Biomechanical attributes of microcatheters used in liquid embolization of intracranial aneurysms.

OBJECTIVE: A steel-reinforced and a nitanol-reinforced microcatheter are both approved for use with Onyx HD-500 embolization of intracranial aneurysms. The biomechanical behavior of these catheters when used with high viscosity embolic liquids is poorly understood. We performed biomechanical laboratory testing and examined our clinical experience to identify situations where one catheter might have an advantage over the other. METHODS: The catheters were tested for detachment force from aneurysm cast, burst pressure, burst location, and pressure under dynamic delivery pressure. The results were compared using ANOVA. RESULTS: The average detachment forces for the Echelon 10, 14, and Rebar 14 catheters were 97.6, 76.825, and 62.6 g, respectively (p=0.023). The average burst pressures for the Echelon 10, 14, and Rebar 14 were 1108, 1213, and 1365 psi, respectively (p=0.003). The average burst location was 26.0, 20.0, and 4.5 mm, respectively, from the tip (p=0.035). There was no significant difference regarding burst location (p=0.39). The delivery pressures of the catheters were not significant (p=0.98). Two cases are presented that illustrate the importance of these findings and how they can be incorporated into practice. CONCLUSION: The lower detachment force of the Rebar 14 makes it ideal for liquid embolization, but its stiffness makes it less desirable for accessing smaller aneurysms or navigating tortuous anatomy. The Echelon 10 should be avoided unless it is the only catheter that can access an aneurysm because of small size or tortuous anatomy. In such cases, the higher detachment force suggests a stent should be in place to prevent the cast from being destabilized.

Findings on preoperative brain MRI predict histopathology in children with cerebellar neoplasms.

BACKGROUND/AIMS: The majority of pediatric patients with cerebellar neoplasms harbor pilocytic astrocytomas (PAs), medulloblastomas, or ependymomas. Knowledge of a preoperative likelihood of histopathology in this group of patients has the potential to influence many aspects of care. Previous studies have demonstrated hyperintensity on diffusion-weighted imaging to correlate with medulloblastomas. Recently, measurement of T(2)-weighted signal intensity (T2SI) was shown to be useful in identification of low-grade cerebellar neoplasms. The goal of this study was to assess whether objective findings on these MRI sequences reliably correlated with the underlying histopathology. METHODS: We reviewed the radiologic findings of 50 pediatric patients who underwent resection of a cerebellar neoplasm since 2003 at our institution. Region of interest placement was used to calculate the relative diffusion-weighted signal intensity (rDWSI) and relative T2SI (rT2SI) of each neoplasm. RESULTS: Tukey's multiple comparison test demonstrated medulloblastomas to have significantly higher rDWSIs than PAs/ependymomas, and PAs to have significantly higher rT2SIs than medulloblastomas/ependymomas. A simple method consisting of sequential measurement of rDWSI and rT2SI to predict histopathology was then constructed. Using this method, 39 of 50 (78%) tumors were accurately predicted. CONCLUSION: Measurement of rDWSI and rT2SI using standard MRI of the brain can be used to predict histopathology with favorable accuracy in pediatric patients with cerebellar tumors.

Eight-year follow-up after palliative embolization of a neonatal intracranial dural arteriovenous fistula with high-output heart failure: management strategies for symptomatic fistula growth and bilateral femoral occlusions in pediatric patients.

The authors report the 8-year follow-up of a patient previously described in the literature who originally presented in high-output cardiac failure secondary to a complex neonatal intracranial dural arteriovenous fistula (DAVF). The earlier case report described palliative treatment with a combination of extracorporeal membrane oxygenation (ECMO) and endovascular embolization for life-threatening high-output cardiac failure secondary to a DAVF. Access was obtained using the ECMO cannula, and embolization was performed while the patient was connected to the ECMO machine. The patient made an excellent recovery following partial embolization of the fistula, but then presented again 7 years later with worsening headaches secondary to significant growth of the known residual portion of the fistula identified on CT angiography. The child also developed bilateral femoral artery (FA) occlusions secondary to multiple previous FA punctures. To achieve complete obliteration of the remaining fistula, the patient required a retroperitoneal approach to the iliac artery and percutaneous puncture of the internal jugular vein. Embolization was performed with a combination of platinum coils and ethylene vinyl alcohol copolymer liquid embolic agent. There were no complications, and the child remains neurologically normal, with no signs of permanent cardiovascular sequelae. In this case report, the authors discuss the long-term management of AVFs treated by endovascular strategies early in life. After neonatal access, sometimes the FAs occlude, requiring more invasive access strategies. The authors also discuss the follow-up method, intervals, and threshold for further treatment for these lesions, and present a review of the literature.

Intracranial hypertension caused by a depressed skull fracture resulting in superior sagittal sinus thrombosis in a pediatric patient: treatment with ventriculoperitoneal shunt insertion.

OBJECT: Intracranial hypertension resulting from compression of the superior sagittal sinus (SSS) by an overlying depressed calvarial fracture is a rare condition. Primary surgical treatment for the symptomatic patient in this setting traditionally involves elevation of the fracture, which often carries significant associated morbidity. METHODS: The authors report a case involving a 6-year-old boy who suffered a closed, depressed, parietooccipital fracture as the result of an unhelmeted all-terrain vehicle accident. This fracture caused compression and subsequent thrombosis of the SSS, which resulted in CSF malabsorption and progressive intracranial hypertension. Initially headache free following the injury, he had developed severe and unremitting headaches by postinjury Day 7. A CT angiography study of the head obtained at this time exhibited thrombosis of the SSS underlying the depressed calvarial fracture. Subsequent lumbar puncture demonstrated markedly elevated intrathecal pressures. Large volumes of CSF were removed, with temporary improvement in symptoms. After medical management with anticoagulation failed, the decision was made to proceed with image-guided ventriculoperitoneal shunt insertion. RESULTS: The patient's headaches resolved immediately following the procedure, and anticoagulation therapy was reinstituted. Follow-up images obtained 4 months after the injury demonstrated evidence of resolution of the depressed fracture, with recanalization of the SSS. The anticoagulation therapy was then discontinued. To the authors' knowledge, this report is the first description of ventriculoperitoneal shunt insertion as the primary treatment of this infrequent condition. CONCLUSIONS: This report demonstrates that select patients with this presentation can undergo CSF diversion in lieu of elevation of the depressed skull fracture-a surgical procedure shown to be associated with increased risks when the depressed fracture overlies the posterior SSS. The literature on this topic is reviewed and management of this condition is discussed.

CT-based, fiducial-free frameless stereotaxy for difficult ventriculoperitoneal shunt insertion: experience in 26 consecutive patients.

BACKGROUND: Patients with small or dysmorphic ventricles requiring ventriculoperitoneal shunt (VPS) insertion for hydrocephalus can be challenging. The 'freehand' technique does not always provide for accurate catheter insertion, particularly in patients with slit ventricles, complex hydrocephalus or displaced ventricles. Consequently, many surgeons use stereotaxy for assistance. We have employed a frameless stereotactic technique, obviating the need for fiducials or preoperative MRI, for difficult ventricular catheter placement over the past 1.5 years with excellent results. We describe our experience with frameless stereotactic VPS insertion. METHODS: We retrospectively reviewed the charts of 26 patients who underwent frameless stereotactic VPS insertion. All patients had preoperative CT scans using a navigation protocol and were registered into the Stealth Station via the face tracer program. Catheters were inserted using the Medtronic frameless trajectory guide kit. We recorded demographic data, operative time, complications and follow-up. RESULTS: The mean patient age was 31 years. The average operative time was 46 min. There were 3 complications. The average follow-up was 5 months. Twenty-one patients had postoperative imaging, with 20 having excellent catheter positioning. CONCLUSIONS: Our results confirm that frameless stereotactic VPS without fiducial marker placement is a feasible technique for catheter insertion in patients who have small/dysmorphic ventricles. In experienced hands, there is negligible added operative time and a low complication rate.

Relative cost comparison of embolic materials used for treatment of wide-necked intracranial aneurysms.

INTRODUCTION: Embolization of wide-necked intracranial aneurysms can be associated with excessive expense, especially for large/giant aneurysms. Depending on the material used, endovascular treatment may be cost prohibitive. The goal of this study was to evaluate the relative cost of various embolic agents. METHODS: Utilizing software available at http://www.angiocalc.com, theoretical aneurysm volumes were calculated using aneurysm diameters ranging from 3 to 25 mm increasing in 1 mm increments. For each volume, the software calculated the length of coil needed to fill each size of aneurysm to a consistent, standardized and desirable packing density (25% coil:aneurysm volume). Each theoretical aneurysm was embolized by filling volume in a consistent, standardized, step-wise fashion. The cost of liquid embolics was calculated by adding the cost of 1.5 ml vials of Onyx HD 500 required to fill each volume. The embolic agents were then grouped into seven categories depending on the coil type and the cost of each aneurysm size was averaged. RESULTS: The average embolization with small outer diameter (0.010 inches) helical coils ranged between $714 for a 3 mm aneurysm to $113,009 for a 25 mm aneurysm, and between $2855 and $157,245 for small diameter spherical coils. Large outer diameter (>0.010 inches) helical coils cost between $2195 and $34,034 and large diameter spherical coils cost between $2195 and $86,957. Bioactive coils ranged between $1984 and $172,179, liquid embolic $5950 and $35,700, and hydrocoils $1295 and $32,873. CONCLUSIONS: Larger outer diameter helical coils, hydrocoils and liquid embolics provide a relative cost savings compared with standard, spherical or bioactive coils when aneurysm size, shape, packing density and embolic agent were controlled and standardized. This cost differential increases as the size of the aneurysm increases.

Complete angiographic obliteration of intracranial AVMs with endovascular embolization: incomplete embolic nidal opacification is associated with AVM recurrence.

BACKGROUND: Embolization of intracranial arteriovenous malformations (AVMs) is generally a preoperative adjunctive procedure in the USA. However, sometimes embolization can result in complete angiographic obliteration of the AVM. There is significant controversy regarding the best management strategy for this subset of patients. There is a scarcity of literature predicting which embolized, angiographically obliterated AVMs are likely to recur and which ones are cured. We present our series of patients with complete obliteration of their AVMs from embolization. METHODS: A prospectively maintained database identified 122 patients who underwent embolization of an intracerebral pial AVM with liquid embolics. Eighteen patients (15%) achieved complete angiographic obliteration of the AVM with embolization. We followed several parameters to assess possible predictors of recurrence. RESULTS: Fifteen of 18 patients (83%) had angiographic/anatomical follow-up to assess for AVM recurrence and 3 (17%) refused angiographic follow-up. Three patients underwent surgical resection with intraoperative angiography despite complete AVM obliteration with embolization alone. Thirteen of the 15 (87%) patients with follow-up remained obliterated at time of follow-up, and all of these patients had an embolic cast that had a similar morphology to the AVM nidus. Two of 15 patients (13%) had AVM recurrence, both of whom had incomplete embolic nidal opacification (proximal pedicle embolization). CONCLUSIONS: A minority of intracranial AVMs can be safely obliterated with stand-alone embolization. Proximal occlusion of feeding arteries appears to be associated with recurrence. Prospective studies with longer follow-up and larger patient numbers are necessary.

Embolization of a giant pediatric, posttraumatic, skull base internal carotid artery aneurysm with a liquid embolic agent.

Many treatments for posttraumatic, skull base aneurysms have been described. Eight months after an all-terrain-vehicle accident, this 12-year-old girl presented with right-side Horner syndrome caused by a 33 x 19-mm internal carotid artery aneurysm at the C-1 level. We chose to treat the aneurysm with a new liquid embolic agent for wide-necked, side-wall aneurysms (Onyx HD 500). We felt this treatment would result in less morbidity than surgery and was less likely to occlude the parent artery than placement of a covered stent, especially in a smaller artery in a pediatric patient. Liquid embolic agents also appear to be associated with a lower chance of recanalization and lower cost compared with stent-assisted coil embolization. After the patient was treated with loading doses of aspirin, clopidogrel bisulfate, and heparin, 99% of the aneurysm was embolized with 9 cc of the liquid embolic agent. There were no complications, and the patient remained neurologically stable. Follow-up angiography revealed durable aneurysm occlusion after 1 year. The cost of Onyx was less than the cost of coils required for coil embolization of similarly sized intracranial aneurysms at our institution. Liquid embolic agents can provide a safe, efficacious, and cost-effective approach to treatment of select giant, posttraumatic, skull base aneurysms in pediatric patients.

Endovascular surgery for proximal posterior inferior cerebellar artery aneurysms: an analysis of Glasgow Outcome Score by Hunt-Hess grades.

OBJECTIVE: Proximal posterior inferior cerebellar artery (PICA) aneurysms represent a subset of posterior circulation aneurysms that can be routinely treated with either clipping or coiling. The literature contains limited numbers of patients with proximal PICA aneurysms treated with endovascular surgery. We report our experience with endovascular surgery of proximal PICA aneurysms with emphasis on patients with poor Hunt-Hess grades. METHODS: We reviewed 31 consecutive patients with proximal PICA aneurysms who were treated with endovascular surgery. The following data were analyzed: age, sex, size of aneurysm, Hunt-Hess grade at presentation, Fisher grade at presentation, angiographic result after embolization, complications, number of days hospitalized, duration of follow-up, angiographic follow-up results, and Glasgow Outcome Score at follow-up. RESULTS: Excellent angiographic occlusion was achieved in 30 of 31 (97%) patients. Clinical follow-up with Glasgow Outcome Score was performed on every patient an average of 10 months later. Twenty-one of 31 (68%) patients had good outcomes (Glasgow Outcome Score I or II) at follow-up. Of the patients who presented with a favorable clinical grade (Hunt-Hess 0-III), 13 of 15 (87%) had good outcomes at follow-up. Of the patients who presented with a poor clinical grade (Hunt-Hess Grade IV or higher), 8 of 16 (50%) had good outcomes at follow-up. CONCLUSION: This series demonstrates the safety and efficacy of endovascular surgery for proximal PICA aneurysms. Many patients with poor Hunt-Hess grades from ruptured PICA aneurysms ultimately had a good outcome. This could be secondary to early, aggressive treatment of hydrocephalus and the minimally invasive nature of the endovascular approach.

Extracorporeal membrane oxygenation combined with endovascular embolization for management of neonatal high-output cardiac failure secondary to intracranial arteriovenous fistula. Case report.

The authors describe a novel approach to the management of high-output heart failure secondary to an intracranial high-flow dural arteriovenous fistula (DAVF) by using extracorporeal membrane oxygenation (ECMO). To the best of the authors' knowledge, this represents the first report of an embolization performed in conjunction with the use of an ECMO circuit and the first report in which an ECMO cannula was used for intraarterial access for cerebral angiography. A 2-day-old girl presented with severe, high-output heart failure secondary to a high-flow intracranial DAVF. The patient was neurologically intact and no brain parenchymal abnormalities were revealed on computerized tomography scanning of the head, but she suffered severe heart failure, pulmonary hypertension, and liver and renal dysfunction. The patient underwent three endovascular embolization procedures involving coils and liquid embolic agents. Despite a decrease in the DAVF flow, the patient had only transient improvement in her pulmonary hypertension, and venoarterial ECMO therapy was instituted. Another embolization was performed while the patient was receiving ECMO therapy. Her cardiovascular status improved, she was weaned from ECMO, and she was eventually discharged home to her family. Extracorporeal membrane oxygenation can be used to sustain severely ill neonates with high-output heart failure secondary to intracranial AVFs. Embolization can be performed while the patient is receiving ECMO therapy.