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Clayton Haldeman and Amgad Hanna

Neurofibromas are benign tumors composed of different cell types from the peripheral nervous system. Neurofibromas infiltrate between nerve fascicles and do not have a discrete capsule. On MRI, they are T1 hypointense or isointense, T2 hyperintense, often with a “target sign,” and contrast enhancing. The video shows gross-total resection of a peroneal nerve neurofibroma presenting as a painful mass in the popliteal fossa. Incisions across a skin crease can be either oblique or zigzag, but never perpendicular to it. It is also key to expose normal nerve proximal and distal to the tumor. The patient had a good functional outcome.

The video can be found here:

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Clayton L. Haldeman, Christopher D. Baggott and Amgad S. Hanna

Historically, peripheral nerve surgery has relied on landmarks and fairly extensive dissection for localization of both normal and pathological anatomy. High-resolution ultrasonography is a radiation-free imaging modality that can be used to directly visualize peripheral nerves and their associated pathologies prior to making an incision. It therefore helps in localization of normal and pathological anatomy, which can minimize the need for extensive exposures. The authors found intraoperative ultrasound (US) to be most useful in the management of peripheral nerve tumors and neuromas of nerve branches that are particularly small or have a deep location. This study presents the use of intraoperative US in 5 cases in an effort to illustrate some of the applications of this useful surgical adjunct.

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Joyce Koueik, Mark R. Kraemer, David Hsu, Elias Rizk, Ryan Zea, Clayton Haldeman and Bermans J. Iskandar


Recent evidence points to gravity-dependent chronic shunt overdrainage as a significant, if not leading, cause of proximal shunt failure. Yet, shunt overdrainage or siphoning persists despite innovations in valve technology. The authors examined the effectiveness of adding resistance to flow in shunt systems via antisiphon devices (ASDs) in preventing proximal shunt obstruction.


A retrospective observational cohort study was completed on patients who had an ASD (or additional valve) added to their shunt system between 2004 and 2016. Detailed clinical, radiographic, and surgical findings were examined. Shunt failure rates were compared before and after ASD addition.


Seventy-eight patients with shunted hydrocephalus were treated with placement of an ASD several centimeters distal to the primary valve. The records of 12 of these patients were analyzed separately due to a complex shunt revision history (i.e., > 10 lifetime shunt revisions). The authors found that adding an ASD decreased the 1-year ventricular catheter obstruction rates in the “simple” and “complex” groups by 67.3% and 75.8%, respectively, and the 5-year rates by 43.3% and 65.6%, respectively. The main long-term ASD complication was ASD removal for presumed valve pressure intolerance in 5 patients.


Using an ASD may result in significant reductions in ventricular catheter shunt obstruction rates. If confirmed with prospective studies, this observation would lend further evidence that chronic shunt overdrainage is a central cause of shunt malfunction, and provide pilot data to establish clinical and laboratory studies that assess optimal ASD type, number, and position, and eventually develop shunt valve systems that are altogether resistant to siphoning.