The adherends notching technique has been the subject of a few recent studies and consists of tailoring the geometry of the adjoined layers to mitigate the bondline peak stresses and enhance the joint strength. In the present study, we explored the effect of the adherends notching technique on crack propagation using finite element (FE) simulations based on the cohesive zone model (CZM) of fracture. Double cantilever beam (DCB) adhesive joints subjected to quasistatic loading were considered as a model material system. An array of equally spaced notches was placed on the faying sides of the adherends, oriented perpendicularly to the direction of crack growth. A parametric investigation was carried out to ascertain the role of the notches and the input cohesive properties on various performance metrics, e.g., load-displacement response and dissipated energy. The proposed notching strategy promotes an unstable crack pinning/depinning process, which effectively delays crack growth and increases the effective work of fracture. Additionally, we found that the overall behaviour is tunable by changing geometric (i.e., notch spacing and depth) and bondline material properties.
Flow diverters have become a safe and well-accepted treatment option for intracranial aneurysms of most sizes in the anterior and posterior circulation. Surpass Evolve (SE, Stryker Neurovascular, Kalamazoo, Michigan, USA) is a new flow diverter that is available in large diameters (2.5–5 mm) and long lengths (12–40 mm), with high radial force and a high in-vitro flow diverting effect irrespective of the parent vessel tortuosity. This is secondary to a consistency in mesh density (15–30 pores/mm2) and a high number of wires (48–64, depending on the device length). SE can be deployed through an 0.027' microcatheter, allowing easy navigation within tortuous anatomies. We describe device characteristics and mid-term results in the first patients treated with the SE for intracranial aneurysms.
Materials and Methods
We included in this report all patients that underwent aneurysm embolization with the SE at two different institutions. Patients' data was prospectively collected in two databases and reviewed retrospectively. We included adult patients harboring non-ruptured saccular or fusiform intracranial aneurysms with a wide neck (>4 mm) located in the anterior or posterior circulation. Standard dual anti-platelet therapy was started 5 days pre-procedure and continued for at least 6 months. Neurological complications were classified as intra-procedural, early or delayed if they arose within 1, 30 or more than 30 days from treatment, respectively. Neurological complications were considered minor and major if resulting in transient or permanent neurological morbidity, respectively. Clinical status at discharge and follow up was assessed by independent neurologists or neurosurgeons and imaging included MRI angiography (MRA), CT angiography (CTA) and DSA, depending on the institution.
Results
The study included 28 patients (23 females, 82%; age range: 36–86, median age: 56) treated between April and November 2019, harboring 29 aneurysms. Twenty-eight aneurysms were saccular and in the anterior circulation. The majority of aneurysms were <12 mm in diameter (18/29, 62%), 8/29 (28%) were large (<25 mm), 2/29 (7%) were giant (>25 mm) and one was fusiform and partially thrombosed (3%). The SE was delivered in all cases via a tri-axial approach with an intermediate catheter and a 0.027' microcatheter for implant delivery. This low-profile catheter allowed delivery of the implant through the trans-radial route. Thirty-two implants were used (4 in the patient with the fusiform aneurysm) with an average of 1.1 stents/patient. There were no intra-procedural complications. Median clinical and imaging follow up time was 6 months (range: 2–6 months). There were no deaths. Three patients (3/28, 11%) had early minor neurological complications. There was one (4%) early major neurological complication in a patient with a hemispheric stroke on post-op day 4. Two patients had minor delayed neurological complications (2/28, 7%). Complete thrombosis was seen in 16/29 aneurysms (55%, most of those imaged at 6 months), while partial thrombosis was seen in 12/29 aneurysms (41%). Covered side branches were patent in all patient but the one who experienced the stroke.
Conclusion
The SE shows excellent navigability while keeping a high flow-diverting effect. Mid-term clinico-radiological results show good efficacy and acceptable safety of the implant.
Disclosures
E. Orru: None. H. Rice: 2; C; Medtronic, Stryker, Philips, Penumbra, Microvention. L. De Villiers: None. A. Wakhloo: 1; C; Philips. 2; C; Stryker, Phenox. 3; C; SCENT trial. 4; C; InNeuroCo, EpiEP, Neural Analytics, Rist, Analytics 4 Life, ThrombX. G. Song Chia: None. A. Qureshi: None. T. Krings: 2; C; Stryker, Medtronic, Penumbra. 4; C; Marblehead Inc. V. Pereira: 1; C; Philips Healthcare. 2; C; Stryker, Balt, Cerenovous, Medtronic.
This is the eighth case report of a pediatric dissecting posterior inferior cerebellar artery aneurysm. The authors present the case of a 13-year-old boy who presented with posttraumatic posterior fossa subdural, subarachnoid, and intraventricular hemorrhage with hydrocephalus. Initial vascular imaging findings were negative; however, a high level of suspicion is necessary. The aneurysm was identified on day 20, after recurrence of hydrocephalus, and was treated with endovascular vessel sacrifice. The patient made a good recovery. It is important to consider arterial dissection in pediatric traumatic brain injury, especially with suspicious findings on initial CT scan and clinical presentation out of proportion to the mechanism of injury. Delayed vascular imaging is imperative for appropriate management.
Renal pelvis contrast opacification (RPO) in CT myelography has been proposed as a specific sign of CSF leak in spontaneous intracranial hypotension (SIH). However, published studies have been limited in size and differences in prevalence of this sign in distinct CSF leak aetiologies remain of uncertain significance.
Aim of Study
This study aimed to re-evaluate the significance of RPO in SIH, and investigate any correlation between RPO, time from contrast administration to identification of RPO, and aetiology of CSF leak.
Methods
All CT myelography during a 4 year period at a single neuroscience centre was investigated. Time of intrathecal contrast injection, time of first evidence of RPO, contemporaneous renal function, and aetiology of CSF leak (if identified) were recorded and analysed.
Results
169 studies were included. 26 studies were for non-SIH indications – none demonstrated RPO. 46/143 SIH studies were positive for RPO: 52% were dural CSF leaks and 39% were CSF-venous fistulae. The remaining 9% had no aetiology identified but either had confirmed low intracranial pressure or responded to treatment. In the 97 RPO negative SIH studies, 54% had no CSF leak aetiology identified. 41% were dural leaks and only 5% were CSF-venous fistulae. No significant correlation between time of first evidence of RPO and CSF leak aetiology was identified.
Conclusion
This study confirms renal pelvis opacification is a highly specific marker of CSF leak with a 100% positive predictive value for SIH. The findings suggest the sign is more sensitive for CSF-venous fistulae than dural CSF leaks.
Hemorrhage from brain arteriovenous malformations (bAVMs) is estimated at 3% per annum. Features influencing risk of hemorrhage include perforator/posterior circulation supply, associated aneurysms, and deep drainage. Children are more likely to present with bAVM bleeds.To analyze differences in bAVM angioarchitecture between children and adults and describe predictors of poor outcome.Data were collected from adult and pediatric tertiary referral hospitals. Demographic data, bleed location, treatment, and follow-up modified Rankin Scale (mRS) were collected. Angioarchitectural assessment included aneurysm presence, nidus morphology, perinidal angiogenesis, intranidal shunting, steal phenomenon, venous ectasia, venous stenosis, venous reflux, and pseudophlebitic pattern. Regression analyses conducted to determine predictors of mRS > 2.A total of 270 adult and 135 pediatric ruptured bAVMs were assessed. Median age was 42 (adults) and 10.9 (children) yr. Intranidal aneurysms were more frequent in children (P = .012), whereas prenidal aneurysms were more common in adults (P < .01). Children demonstrated more perinidal angiogenesis (P = .04), whereas steal phenomenon was commoner in adults (P < .01). Venous ectasia (P < .01), reflux (P < .01), and pseudophlebitic pattern (P = .012) were more frequent in adults. Children had better outcome (mRS score ≤ 2) (P < .01). Older age (odds ratio [OR] = 1.02), eloquent location (OR = 2.5), multicompartmental hemorrhage (OR = 1.98), venous reflux (OR = 2.5), diffuse nidus (OR = 1.83), pseudophlebitic pattern (OR = 1.96), intranidal shunts (OR = 2), and no treatment (OR = 3.68) were significant predictors of mRS > 2.Children are more likely to have intranidal aneurysms and perinidal angiogenesis, whereas adults have more prenidal aneurysms, venous ectasia, corticovenous reflux, and pseudophlebitic pattern. Eloquent location, diffuse nidus, intranidal shunts, venous reflux, and pseudophlebitic pattern predict poorer outcome.
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