Spinal Dural Arteriovenous Fistula: Diagnosis, Outcomes, and Prognostic Factors.

OBJECTIVE: Typically, the clinical presentation of a spinal dural arteriovenous fistula (SDAVF) will be insidious, with patients' symptoms regularly attributed to other conditions. Although previous studies have characterized the neurologic outcomes after treatment for SDAVFs, little is known about the pretreatment patient characteristics associated with poor and/or positive patient outcomes. We sought to characterize the pretreatment patient demographics, diagnostic history, and neurologic outcomes of patients treated for SDAVFs and to identify the patient factors predictive of these outcomes. METHODS: The medical records of patients who had been treated for SDAVFs from 2006 to 2018 across 1 healthcare system were retrospectively analyzed. Neurologic status was assessed both before and after intervention using the Aminoff-Logue scales for gait and micturition disturbances. RESULTS: Of 46 total patients, 16 (35%) had a documented misdiagnosis. Patients with a history of misdiagnosis had had a significantly longer symptom duration before treatment compared with those without a misdiagnosis (median, 2.3 vs. 0.9 years; P = 0.018). A shorter symptom duration before intervention was significantly associated with both improved motor function (median, 0.8 vs. 3.1 years; P = 0.001) and improved urinary function (median, 0.8 vs. 2.2 years; P = 0.040) after intervention. CONCLUSIONS: Misdiagnosis has been relatively common in patients with SDAVFs and contributes to delays in treatment. Delays in diagnosis and treatment of SDAVFs appear to be associated with worse clinical outcomes for patients who, ultimately, receive treatment.

Early post-Humanitarian Device Exemption experience with the Neuroform Atlas stent.

INTRODUCTION: The low-profile Neuroform Atlas stent received FDA Humanitarian Device Exemption status (HDE) in January 2018 for stent-assisted coil embolization of wide-necked saccular aneurysms. We review and report our results with the Atlas stent in our institution within the first year after its HDE approval. METHODS: Our retrospective chart review identified patients treated with the Atlas stent. We analyzed the patient demographics, aneurysm characteristics, stent parameters and configuration, complications, angiographic, and clinical outcomes at discharge. RESULTS: From January to December 2018, 76 Atlas stents were deployed in 58 patients (average 1.3 stents/patient). Median patient age was 63.5 (IQR 56-71) years. Fifty-six (96.6%) patients had elective embolization of unruptured aneurysms, while two (3.4%) patients underwent embolization of a ruptured aneurysm within 2 weeks of subarachnoid hemorrhage. Forty (69.0%) patients were treated with a single stent, 15 (25.9%) with a Y-stent, and three (5.2%) with X-stent configuration. All stent deployments were technically successful. Most stents (82.9%) were the smallest 3 mm diameter devices. Procedural complications included transient stent-associated thrombosis in three (5.2%) patients and aneurysm rupture in one (1.7%). None had distal embolization, associated cerebral infarction, or permanent neurological deficits. Immediate Raymond-Roy 1 occlusion was achieved in 41 (70.7%) patients. Median hospital length of stay for elective aneurysm embolization was 1 day. Excellent outcomes with median National Institute of Health Stroke Scale score 0 (IQR 0-0) and modified Rankin Score 0 (IQR 0-1) were seen for elective patients at discharge. CONCLUSION: The Neuroform Atlas stent provided a reliable technical and safety profile for the treatment of intracranial wide-neck aneurysms. Further experience is needed to determine long-term durability and safety of this device.

Long-term Follow-up of In-stent Stenosis After Pipeline Flow Diversion Treatment of Intracranial Aneurysms.

BACKGROUND: There is scant information on in-stent stenosis after flow diversion treatment of intracranial aneurysms with the Pipeline Embolization Device (PED). OBJECTIVE: To assess the incidence, severity, nature, and clinical consequences of in-stent stenosis on angiographic follow-up after treatment with the PED. METHODS: A retrospective study of patients who underwent aneurysm treatment with the PED was conducted. In-stent stenosis was assessed on subsequent follow-up angiography. Intimal hyperplasia was defined as a uniform growth process beyond the limits of the metallic mesh at <25%. In-stent stenosis represented an area of parent vessel narrowing, most often focal, graded as mild (25%-50%), moderate (50%-75%), or severe (>75%). RESULTS: Between June 2011 and April 2015, 80 patients were treated with the PED. Angiographic follow-up was available for 51 patients (representing 76% of available or 64% of all patients). Mean follow-up was 12.5 months. In-stent stenosis was detected in 5 patients (9.8%) at a median of 6 months. Stenosis was mild in 4 of 5 (80%) and moderate in 1 of 5 (20%) patients. There were no cases of severe stenosis. No stenosis caused flow limitation, clinical symptoms, or required re-treatment. Additional follow-up angiography was available in 2 of 5 stenosis patients showing marked improvement. Sixteen patients (31%) had intimal hyperplasia, and 28 patients (55%) had no stenosis. Asymptomatic stent occlusion occurred in 2 patients (4%) related to medication noncompliance. CONCLUSION: Treatment with the PED was associated with a 9.8% rate of in-stent stenosis, detected on first angiographic follow-up, at a median of 6 months. None were symptomatic or required re-treatment, and they showed significant improvement on follow-up. ABBREVIATION: FD, flow diverter.

The location of pretreatment hyperdense middle cerebral artery sign predicts the outcome of intraarterial thrombectomy for acute stroke.

BACKGROUND AND PURPOSE: Intraarterial (IA) mechanical thrombectomy has an excellent recanalization rate but does not always correlate with good clinical outcomes. We aimed to investigate whether hyperdense middle cerebral artery sign (HMCAS) on preintervention nonenhanced CT (NECT) predicts IA therapy outcome for acute stroke. METHODS: Data were abstracted from our Hyperacute Ischemic Stroke database. Patients with occlusion in ICA, MCA, or MCA M2 branches who underwent IA therapy were included. RESULTS: Among 126 patients who underwent IA treatment, 64 (51%) had hyperdense M1 MCA sign (M1 HMCAS), 11 (9%) had hyperdense M2, and 51 (40%) had No HMCAS (NHMCAS).M1 HMCAS and NHMCAS group has comparable baseline stroke severity and infarct volume (P > .05); and the differences of favorable outcome (modified Rankin Score 0-2) at 30 days were not significant (21% vs. 30%, P = .259). For those with HMCAS, favorable 30-day outcome was most frequent in Distal HMCAS (39%), followed by hyperdense M2 (27%), HMCAS proximal (11%), and HMCAS full length (0%). CONCLUSIONS: For acute ischemic stroke due to large vessel occlusion, the lack of HMCAS on NECT does not predict favorable outcome after IA therapy. Among those with HMCAS, proximal and longer HMCAS predicts unfavorable outcome.

A history of detachable coils: 1987-2012.

BACKGROUND: The development of detachable coils is one of the most pivotal developments in neurointervention, providing a tool that could be used to treat a wide variety of hemorrhagic stroke. From the original Guglielmi detachable coil, a number of different coil designs and delivery designs have evolved. This article reviews the history of commercially available detachable coils. METHODS: A timeline of detachable coils was constructed and coil design philosophies were reviewed. RESULTS: A complete list of commercially available coils is presented in a timeline format. CONCLUSIONS: Detachable coil technology continues to evolve. Advances in construction and design have yielded products which may benefit patients in terms of safety, radiation dose reduction and cost of treatment. Continued evolution is expected, irrespective of competing disruptive technologies.

Simulated diagnostic cerebral angiography in neurosurgical training: a pilot program.

INTRODUCTION: Surgical simulation provides a zero-risk setting in which technical skills can be obtained through repetition. The feasibility and utility of simulated diagnostic cerebral angiography among neurosurgical residents and fellows was studied using an endovascular biplane angiography simulator. METHODS: Ten neurosurgical residents and four endovascular neurosurgery fellows were recruited into a standardized training protocol consisting of a didactic, demonstration and hands-on learning environment using the Simbionix simulator. Participants were instructed to catheterize the right internal carotid artery, left internal carotid artery and left vertebral artery. The task was repeated five times. RESULTS: All participants demonstrated improvement over the five trials. Residents performed actions that were perceived as potentially dangerous (n=8) while fellows performed the procedure with superior technique. Residents performed the task with an initial total procedure and fluoroscopy time of 6.6 ± 4.3 min and 4.9 ± 3.7 min, respectively, and improved on the fifth trial to 3.4 ± 1.3 min (p=0.03) and 2.3 ± 0.78 min (p=0.004), respectively. Residents approximated the efficiency of fellows for the third and fourth trial. CONCLUSIONS: Incorporating an endovascular simulator is feasible for training purposes in a neurosurgical residency program. This study provides objective documentation of the facilitation of technical angiography skill acquisition by the use of simulation technology.

Evolution of a multidisciplinary cerebrovascular center: lessons learned.

The Cerebrovascular Center at the Cleveland Clinic is an integrated, multidisciplinary center comprising vascular neurologists, neurointensivists, physiatrists, open and endovascular neurosurgeons, interventional neurologists and interventional neuroradiologists administered through a single financial center with unified governance and leadership. This report describes the history and evolution of the center from conceptualization to the present, as well as outlining lessons learned in the formation and maturation of the group.

Particle embolization of the bilateral superior and inferior alveolar arteries for life threatening dental socket hemorrhage.

Particle embolization for epistaxis and intra-oral hemorrhage are performed on an as needed basis by neurointerventionalists. A case is presented of massive oral hemorrhage associated with end stage liver disease coagulopathy after tooth extraction of bilateral maxillary and mandibular molars. A man in his fifties with end stage liver disease who presented for evaluation of a syncopal episode was determined to be in hemorrhagic shock from 2 days of persistent oral bleeding after elective tooth extractions. Conservative management with multiple blood transfusion products, packing and vasoconstrictive spray was ineffective. Microcatheter angiograms of the alveolar arteries demonstrated blood and contrast pooling within the sockets of the extracted teeth. Selection of the bilateral supplying alveolar and inferior alveolar artery branches was achieved followed by polyvinyl alcohol particle embolization (250-355 µm). Polyvinyl alcohol particle embolization of dental socket hemorrhages is technically feasible and effective.

Thromboembolic events associated with endovascular treatment of cerebral aneurysms.

OBJECTIVE: To evaluate the rate of peri-procedural thromboembolic events after the endovascular treatment of cerebral aneurysms. The rate of diffusion-positive lesions was assessed in relation to selected procedural and technical factors. METHODS: 184 patients treated with coil embolization (198 total procedures) between July 2004 and February 2007 were included. In 65, the procedure was coiling alone; in 55, coiling with balloon remodeling; in 48, coiling with Neuroform stenting; and in 30, coiling, Neuroform stenting and balloon remodeling. All patients underwent a routine diffusion weighted magnetic resonance imaging (DWI) within the 72 h after the intervention for the detection of ischemic complications. RESULTS: Regardless of the technique used, thromboembolic complications were more common (p<0.0001) in patients with ruptured aneurysms (33/65, 51%) than in those with unruptured aneurysms (40/133, 30%). Balloon remodeling tended to be associated with a lower rate of DWI positivity than the other techniques. Younger patients (≤60) with unruptured aneurysms had the lowest rates of DWI lesions regardless of the technique used. CONCLUSION: In this study, peri-procedural DWI-positive lesions occurred in approximately one-third of all cases. These were threefold more common in the setting of ruptured aneurysms. Adjunctive devices did not increase the rate of ischemic events. On the contrary, there was a trend toward fewer DWI abnormalities in the procedures in which balloon remodeling was employed. This may, in part, be related to the application of the conglomerate coil mass technique of balloon remodeling.

Combined endovascular and surgical resection of a giant lumbosacral arteriovenous malformation in a patient with Cobb syndrome.

OBJECTIVE AND IMPORTANCE: Cobb syndrome is a rare condition that includes a cutaneous nevus with an associated spinal vascular lesion at the same dermatome. We present a challenging case of a progressively symptomatic massive lumbosacral arteriovenous malformation (AVM) in a patient with Cobb's syndrome requiring a multimodality approach including staged preoperative transarterial and transvenous endovascular embolization followed by surgical excision and wound reconstruction. CLINICAL PRESENTATION: The patient presented with a massive lumbosacral AVM with symptoms of congestive heart failure. Angiography demonstrated arterial feeders predominantly from internal iliac, median sacral and lumbar segmental arteries. INTERVENTION: The patient underwent staged transarterial and transvenous endovascular embolization resulting in 90% reduction in the AVM size, followed by surgical resection of the lesion. The patient made an excellent recovery with improvement in his symptoms of congestive heart failure. CONCLUSION: The treatment algorithm for massive AVMs must be individualized. A combination of staged embolization and subsequent surgery may be required to obtain a good result. Through this carefully planned multidisciplinary approach a previously incurable lesion in this patient with Cobb syndrome was able to be treated successfully.

Balloon-augmented Onyx embolization of a dural arteriovenous fistula arising from the neuromeningeal trunk of the ascending pharyngeal artery: technical report.

INTRODUCTION: Intracranial dural arteriovenous fistulas (dAVFs) with perimedullary drainage are an uncommon but well-recognized lesion that can lead to spinal cord edema. The authors present a case of a foramen magnum dAVF with unilateral arterial supply from the ascending pharyngeal artery. PRESENTATION: A 49-year-old male presented with a 1-year history of slowly progressive lower extremity weakness and underwent a two-level cervical corpectomy for presumed spondylotic myelopathy. On further workup, he was found to have a dAVF arising from the ascending pharyngeal artery. INTERVENTION: Selective angiography revealed the origin of the neuromeningeal trunk, which was proximal to the arteriovenous fistula. The microcatheter was advanced into the neuromeningeal trunk past the origin of the inferior tympanic artery and origin of the hypoglossal artery. A 4×7 mm Hyperform balloon (EV3, Irvine, California, USA) was then delivered past the origin of the vessel supplying the skull base cranial nerves, but proximal to the microcatheter tip. The balloon was inflated and Onyx embolization was employed to obliterate the fistula with controlled penetration. The patient showed immediate postprocedural improvement in motor function. DISCUSSION: Embolization of branches of the ascending pharyngeal artery carries risks of inadvertent embolization of branches of the neuromeningeal trunk as well as the risk for extracranial to intracranial anastamoses. An awareness of the highly variable anatomy of the ascending pharyngeal artery is necessary for the safe treatment of lesions supplied by this artery. This is, to the authors' knowledge, the first report of balloon-augmented embolization of an arteriovenous fistula arising from the neuromeningeal trunk.

U.S. Wingspan Registry: 12-month follow-up results.

BACKGROUND AND PURPOSE: The purpose of this study is to present 12-month follow-up results for a series of patients undergoing percutaneous transluminal angioplasty and stenting with the Gateway-Wingspan stenting system (Boston Scientific) for the treatment of symptomatic intracranial atherostenosis. METHODS: Clinical and angiographic follow-up results were recorded for patients from 5 participating institutions. Primary end points were stroke or death within 30 days of the stenting procedure or ipsilateral stroke after 30 days. RESULTS: During a 21-month study period, 158 patients with 168 intracranial atherostenotic lesions (50% to 99%) were treated with the Gateway-Wingspan system. The average follow-up duration was 14.2 months with 143 patients having at least 3 months of clinical follow-up and 110 having at least 12 months. The cumulative rate of the primary end point was 15.7% for all patients and 13.9% for patients with high-grade (70% to 99%) stenosis. Of 13 ipsilateral strokes occurring after 30 days, 3 resulted in death. Of these strokes, 76.9% (10 of 13) occurred within the first 6 months of the stenting procedure and no events were recorded after 12 months. An additional 9 patients experienced ipsilateral transient ischemic attack after 30 days. Most postprocedural events (86%) could be attributed to interruption of antiplatelet medications (n=6), in-stent restenosis (n=12), or both (n=1). In 3 patients, the events were of uncertain etiology. CONCLUSIONS: After successful Wingspan percutaneous transluminal angioplasty and stenting, some patients continued to experience ipsilateral ischemic events. Most of these ischemic events occurred within 6 months of the procedure and were associated with the interruption of antiplatelet therapy or in-stent restenosis.

Reduction of false-negative results in inferior petrosal sinus sampling with simultaneous prolactin and corticotropin measurement.

OBJECTIVE: To investigate the value of prolactin as an independent marker of catheter placement to improve the diagnostic accuracy of inferior petrosal sinus sampling (IPSS) in patients with corticotropin-dependent Cushing syndrome. METHODS: In this retrospective cohort study, we reviewed hospital records of patients who underwent IPSS procedures at the Cleveland Clinic between 1997 and 2009. Serum prolactin and plasma corticotropin levels were measured prospectively in peripheral and inferior petrosal sinus (IPS) samples. RESULTS: Forty-one patients underwent 42 IPSS procedures at our institution during the study period. Among 35 patients with Cushing disease, 1 patient had erroneous IPSS results: all pre-corticotropin-releasing hormone (CRH) and post-CRH IPS to peripheral (IPS:P) ACTH ratios were less than 2 and less than 3, respectively. Despite radiologic evidence of appropriate IPS catheter placement, concurrent IPS:P prolactin ratios indicated that successful IPS venous sampling was not achieved. A second case with equivocal IPSS results could also be explained by corresponding IPS:P prolactin ratios. During IPSS, all patients with an identifiable ACTH-staining adenoma localizing to 1 side of the pituitary gland (n = 22) who demonstrated absent IPS:P ACTH gradients (<2 before or <3 after CRH administration) on the ipsilateral side of the corticotroph adenoma had corresponding IPS:P prolactin ratios less than 1.3. CONCLUSIONS: Measurement of prolactin during IPSS testing may reduce false-negative results in patients with Cushing disease who do not demonstrate an appropriate central-to-peripheral ACTH gradient. In our series, all false-negative IPS:P ACTH ratios had a corresponding IPS:P prolactin ratio less than 1.3.

Symptomatic delayed reocclusion after initial successful revascularization in acute ischemic stroke.

BACKGROUND: Endovascular stroke therapy is used for patients with ischemic stroke after failed intravenous thrombolysis or in patients not eligible for thrombolytics. With increasing experience, acute reocclusion has been described and likely worsens clinical outcomes. We assessed the rates and outcomes of delayed symptomatic reocclusion after endovascular therapy for acute ischemic stroke. METHODS: Patients with acute ischemic stroke undergoing endovascular procedures at out institutions from January 2008 to August 2008 were reviewed. In all, 107 consecutive acute stroke interventions were performed. Four patients (3.5%) experienced delayed symptomatic reocclusion detectable by the National Institutes of Health Stroke Scale (NIHSS). RESULTS: The 4 patients (age 45-79 years) had baseline NIHSS score ranging from 8 to 24. Three had right middle cerebral artery occlusions and one had a left middle cerebral artery occlusion. Successful recanalization (thrombolysis in myocardial infarction score 2-3) occurred in all cases after initial treatment. All patients improved postprocedure (NIHSS score 5-10). Clinical deterioration (NIHSS score 14-22) occurred 12 to 18 hours postprocedure. Successful recanalization was achieved in each patient, with improvement in NIHSS score (range 6-13) but not to a lower level compared with after the initial intervention. CONCLUSIONS: Delayed symptomatic reocclusion after initial endovascular stroke therapy can lead to sudden clinical deterioration and impact outcomes. The entity may be missed as many patients present with large clinical deficits at presentation thus requiring careful assessments of patients treated via endovascular methods.

Mechanical thrombectomy for acute stroke with the alligator retrieval device.

BACKGROUND AND PURPOSE: Recanalization of occluded vessels in acute ischemic stroke is associated with improved outcome. Devices that can quickly and safely remove thrombus and promote recanalization are useful in the management of these patients. The Alligator retrieval device, developed for endovascular foreign body retrieval, may also be useful for thrombus removal. METHODS: Seven patients with acute ischemic stroke (aged 31 to 88 years) who underwent intra-arterial therapy with the Alligator retrieval device at our center are presented. RESULTS: The Alligator retrieval device was able to retrieve the thrombus in 5 of 7 cases with good to excellent recanalization seen and was unsuccessful in 2 of 7 patients. Complete recanalization was obtained in one of 7 patients and near complete recanalization obtained in 4 of 7 patients. Three of the 7 patients had good outcome at 3 months and 3 of 7 patients died within 30 days of treatment. CONCLUSIONS: The Alligator retrieval device was successfully able to remove thrombus in the majority of cases. It appears to have increased success in proximal occlusions in relatively straight segments. In properly selected cases, it may be a useful device in intra-arterial stroke management.

Delayed symptomatic coil migration after initially successful balloon-assisted aneurysm coiling: technical case report.

OBJECTIVE: To describe delayed migration of a coil loop after adjunctive balloon remodeling of an anterior communicating artery aneurysm. METHODS: A 56-year-old man with a subarachnoid hemorrhage from a small anterior communicating artery aneurysm underwent successful coil embolization with adjunctive balloon remodeling. RESULTS: Eight days after the procedure, the patient returned with the acute onset of right lower extremity paralysis. Magnetic resonance imaging demonstrated an acute left anterior cerebral artery territory infarction. Angiography demonstrated that this infarct was secondary to the delayed migration of a coil loop out of the aneurysm and into the left A1 to A2 junction. CONCLUSION: Delayed migration of a coil loop after adjunctive balloon remodeling represents a rare but potentially severe complication of this technique.

Target lesion revascularization after wingspan: assessment of safety and durability.

BACKGROUND AND PURPOSE: In-stent restenosis (ISR) occurs in approximately one-third of patients after the percutaneous transluminal angioplasty and stenting of intracranial atherosclerotic lesions with the Wingspan system. We review our experience with target lesion revascularization (TLR) for ISR after Wingspan treatment. METHODS: Clinical and angiographic follow-up results were recorded for all patients from 5 participating institutions in our US Wingspan Registry. ISR was defined as >50% stenosis within or immediately adjacent (within 5 mm) to the implanted stent and >20% absolute luminal loss. RESULTS: To date, 36 patients in the registry have experienced ISR after percutaneous transluminal angioplasty and stenting with Wingspan. Of these patients, 29 (80.6%) have undergone TLR with either angioplasty alone (n=26) or angioplasty with restenting (n=3). Restenting was performed for in-stent dissections that occurred after the initial angioplasty. Of the 29 patients undergoing TLR, 9 required >/=1 interventions for recurrent ISR, for a total of 42 interventions. One major complication, a postprocedural reperfusion hemorrhage, was encountered in the periprocedural period (2.4% per procedure; 3.5% per patient). Angiographic follow-up is available for 22 of 29 patients after TLR. Eleven of 22 (50%) demonstrated recurrent ISR at follow-up angiography. Nine patients have undergone multiple retreatments (2 retreatments, n=6; 3 retreatments, n=2; 4 retreatments, n=1) for recurrent ISR. Nine of 11 recurrent ISR lesions were located within the anterior circulation. The mean age for patients with recurrent anterior circulation ISR was 57.9 years (vs 81 years for posterior circulation ISR). CONCLUSIONS: TLR can be performed for the treatment of intracranial Wingspan ISR with a relatively high degree of safety. However, the TLR results are not durable in approximately 50% of patients, and multiple revascularization procedures may be required in this subgroup.

Revascularization of symptomatic subacute cerebrovascular occlusions with a self-expanding intracranial stent system.

OBJECTIVE: In some patients, collateral circulation may preserve the viability of brain parenchyma distal to an intracranial arterial occlusion for hours or days after the presenting event. These patients may be good candidates for revascularization, even when they present outside of the accepted 6-hour time window for stroke intervention. METHODS: Three patients were revascularized with the Wingspan stent system (Boston Scientific/Target, Fremont, CA) after presenting with subacute occlusions of intracranial arteries and progressive ischemic symptoms despite maximal medical therapy. All pre- and postprocedural imaging data and clinical records were reviewed. RESULTS: Three patients (mean age, 64 years; 2 women, 1 man) presented with symptomatic intracranial occlusions of the internal carotid artery (n = 2) and vertebrobasilar system (n = 1). All 3 patients presented more than 6 hours after symptom onset, and no intravenous or intra-arterial thrombolysis had been instituted. In all cases, despite supportive medical therapy (anticoagulation and antiplatelet therapy and induced hypertension), the patients continued to demonstrate progressive ischemia, both clinically and on diffusion magnetic resonance imaging. All patients were successfully revascularized without periprocedural complications and improved clinically after revascularization. CONCLUSION: In selected patients, symptomatic subacute occlusions of intracranial arteries may be revascularized using the Wingspan stent system.

Angiographic patterns of Wingspan in-stent restenosis.

OBJECTIVE: A classification system developed to characterize in-stent restenosis (ISR) after coronary percutaneous transluminal angioplasty with stenting was modified and applied to describe the appearance and distribution of ISR occurring after Wingspan (Boston Scientific, Fremont, CA) intracranial percutaneous transluminal angioplasty with stenting. METHODS: A prospective, intention-to-treat, multicenter registry of Wingspan treatment for symptomatic intracranial atherosclerotic disease was maintained. Clinical and angiographic follow-up results were recorded. ISR was defined as greater than 50% stenosis within or immediately adjacent (within 5 mm) to the implanted stent(s) and greater than 20% absolute luminal loss. ISR lesions were classified by angiographic pattern, location, and severity in comparison with the original lesion treated. RESULTS: Imaging follow-up (3-15.5 months) was available for 127 intracranial stenotic lesions treated with Wingspan percutaneous transluminal angioplasty with stenting. Forty-one lesions (32.3%) developed either ISR (n = 36 [28.3%]) or complete stent occlusion (n = 5 [3.9%]) after treatment. When restenotic lesions were characterized using the modified classification system, 25 of 41 (61.0%) were focal lesions involving less than 50% of the length of the stented segment: three were Type IA (focal stenosis involving one end of the stent), 21 were Type IB (focal intrastent stenosis involving a segment completely contained within the stent), and one was Type IC (multiple noncontiguous focal stenoses). Eleven lesions (26.8%) demonstrated diffuse stenosis (>50% of the length of the stented segment): nine were Type II with diffuse intrastent stenosis (completely contained within the stent) and two were Type III with proliferative ISR (extending beyond the stented segment). Five stents were completely occluded at follow-up (Type IV). Of the 36 ISR lesions, 16 were less severe or no worse than the original lesion with respect to severity of stenosis or length of the segment involved; 20 lesions were more severe than the original lesion with respect to the segment length involved (n = 5), actual stenosis severity (n = 6), or both (n = 9). Nine of 10 supraclinoid internal carotid artery ISR lesions and nine of 13 middle cerebral artery ISR lesions were more severe than the original lesion. CONCLUSION: Wingspan ISR typically occurs as a focal lesion. In more than half of ISR cases, the ISR lesion was more extensive than the original lesion treated in terms of lesion length or stenosis severity. Supraclinoid internal carotid artery and middle cerebral artery lesions have a propensity to develop more severe posttreatment stenosis.