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Michael J. Ellis, Abhaya V. Kulkarni, James M. Drake, James T. Rutka, Derek Armstrong and Peter B. Dirks

Object

Confirming the successful management of pediatric arteriovenous malformations (AVMs) requires high-quality postoperative digital subtraction angiography. Although the role of intraoperative angiography during the microsurgical removal of AVMs is well established in adults, the technique has several limitations including poor image quality, uniplanar image acquisition, and absent full heparin protection. Here, the authors report on their experience with high-quality intraoperative angiography during the surgical management of pediatric AVMs in their image-guided therapy (IGT) facility.

Methods

The authors retrospectively reviewed the demographic, clinical, and radiological characteristics of 22 patients who underwent the surgical management of AVMs at the Hospital for Sick Children in Toronto, with the aid of high-quality intraoperative or immediate postresection cerebral angiography via a transfemoral approach.

Results

Between January 2000 and August 2009, 18 children (mean age 13.05 ± 4.04 years, range 4–21 years) underwent both surgical management of an AVM and intraoperative cerebral angiography at an IGT facility. An additional 4 children underwent angiography immediately after surgery in the regular operating room while under the same anesthesia. The mean AVM size was 2.55 ± 1.43 cm (range 1–6 cm) with a mean Spetzler-Martin grade of 2.27 (range 1–4). Intraoperative angiography in 4 of the 18 patients demonstrated residual AVM requiring additional resection. One patient demonstrated residual AVM on immediate postoperative angiography and underwent immediate reoperation. Successful excision of the residual AVM was confirmed on angiography the following day in that case. Procedural complications occurred in connection with 1 (3.3%) of 30 angiograms, including asymptomatic transient nonfilling of an ophthalmic artery, which was resolved on follow-up angiography. Negative intraoperative angiograms were confirmed with follow-up angiograms in 15 (93.75%) of 16 patients at a mean of 9.93 ± 5.70 months. One patient with a negative intraoperative angiogram demonstrated a tiny residual AVM on follow-up angiography at 8 months (false-negative rate 6.25%), but had a negative preoperative angiogram 1 year later in the IGT facility. No patient with a negative intraoperative angiogram required further AVM-directed treatment.

Conclusions

Intraoperative angiography is a safe and effective adjunct to the surgical management of AVMs in children. This novel approach allows the pre-, intra-, and postoperative acquisition of high-quality images, which can help guide the resection of AVMs, especially those that are small, diffuse, or of a complex angioarchitecture.

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Jay Riva-Cambrin, Allan S. Detsky, Maria Lamberti-Pasculli, Michael A. Sargent, Derek Armstrong, Rahim Moineddin, D. Douglas Cochrane and James M. Drake

Object

Approximately 30% of children with posterior fossa tumors exhibit hydrocephalus after tumor resection. Recent literature has suggested that prophylactic endoscopic third ventriculostomy diminishes the risk of this event. Because the majority of patients will not have postoperative hydrocephalus, a preoperative clinical prediction rule that identifies patients at high or low risk for postresection hydrocephalus would be helpful to optimize the care of these children.

Methods

The authors evaluated a derivation cohort of 343 consecutive children with posterior fossa tumors who underwent treatment between 1989 and 2003. Multivariate methods were used on these data to generate the Canadian Preoperative Prediction Rule for Hydrocephalus. The rule's estimated risk of postresection hydrocephalus was compared with risk observed in 111 independent patients in the validation cohort.

Results

Variables identified as significant in predicting postresection hydrocephalus were age < 2 years (score of 3), papilledema (score of 1), moderate to severe hydrocephalus (score of 2), cerebral metastases (score of 3), and specific estimated tumor pathologies (score of 1). Patients with scores ≥ 5 were deemed as high risk. Predicted probabilities for the high- and low-risk groups were 0.73 and 0.25, respectively, from the derivation cohort, and 0.59 and 0.14 after prevalence adjustment compared with the observed values of 0.42 and 0.17 in the validation cohort.

Conclusions

A patient's score on the Preoperative Prediction Rule for Hydrocephalus will allow improved patient counseling and surgical planning by identifying patients at high risk of developing postresection hydrocephalus. These patients might selectively be exposed to the risks of preresection CSF diversion to improve outcome.