External Carotid Artery Stenting to Treat Patients With Symptomatic Ipsilateral Internal Carotid Artery Occlusion

BACKGROUND

The external carotid artery (ECA) anastomoses in many distal territories supplied by the internal carotid artery (ICA) and is an important source of collateral circulation to the brain. Stenosis of the ECA in ipsilateral ICA occlusion can produce ischemic sequelae.

OBJECTIVE

To examine the effectiveness of ECA stenting in treating symptomatic ipsilateral ICA occlusion.

METHODS

We retrospectively reviewed patient databases from 5 academic medical centers to identify all individuals who underwent ECA stenting after 1998. For all discovered cases, coinvestigators used a common submission form to harvest relevant demographic information, clinical data, procedural details, and follow-up results for further analysis.

RESULTS

Twelve patients (median age, 66 years; range, 45–79 years) were identified for our cohort. Vessel disease involvement included severe ECA stenosis ≥ 70% in 11 patients and ipsilateral ICA occlusion in all patients. Presenting symptoms included signs of transient ischemic attack, stroke, and amaurosis fugax. ECA stenting was associated with preservation of neurological status in 11 patients and resolution of symptoms in 5 patients at a median follow-up time of 26 months (range, 1–87 months; mean, 29 months). Symptomatic in-stent restenosis did not occur within any patient during the follow-up course.

CONCLUSION

We found ECA stenting in symptomatic ipsilateral ICA disease to be a potentially effective strategy to preserve neurological function and to relieve ischemic symptoms. Further investigation with larger studies and longer follow-up periods is warranted to elucidate the true indications of this management strategy.

Surgical and endovascular treatments for intracranial aneurysms

The goals of microsurgical and endovascular treatment of intracranial aneurysms are to prevent subarachnoid hemorrhage and/or eliminate mass effect symptoms. Debate has raged regarding which aneurysms to treat and with which technique or combination of techniques. It is our impression that studies that have assessed aneurysm natural history and treatment options are compromised by the inherent limitations of clinical trials, with many natural history studies likely underestimating rupture risk over long-term follow-up. Endovascular therapy and open neurosurgery should both be used strategically, and our current interest is in integrating these techniques in a fashion extending beyond the simplistic clip-versus-coil debate.

Delayed Cranial Nerve Palsy After Coiling of Carotid Cavernous Sinus Aneurysms

OBJECTIVE

Detachable endovascular coils have become a common treatment strategy for carotid cavernous sinus aneurysms (CCAs), but previously unrecognized postprocedure complications may emerge as longer follow-up data are accumulated. In this report, the authors document the first known cases of delayed cranial neuropathy following CCA coiling in 3 patients, all of whom present at least a year postprocedure without aneurysm regrowth. The potential mechanisms underlying this syndrome are discussed as well as their implications on the selection and optimal endovascular management of CCA patients.

CLINICAL PRESENTATION

Three previously healthy females aged 50, 60, and 62 underwent CCA coiling at our institution and subsequently developed ipsilateral cranial nerve palsies at 56, 28, and 14 months, respectively, post-procedure. At presentation, all 3 patients had a new, recurrent area of flow in their CCA without changes in aneurysm size.

INTERVENTION

One patient declined further treatment. In the other 2 patients, a stent was placed across the aneurysm neck, and one patient underwent additional coiling. Unfortunately, all 3 patients remained symptomatic at their latest follow-up.

Conclusion

Because of the intimate anatomic environment of the cavernous sinus, neural elements within it may be particularly susceptible to persistent mass or dynamic effects exacerbated by remnant or recurrent flow across the neck of a coiled aneurysm. These 3 cases prompted the authors to advocate for more aggressive efforts to achieve and maintain CCA occlusion. Furthermore, when such efforts are unsuccessful, consideration of traditional carotid occlusion strategies with or without bypass is warranted.

Anticonvulsant use and outcomes after intracerebral hemorrhage

BACKGROUND AND PURPOSE

There are few data on the effectiveness and side effects of antiepileptic drug therapy after intracerebral hemorrhage. We tested the hypothesis that antiepileptic drug use is associated with more complications and worse outcome after intracerebral hemorrhage.

METHODS

We prospectively enrolled 98 patients with intracerebral hemorrhage and recorded antiepileptic drug use as either prophylactic or therapeutic along with clinical characteristics. Antiepileptic drug administration and free phenytoin serum levels were retrieved from the electronic medical records. Patients with depressed mental status underwent continuous electroencephalographic monitoring. Outcomes were measured with the National Institutes of Health Stroke Scale and modified Rankin Scale at 14 days or discharge and the modified Rankin Scale at 28 days and 3 months. We constructed logistic regression models for poor outcome at 3 months with a forward conditional model.

RESULTS

Seven (7%) patients had a clinical seizure, 5 on the day of intracerebral hemorrhage. Phenytoin was associated with more fever (P=0.03), worse National Institutes of Health Stroke Scale at 14 days (23 [9 to 42] versus 11 [4 to 23], P=0.003), and worse modified Rankin Scale at 14 days, 28 days, and 3 months. In a forward conditional logistic regression model, phenytoin prophylaxis was associated with an increased risk of poor outcome (OR, 9.8; 1.4 to 68.6; P=0.02), entering after admission National Institutes of Health Stroke Scale and age. Excluding patients with a seizure did not change the results. Levetiracetam was not associated with demographics, seizures, complications, or outcomes.

CONCLUSIONS

Phenytoin was associated with more fever and worse outcomes after intracerebral hemorrhage.

4D radial acquisition contrast-enhanced MR angiography and intracranial arteriovenous malformations: quickly approaching digital subtraction angiography

BACKGROUND AND PURPOSE

The current gold standard for imaging intracranial AVMs involves catheter-based techniques, namely cerebral digital subtraction angiography (DSA). However, DSA presents some procedural risks to the patient. Unfortunately, AVM patients usually undergo multiple DSA exams throughout their diagnostic and therapeutic course, significantly increasing their procedural risk exposure. As such, high-quality noninvasive imaging is desired. We hypothesize that 4D radial acquisition contrast-enhanced MRA approximates the vascular architecture and hemodynamics of AVMs compared to conventional angiography.

METHODS

Thirteen consecutive AVM patients were assessed by 4D radial acquisition contrast-enhanced MRA and DSA. The 4D rCE-MRA images were independently assessed regarding the location, nidal size, Spetzler-Martin grade, and identification of arterial feeders, drainage pattern, and any other vascular anomalies.

RESULTS

4D rCE-MRA correctly depicted the size, venous drainage pattern, and prominent arterial feeders in all cases. Spetzler-Martin grade was correctly determined between reviewers and between the different imaging modalities in all cases except 1. The nidus size was in good correlation between the reviewers, where r=0.99, P<0.000001. There was very good agreement between reviewers regarding the individual scans (kappa=0.63 to 1), whereas the agreement between the DSA and 4D rCE-MRA images was also good (kappa=0.61 to 0.85).

CONCLUSIONS

We have developed a 4D radial acquisition contrast-enhanced MRA sequence capable of imaging intracranial AVMs approximating that of DSA. Image analysis demonstrates equivalency in terms of grading AVMs using the Spetzler-Martin grading scale. This 4D rCE-MRA sequence has the potential to avoid some applications of DSA, thus saving patients from potential procedural risks.

Surgical management of superficial siderosis

BACKGROUND CONTEXT

Superficial siderosis is a rare condition resulting from the presence of chronic bleeding into the subarachnoid space usually causing gait instability and deafness. The surgical management of superficial siderosis depends on localizing the source of hemorrhage.

PURPOSE

The surgical treatment of this rare condition has not been well described in the literature. We present a case illustrating the surgical treatment for superficial siderosis.

STUDY DESIGN

Case report.

PATIENT SAMPLE

The authors describe the case report of a 70-year-old gentleman with gait instability and deafness found to have an abnormal communication between the spinal epidural venous plexus and the subarachnoid space.

METHODS

The source of hemorrhage into the subarachnoid space was identified to be a fistula in the ventral thoracic dural. A costotransversectomy approach was undertaken at the T4-T5 level to expose the fistula. The abnormal communication was patched and sealed.

RESULTS

The patient's symptoms remained stable on follow-up at 15 months with no worsening of his symptoms.

CONCLUSIONS

Superficial siderosis is a neurologic disorder that arises from chronic hemosiderin deposition into the subarachnoid space. The progressive nature of the disease can be halted if a source of hemorrhage can be found and treated surgically.

Radiosurgery for angiographically occult vascular malformations

The use of radiosurgery for angiographically occult vascular malformations (AOVMs) is a controversial treatment option for those that are surgically inaccessible or located in eloquent brain. To determine the efficacy of this treatment, the authors reviewed the literature reporting hemorrhage rates, seizure control, and radiation-induced morbidity. They found overall hemorrhage rates of 2-6.4%, overall postradiosurgery hemorrhage rates of 1.6-8%, and stratified postradiosurgery hemorrhage rates of 7.3-22.4% in the period immediately to 2 years after treatment; these latter rates declined to 0.8-5.2% > 2 years after treatment. Of 291 patients presenting with seizure across 16 studies, 89 (31%) attained a seizure-free status and 102 (35%) had a reduction in seizure frequency after radiosurgery. Overall radiation-induced morbidity ranged from 2.5 to 59%, with higher complication rates in patients with brainstem lesion locations. Researchers applying mean radiation doses of 15-16.2 Gy to the tumor margin saw both low radiation-induced complication rates (0-9.1%) and adequate hemorrhage control (0.8-5.2% > 2 years after treatment), whereas mean doses >or= 16.5 Gy were associated with higher total radiation-induced morbidity rates (> 17%). Although the use of stereotactic radiosurgery remains controversial, patients with AOVMs located in surgically inaccessible areas of the brain may benefit from such treatment.

Posterior fossa arteriovenous malformations

Arteriovenous malformations (AVMs) of the posterior fossa are complex neurovascular lesions that are less common than their supratentorial counterparts, accounting for < 15% of all AVMs. The majority of patients with these lesions present with intracranial hemorrhage, a factor that has been consistently shown to increase one's risk for subsequent bleeding. Studies have additionally shown a posterior fossa or deep AVM location to portend a more aggressive natural history. The authors reviewed the literature on posterior fossa AVMs, finding their annual rupture rates to be as high as 11.6%, an important factor that underscores the importance of aggressive treatment of lesions amenable to intervention as therapeutic options and results continue to improve.

Radial sliding-window magnetic resonance angiography (MRA) with highly-constrained projection reconstruction (HYPR)

Sufficient temporal resolution is required to image the dynamics of blood flow, which may be critical for accurate diagnosis and treatment of various intracranial vascular diseases, such as arteriovenous malformations (AVMs) and aneurysms. Highly-constrained projection reconstruction (HYPR) has recently become a technique of interest for high-speed contrast-enhanced magnetic resonance angiography (CE-MRA). HYPR provides high frame rates by preferential weighting of radial projections while maintaining signal-to-noise ratio (SNR) by using a high SNR composite. An analysis was done to quantify the effects of HYPR on SNR, contrast-to-noise ratio (CNR), and temporal blur compared to the previously developed radial sliding-window technique using standard filtered backprojection or regridding methods. Computer simulations were performed to study the effects of HYPR processing on image error and the temporal information. Additionally, in vivo imaging was done on patients with angiographically confirmed AVMs to measure the effects of alteration of various HYPR parameters on SNR as well as the fidelity of the temporal information. The images were scored by an interventional radiologist in a blinded read and were compared with X-ray digital subtraction angiography (DSA). It was found that with the right choice of parameters, modest improvements in both SNR and dynamic information can be achieved as compared to radial sliding-window MRA.

Moyamoya disease: a summary

Moyamoya, meaning a "hazy puff of smoke" in Japanese, is a chronic, occlusive cerebrovascular disease involving bilateral stenosis or occlusion of the terminal portion of the internal carotid arteries (ICAs) and/or the proximal portions of the anterior cerebral arteries and middle cerebral arteries (MCAs). The Ministry of Health and Welfare of Japan has defined 4 types of moyamoya disease (MMD): ischemic, hemorrhagic, epileptic, and "other." The ischemic type has been shown to predominate in childhood, while the hemorrhagic type is more often observed in the adult population. The highest prevalence of MMD is found in Japan, with a higher female to male ratio. Studies have shown a possible genetic association of MMD linked to chromosome 17 in Japanese cases as well as in cases found in other demographics. During autopsy, intracerebral hematoma is found and most commonly serves as the major cause of death in patients with MMD. Moyamoya vessels at the base of the brain are composed of medium-sized or small muscular arteries emanating from the circle of Willis, mainly the intracranial portions of ICAs, anterior choroidal arteries, and posterior cerebral arteries, forming complex channels that connect with distal positions of the MCAs. Off of these channels are small tortuous and dilated vessels that penetrate into the base of the brain at the site of the thalamoperforate and lenticulostriate arteries. On angiography, there is the characteristic stenosis or occlusion bilaterally at the terminal portion of the ICAs as well as the moyamoya vessels at the base of the brain. Six angiographic stages have been described, from Stage 1, which reveals a narrowing of the carotid forks, to Stage 6, in which the moyamoya vessels disappear and collateral circulation is produced solely from the external carotid arteries. Cases with milder symptoms are usually treated conservatively; however, more severe symptomatic cases are treated using revascularization procedures. Surgical treatments are divided into 3 types: direct, indirect, and combined/other methods. Direct bypass includes superficial temporal artery-MCA bypass or use of other graft types. Indirect procedures bring in circulation to the intracranial regions by introducing newly developed vasculature from newly approximated tissues. These procedures may not be enough to prevent further ischemia; therefore, a combination of direct and indirect procedures is more suitable. This article will give a review of the epidemiology, natural history, pathology, pathophysiology, and diagnostic criteria, including imaging, and briefly describe the surgical treatment of MMD.

CAVERNOUS MALFORMATIONS OF THE BASAL GANGLIA AND THALAMUS

CAVERNOUS MALFORMATIONS OF the basal ganglia and thalamus present a unique therapeutic challenge to the neurosurgeon given their unclear natural history, the risk of surgical treatment, and the unproven efficacy of radiosurgical therapy. Via a PubMed search of the English and French literature, we have systematically reviewed the natural history and surgical and radiosurgical management of these lesions reported through April 2008. Including rates cited for “deep” cavernous malformations, annual bleeding rates for these lesions varied from 2.8% to 4.1% in the natural history studies. Across surgical series providing postoperative or long-term outcome data on 103 patients, we found an 89% resection rate, a 10% risk of long-term surgical morbidity, and a 1.9% risk of surgical mortality. The decrease in hemorrhage risk reported 2 years after radiosurgery might be a result of natural hemorrhage clustering, underscoring the unproven efficacy of this therapeutic modality. Given the compounded risks of radiation-induced injury and post-radiosurgical rebleeding, radiosurgery at modest dosimetry (12–14 Gy marginal doses) is only an option for patients with surgically inaccessible, aggressive lesions.

Resident duty hour regulation and patient safety: establishing a balance between concerns about resident fatigue and adequate training in neurosurgery

Postgraduate training in medicine has been under scrutiny over the past 10 years with a major focus on physician personal health and patient safety. The culmination of a series of events led to the 80-hour work week instituted by the Accreditation Council on Graduate Medical Education in 2003. The effect this mandate has had on surgical education, and specifically training in neurological surgery, has been incompletely evaluated. Nevertheless, external pressure has prompted the Institute of Medicine to issue a new report on resident work hours and patient safety. In this report, the authors focus on the unique aspects of neurosurgical training in which physicians are trained to safely and effectively carry out complex high-risk tasks, the experience from abroad where work hours are reduced to well below 80 hours/week, and the risk that further reduction in work hours poses to the public. The authors conclude that there must be an adequate balance between the risks associated with resident fatigue and those associated with an inexperienced neurosurgical work force for public health.

High-grade dural arteriovenous fistula simulating a bilateral thalamic neoplasm

Dural arteriovenous fistulae (dAVF) provide a diagnostic challenge and must be part of a broad differential in pursuit of a difficult diagnosis or unusual presentation. This case report demonstrates an initially misguided diagnosis of bilateral thalamic neoplasm and demonstrates the importance of continued pursuit until the correct diagnosis is obtained. Moreover, to our knowledge, this is the first reported case of a dAVF simulating a bilateral thalamic neoplasm. We present a patient with a provisional diagnosis of bilateral thalamic neoplasm based on clinical history and an advanced imaging workup including MR spectroscopy. Subsequent biopsy suggested venous congestion, hypoxia, and edema without neoplasia. Routine post-operative CT the following day revealed suggestion of dAVF due to the presence of residual contrast from prior unrelated abdominal CT. Cerebral angiography eventually revealed a Cognard grade IIb dAVF. Trans-arterial Onyx embolization resulted in a dramatic clinical and radiographic improvement. This case highlights an unusual presentation and challenging diagnosis of a dAVF and the importance of pursuing the correct diagnosis.

CLASSIFICATION OF CEREBRAL INFARCTION AFTER SUBARACHNOID HEMORRHAGE IMPACTS OUTCOME

OBJECTIVE

Cerebral infarction (CI) after subarachnoid hemorrhage (SAH) is well described, but there is no validated classification.

METHODS

We prospectively enrolled 119 consecutive patients with SAH. We recorded admission World Federation of Neurological Societies grade and Columbia computed tomographic scores. Vasospasm was defined as transcranial Doppler of greater than 120 cm/second or typical clinical symptoms. CI was defined by computed tomographic or magnetic resonance imaging scan, and the date of discovery was recorded. CI was classified by a previously published method (single versus multiple, cortical versus deep versus combined). Outcomes were assessed at 14 days or discharge with the National Institutes of Health Stroke Scale and modified Rankin Scale (mRS), and at 28 days and 3 months with the mRS.

RESULTS

Vasospasm was associated with a higher risk of CI (odds ratio, 2.6; 95% confidence interval, 1.3–5.6; P = 0.01). The median time to detection was 4.2 days (interquartile range, 1.6–7.6 days) after SAH onset. CI classification was associated with the National Institutes of Health Stroke Scale score at 14 days (P = 0.002) and intensive care unit length of stay (P = 0.001). CI location (cortical, deep, or combined) was associated with National Institutes of Health Stroke Scale and mRS score at 14 days, and mRS score at 28 days and 3 months (P ≤ 0.02 for all). In a multiple logistic regression model, CI classification, World Federation of Neurological Societies grade, aneurysm diameter, and age were all associated with mRS score at 28 days and 3 months (P ≤ 0.05). Combined cortical and deep CI was associated with less improvement and poor outcome.

CONCLUSION

CI classification predicts outcomes after SAH. Future reports of CI after SAH should include this or similar descriptive information.

Introduction: vascular neurosurgery

This issue of Neurosurgical Focus comes at an exciting and perhaps transformational time for those neuroscientists and clinicians involved in the study and treatment of complex cerebrovascular disease. Our diagnostic and therapeutic practices have seen dramatic advances. Imaging capabilities, both anatomical and functional, have improved at a dramatic rate and include neuronavigation modalities for intraoperative guidance, the application of new MR imaging sequences to cerebrovascular disease, and fluorescence angiography to aid in intraoperative decision making.

Challenging traditional beliefs: microsurgery for arteriovenous malformations of the basal ganglia and thalamus

OBJECTIVE

Arteriovenous malformations of the basal ganglia and thalamus are often managed with radiosurgery or observation, without consideration of microsurgery. Given the devastating effects of hemorrhage from these lesions, the accumulating evidence that they bleed more frequently than their lobar counterparts should prompt more creative thinking regarding their management.

METHODS

A review of the endovascular, microsurgical, and radiosurgical literature for arteriovenous malformations of the basal ganglia and thalamus was performed, with close attention to surgical approaches, obliteration rates, and procedure-related complications.

RESULTS

A complete resection rate of 91% and a mortality rate of 2.4% were found across surgical series of these lesions. These contrast with a 69% rate of complete obliteration and a 5.3% mortality rate (from latency-period hemorrhage) found when compiling results across the radiosurgical literature.

CONCLUSION

Given an appropriate surgical corridor of access, often afforded by incident hemorrhage, arteriovenous malformations of the basal ganglia and thalamus should be considered for microsurgical extirpation with preoperative embolization. In experienced hands, this approach presents an expeditious and definitive opportunity to eliminate the risk of subsequent hemorrhage and resultant morbidity and mortality.