The maxillary artery and its variants: an anatomical study with neurosurgical applications.

BACKGROUND: The maxillary artery (MA) has gained attention in neurosurgery particularly in cerebral revascularization techniques, intracranial endonasal approaches and endovascular procedures. OBJECTIVES: To describe and illustrate the anatomy of the MA and its neurosurgical importance in a detailed manner. METHODS: Six cadaveric heads (12 MAs) were injected with latex. The arteries and surrounding structures were dissected and studied using microsurgical techniques. The dimensions, course and branching patterns of the MA were recollected. In addition, 20 three-dimensional reconstruction CT head and neck angiograms (3D CTAs) of actual patients were correlated with the cadaveric findings. RESULTS: The MA can be divided in three segments: mandibular, pterygoid and pterygopalatine. Medial and lateral trunk variants regarding its course around the lateral pterygoid muscle can be found. The different branching patterns of the MA have a direct correlation with the course of its main trunk at the base of the skull. Branching and trunk variants on one side do not predict the findings on the contralateral side. CONCLUSION: In this study the highly variable course, branching patterns and relations of the MA are illustrated and described in human cadaveric heads and 3D CTAs. MA 3D CTA with bone reconstruction can be useful preoperatively for the identification of the medial or lateral course variants of this artery, particularly its pterygoid segment, which should be taken into account when considering the MA as a donor vessel for an EC-IC bypass.

Microendoscopic Tailored Spine Decompression as a Less-Invasive, Stability-Preserving Surgical Option to Instrumented Correction in Complex Spine Deformities: A Preliminary Multicenter Experience.

OBJECTIVES: The aim of this study was to explore the effectiveness of a less-invasive posterior spine decompression in complex deformities. We studied the potential advantages of the microendoscopic approach, supplemented by the piezoelectric technique, to decompress both sides of the vertebral canal from a one-sided approach to preserve spine stability, ensuring adequate neural decompression. METHODS: A series of 32 patients who underwent a tailored stability-preserving microendoscopic decompression for lumbar spine degenerative disease was retrospectively analyzed. The patients underwent selective bilateral decompression via a monolateral approach, without the skeletonization of the opposite side. For omo- and the contralateral decompression, we used a microscopic endoscopy-assisted approach, with the assistance of piezosurgery, to work safely near the exposed dura mater. Piezoelectric osteotomy is extremely effective in bone removal while sparing soft tissues. RESULTS: In all patients, adequate decompression was achieved with a high rate of spine stability preservation. The approach was essential in minimizing the opening, therefore reducing the risk of spine instability. Piezoelectric osteotomy was useful to safely perform the undercutting of the base of the spinous process for better contralateral vision and decompression without damaging the exposed dura. In all patients, a various degree of neurologic improvement was observed, with no immediate spine decompensation. CONCLUSIONS: In selected cases, the tailored microendoscopic monolateral approach for bilateral spine decompression with the assistance of piezosurgery is adequate and safe and shows excellent results in terms of spine decompression and stability preservation.

Low-Profile Visualized Intraluminal Support Junior Flow-Diversion Properties Used for Stabilization of a Superior Cerebellar Artery Pseudoaneurysm.

BACKGROUND: Pseudoaneurysms of the posterior circulation pose a unique management challenge. The fragile nature of the pseudoaneurysm wall presents a high risk of rupture and demands treatment. Small vasculature, particularly distal in the posterior circulation, can preclude management with traditional flow diverters, where the alternative of vessel sacrifice is unacceptable. Small stents can have flow-diversion properties and can be used in these high-risk, difficult-to-access aneurysms. METHODS: We describe a 40-year-old woman presenting with a ruptured dissecting right superior cerebellar artery pseudoaneurysm after minor trauma. Given the aneurysm's small size and morphology, it was not amenable to coiling and parent vessel sacrifice was potentially morbid. The pseudoaneurysm was initially stabilized with a Low-Profile Visualized Intraluminal Support Junior (LVIS Jr.) stent due to its reported flow-diverting properties. RESULTS: At six-month follow-up the pseudoaneurysm was stable and the vasospasm had resolved. At this point, definitive treatment with a "FRED Jr." (Flow Re-Direction Endoluminal Device Junior) flow diverter was pursued. Complete obliteration of the pseudoaneurysm was seen at 12 months' follow-up after staged treatment. CONCLUSIONS: Due to the unique challenges associated with ruptured pseudoaneurysms located on small-caliber vessels, the options for definitive treatment are limited. The small size of the LVIS Jr. stent and its flow-diverting properties make it a practical treatment option in a difficult situation. This case report provides further support for the flow-diverting properties of the LVIS Jr. and its potential application in the treatment of ruptured pseudoaneurysms in small-caliber intracranial vessels.

Anatomical study of the thoracolumbar radiculomedullary arteries, including the Adamkiewicz artery and supporting radiculomedullary arteries.

OBJECTIVE: The aim of this paper was to identify and characterize all the segmental radiculomedullary arteries (RMAs) that supply the thoracic and lumbar spinal cord. METHODS: All RMAs from T4 to L5 were studied systematically in 25 cadaveric specimens. The RMA with the greatest diameter in each specimen was termed the artery of Adamkiewicz (AKA). Other supporting RMAs were also identified and characterized. RESULTS: A total of 27 AKAs were found in 25 specimens. Twenty-two AKAs (81%) originated from a left thoracic or a left lumbar radicular branch, and 5 (19%) arose from the right. Two specimens (8%) had two AKAs each: one specimen with two AKAs on the left side and the other specimen with one AKA on each side. Eight cadaveric specimens (32%) had 10 additional RMAs; among those, a single additional RMA was found in 6 specimens (75%), and 2 additional RMAs were found in each of the remaining 2 specimens (25%). Of those specimens with a single additional RMA, the supporting RMA was ipsilateral to the AKA in 5 specimens (83%) and contralateral in only 1 specimen (17%). The specimens containing 2 additional RMAs were all (100%) ipsilateral to their respective AKAs. CONCLUSIONS: The segmental RMAs supplying the thoracic and lumbar spinal cord can be unilateral, bilateral, or multiple. Multiple AKAs or additional RMAs supplying a single anterior spinal artery are common and should be considered when dealing with the spinal cord at the thoracolumbar level.

Side-Firing Intraoperative Ultrasonograhy for Resection of Giant Pituitary Adenomas.

BACKGROUND: Suprasellar extension, cavernous sinus invasion, and involvement of intracranial vascular structures and cranial nerves are among the challenges faced by surgeons operating on giant pituitary macroadenomas. Intraoperative tissue shifts may render neuronavigation techniques inaccurate. Intraoperative magnetic resonance imaging can solve this problem, but it may be costly and time consuming. However, intraoperative ultrasonography (IOUS) allows for quick, real-time feedback and may be particularly useful when facing giant invasive adenomas. Here, we present the first study examining technique for IOUS-guided resection specifically focusing on giant pituitary adenomas. OBJECTIVE: To describe the use of a side-firing ultrasound probe in the resection of giant pituitary macroadenomas. METHODS: We describe an operative technique using a side-firing ultrasound probe (Fujifilm/Hitachi) to identify the diaphragma sellae, confirm optic chiasm decompression, identify vascular structures related to tumor invasion, and maximize extent of resection in giant pituitary macroadenomas. RESULTS: Side-firing IOUS allows for identification of the diaphragma sellae to help prevent intraoperative cerebrospinal fluid leak and maximize extent of resection. Side-firing IOUS also aids in confirmation of decompression of the optic chiasm via identification of a patent chiasmatic cistern. Furthermore, direct identification of the cavernous and supraclinoid internal carotid arteries and arterial branches is achieved when resecting tumors with significant parasellar and suprasellar extension. CONCLUSIONS: We describe an operative technique in which side-firing IOUS may assist in maximizing extent of resection and protecting vital structures during surgery for giant pituitary adenomas. Use of this technology may be particularly valuable in settings in which intraoperative magnetic resonance imaging is not available.

Case report: Side-firing intraoperative ultrasound guided endoscopic endonasal resection of a clival chordoma.

Clival chordomas are locally invasive midline skull base tumors arising from remnants of the primitive notochord. Intracranial vasculature and cranial nerve involvement of tumors in the paraclival region necessitates image guidance that provides accurate real-time feedback during resection. Several intraoperative image guidance modalities have been introduced as adjuncts to endoscopic endonasal surgery, including stereotactic neuronavigation, intraoperative ultrasound, intraoperative MRI, and intraoperative CT. Gross total resection of chordomas is associated with a lower recurrence rate; therefore, intraoperative imaging may improve long-term outcomes by enhancing the extent of resection. However, among these options, effectiveness and accessibility vary between institutions. We previously published the first use of an end-firing probe in the resection of a clival chordoma. End-firing probes provide a single field of view, primarily limited to depth estimation. In this case report, we discuss the benefits of employing a novel minimally invasive side-firing ultrasound probe as a cost-effective and time-efficient option to navigate the anatomy of the paraclival region and guide endoscopic endonasal resection of a large complex clival chordoma.

Side-firing intraoperative ultrasound applied to resection of pituitary macroadenomas and giant adenomas: A single-center retrospective case-control study.

Introduction: Multiple intraoperative navigation and imaging modalities are currently available as an adjunct to endoscopic transsphenoidal resection of pituitary adenomas, including intraoperative CT and MRI, fluorescence guidance, and neuronavigation. However, these imaging techniques have several limitations, including intraoperative tissue shift, lack of availability in some centers, and the increased cost and time associated with their use. The side-firing intraoperative ultrasound (IOUS) probe is a relatively new technology in endoscopic endonasal surgery that may help overcome these obstacles. Methods: A retrospective analysis was performed on patients admitted for resection of pituitary adenomas by a single surgeon at the University of Mississippi Medical Center. The control (non-ultrasound) group consisted of twelve (n=12) patients who received surgery without IOUS guidance, and the IOUS group was composed of fifteen (n=15) patients who underwent IOUS-guided surgery. Outcome measures used to assess the side-firing IOUS were the extent of tumor resection, postoperative complications, length of hospital stay (LOS) in days, operative time, and self-reported surgeon confidence in estimating the extent of resection intraoperatively. Results: Preoperative data analysis showed no significant differences in patient demographics or presenting symptoms between the two groups. Postoperative data revealed no significant difference in the rate of gross total resection between the groups (p = 0.716). Compared to the non-US group, surgeon confidence was significantly higher (p < 0.001), and operative time was significantly lower for the US group in univariate analysis (p = 0.011). Multivariate analysis accounting for tumor size, surgeon confidence, and operative time confirmed these findings. Interestingly, we noted a trend for a lower incidence of postoperative diabetes insipidus in the US group, although this did not quite reach our threshold for statistical significance. Conclusion: Incorporating IOUS as an aid for endonasal resection of pituitary adenomas provides real-time image guidance that increases surgeon confidence in intraoperative assessment of the extent of resection and decreases operative time without posing additional risk to the patient. Additionally, we identified a trend for reduced diabetes insipidus with IOUS.

Meningeal Hemangiopericytoma Presenting as Pure Gerstmann Syndrome: A Double Rarity.

Gerstmann syndrome is a neurobehavioral syndrome characterized by four cardinal symptoms: acalculia, agraphia, finger-toe agnosia, and dysgraphia. The syndrome is caused primarily by lesions at the confluence of parietal, temporal, and occipital lobes, but also can involve the middle frontal lobe of the dominant hemisphere. Documented inciting lesions include stroke, tumor, hemorrhage, arteriovenous malformations, and seizures. A meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is a diagnostic challenge due to its resemblance to more common brain tumors like meningioma, with histopathology being the definitive diagnostic test. A 37-year-old male presented to our tertiary center with blurred vision, "not being himself," and "acting funny" for three weeks. On exam, he was found to have a right inferior quadrantanopia, grade II papilledema and demonstrated all four symptoms of Gerstmann syndrome - inability to perform simple calculations (acalculia), or identify his fingers (finger agnosia), could not distinguish his left side from the right (left-right disorientation), nor write out his name (agraphia). Brain imaging showed an extra-axial, highly vascularized 7.6-cm mass compressing the left parietal lobe. He underwent a complete resection of the mass. Postoperatively, he had gradual improvement with complete resolution of agraphia, acalculia, finger agnosia, and left-right disorientation within a week status post-resection. Tumor pathology indicated hemangiopericytoma/solitary fibrous tumor. This case enunciates the enigmatic tetrad of Gerstmann syndrome. Though classically described as a sequela of stroke, the mass effect of the tumor on the parietal lobe may produce the symptoms, which can resolve following resection.

Coronavirus Disease 2019 and Pituitary Apoplexy: A Single-Center Case Series and Review of the Literature.

BACKGROUND: Pituitary apoplexy (PA) is a rare, but life-threatening, condition characterized by pituitary infarction and hemorrhage, most often in the setting of a preexisting adenoma. The risk factors and mechanisms associated with PA are poorly understood. Although neurovascular manifestations of coronavirus disease 2019 (COVID-19) infection have been documented, its association with PA has not yet been determined. METHODS: From a prospectively collected database of patients treated at a tertiary care center for pituitary adenoma, we conducted a retrospective medical record review of PA cases during the COVID-19 pandemic from March 2020 to December 2020. We also conducted a literature review to identify other reported cases. RESULTS: We identified 3 consecutive cases of PA and concomitant COVID-19 infection. The most common symptoms at presentation were headache and vision changes. The included patients were successfully treated with surgical decompression and medical management of the associated endocrinopathy, ultimately experiencing improvement in their visual symptoms at the latest follow-up examination. COVID-19 infection in the perioperative period was corroborated by polymerase chain reaction test results in all the patients. CONCLUSIONS: With the addition of our series to the literature, 10 cases of PA in the setting of COVID-19 infection have been confirmed. The present series was limited in its ability to draw conclusions about the relationship between these 2 entities. However, COVID-19 infection might represent a risk factor for the development of PA. Further studies are required.

Advanced imaging assessment of posterior circulation stroke before and after endovascular intervention.

BACKGROUND: Perfusion-computed tomography (CTP) is a relatively new technique that allows rapid semiquantitative noninvasive evaluation of cerebral perfusion aiding in the diagnosis of cerebral ischemia and infarction. There is a paucity of data on its application within the posterior circulation, especially, the brainstem. We describe a case of basilar artery thrombosis with cerebellar and brainstem CTP mismatch and discuss possible future applications of CTP for acute posterior fossa circulation and infarction. METHODS: Case report. RESULTS: Successful use of CTP to aid in decision to proceed with neurointervention in acute basilar artery occlusion and confirm its resolution after mechanical clot retrieval. CONCLUSION: Perfusion-computed tomography can successfully be used to define cerebral ischemia and infarction within the posterior fossa and aid in decisions to proceed with neurointervention.