Dale Ding and Kenneth C. Liu
Intracranial atherosclerosis presents a therapeutic challenge to medical and surgical physicians alike. Despite maximal medical therapy, the stroke rate from this disease is still high, especially when arterial stenosis is severe and patients are symptomatic. Open surgical therapy has yet to be shown to be a more efficacious treatment than medical therapy alone, largely due to the relatively high rates of perioperative complications. Angioplasty has a similar fate, with the risk of periprocedural complications outweighing the overall benefit of treatment. With the advent of stents for use in intracranial vasculature, new hope has arisen for the treatment of intracranial atherosclerosis. The NEUROLINK system, the drug-eluting stents Taxus and Cypher, the flexible Wingspan stent, the Apollo stent, and the Pharos stent have all been used in various prospective and retrospective clinical studies with varying technical and clinical results. The authors' objective is to review and loosely compare the data presented for each of these stenting systems. While the Wingspan stent appears to have somewhat of an advantage with regard to technical success in comparison with the other stenting systems, the clinical follow-up time of its studies is too short to properly compare its complication rates with those of other stents. Before we continue to move forward with stenting for intracranial stenosis, a randomized prospective trial is ultimately needed to directly compare intracranial stenting to medical therapy.
Daling Ding, Ailing Zhao, Bo Qiu, Deguang Xing, Gefei Guan and Zongze Guo
Ependymoblastoma is a rare and devastating primitive neuroectodermal tumor with ependymal differentiation. This tumor occurs very early in life and shows rapid growth and a diffuse infiltration through the leptomeningeal space. This neoplasm is characterized by uniform neuroepithelial cells, multilayered ependymal rosettes, perivascular pseudorosettes, and numerous mitotic figures. In this article, the authors report on a 4-year-old girl who was diagnosed as having an ependymoblastoma with cystic change. After a series of laboratory and imaging examinations, the left frontal solid-cystic lesion was surgically excised. Histological examinations confirmed the diagnosis of ependymoblastoma. The patient's intracranial hypertension symptoms were alleviated, and postoperative chemotherapy was performed. At the 6-month follow-up visit, MRI demonstrated evidence of relapse, and the girl died of tumor recurrence 14 months after surgery.
Databases (PubMed, MEDLINE, Embase, and Web of Science) were searched for relevant articles published from 1970 to 2012; 71 eligible cases of ependymoblastoma were obtained, and 42 provided complete clinical details. Prognosis of children with ependymoblastoma is poor, and data on clinical behavior and optimal treatment strategies are lacking, but sustained remissions have been achieved after multimodal treatment according to existing literature. In this report, the clinical and histopathological features and therapeutic options of this tumor are discussed in the light of the published data. Further studies, especially those examining multimodality therapy, are needed to improve survival of children with this rare malignant CNS tumor.
Jason Sheehan, Dale Ding and Robert M. Starke
Chun-Po Yen, Dale Ding, Ching-Hsiao Cheng, Robert M. Starke, Mark Shaffrey and Jason Sheehan
A relatively benign natural course of unruptured cerebral arteriovenous malformations (AVMs) has recently been recognized, and the decision to treat incidentally found AVMs has been questioned. This study aims to evaluate the long-term imaging and clinical outcomes of patients with asymptomatic, incidentally discovered AVMs treated with Gamma Knife surgery (GKS).
Thirty-one patients, each with an incidentally diagnosed AVM, underwent GKS between 1989 and 2009. The nidus volumes ranged from 0.3 to 11.1 cm3 (median 3.2 cm3). A margin dose between 15 and 26 Gy (median 20 Gy) was used to treat the AVMs. Four patients underwent repeat GKS for still-patent AVM residuals after the initial GKS procedure. Clinical follow-up ranged from 24 to 196 months, with a mean of 78 months (median 51 months) after the initial GKS.
Following GKS, 19 patients (61.3%) had a total AVM obliteration on angiography. In 7 patients (22.6%), no flow voids were observed on MRI but angiographic confirmation was not available. In 5 patients (16.1%), the AVMs remained patent. A small nidus volume was significantly associated with increased AVM obliteration rate. Thirteen patients (41.9%) developed radiation-induced imaging changes: 11 were asymptomatic (35.5%), 1 had only headache (3.2%), and 1 developed seizure and neurological deficits (3.2%). Two patients each had 1 hemorrhage during the latency period (116.5 risk years), yielding an annual hemorrhage rate of 1.7% before AVM obliteration.
The decision to treat asymptomatic AVMs, and if so, which treatment approach to use, remain the subject of debate. GKS as a minimally invasive procedure appears to achieve a reasonable outcome with low procedure-related morbidity. In those patients with incidental AVMs, the benefits as well as the risks of radiosurgical intervention will only be fully defined with long-term follow-up.
Gautam U. Mehta, Michael J. Feldman, Herui Wang, Dale Ding and Prashant Chittiboina
The presence of vestibular schwannomas has long been considered an exclusion criterion for the diagnosis of schwannomatosis. Recently, 2 cases of vestibular schwannoma were reported in patients with schwannomatosis, leading to a revision of the diagnostic criteria for this genetic disorder. Overall, the relative infrequency of vestibular schwannomas in schwannomatosis is unexplained, and the genetics of this uncommon phenomenon have not been described. The authors report on a family with clinical manifestations consistent with schwannomatosis, including 4 affected members, that was identified as having an affected member harboring a unilateral cerebellopontine angle mass with extension into the internal auditory canal. Radiologically, this mass was consistent with a vestibular schwannoma and resulted in a symptomatic change in ipsilateral hearing (word recognition 86% at 52 dB) and increased latency of the wave I–V interval on auditory brainstem response testing. The patient was found to be negative for a germline mutation of NF2 and LZTR1, and her affected mother was found to harbor neither NF2 nor SMARCB1 mutations on genetic testing. Although vestibular schwannomas have been classically considered to not occur in the setting of schwannomatosis, this patient with schwannomatosis and a vestibular schwannoma further confirms that schwannomas can occur on the vestibular nerve in this syndrome. Further, this is the first such case found to be negative for a mutation on the LZTR1 gene.
Bruce E. Pollock
Dale Ding, Chun-Po Yen, Zhiyuan Xu, Robert M. Starke and Jason P. Sheehan
The appropriate management of unruptured intracranial arteriovenous malformations (AVMs) remains controversial. In the present study, the authors evaluate the radiographic and clinical outcomes of radiosurgery for a large cohort of patients with unruptured AVMs.
From a prospective database of 1204 cases of AVMs involving patients treated with radiosurgery at their institution, the authors identified 444 patients without evidence of rupture prior to radiosurgery. The patients' mean age was 36.9 years, and 50% were male. The mean AVM nidus volume was 4.2 cm3, 13.5% of the AVMs were in a deep location, and 44.4% were at least Spetzler-Martin Grade III. The median radiosurgical prescription dose was 20 Gy. Univariate and multivariate Cox regression analyses were used to determine risk factors associated with obliteration, postradiosurgery hemorrhage, radiation-induced changes, and postradiosurgery cyst formation. The mean duration of radiological and clinical follow-up was 76 months and 86 months, respectively.
The cumulative AVM obliteration rate was 62%, and the postradiosurgery annual hemorrhage rate was 1.6%. Radiation-induced changes were symptomatic in 13.7% and permanent in 2.0% of patients. The statistically significant independent positive predictors of obliteration were no preradiosurgery embolization (p < 0.001), increased prescription dose (p < 0.001), single draining vein (p < 0.001), radiological presence of radiation-induced changes (p = 0.004), and lower Spetzler-Martin grade (p = 0.016). Increased volume and higher Pittsburgh radiosurgery-based AVM score were predictors of postradiosurgery hemorrhage in the univariate analysis only. Clinical deterioration occurred in 30 patients (6.8%), more commonly in patients with postradiosurgery hemorrhage (p = 0.018).
Radiosurgery afforded a reasonable chance of obliteration of unruptured AVMs with relatively low rates of clinical and radiological complications.