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James S. Walkden, Zsolt Zador, Amit Herwadkar, and Ian D. Kamaly-Asl

OBJECT

Over the last 20 years, several intraoperative adjuncts, including ultrasonography, neuronavigation, and angiography, have been said to aid the intraoperative localization and resection of cerebral arteriovenous malformations (AVMs). The authors assessed the value of intraoperative Doppler ultrasonography in conjunction with neuronavigation during surgery for cerebral AVMs in the pediatric population.

METHODS

The authors reviewed all cranial AVM resections performed by a single surgeon at their institution in the period from 2007 to 2013 and here describe their experience and results in a series of 20 consecutive AVM resections in 19 pediatric patients. Intraoperative Doppler ultrasonography had been used in conjunction with preoperative CT or neuronavigational MRI. Preoperative and postoperative clinical findings, patient age, and Spetzler-Martin AVM grade were identified in all patients.

RESULTS

All patients, whose ages ranged from 2 to 16 years, underwent craniotomy and excision of an AVM, which was supratentorial in 18 cases and infratentorial in 2. Patients in 11 cases underwent preoperative embolization, and all other patients underwent cerebral angiography prior to surgery, except for 2 patients who were urgently surgically treated because of low Glasgow Coma Scale scores and associated hematoma. Spetzler-Martin Grades I (3 cases), II (6), III (7), and IV (4) AVMs were represented in this series. Intraoperative Doppler ultrasound provided high-quality images in all cases and demonstrated the location, size, and flow characteristics of the AVM and any associated hematoma. Delayed postoperative cerebral angiography demonstrated successful AVM resection in all cases. An assessment of clinical outcomes revealed no new long-term neurological deficits at 3 months postoperatively.

CONCLUSIONS

Intraoperative Doppler ultrasonography is a reliable and useful tool for intraoperative localization and guidance for AVM resection in the pediatric population. When used in conjunction with neuronavigation equipment and modern microscopes, this technique has shown a very high complete resection rate with extremely low associated morbidity.

Free access

Zsolt Zador, David J. Coope, and Ian D. Kamaly-Asl

OBJECT

Endoscopic third ventriculostomy (ETV) has become a widely used method for CSF diversion when treating obstructive hydrocephalus. There are multiple recommendations on the transcortical ETV entry points, and some are specifically designed to provide a trajectory that avoids displacement to the eloquent periventricular structures. However, the morphology of the ventricular system is highly variable in hydrocephalus, and therefore a single best ETV trajectory may not be applicable to all cases. In the current study, 3 frequently quoted ETV entry points are compared in a cohort of pediatric cases with different degrees of ventriculomegaly.

METHODS

The images of 30 consecutive pediatric patients with varying degrees of ventriculomegaly were reviewed. Three-dimensional models were created using radiological analysis of anatomical detail and preoperative MRI scans in order to simulate 3 frequently quoted ETV trajectories for rigid neuroendoscopes. These trajectories were characterized based on the frequency and depth of tissue displacement to structures such as the fornix, caudate nucleus, genu of the internal capsule, and thalamus. The results are stratified based on ventricle size using the frontal horn ratio (FHR).

RESULTS

Eloquent areas were displaced in nearly all analyzed entry points (97%–100%). Stratifying the data based on ventricle size revealed that 1) lateral structures were more likely to be displaced in cases of intermediate ventriculomegaly (FHR < 0.4) using all 3 trajectories, whereas 2) the fornix was less likely to be displaced using more posteriorly placed trajectories for severe ventriculomegaly (FHR > 0.4). Allowing for minimal (2.4 mm) tissue displacement, a more posterior entry point was less traumatic for severe ventriculomegaly.

CONCLUSIONS

There is no single best ETV trajectory that fully avoids displacement of the eloquent periventricular structures. Larger ventricles require a more posteriorly placed entry point in order to reduce injury to the eloquent structures, and intermediate ventricles would dictate a medial entry point. These results suggest that the optimal entry point should be selected on a case-by-case basis after incorporating ventricle size.

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Alexander P. Landry, Windsor K. C. Ting, Zsolt Zador, Alireza Sadeghian, and Michael D. Cusimano

OBJECTIVE

Artificial neural networks (ANNs) have shown considerable promise as decision support tools in medicine, including neurosurgery. However, their use in concussion and postconcussion syndrome (PCS) has been limited. The authors explore the value of using an ANN to identify patients with concussion/PCS based on their antisaccade performance.

METHODS

Study participants were prospectively recruited from the emergency department and head injury clinic of a large teaching hospital in Toronto. Acquaintances of study participants were used as controls. Saccades were measured using an automated, portable, head-mounted device preprogrammed with an antisaccade task. Each participant underwent 100 trials of the task and 11 saccade parameters were recorded for each trial. ANN analysis was performed using the MATLAB Neural Network Toolbox, and individual saccade parameters were further explored with receiver operating characteristic (ROC) curves and a logistic regression analysis.

RESULTS

Control (n = 15), concussion (n = 32), and PCS (n = 25) groups were matched by age and level of education. The authors examined 11 saccade parameters and found that the prosaccade error rate (p = 0.04) and median antisaccade latency (p = 0.02) were significantly different between control and concussion/PCS groups. When used to distinguish concussion and PCS participants from controls, the neural networks achieved accuracies of 67% and 72%, respectively. This method was unable to distinguish study patients with concussion from those with PCS, suggesting persistence of eye movement abnormalities in patients with PCS. The authors’ observations also suggest the potential for improved results with a larger training sample.

CONCLUSIONS

This study explored the utility of ANNs in the diagnosis of concussion/PCS based on antisaccades. With the use of an ANN, modest accuracy was achieved in a small cohort. In addition, the authors explored the pearls and pitfalls of this novel approach and identified important future directions for this research.