Modern Imaging of Aneurysmal Subarachnoid Hemorrhage.

In this review, we discuss the imaging of aneurysmal subarachnoid hemorrhage (SAH). We discuss emergency brain imaging, aneurysm detection techniques, and the management of CTA-negative SAH. We also review the concepts of cerebral vasospasm and delayed cerebral ischemia that occurs after aneurysm rupture and their impact on patient outcomes. These pathologies are distinct, and the use of multimodal imaging modalities is essential for prompt diagnosis and management to minimize morbidity from these conditions. Lastly, new advances in artificial intelligence and advanced imaging modalities such as PET and MR imaging scans have been shown to improve the detection of aneurysms and potentially predict outcomes early in the course of SAH.

Revascularization improves vascular hemodynamics - a study assessing cerebrovascular reserve and transit time in Moyamoya patients using MRI.

Cerebrovascular reserve (CVR) reflects the capacity of cerebral blood flow (CBF) to change. Decreased CVR implies poor hemodynamics and is linked to a higher risk for stroke. Revascularization has been shown to improve CBF in patients with vasculopathy such as Moyamoya disease. Dynamic susceptibility contrast (DSC) can measure transit time to evaluate patients suspected of stroke. Arterial spin labeling (ASL) is a non-invasive technique for CBF, CVR, and arterial transit time (ATT) measurements. Here, we investigate the change in hemodynamics 4-12 months after extracranial-to-intracranial direct bypass in 52 Moyamoya patients using ASL with single and multiple post-labeling delays (PLD). Images were collected using ASL and DSC with acetazolamide. CVR, CBF, ATT, and time-to-maximum (Tmax) were measured in different flow territories. Results showed that hemodynamics improved significantly in regions affected by arterial occlusions after revascularization. CVR increased by 16 ± 11% (p < 0.01) and 25 ± 13% (p < 0.01) for single- and multi-PLD ASL, respectively. Transit time measured by multi-PLD ASL and post-vasodilation DSC reduced by 13 ± 7% (p < 0.01) and 9 ± 5% (p < 0.01), respectively. For all regions, ATT correlated significantly with Tmax (R2 = 0.59, p < 0.01). Thus, revascularization improved CVR and decreased transit times. Multi-PLD ASL can serve as an effective and non-invasive modality to examine vascular hemodynamics in Moyamoya patients.

Application of FLOW 800 in extracranial-to-intracranial bypass surgery for moyamoya disease.

The surgical treatment of moyamoya disease is heavily reliant upon a real-time understanding of cerebral hemodynamics. The application of FLOW 800 allows the surgeon to semiquantify the degree of perfusion to the cerebral cortex following extracranial-to-intracranial (EC-IC) bypass surgery. The authors present three illustrative cases demonstrating common intraoperative findings prior to and following anastomosis using FLOW 800. All patients were diagnosed by catheter angiogram with moyamoya disease and noninvasive imaging demonstrating hemispheric hypoperfusion. Superficial temporal artery (STA)-to-middle cerebral artery (MCA or M4) bypasses were performed to augment intracranial perfusion. The patients tolerated the procedures well and were discharged without event in stable neurological condition. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21191.

Scalpel sign: Dorsal thoracic arachnoid web, thoracic arachnoid cyst and ventral cord herniation.

The "Scalpel sign" is a radiological sign which can be identified on magnetic resonance imaging and indicates dorsal compression of the spinal cord [1]. Prior descriptions of a "Scalpel sign" have been reported in the literature and the awareness and identification of this pathognomonic sign may aid in the rapid diagnosis and treatment of patients with dorsal arachnoid web, dorsal arachnoid cyst or ventral cord herniation. We describe 3 cases which highlight these rare conditions for which this sign is pathognomonic and summarize the pertinent literature related to these disorders [1,2].

Occlusion of Animal Model Arteriovenous Malformations Using Vascular Targeting.

Brain arteriovenous malformations (AVMs) are a significant cause of intracerebral hemorrhage in children and young adults. Currently, one third of patients have no viable treatment options. Vascular targeting agents (VTAs) are being designed to deliver pro-thrombotic molecules to the abnormal AVM vessels for rapid occlusion and cure. This study assessed the efficacy of a pro-thrombotic VTA targeting phosphatidylserine (PS) in a radiation-primed AVM animal model. The model AVM was surgically created in rats by anastomosis of the left external jugular vein to the adjacent common carotid artery. After 6 weeks, the AVM was irradiated (20 Gy) using gamma knife surgery (GKS). A PS-targeting VTA was created by conjugation of annexin V with human thrombin and administered intravenously 3 weeks post-GKS or sham. Unconjugated thrombin was used as a non-targeting control. AVM thrombosis and occlusion was monitored 3 weeks later by angiography and histology. Preliminary experiments established a safe dose of active thrombin for systemic administration. Subsequently, a single dose of annexin V-thrombin conjugate (0.77 mg/kg) resulted in angiographic AVM occlusion in sham (75%) and irradiated (63%) animals, while non-targeted thrombin did not. Lowering the conjugate dose (0.38 mg/kg) decreased angiographic AVM occlusion in sham (13%) relative to irradiated (80%) animals (p = 0.03) as did delivery of two consecutive doses of 0.38 mg/kg, 2 days apart (sham (0%); irradiated (78%); p = 0.003). These findings demonstrate efficacy of the PS-targeting VTA and the feasibility of a vascular targeting approach for occlusion of high-flow AVMs. Targeting specificity can be enhanced by radiation-sensitization and VTA dose modification.

Radiation-Stimulated Translocation of CD166 and CRYAB to the Endothelial Surface Provides Potential Vascular Targets on Irradiated Brain Arteriovenous Malformations.

Vascular targeting with pro-thrombotic antibody-conjugates is a promising biological treatment for brain arteriovenous malformations (bAVMs). However, targeted drug delivery relies on the identification of unique or overexpressed markers on the surface of a target cell. In the absence of inherent biological markers, stereotactic radiosurgery may be used to prime induction of site-specific and targetable molecular changes on the endothelial surface. To investigate lumen-accessible, endothelial targets induced by radiation, we combined Gamma knife surgery in an AVM animal model with in vivo biotin-labeling and comparative proteomics. Two proteins, αB-crystallin (CRYAB)-a small heat shock protein that normally acts as an intracellular chaperone to misfolded proteins-and activated leukocyte cell adhesion molecule CD166, were further validated for endothelial surface expression after irradiation. Immunostaining of endothelial cells in vitro and rat AVM tissue ex vivo confirmed de novo induction of CRYAB following irradiation (20 Gy). Western analysis demonstrated that CRYAB accumulated intracellularly as a 20 kDa monomer, but, at the cell surface, a novel 65 kDa protein was observed, suggesting radiation stimulates translocation of an atypical CRYAB isoform. In contrast, CD166 had relatively high expression in non-irradiated cells, localized predominantly to the lateral surfaces. Radiation increased CD166 surface exposure by inducing translocation from intercellular junctions to the apical surface without significantly altering total protein levels. These findings reinforce the dynamic molecular changes induced by radiation exposure, particularly at the cell surface, and support further investigation of radiation as a priming mechanism and these molecules as putative targets for focused drug delivery in irradiated tissue.

Orbital compartment syndrome following aneurysm surgery.

Orbital compartment syndrome (OCS) is a rare cause of blindness following intracranial surgery. We report a patient with OCS following intracranial cerebrovascular surgery precipitated by severe straining. OCS occurred due to a rapid increase in intraorbital pressure within the rigid confines of the orbit causing hypoperfusion of critical neural structures, which resulted in visual loss and a complete external ophthalmoplegia. Treatment involved urgent surgical soft tissue decompression of the orbit, corticosteroids and osmotic agents. It is important to consider OCS as a cause of blindness in the neurosurgical postoperative setting as without rapid treatment this condition has a very poor prognosis.

Intracranial neuroenteric cysts: a concise review including an illustrative patient.

Neuroenteric cysts (NC) are rare, benign lesions lined by mucin-secreting cuboidal or columnar epithelium of an intestinal or respiratory type. They are regarded as ectopic endodermal cysts, and tend to be found in the spine rather than an intracranial location. Advances in neuroimaging have led to an increased frequency of diagnosis of NC, especially as an incidental finding, although such cysts may be confused radiologically with other lesions such as epidermoid and arachnoid cysts. We undertook a PubMed search of the literature using the search terms "neuroenteric cyst" and its many pseudonyms, including "endodermal cyst", "enterogenous cyst", "neurenteric cyst", "epithelial cyst", "intestinome", "teratomatous cyst", "gastrocytoma", and also "enterogenic", "foregut", "respiratory", and "bronchogenic cyst". Only reports in English and those containing histopathologically-confirmed NC were considered for this review. In total, 140 patients with intracranial NC were found, including the patient reported in the present review. This review describes the classification, epidemiology, embryology, clinical presentation, radiology, histopathology, and surgical treatment of NC, and includes an illustrative patient.

MRI safety: nephrogenic systemic fibrosis and other risks.

Magnetic resonance imaging (MRI) is now a commonly used imaging modality in many neurosurgical and neurological conditions. Although generally regarded as safe, there are a number of important safety considerations. These include a recently recognised, rare condition termed nephrogenic systemic fibrosis (NSF) that occurs in patients with significant renal impairment who receive gadolinium based contrast. Currently, NSF remains poorly understood and there is no universally effective treatment beyond the avoidance of contrast in patients with significant renal impairment. Other safety considerations include MRI contraindicated devices and the role of MRI in pregnancy.

Multiple cerebral metastases as a primary presentation in papillary thyroid carcinoma.

Cerebral metastases from papillary thyroid carcinoma are rare. They are aggressive tumours associated with a poor prognosis. We report a patient presenting with multiple cerebral metastases as the primary presentation of her disseminated disease. These metastases were treated with surgical resection followed by external beam radiotherapy and radioactive iodine therapy. We suggest that early diagnosis and treatment of cerebral metastases of papillary thyroid carcinoma can result in good outcomes.

Combined modality treatment of newly diagnosed glioblastoma multiforme in a regional neurosurgical centre.

The "local experience" of the Stupp protocol was examined in the treatment of patients with newly diagnosed glioblastoma multiforme (GBM) with particular emphasis given to the extent of surgical resection and its effect on survival. Thirty-one patients with newly diagnosed GBM who underwent combined modality treatment according to the Stupp protocol were assessed retrospectively. Variables assessed were the extent of surgery, size and site of the tumour, age and performance status. Primary end points were overall survival (OS) and progression-free survival (PFS). Median OS was 33 months for macroscopic tumour resection (9 patients; 29%), 15 months for debulking (15; 48%) and 9 months for biopsy (7; 22%). Macroscopic tumour resection resulted in significantly improved OS and PFS compared to the two less radical surgical options (p<0.001). Patients with GBM undergoing maximal resection of the tumour followed by adjuvant radiotherapy and chemotherapy have an improved survival compared to patients undergoing either subtotal resection or biopsy alone. This statistically significant survival benefit was achieved in a regional neurosurgical centre with minimal additional toxicity.