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Brice A. Kessler, Scott Elton, and Carolyn Quinsey

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Nathaniel K. Coulson, Peter A. Chiarelli, David K. Su, Jason J. Chang, Brian MacConaghy, Revathi Murthy, Peter Toms, Terrence L. Robb, Richard G. Ellenbogen, Samuel R. Browd, and Pierre D. Mourad

OBJECT

Urgent ventriculostomy placement can be a lifesaving procedure in the setting of hydrocephalus or elevated intracranial pressure. While external ventricular drain (EVD) insertion is common, there remains a high rate of suboptimal drain placement. Here, the authors seek to demonstrate the feasibility of an ultrasound-based guidance system that can be inserted into an existing EVD catheter to provide a linear ultrasound trace that guides the user toward the ventricle.

METHODS

The ultrasound stylet was constructed as a thin metal tube, with dimensions equivalent to standard catheter stylets, bearing a single-element, ceramic ultrasound transducer at the tip. Ultrasound backscatter signals from the porcine ventricle were processed by custom electronics to offer real-time information about ventricular location relative to the catheter. Data collected from the prototype device were compared with reference measurements obtained using standard clinical ultrasound imaging.

RESULTS

A study of porcine ventricular catheterization using the experimental device yielded a high rate of successful catheter placement after a single pass (10 of 12 trials), despite the small size of pig ventricles and the lack of prior instruction on porcine ventricular architecture. A characteristic double-peak signal was identified, which originated from ultrasound reflections off of the near and far ventricular walls. Ventricular dimensions, as obtained from the width between peaks, were in agreement with standard ultrasound reference measurements (p < 0.05). Furthermore, linear ultrasound backscatter data permitted in situ measurement of the stylet distance to the ventricular wall (p < 0.05), which assisted in catheter guidance.

CONCLUSIONS

The authors have demonstrated the ability of the prototype ultrasound stylet to guide ventricular access in the porcine brain. The alternative design of the device makes it potentially easy to integrate into the standard workflow for bedside EVD placement. The availability of a fast, easy-to-use, inexpensive guidance system can play a role in reducing the complication rate for EVD placement.

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Jason K. Chu, Peter A. Chiarelli, Nolan D. Rea, Norianne Pimentel, Benjamin E. Flyer, J. Gordon McComb, Susan R. Durham, and Mark D. Krieger

OBJECTIVE

Facial palsy can be caused by masses within the posterior fossa and is a known risk of surgery for tumor resection. Although well documented in the adult literature, postoperative facial weakness after posterior fossa tumor resection in pediatric patients has not been well studied. The objective of this work was to determine the incidence of postoperative facial palsy after tumor surgery, and to investigate clinical and radiographic risk factors.

METHODS

A retrospective analysis was conducted at a single large pediatric hospital. Clinical, radiographic, and histological data were examined in children who were surgically treated for posterior fossa tumors between May 1, 1994, and June 1, 2011. The incidence of postoperative facial weakness was documented. A multivariate logistic regression model was used to analyze the predictive ability of clinicoradiological variables for facial weakness.

RESULTS

A total of 163 patients were included in this study. The average age at surgery was 7.4 ± 4.7 years, and tumor pathologies included astrocytoma (44%), medulloblastoma (36%), and ependymoma (20%). The lesions of 27 patients (17%) were considered high grade in nature. Thirteen patients (8%) exhibited preoperative symptoms of facial palsy. The overall incidence of postoperative facial palsy was 26% (43 patients), and the incidence of new postoperative facial palsy in patients without preoperative facial weakness was 20% (30 patients). The presence of a preoperative facial palsy had a large and significant effect in univariate analysis (OR 11.82, 95% CI 3.07–45.44, p < 0.01). Multivariate logistic regression identified recurrent operation (OR 4.45, 95% CI 1.49–13.30, p = 0.01) and other preoperative cranial nerve palsy (CNP; OR 3.01, 95% CI 1.24–7.29, p = 0.02) as significant risk factors for postoperative facial weakness.

CONCLUSIONS

Facial palsy is a risk during surgical resection of posterior fossa brain tumors in the pediatric population. The study results suggest that the incidence of new postoperative facial palsy can be as high as 20%. The presence of preoperative facial palsy, an operation for recurrent tumor, and the presence of other preoperative CNPs were found to be significant risk factors for postoperative facial weakness.

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Erik B. Vanstrum, Matthew T. Borzage, Jason K. Chu, Shuo Wang, Nolan Rea, J. Gordon McComb, Mark D. Krieger, and Peter A. Chiarelli

Preterm infants commonly present with a hemodynamically significant patent ductus arteriosus (hsPDA). The authors describe the case of a preterm infant with posthemorrhagic ventricular dilation, which resolved in a temporally coincident fashion to repair of hsPDA. The presence of a PDA with left-to-right shunting was confirmed at birth on echocardiogram and was unresponsive to repeated medical intervention. Initial cranial ultrasound revealed periventricular-intraventricular hemorrhage. Follow-up serial ultrasound showed resolving intraventricular hemorrhage and progressive bilateral hydrocephalus. At 5 weeks, the ductus was ligated with the goal of improving hemodynamic stability prior to CSF diversion. However, neurosurgical intervention was not required due to improvement of ventriculomegaly occurring immediately after PDA ligation. No further ventricular dilation was observed at the 6-month follow-up.

Systemic venous flow disruption and abnormal patterns of cerebral blood circulation have been previously associated with hsPDA. Systemic hemodynamic change has been reported to follow hsPDA ligation, although association with ventricular normalization has not. This case suggests that the unstable hemodynamic environment due to left-to-right shunting may also impede CSF outflow and contribute to ventriculomegaly. The authors review the literature surrounding pressure transmission between a PDA and the cerebral vessels and present a mechanism by which PDA may contribute to posthemorrhagic ventricular dilation.