US nationwide trends in carotid revascularization: is there a clinical opportunity cost associated with the introduction of novel medical devices?

OBJECTIVES: Nationwide practice patterns during the implementation of novel technology, such as carotid angioplasty and stenting (CAS) and embolic protection devices (EPD), and the clinical impact thereof have received less attention. METHODS: The Nationwide Inpatient Sample, constituting a 20% representative sample of non-federal US hospitals, was analyzed from years 1998 to 2007. Hospital outcome was stratified into in-hospital mortality (IHM), long-term facility discharge, and home/ short-term facility discharge (HSF). RESULTS: Discharge outcome improved for CAS over the decade. However, this improvement occurred in two phases with a period of worsening (2003-2005) in between. During this transition period, the risk of IHM following CAS was increased (RR 1.29-2.43) and was lower for good outcome (HSF: RR 0.97-0.99) when compared with 2002/2003. During the same transition period, carotid endarterectomy (CEA) was associated with a lower risk of IHM (RR 0.75-1.00), but also a lower risk of HSF (RR 0.98-0.99). CONCLUSIONS: The results lead to the hypothesis that the nationwide introduction of CAS-EPD may have been associated with temporary increases in in-hospital mortality and discharge morbidity. If such 'clinical opportunity costs' exist with the widespread introduction and adoption of new medical technology with proven efficacy in randomized trials, effective mechanisms are needed for mitigation or prevention during the transition period.

US nationwide trends in carotid revascularization: hospital outcome and predictors of outcome from 1998 to 2007.

OBJECTIVES: The goals of the study were to assess US nationwide trends in hospital outcome following carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS) and to determine potential predictors of outcome. METHODS: The Nationwide Inpatient Sample, constituting a 20% representative and stratified sample of non-federal US hospitals, was analyzed retrospectively from years 1998 to 2007. RESULTS: The annual number of CEA decreased (137,877-111,658) and increased for CAS (2318-14,415). Inhospital mortality following CEA decreased from 0.4% to 0.3% (P < 0.001), whereas long-term facility (LTF) discharge increased from 8.2% to 10.5% (P < 0.001). Discharge outcome improved for CAS in both categories (mortality 2-0.5%; LTF discharge 10.7-8.3%; both P < 0.001). The trend analysis revealed an increase in patient age and a worsening comorbid profile over time. Age, women, length of stay, atrial fibrillation, and carotid stenosis with infarction were important determinants of unfavorable hospital outcome. CONCLUSION: From a nationwide practice perspective, the number of carotid revascularizations fell by 10%. CEA has resulted in stable hospital mortality rates. Meanwhile, CAS has been increasingly utilized with overall improvement in short-term outcome. Our results further suggest a decrease in the number of patients with treatment-eligible carotid disease over time. However, the increasing prevalence of high-risk comorbidity in the aging population may pose a challenge to revascularization strategies.

Contrast enhancement hyperdensity after endovascular coiling of intracranial aneurysms.

BACKGROUND AND PURPOSE: Endovascular coil embolization is used increasingly to treat cerebral aneurysms. The purpose of our study was to quantify the incidence of CT-detectable abnormalities after aneurysm coiling and map the radiographic and clinical progression. MATERIALS AND METHODS: We reviewed the radiographic and clinical sequelae of 30 consecutive patients with aneurysms who underwent endosaccular coiling followed by head CT scans. Patients with CT abnormalities received follow-up scans at 4 to 6 hours and 20 to 25 hours. Contrast enhancement was defined as CT hyperdensities with progressive resolution over 25 hours and a Hounsfield unit (HU) of less than 70. The incidence of CT abnormalities was recorded and correlated with amount of contrast used, use of antiplatelet agents, procedure time, and clinical sequelae. RESULTS: Seven patients (23%) had new hyperdensities on CT scan. Four showed gyral hyperattenuation; 1 showed basal ganglia hyperattenuation, and 2 showed a combination of these patterns. All were asymptomatic and were consistent with contrast enhancement, with complete resolution in 5 of 7 and partial resolution in 2 of 7 by 20 to 25 hours. Antithrombotic or antiplatelet medication was continued in all cases. The amount of contrast used (P = .014) and the use of antiplatelet medication (P = .029) were statistically correlated with the presence of hyperattenuation after aneurysm coiling, whereas the length of the procedure was not (P = .162). CONCLUSION: Contrast enhancement, unlike contrast extravasation, is a fairly common and clinically benign finding after aneurysm coiling. The enhancement resolves by 25 hours in most cases, regardless of the continuation of antithrombotic or antiplatelet therapy.

Treatment of cerebral aneurysms with hydrogel-coated platinum coils (HydroCoil): early single-center experience.

PURPOSE: The authors report their experience using HydroCoils in the treatment of cerebral aneurysms. METHODS: We performed a retrospective review of the first 100 nonrandomized patients (104 coiled saccular cerebral aneurysms) treated with HydroCoils during a 27-month period. RESULTS: The average percentage of HydroCoil by length detached in treated aneurysms was 45.5% (range, 9.9-100%). Immediate postprocedure angiography demonstrated complete aneurysm occlusion in 34%, neck remnant in 35%, and incomplete occlusion in 32%. Immediate procedure-related morbidity and mortality rates were 5.8% and 0%, respectively. Angiographic follow-up was obtained in 51% (51/100 patients; 53/104 aneurysms; average, 10.3 months; range, 0-31 months). In these 53 angiographically followed aneurysms, the overall recanalization rate was 21%: no recanalization occurred in 23 aneurysms with small size (<10 mm)/small neck (<4 mm) (S/S); 4 recanalizations occurred in 7 aneurysms with small size/wide neck (>4 mm) (S/W); 6 recanalizations (27%) occurred in 22 large (L) aneurysms (>10-25 mm, 70% angiographic follow-up); and 1 giant (G) (>25 mm) aneurysm recanalized. A large proportion of aneurysms that were not initially completely occluded were completely occluded on follow-up (15/43 [35%]). Clinical follow-up was obtained in 73 patients (73%; average, 5.3 months; range, 0-24 months): 93% of these patients were neurologically improved or unchanged. Three patients rehemorrhaged and 3 patients with unruptured aneurysms developed delayed hydrocephalus. CONCLUSIONS: The overall safety profile of HydroCoils appears acceptable. Preliminary midterm observations suggest less coil compaction/aneurysm recanalization in large aneurysms. However, HydroCoil-related delayed hydrocephalus is a concern.

MR spectroscopic changes in the rat hippocampus following proton radiosurgery.

PURPOSE: To identify MR spectroscopic changes in the rat hippocampus following proton radiosurgery. METHODS AND MATERIALS: A group of 12 rats were treated with Bragg peak proton beam irradiation involving the right hippocampus. Single doses of 30 CGE, 50 CGE, 70 CGE, 90 CGE were delivered to groups of 3 animals using single fraction technique. Animals were imaged using a standard 3 T GE Signa MRI at 4 months following treatment. An untreated animal was also studied. A 3'' surface coil was employed to obtain T1 weighted coronal pre- and post-gadolinium images (TR 600 and TE 30) and dual echo T2 weighted coronal images (TR 3000, TE 30/90). Volumetric analysis with custom software was done to evaluate areas of increased signal on T2 weighted images and the development of hydrocephalus was examined. Animals were sacrificed and specimens of the treated hippocampus were harvested for High Resolution Magic Angle Spinning MR Spectroscopy (HRMAS) followed by histopathology of the tissue samples. Peak values of choline, creatine, N-acetyl aspartate and lipids were evaluated and compared. RESULTS: Peak tissue injury occurred in the surviving 90 CGE animal by both T2 weighted and post-gadolinium imaging. Gadolinium enhancement was seen in decreasing volumes of tissue at dosage levels from 90 to 50 CGE. Hydrocephalus was seen on the untreated side in the 90 CGE animal likely because of mass effect, while it was seen in small degrees in the side of treatment in the 70 and 50 CGE animals. Histopathology showed changes at 90 and 70 CGE, but not at 50 or 30 CGE at this time point using H and E stains. HRMAS showed spectroscopic changes in the surviving 90 and 70 CGE animals but not in the 50 and 30 CGE animals. Statistical significance was not reached because of the small sample size. CONCLUSIONS: Following single dose proton radiosurgery of rat hippocampus, HRMAS is able to identify metabolic changes induced by radiation. Studies built on these principles may help develop non-invasive MR spectroscopic methods to distinguish radiation changes from tumor recurrence.

Pediatric Thoraco-lumbar Paraspinal Arteriovenous Fistulas along the Segmental Nerve. Diagnosis and Endovascular Treatment.

SUMMARY: To characterize the clinical presentation, imaging features and endovascular treatment of paraspinal non-vertebral arteriovenous fistulas along the segmental nerve. Retrospective review was performed on the five patients identified in our database covering 1985 to 2003. All patients presented with an incidentally found continuous murmur over the upper paraspinal or parasternal regions before three years old. In four patients, the AV fistula was in the mid-thoracic level and at L3 in one. All AV fistulas were a high-flow single-hole fistula at the neural foramen with venous drainage into paraspinal and epidural veins without intradural reflux. All fistulas were endovascularly occluded in the same session as the diagnostic angiography. The fistula was occluded with detachable coils in one case and with N-butylcyanoacrylate (NBCA) with flow control in four cases. Complete occlusion of the fistula was obtained in all cases and all patients remained neurologically intact at the last follow up (average six years). Non-vertebral paraspinal arteriovenous fistula along the segmental nerve is a specific disease entity seen in children. Embolization is the first choice of treatment for this disease.

Extramedullary hemangioblastoma of the conus medullaris.

BACKGROUND: We report the case of an extramedullary pathologically proven hemangioblastoma of the conus medullaris. As spinal dural arteriovenous fistulas most commonly present with a conus medullaris syndrome, our presentation of the MRI, myelographic, and angiographic findings of this unique lesion may be useful in differentiating these two entities. CLINICAL MATERIAL: We report the case of a 57 year old woman with a two year history of progressive low back and right lower extremity pain and weakness. Spinal MRI and myelography demonstrated serpiginous vasculature on the dorsum of the spinal cord consistent with either a vascular tumor or malformation. Selective spinal angiography was thus undertaken by the neuroendovascular team which revealed a tumor nodule consistent with vascular tumor. T12-L1 laminectomy was performed and a 6 mm vascularized tumor was found in the intradural extramedullary compartment adjacent to the conus medullaris. The tumor was completely removed and pathological analysis was consistent with hemangioblastoma. CONCLUSION: This report documents a unique location for extramedullary spinal hemangioblastomas. Although both MRI and myelography are helpful in studying these lesions, angiography remains the gold standard in differentiating between vascular tumor and malformation. We suggest that the angiography be performed by a neurointerventional team to facilitate embolization, should this be warranted.

Eosinophilic granuloma of the clivus: case report, follow-up of two previously reported cases, and review of the literature on cranial base eosinophilic granuloma.

OBJECTIVE AND IMPORTANCE: To our knowledge, this is the first reported case of the use of stereotactic radiotherapy for an eosinophilic granuloma (EG) of the clivus. We report follow-up information on two previously reported cases and suggest a management plan for this rare lesion. CLINICAL PRESENTATION: We report the case of a 4.5-year-old boy who presented with a complete abducens palsy on the right with an associated head turn. A computed tomographic scan of his head revealed a lytic lesion on that side, and magnetic resonance imaging showed the mass to be of low intensity on T1-weighted images and of high intensity on T2-weighted images with heterogeneous enhancement. INTERVENTION: A transnasal stereotactic biopsy was performed, revealing an EG. The patient was treated with stereotactic radiotherapy, and he became symptom-free with radiographic resolution of his lesion. Reviewing the literature, we found 13 series with 87 cases of EG in the petrous portion of the temporal bone. EG in the cranial base occurring outside of the temporal bone or in the temporal bone and extending intracranially is, however, quite rare, with only nine other cases reported, two of them clival. CONCLUSION: These findings suggest a classification schema in which cranial base EG lesions be grouped with either the more common extracranial petrous temporal bone lesions or the very rare intracranial lesions. Although there are few cases in the literature, treatment results indicate that clival EG, and perhaps all intracranial cranial base EGs, be treated by a biopsy alone, followed by surgery or stereotactic radiotherapy if there is an incomplete resolution of the symptoms or if there is a recurrence.

Lateral inhibition and granule cell synchrony in the rat hippocampal dentate gyrus.

Studies of patients with temporal lobe epilepsy and of experimental models of this disorder suggest that the hippocampal dentate gyrus may be a common site of seizure onset and propagation. However, the nature of the dentate "network defect" that could give rise to spontaneous, intermittent, and synchronous population discharges is poorly understood. We have hypothesized that large expanses of the dentate granule cell layer have an underlying tendency to discharge synchronously in response to afferent excitation, but do not do so normally because vulnerable dentate hilar neurons establish lateral inhibition in the granule cell layer and thereby prevent focal discharges from spreading to surrounding segments. To address this hypothesis, we (1) identified functionally independent segments of the granule cell layer; (2) determined whether discharges in one segment evoke lateral inhibition in surrounding segments; and, (3) determined if disinhibition induces normally independent segments of the granule cell layer to discharge synchronously. Simultaneous extracellular recordings were made from two locations along the longitudinal or transverse axes of the granule cell layer using saline- and bicuculline-filled electrodes that were glued together. Leakage of 10 mM bicuculline from the electrode tip produced no detectable spontaneous activity. However, single perforant path stimuli evoked multiple population spikes at the bicuculline electrode and simultaneous normal responses at the nearby saline electrode. The multiple spikes evoked at the bicuculline electrode did not propagate to, and were not detected by, the adjacent saline electrode, indicating functional separation between neighboring subgroups of granule cells. Paired-pulse stimulation revealed that multiple discharges were not only restricted to one segment of the granule cell layer, but strongly inhibited surrounding segments. This lateral inhibition in surrounding segments often lasted longer than 150 msec. Finally, we evaluated granule cell activity at two normally independent sites within the granule cell layer both before and after disinhibition was induced by high frequency stimulus trains or bicuculline injection. Following a 10 sec, 20 Hz perforant path stimulus train, 2 Hz stimulation evoked virtually identical synchronized epileptiform discharges from normally separated sites. Similarly, intrahippocampal or intravenous bicuculline injection produced spontaneous synchronous epileptiform discharges throughout the granule cell layer. These results indicate that lateral or "surround" inhibition is an operant physiological mechanism in the normal dentate gyrus and suggest that afferent stimuli to a disinhibited dentate network evoke highly synchronized discharges from large expanses of the granule cell layer that are normally kept functionally separated by GABA-mediated inhibition.