Adam S. Reig

Endovascular treatment of side wall aneurysms using a liquid embolic agent: a US single-center prospective trial.

OBJECTIVEOnyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms. CLINICAL PRESENTATIONWe present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths. CONCLUSIONThis is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

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.

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.

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 T2-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.

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.

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.

Five-level sub-axial cervical vertebrectomy and reconstruction: technical report

PurposeRegardless of the etiology, severe cervical deformities can be extremely debilitating and are a challenge to correct. Often a multi-modality team approach is required to safely and effectively reduce the deformity, provide adequate decompression, and ensure solid fixation and fusion. In cases of iatrogenic cervical deformity necessitating five-level corpectomy and fixation, the feasibility, safety, and durability of this procedure remains unknown.ResultsWe describe a patient who presented with debilitating pain and inability to eat due to an iatrogenic chin-on-chest cervical kyphotic deformity. The patient underwent a back–front–back staged procedure requiring five-level cervical vertebrectomy, C3–T1 anterior fixation, and occipital to T5 posterior fusion, resulting in successful reduction of cervical kyphosis from 75 to 0 degrees. At 6 months post-operatively, the patient demonstrated marked improvement in neurologic function and reported substantial improvements in neck pain-specific disability (NDI) and quality of life (SF-12 and EQ-5D).ConclusionThe feasibility and safety of five-level vertebrectomy and reconstruction for chin-on-chest deformity remains poorly described. The current case suggests that thoughtful planning that involves maximizing the patient’s health status, judicious use of traction under direct neurological examination, staged circumferential release, and design of a construct that provides anterior and posterior column support with several points of fixation beyond the axis of rotation will attenuate the risk of peri-operative morbidity and potentiate the durability of deformity correction.