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Ruth E. Bristol, Felipe C. Albuquerque, and Cameron G. McDougall

✓ Endovascular therapy for arteriovenous malformations (AVMs) remains a relatively new approach. Beginning in the 1960s with the use of flow-directed techniques for selective embolization, hemodynamic alterations have been used to treat these lesions. In every aspect of treatment, technological advances, including catheters, embolic materials, angiography suites, and pharmacological agents, have improved outcomes while lowering the risk to patients.

In this article, the authors review the technical evolution of endovascular AVM therapy. Developments in embolic materials, beginning with foreign bodies and autografts and continuing through to highly engineered contemporary substances, are discussed. Finally, changes in treatment paradigms that have occurred over the years are traced. Within neurosurgery, this specialty has shown some of the fastest growth and development in recent decades. As minimally invasive approaches are embraced in all areas of medicine, it is clear that this treatment modality will continue to be refined.

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De novo presentation of an arteriovenous malformation

Case report and review of the literature

L. Fernando Gonzalez, Ruth E. Bristol, Randall W. Porter, and Robert F. Spetzler

✓ The authors report the case of a patient with a de novo arteriovenous malformation (AVM), indicating that the origin of these lesions may not always be congenital.

A 3-year-old girl who was struck by a car suffered a mild head injury and experienced posttraumatic epilepsy. The initial magnetic resonance (MR) image obtained in this child revealed only a small contusion in the left frontal lobe. Intractable epilepsy subsequently developed. A second MR image obtained almost 4 years after the injury demonstrated an AVM in the right posterior temporal lobe that was verified using angiography. The lesion was classified as a Spetzler—Martin Grade III AVM. The patient underwent embolization of the feeding vessels followed by gamma knife surgery. Fourteen months after treatment she was asymptomatic. Follow-up MR images demonstrate no evidence of an AVM and no changes in the white matter.

This case presents a de novo AVM that developed within approximately 4 years. The findings indicate that AVMs may not always be congenital and reinforce the concept that the natural history of AVMs is dynamic. Lesions may appear de novo, grow, and thrombose spontaneously.

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Ruth E. Bristol, Felipe C. Albuquerque, Cameron McDougall, and Robert F. Spetzler

✓Although many arachnoid cysts are discovered incidentally and require no intervention, a small subset has been known to rupture. Note that rupture can occur either spontaneously or in association with trauma. Based on a review of the literature on ruptured arachnoid cysts, it appears that patients with middle fossa cysts are more likely to experience symptomatic traumatic rupture than those with cysts in other locations. Middle fossa cysts are more commonly associated with hemispheric subdural collections and hematomas than are any other cysts. The authors report on two representative cases illustrating the distinct presentation, imaging characteristics, and management of these cysts.

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Timothy Uschold, Adib A. Abla, David Fusco, Ruth E. Bristol, and Peter Nakaji


The heterogeneous clinical manifestations and operative characteristics of pathological entities in the pineal region represent a significant challenge in terms of patient selection and surgical approach. Traditional surgical options have included endoscopic transventricular resection; open supratentorial microsurgical approaches through the midline, choroidal fissure, lateral ventricle, and tentorium; and supracerebellar infratentorial (SCIT) approaches through the posterior fossa. The object of the current study was to review the preoperative characteristics and outcomes for a cohort of patients treated purely via the novel endoscopically controlled SCIT approach.


A single-institution series of 9 consecutive patients (4 male and 5 female patients [10 total cases]; mean age 21 years, range 6–37 years) treated via the endoscopically controlled SCIT approach for a pathological entity in the pineal region was retrospectively reviewed. The mean follow-up time was 13.2 months.


The endoscopically controlled SCIT approach was successfully used to approach a variety of pineal lesions, including pineal cysts (6 patients), epidermoid tumor, WHO Grade II astrocytoma (initial biopsy and recurrence), and malignant mixed germ cell tumor (1 patient each). Gross-total resection and/or adequate cyst fenestration was achieved in 8 cases. Biopsy with conservative debulking was performed for the single case of low-grade astrocytoma and again at the time of recurrence.

The mean preoperative tumor and cyst volumes were 9.9 ± 4.4 and 3.7 ± 3.2 cm3, respectively. The mean operating times were 212 ± 71 minutes for tumor cases and 177 ± 72 minutes for cysts. Estimated blood loss was less than 150 ml for all cases. A single case (pineal cyst) was converted to an open microsurgical approach to enhance visualization. There were no operative complications, as well as no documented CSF leaks, additional CSF diversion procedures, or air emboli. Seven patients underwent concomitant third ventriculostomy into the quadrigeminal cistern. At the time of the last follow-up evaluation, all patients had a stable or improved modified Rankin Scale score.


The endoscopically controlled SCIT approach may be used for the biopsy and resection of appropriately selected solid tumors of the pineal region, in addition to the fenestration and/or resection of pineal cysts. Preoperative considerations include patient presentation, anticipated disease and vascularity, degree of local venous anatomical distortion, and selection of optimal paramedian trajectory.

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Ruth E. Bristol, Felipe C. Albuquerque, Robert F. Spetzler, Harold L. Rekate, Cameron G. McDougall, and Joseph M. Zabramski


Children compose 3 to 20% of the patients with arteriovenous malformations (AVMs); however, AVMs are responsible for 30 to 50% of intracranial hemorrhages in children.


The medical records of 82 children with 84 AVMs treated surgically between 1983 and 2005 were reviewed. Fifty-two patients (63%) presented with hemorrhage, 13.4% presented with seizures, and AVMs in 12% were found incidentally. Patients with brainstem lesions presented at a significantly younger age (p = 0.002) than those harboring lesions in other locations. Frontal lobe lesions were significantly smaller than those in other locations, and thalamic lesions were significantly larger (p = 0.012 and 0.005, respectively). Most patients with Spetzler–Martin Grades I to III lesions underwent craniotomy only. Half of the patients with Grade IV and V lesions underwent embolization, craniotomy, and radiosurgery.

The mean follow-up period was 43 months. Postoperatively, the initial obliteration rate was 65%, with a long-term obliteration rate of 90%. The perioperative mortality rate was 3.7%. Altogether, 81% of patients had excellent outcomes, and patients with Grade I lesions had the best outcomes. Of the 52 patients who presented with hemorrhage, 17% had fair or poor outcomes. The recurrence rate was 5.6%.


Children with AVMs may be more prone than adults to present with a hemorrhage and to experience recurrence of the lesion after treatment. The authors favor resection for most AVMs in children and use embolization as a preoperative strategy for Grades II to V lesions treated surgically. Prehemorrhagic Grade IV and V lesions may best be treated conservatively and observed carefully for the development of symptoms. Long-term follow up of all patients is essential.

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Eric M. Horn, Ruth E. Bristol, Iman Feiz-Erfan, Elisa J. Beres, Nicholas C. Bambakidis, and Nicholas Theodore

✓Pseudomeningoceles rarely develop after cervical trauma; in all reported cases the lesions have extended outside the spinal canal.

The authors report the first known cases of anterior cervical pseudomeningoceles contained entirely within the spinal canal and causing cord compression and neurological injury. The authors retrospectively reviewed the cases of three patients with traumatic cervical spine injuries and concomitant compressive anterior pseudomeningoceles. The lesion was recognized in the first case when the patient’s neurological status declined after he sustained a severe atlantoaxial injury; the pseudomeningocele was identified intraoperatively and decompressed. After the decompressive surgery, the patient’s severe tetraparesis partially resolved. In the other two patients diagnoses of similar pseudomeningoceles were established by magnetic resonance imaging. Both patients were treated conservatively, and their mild to moderate hemiparesis due to the pseudomeningocele-induced compression abated.

The high incidence of anterior cervical pseudomeningoceles seen at the authors’ institution within a relatively brief period suggests that this lesion is not rare. The authors believe that it is important to recognize the compressive nature of these lesions and their potential to cause devastating neurological injury.

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David S. Hersh, Jonathan E. Martin, Ruth E. Bristol, Samuel R. Browd, Gerald Grant, Nalin Gupta, Todd C. Hankinson, Eric M. Jackson, John R. W. Kestle, Mark D. Krieger, Abhaya V. Kulkarni, Casey J. Madura, Jonathan Pindrik, Ian F. Pollack, Jeffrey S. Raskin, Jay Riva-Cambrin, Curtis J. Rozzelle, Jodi L. Smith, and John C. Wellons III


Long-term follow-up is often recommended for patients with hydrocephalus, but the frequency of clinical follow-up, timing and modality of imaging, and duration of surveillance have not been clearly defined. Here, the authors used the modified Delphi method to identify areas of consensus regarding the modality, frequency, and duration of hydrocephalus surveillance following surgical treatment.


Pediatric neurosurgeons serving as institutional liaisons to the Hydrocephalus Clinical Research Network (HCRN), or its implementation/quality improvement arm (HCRNq), were invited to participate in this modified Delphi study. Thirty-seven consensus statements were generated and distributed via an anonymous electronic survey, with responses structured as a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree). A subsequent, virtual meeting offered the opportunity for open discussion and modification of the statements in an effort to reach consensus (defined as ≥ 80% agreement or disagreement).


Nineteen pediatric neurosurgeons participated in the first round, after which 15 statements reached consensus. During the second round, 14 participants met virtually for review and discussion. Some statements were modified and 2 statements were combined, resulting in a total of 36 statements. At the conclusion of the session, consensus was achieved for 17 statements regarding the following: 1) the role of standardization; 2) preferred imaging modalities; 3) postoperative follow-up after shunt surgery (subdivided into immediate postoperative imaging, delayed postoperative imaging, routine clinical surveillance, and routine radiological surveillance); and 4) postoperative follow-up after an endoscopic third ventriculostomy. Consensus could not be achieved for 19 statements.


Using the modified Delphi method, 17 consensus statements were developed with respect to both clinical and radiological follow-up after a shunt or endoscopic third ventriculostomy. The frequency, modality, and duration of surveillance were addressed, highlighting areas in which no clear data exist to guide clinical practice. Although further studies are needed to evaluate the clinical utility and cost-effectiveness of hydrocephalus surveillance, the current study provides a framework to guide future efforts to develop standardized clinical protocols for the postoperative surveillance of patients with hydrocephalus. Ultimately, the standardization of hydrocephalus surveillance has the potential to improve patient care as well as optimize the use of healthcare resources.