Lee A. Tan

Thromboembolic complications with Pipeline Embolization Device placement: impact of procedure time, number of stents and pre-procedure P2Y12 reaction unit (PRU) value.

Background Thromboembolic events after Pipeline Embolization Device (PED) placement remain a feared complication among neuroendovascular surgeons. This study aimed to investigate potential risk factors for thromboembolic events in patients undergoing PED placement. Methods Medical records of patients who underwent PED placement from April 2011 to August 2013 were reviewed. Variables including pre-procedure P2Y12 reaction unit (PRU) value, procedure time, number of PEDs deployed and perioperative neurovascular complications were recorded. Multivariate analysis was performed to identify risk factors for perioperative thromboembolic complications. Results Seventy-four patients were identified. Six patients (8.1%) had changes in neurological status after PED placement including five (6.8%) thromboembolic complications and one (1.4%) delayed intracranial hemorrhage; 50.9% of patients had diffusion-weighted imaging (DWI) changes on post-procedural MRI. Longer procedure time (>116 min) and multiple PED placements (>1) were statistically significant risk factors for symptomatic thromboembolic events (p<0.01). A pre-procedural PRU value >208 had an OR of 11.32 (95% CI 0.06 to 212.57) for symptomatic thromboembolic complications, but the result was not statistically significant. Conclusions DWI changes on MRI occurred at a much higher rate than new neurological symptoms following PED placement. Longer procedure time and multiple PED deployment are associated with higher risks of new neurological changes due to thromboembolic events. There was a trend for an increased risk of a symptomatic thromboembolic event in patients with pre-procedural PRU values >208. Reloading (clopidogrel 600 mg) patients with preoperative PRU >208 was safe and may have a protective effect on thromboembolic events.

The Pipeline Embolization Device for the treatment of posterior circulation fusiform aneurysms: lessons learned at a single institution

OBJECT Vertebrobasilar fusiform aneurysms (VFAs) are rare lesions characterized by abnormal dilation and tortuosity of the vertebral and/or basilar arteries. Untreated, these aneurysms have a tendency to progress, often resulting in neurological symptoms or rupture leading to subarachnoid hemorrhage. The microsurgical treatment of these lesions can be difficult due to their location and the circumferential involvement of the arteries. These features make microsurgical treatment prone to high morbidity. The Pipeline Embolization Device (PED) has gained popularity for the treatment of aneurysms of the internal carotid artery. Its use in the posterior circulation has been limited, likely due to a fear of perforating artery occlusion. METHODS The authors retrospectively reviewed their database of patients treated with the PED and identified 12 patients who had VFAs. The clinical features, complications, and outcomes of these patients were analyzed. RESULTS At an average follow-up of 11 months, the mean modified Rankin Scale score was 1.9. Complete aneurysm occlusion was seen in 90% of the patients with radiographic follow-up. Three patients suffered new neurological deficits postoperatively. One of these patients died, while the remaining 2 demonstrated significant clinical improvement at follow-up. CONCLUSIONS With attention to the anatomy of perforating arteries, staged contralateral vertebral artery sacrifice, and adequate platelet inhibition, PED may be an effective treatment option-alone or in a hybrid construct with stents of less coverage for VFAs-with an acceptable complication rate.

Infection with spinal instrumentation: Review of pathogenesis, diagnosis, prevention, and management.

Background: Instrumentation has become an integral component in the management of various spinal pathologies. The rate of infection varies from 2% to 20% of all instrumented spinal procedures. Every occurrence produces patient morbidity, which may adversely affect long-term outcome and increases health care costs. Methods: A comprehensive review of the literature from 1990 to 2012 was performed utilizing PubMed and several key words: Infection, spine, instrumentation, implant, management, and biofilms. Articles that provided a current review of the pathogenesis, diagnosis, prevention, and management of instrumented spinal infections over the years were reviewed. Results: There are multiple risk factors for postoperative spinal infections. Infections in the setting of instrumentation are more difficult to diagnose and treat due to biofilm. Infections may be early or delayed. C Reactive Protein (CRP) and Magnetic Resonance Imaging (MRI) are important diagnostic tools. Optimal results are obtained with surgical debridement followed by parenteral antibiotics. Removal or replacement of hardware should be considered in delayed infections. Conclusions: An improved understanding of the role of biofilm and the development of newer spinal implants has provided insight in the pathogenesis and management of infected spinal implants. This literature review highlights the mechanism, pathogenesis, prevention, and management of infection after spinal instrumentation. It is important to accurately identify and treat postoperative spinal infections. The treatment is often multimodal and prolonged.

Treatment of a Ruptured Vertebrobasilar Fusiform Aneurysm Using Pipeline Embolization Device

Treatment options of ruptured vertebrobasilar fusiform aneurysms (VFA) are limited and often carry significant mortality and morbidity. We report the use of Pipeline Embolization Device (PED) to successfully treat a patient with a ruptured vertebrobasilar fusiform aneurysm (VFA) who presented with subarachnoid hemorrhage (SAH). A 73 year-old man with a history of cardiac stent placement seven days earlier presented with Hunt-Hess II SAH. He was taking aspirin and clopidogrel. Computed tomography angiogram revealed a large vertebrobasilar fusiform aneurysm. Microsurgical treatment options are technically challenging and carry high risk. He underwent endovascular treatment of the ruptured VFA using overlapping PEDs. Five PEDs were placed in a telescoping fashion to reconstruct the affected portions of the left vertebral and basilar arteries. An additional 2-mm blister aneurysm in the right vertebral artery was also discovered during the conventional cerebral angiography and was treated with one additional PED. The patient remained neurologically intact after the procedure. He was continued on aspirin and clopidogrel. Follow-up magnetic resonance imaging at three months demonstrated patency of the stents without any evidence of ischemic change. Follow-up conventional cerebral angiogram at six months demonstrated thrombosis of the VFA and reconstruction of the vertebrobasilar system. The patient remained clinically well. An endovascular approach using PEDs can be a safe and effective treatment option for ruptured VFA in selected cases.

Complication analysis in nitinol stent-assisted embolization of 486 intracranial aneurysms.

OBJECT Stent-assisted embolization (SAE) has broadened the scope of endovascular cerebral aneurysm treatment. The risks associated with stent selection and configuration are poorly defined. In this study, the authors aimed to characterize the risk factors that contribute to complications in SAE of intracranial aneurysms. METHODS Over a 10-year period, a single surgeon treated 486 aneurysms with SAE in which open-cell Neuroform or closed-cell Enterprise stents were used. Single stents were used in 386 cases, overlapping stents were deployed in 80 cases, and Y-configuration stents were used in the remaining 20 cases. All neurological complications, which included transient deficits, were analyzed; disabling strokes and death were considered major complications. The chi-square test and multivariate logistic regression were used to evaluate the influence of aneurysm size and morphology, aneurysm location, stent selection, and stent configuration on complication rates. RESULTS There were 7 deaths (1.4%), 9 major strokes (1.9%), and 18 minor neurological complications (3.7%). For all complications, multivariate analysis revealed that large aneurysm size (10-25 mm; p = 0.01), giant aneurysm size (> 25 mm; p = 0.04), fusiform aneurysm morphology (p = 0.03), and using a Y-configuration stent (p = 0.048) were independent risk factors. For the major complications, independent risk factors included an aneurysm in the posterior circulation (p = 0.02), using an overlapping stent configuration (p = 0.03), and using a Y-configuration stent (p < 0.01). CONCLUSIONS In this series, SAE for cerebral aneurysm treatment carried an acceptable complication rate. With continued innovations in techniques and devices and with increased experience, the complication rates associated with SAE may be even lower in the future.

Effect of machined interfacet allograft spacers on cervical foraminal height and area

OBJECT Iatrogenic foraminal stenosis is a well-known complication in cervical spine surgery. Machined interfacet allograft spacers can provide a large surface area, which ensures solid support, and could potentially increase foraminal space. The authors tested the hypothesis that machined interfacet allograft spacers increase cervical foraminal height and area. METHODS The C4-5, C5-6, and C6-7 facets of 4 fresh adult cadavers were exposed, and the cartilage was removed from each facet using customized rasps. Machined allograft spacers were tamped into the joints. The spines were scanned with the O-arm surgical imaging system before and after placement of the spacers. Two individuals independently measured foraminal height and area on obliquely angled sagittal images. RESULTS Foraminal height and area were significantly greater following placement of the machined interfacet spacers at all levels. The Pearson correlation between the 2 radiographic reviewers was very strong (r = 0.971, p = 0.0001), as was the intraclass correlation coefficient (ICC = 0.907, p = 0.0001). The average increase in foraminal height was 1.38 mm. The average increase in foraminal area was 18.4% (0.097 cm(2)) [corrected]. CONCLUSIONS Modest distraction of the facets using machined interfacet allograft spacers can increase foraminal height and area and therefore indirectly decompress the exiting nerve roots. This technique can be useful in treating primary foraminal stenosis and also for preventing iatrogenic foraminal stenosis that may occur when the initially nonlordotic spine is placed into lordosis either with repositioning after central canal decompression or with correction using instrumentation. These grafts may be a useful adjunct to the surgical treatment of cervical spine disease.

Rapidly progressive quadriparesis heralding disseminated coccidioidomycosis in an immunocompetent patient.

Coccidioides species are dimorphic fungi endemic to southwestern USA and northern Mexico. Disseminated coccidioidomycosis is rare with an estimated incidence of 1% in affected individuals and usually presents as meningitis when the central nervous system is involved. Spinal involvement with coccidioidomycosis, though not uncommon, predominantly manifests as osseous involvement leading to osteomyelitis and epidural abscess formation. Progressive quadriparesis as a presenting symptom secondary to intramedullary spinal cord coccidioidomycosis is very unusual and to our knowledge has not been described. We report a patient with disseminated coccidioidomycosis who presented with rapidly progressive quadriparesis due to cervical intramedullary spinal cord involvement. The absence of known coccidioidomycosis with atypical clinical presentation made the diagnosis elusive, requiring emergent cervical laminectomies with dural biopsy for decompression of the spinal cord and confirmation of the diagnosis. The patient eventually succumbed to the progressive course of the disease. Although rare, disseminated coccidioidomycosis can present as new, rapidly progressing quadriparesis in patients who have traveled to endemic areas. A high index of suspicion in such patients with appropriately directed laboratory investigations and consideration of early biopsy might unravel the diagnosis facilitating early antifungal treatment with the potential to minimize morbidity and mortality associated with disseminated coccidioidomycosis.

A rare intramedullary spinal cord metastasis from uterine leiomyosarcoma.

Leiomyosarcoma is a rare smooth-muscle-derived malignancy with a significant malignant potential. Systemic metastases are a common late complication of leiomyosarcoma typically to lungs, liver, brain and bones. We report a 44-year-old woman with a prior history of uterine leiomyosarcoma who presented to us with a cervicothoracic intramedullary lesion and recent onset of neurological deficits. She underwent surgery with histological confirmation of a diagnosis of metastatic leiomyosarcoma, which was followed by adjuvant radiation and chemotherapy. To our knowledge there is no prior report of intramedullary spinal cord metastases (ISCM) from a leiomyosarcoma in the English literature. We report the present patient in view of the rarity of ISCM and its clinical significance. Even though ISCM are unusual, they should be suspected in any patient with primary malignancy irrespective of the histology. The overall prognosis remains grim irrespective of the treatment modality chosen and recognition of the same is important in preoperative counseling and overall treatment approach.

Critical assessment of the morbidity associated with ruptured cerebral arteriovenous malformations.

Background An accurate understanding of the morbidity and mortality associated with brain arteriovenous malformation (AVM) hemorrhage is important in determining the management of unruptured AVMs. Recent studies suggest this morbidity to be lower than assumed. We sought to perform a detailed critical assessment of the morbidity associated with ruptured brain AVMs. Methods A retrospective chart review from a single-center tertiary care medical center was performed. Inclusion criteria were patients admitted with intracranial hemorrhage caused by a previously untreated AVM. Forty variables were analyzed including patient demographics, imaging findings, clinical course, and clinical examinations. Results From 2008 to 2013, of the 51 patients who fit our inclusion criteria, we found admission National Institutes of Health Stroke Scale (NIHSS) scores of 0, 1–9, and ≥10 in 22%, 24%, and 55%, respectively. Hematoma location was parenchymal in 33%, intraventricular in 10%, subarachnoid in 4%, and combined in 53%. Deep venous drainage was present in 35% of cases and associated aneurysms were present in 37%. 43% underwent emergency hematoma evacuation while four patients died during their admission. Of those who survived, 74% had neurologic deficits upon discharge (NIHSS ≥1), with 25.5% of patients having a severe deficit (NIHSS ≥10). On follow-up, 55% were independent in their daily activities of living. Conclusions Our assessment of morbidity associated with brain AVM rupture is higher than previously assumed and reported. These results should be further validated in a larger, more representative sample. An accurate understanding of the morbidity associated with AVM rupture is important as more patients with unruptured brain AVMs seek consultation.

Ventriculoperitoneal shunt with a rare twist: small-bowel ischemia and necrosis secondary to knotting of peritoneal catheter

Small-bowel ischemia and necrosis due to knotting of the peritoneal catheter is an extremely rare complication related to a ventriculoperitoneal shunt (VPS). A 3-month-old girl, with a history of Chiari II malformation and myelomeningocele (MM) after undergoing right occipital VPS insertion and MM repair at birth, presented to the emergency department with a high-grade fever. Examination of a CSF sample obtained via shunt tap raised suspicion for the presence of infection. Antibiotic therapy was initiated, and subsequently the VPS was removed and an external ventricular drain was placed. Intraoperatively, as attempts at pulling the distal catheter from the scalp incision were met with resistance, the distal catheter was cut and left in the abdomen while the remainder of the shunt system was successfully removed. While the patient was awaiting definitive shunt revision surgery to replace the VPS, she developed abdominal distension due to small-bowel obstruction. An emergency exploratory laparotomy revealed a knot in the distal catheter looping around and strangulating the distal ileum, causing small-bowel ischemia and necrosis in addition to the obstruction. A small-bowel resection with ileostomy was performed, with subsequent placement of ventriculoatrial shunt for treatment of hydrocephalus. The authors report this exceedingly rare clinical scenario to highlight the fact that any retained distal catheter must be carefully managed with immediate abdominal exploration to remove the distal catheter to avoid bowel necrosis as pulling of a knotted peritoneal catheter may strangulate the bowel and cause ischemia, with significant clinical morbidity and possible mortality.