Micro-balloon-assisted embolization of anterior cranial fossa dural arteriovenous fistula via a trans-ophthalmic approach - a technical report and case series.

PURPOSE: Dural arteriovenous fistulas (dAVF) account for approximately 10-15% of all intracranial arteriovenous abnormalities. dAVFs carry a significant risk of mortality, particularly in cases of acute hemorrhage, of up to 10%. A small proportion of these dAVFs are found in the anterior cranial fossa (ACF), of which the rate of hemorrhage can be as high as up to 91%. The Scepter Mini (SM) is the smallest dual-lumen micro-balloon (MB) available for neurointerventional practice. It consists of a 2.8 French outer diameter, with a 2.2 mm × 9 mm semi-compliant balloon providing a working length of 165 cm. The SM is navigated with a 0.008-inch wire making it a particularly attractive tool accessible to the pedicles normally reached with liquid embolization micro-catheters. METHODS: Five consecutive patients over a 1-year period between 2020 and 2021 were evaluated and treated for ACF dAVF using a liquid embolization approach using the SM balloon. All patients were treated using ethylene-vinyl alcohol copolymer (EVOH), of which Squid 18 and/or Squid 12 were the chosen viscosities. Control angiograms were performed for all patients post-embolization. RESULTS: All patients demonstrated complete occlusion of the ACF dAVF on immediate post-treatment angiography. No immediate complications were encountered; particularly, there were no reports of visual field deficit in any of the patients. CONCLUSION: The MB is a valuable adjunctive tool that can enhance the safety and efficacy of trans-ophthalmic embolization of ACF dAVFs, providing additional protection to the retinal and posterior ciliary arteries against unwanted reflux of liquid embolic agent.

Transarterial CT angiography for surgical planning of spinal dural arteriovenous fistula.

OBJECTIVE: We report a novel method to provide excellent anatomical depiction of a dural arteriovenous fistula (dAVF) for surgical planning. METHODS: A 78-year-old female presented with progressive back pain, deteriorating mobility and urinary incontinence with a background of obesity and severe osteoarthritis. Initial MRI suspected dAVF and subsequent spinal angiography encountered an extremely tortuous and arteriosclerotic aorta, hence catheterisation of the segmental-intercostal and lumbar vessels proved challenging. Contrast injection into the aortic arch via a pigtail catheter for arterial-phase CT angiogram of the descending aorta was performed. RESULTS: This modality of imaging delineated the dAVF showing extensive involvement of the whole spine accounting for the patient's symptoms. Furthermore this allowed characterisation of bony anatomy in relation to the fistula facilitating precise surgical approach. The dAVF was successfully disconnected through a localised laminectomy centred over the lesion. CONCLUSION: This specific technique for dAVF characterisation has not been previously reported, although trans-venous angiography has been used to some effect. In view of diagnostic and therapeutic technical difficulties that are often faced in such patients, this technique may be a useful alternative that is not only helpful in accurate diagnosis but helps in providing an invaluable guide for the surgical approach. ADVANCES IN KNOWLEDGE: This case highlights the difficulties that one may be faced within cases of tortuous vasculature and the obese patient population. With this in mind we demonstrate how a unique hybridised technique may provide valuable alternative to the neurosciences team should such a future scenario arise.

Mechanical thrombectomy for acute stroke in pregnancy.

Several recent randomised control trials have shown adjunctive endovascular mechanical thrombectomy to be an effective and safe treatment for acute stroke superior to medical therapy alone. Despite this, questions remain over certain groups of patients that have been excluded from these studies, such as pregnant women. We believe this is a topic of increasing clinical significance with minimal data in the literature. In this article we discuss stroke in pregnancy and highlight the important technical considerations of endovascular mechanical thrombectomy, including minimising radiation exposure to the mother and fetus.

A computational model for prediction of clot platelet content in flow-diverted intracranial aneurysms.

Treatment of intracranial aneurysms with flow-diverting stents is a safe and minimally invasive technique. The goal is stable embolisation that facilitates stent endothelialisation, and elimination of the aneurysm. However, it is not fully understood why some aneurysms fail to develop a stable clot even with sufficient levels of flow reduction. Computational prediction of thrombus formation dynamics can help predict the post-operative response in such challenging cases. In this work, we propose a new model of thrombus formation and platelet dynamics inside intracranial aneurysms. Our novel contribution combines platelet activation and transport with fibrin generation, which is key to characterising stable and unstable thrombus. The model is based on two types of thrombus inside aneurysms: red thrombus (fibrin- and erythrocyte-rich) can be found in unstable clots, while white thrombus (fibrin- and platelet-rich) can be found in stable clots. The thrombus generation model is coupled to a CFD model and the flow-induced platelet index (FiPi) is defined as a quantitative measure of clot stability. Our model is validated against an in vitro phantom study of two flow-diverting stents with different sizing. We demonstrate that our model accurately predicts the lower thrombus stability in the oversized stent scenario. This opens possibilities for using computational simulations to improve endovascular treatment planning and reduce adverse events, such as delayed haemorrhage of flow-diverted aneurysms.

Foetal radiation exposure caused by mechanical thrombectomy in large-vessel ischaemic stroke in pregnancy.

PURPOSE: There is overwhelming evidence for the clinical benefits that are derived following mechanical thrombectomy in large-vessel acute ischaemic stroke. The risk of stroke is elevated in pregnancy due to many factors. To date, there have been two reports, totalling five patients, who have undergone mechanical thrombectomy in pregnancy, thus demonstrating the feasibility of the procedure; however, there is no data on the radiation exposure to the mother or foetus related to this therapy. METHODS: We highlight the important technical considerations to minimise the risk of the procedure and report the estimated dose received by mother and foetus. We also compare these doses with those received during whole-body CT in trauma and CT pulmonary angiogram (CTPA) examinations. RESULTS: Three cases of mechanical thrombectomy were performed at separate tertiary referral neuroscience centres in the UK. Following diagnostic CT and mechanical thrombectomy, the total whole-body effective dose to the pregnant patient was significantly higher than in patients undergoing CTPA (p < 0.05), but not significant different compared to whole-body CT imaging in trauma patients. The estimated dose received by the foetus following diagnostic CT and mechanical thrombectomy was significantly lower than in whole-body imaging in trauma patients at p < 0.05, with no difference in estimated foetal dose compared to CTPA imaging. CONCLUSION: The estimated doses received by the foetus during diagnostic stroke imaging and mechanical thrombectomy are equivalent to, or less than, purely diagnostic imaging in emergency situations.

Delayed Hemorrhage from an Iatrogenic Vertebral Artery Injury During Anterior Cervical Discectomy and Successful Endovascular Treatment-Report of a Rare Case and Literature Review.

BACKGROUND: Anterior cervical discectomy (ACD) is one of the most common spinal surgeries. Although rare, iatrogenic vertebral artery injuries (VAIs) are potentially life-threatening. Risk factors are anatomic, operative, and pathologic. We report a rare case of iatrogenic VAI during ACD and successful endovascular treatment with no long-term complications. We also review the literature on all VAIs associated with ACD and fusions. Risk factors and the safety and effectiveness of various management modalities are discussed. CASE DESCRIPTION: A 64-year-old patient sustained iatrogenic right VAI during ACD, followed by the delayed formation of a vertebral artery pseudoaneurysm and subsequent rehemorrhage. The patient recovered well with no long-term neurologic sequelae. This case is unusual because the pseudoaneurysm was not apparent on early computed tomography angiography. There is currently no consensus regarding the appropriate intraoperative management for iatrogenic VAIs. Described treatment modalities include direct repair, tamponade, and endovascular procedures. CONCLUSIONS: Delayed pseudoaneurysm formation after iatrogenic VAI can occur. Endovascular embolization can be a safe treatment alternative to surgical repair.

Magnetic Resonance investigation into the mechanisms involved in the development of high-altitude cerebral edema.

Rapid ascent to high altitude commonly results in acute mountain sickness, and on occasion potentially fatal high-altitude cerebral edema. The exact pathophysiological mechanisms behind these syndromes remain to be determined. We report a study in which 12 subjects were exposed to a FiO2 = 0.12 for 22 h and underwent serial magnetic resonance imaging sequences to enable measurement of middle cerebral artery velocity, flow and diameter, and brain parenchymal, cerebrospinal fluid and cerebral venous volumes. Ten subjects completed 22 h and most developed symptoms of acute mountain sickness (mean Lake Louise Score 5.4; p < 0.001 vs. baseline). Cerebral oxygen delivery was maintained by an increase in middle cerebral artery velocity and diameter (first 6 h). There appeared to be venocompression at the level of the small, deep cerebral veins (116 cm3 at 2 h to 97 cm3 at 22 h; p < 0.05). Brain white matter volume increased over the 22-h period (574 ml to 587 ml; p < 0.001) and correlated with cumulative Lake Louise scores at 22 h (p < 0.05). We conclude that cerebral oxygen delivery was maintained by increased arterial inflow and this preceded the development of cerebral edema. Venous outflow restriction appeared to play a contributory role in the formation of cerebral edema, a novel feature that has not been observed previously.

Double trouble: a tale of two radio-treatments.

In recent years, an increasing number of patients are treated with radiation. In the early era of radiotherapy, which began soon after X-rays were discovered by Roentgen in 1895, tumours were irradiated with high doses of X-rays in a single fraction. The major initial setback was the damage caused to normal tissues; however, in recent times the use of stereotactic radiosurgery, which delivers high doses of radiation precisely to abnormal tissue targets while sparing the surrounding normal brain tissue, and particularly for surgically inaccessible tumours, has taken centre stage. Prophylactic whole brain radiation (in conjunction with aggressive chemotherapy) for childhood acute lymphoblastic leukaemia has been shown to improve patient survival, however, this is associated with complications in survivors. We report an interesting case of one of the longest survivors who has had double complications from radiotherapy-based interventions.

C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology.

INTRODUCTION: Flat detector computed tomography (FDCT) is an imaging tool that generates three-dimensional (3-D) volumes from data obtained during C-arm rotation using CT-like reconstruction algorithms. The technique is relatively new and, at current levels of performance, lags behind conventional CT in terms of image quality. However, the advantage of its availability in the interventional room has prompted neuro-radiologists to identify clinical settings where its role is uniquely beneficial. METHODS: We performed a search of the online literature databases to identify studies reporting experience with FDCT in interventional neuro-radiology. The studies were systematically reviewed and their findings grouped according to specific clinical situation addressed. RESULTS: FDCT images allow detection of procedural complications, evaluation of low-radiopacity stents and assessment of endosaccular coil packing in intra-cranial aneurysms. Additional roles are 3-D angiography that provides an accurate depiction of vessel morphology with low concentrations of radiographic contrast media and a potential for perfusion imaging due to its dynamic scanning capability. A single scan combining soft tissue and angiographic examinations reduces radiation dose and examination time. Ongoing developments in flat detector technology and reconstruction algorithms are expected to further enhance its performance and increase this range of applications. CONCLUSION: FDCT images provide useful information in neuro-interventional setting. If current research confirms its potential for assessing cerebral haemodynamics by perfusion scanning, the combination would redefine it as an invaluable tool for interventional neuro-radiology procedures. This facility and its existing capabilities of parenchymal and angiographic imaging would also extend its use to the triage of acute stroke patients.