity to critical neurovascular structures. Several surgical approaches with distinct advantages and limitations have been described to access these tumors, including extended transnasal endoscopic approach (ETEA), subtemporal, translamina terminalis, and transpetrosal approach.1-3 We present a 51-yr-old male with a large retrochiasmatic craniopharyngioma extending into the third ventricle, causing obstructive hydrocephalus. Preoperative magnetic resonance imaging (MRI) showed a tumor cyst abutting the fornices expanding the space between two internal cerebral veins (ICV). After surgical consent, we decided to take advantage of this corridor to approach the tumor in its long axis. Surgical goal was to achieve cyst decompression with "safe maximal" resection of the solid component at last to preserve the pituitary function. Though the long axis of the tumor could be approached using ETEA, we preferred this approach in view of cyst decompression early in the surgery while completely avoiding risks such as cerebrospinal fluid (CSF) rhinorrhea, internal carotid artery (ICA) injury, and sinonasal complications. We utilized a 3-dimensional 4 K exoscope, which provides an excellent ergonomic position, and a high-resolution immersive view compared to a microscope or endoscope. Cyst decompression and near-total resection of the solid component was achieved. Postoperatively, his headaches improved and he was neurologically intact with intact neuroendocrine function. Approach-related risks may include but not limited to hemorrhage due to the rupture of venous sinuses or ICV, stalk or hypothalamus injury, and memory disturbances due to forniceal injury. To conclude, the transcallosal, interforniceal approach to retrochiasmatic craniopharyngiomas may provide a safe surgical corridor in select cases. Patient consented to the proposed procedure. All radiological images have been anonymized. IRB/ethics committee approval was not required.

Hemifacial Spasm Due to Bony Stenosis of the Internal Auditory Meatus: Look Beyond the Loop.

BACKGROUND: Hemifacial spasm (HFS) is a neuromuscular disorder resulting from cranial nerve VII compression at the root entry zone, characterized by brief, involuntary, progressive spasms of muscles on one side of face. The cisternal part of cranial nerve VII myelinated by Schwann cells is considered relatively resistant to compression. Rarely, direct compression over this segment without coexistent root entry zone compression may also result in HFS. An aberrant vessel posterior inferior cerebellar artery/anterior inferior cerebellar artery loop remains the leading cause of compression at this location. Cerebellopontine angle tumors or cysts may affect cranial nerve VII distally. However, bony meatal stenosis with pure distal facial nerve compression leading to HFS in the absence of other clinical symptoms has not been reported. CASE DESCRIPTION: A 53-year-old woman presented with worsening left HFS for 9 years despite multiple trials of medical therapy, which severely impeded her social life and occupation. Temporal bone computed tomography revealed severe stenosis of the left internal auditory meatus (2.36 mm) compared with the right side (4.67 mm). Under three-dimensional exoscope guidance, a left retrosigmoid suboccipital craniotomy was performed, the posterior bony wall of the internal auditory canal was drilled to decompress the canal, and durotomy was performed to release the contents. Her symptoms resolved without developing facial weakness or hearing deficits. CONCLUSIONS: An aberrant anterior inferior cerebellar artery vascular loop is usually the most frequent lesion causing compression of the distal cisternal part of the facial nerve. However, other purely distal or coexistent lesions must be actively sought for both in preoperative radiologic images and during surgery.