Samuel A. Hughes

Effect of Vagus Nerve Stimulator Magnet on Programmable Shunt Settings

OBJECTIVE:Vagus nerve stimulators and programmable shunt valves are used in the operative care of epilepsy and hydrocephalus, respectively. Both devices use magnetic fields to activate and program their various settings and functions. The authors conducted several ex vivo trials to better elucidate any interplay between the two systems. METHODS:A pulse generator controller (Cyberonics Corp., Houston, TX) was brought to within 4 cm of Strata programmable shunt valves (Medtronic Neurosurgery, Goleta, CA). Each of five valves was preset to either a low- or high-pressure setting and then challenged with the vagus nerve stimulator generator. Each valve was challenged 20 times, for a total of 100 trials. RESULTS:In 100 trials, 78 inadvertent pressure setting adjustments were recorded. In 46 attempts, the valve pressure was increased, and in 34 attempts, the pressure was decreased. CONCLUSION:This study provides some support to the anecdotal reports of inadvertent adjustments of programmable shunt valves by the external magnetic field created by vagus nerve stimulator pulse generator controllers. Further trials and a double-blind study are necessary to illustrate more clearly the possible relationship of these magnetically controlled neurosurgical devices.

The Science of Shrinking Human Heads: Tribal Warfare and Revenge among the South American Jivaro-Shuar

THE PRACTICE OF “head-shrinking” has been the proper domain not of Africa but rather of the denizens of South America. Specifically, in the post-Columbian period, it has been most famously the practice of a tribe of indigenous people commonly called the Jivaro or Jivaro-Shuar. The evidence suggests that the Jivaro-Shuar are merely the last group to retain a custom widespread in northwestern South America. In both ceramic and textile art of the pre-Columbian residents of Peru, the motif of trophy heads smaller than normal life-size heads commonly recurs; the motif is seen even in surviving carvings in stone and shell. Moreover, although not true shrunken heads, trophy heads found in late pre-Columbian and even post-Columbian graves of the region demonstrate techniques of display very similar to those used by the Jivaro-Shuar, at least some of which are best understood in the context of head-shrinking. Regardless, the Jivaro-Shuar and their practices provide an illustrative counterexample to popular myth regarding the culture and science of the shrinking of human heads.

Ethical considerations in targeted paediatric neurosurgery missions

Within the context of global health development approaches, surgical missions to provide care for underserved populations remain the least studied interventions with regard to their methodology. Because of the unique logistical needs of delivering operative care, surgical missions are often described solely in terms of cases performed, with a paucity of discourse on medical ethics. Within surgery, subspecialties that serve patients on a non-elective basis should, it could be argued, create mission strategies that involve a didactic approach and the propagation of sustainable surgical care. The ethical considerations have yet to be described for paediatric neurosurgical outreach missions. We present here the perspectives of neurosurgeons who have participated in surgical outreach missions in Central America, South America, Eastern Europe and sub-Saharan Africa from the vantage point of both the visiting mission team and the host team that accommodates the mission efforts.

Strategic design for pediatric neurosurgery missions across the Western Hemisphere

Background: With growing interest in global health, surgeons have created outreach missions to improve health care disparities in less developed countries. These efforts are mainly episodic with visiting surgeons performing the operations and minimal investment in local surgeon education. To create real and durable advancement in surgical services in disciplines that require urgent patient care, such as pediatric neurosurgery, improving the surgical armamentarium of the local surgeons must be the priority. Methods: We propose a strategic design for extending surgical education missions throughout the Western Hemisphere in order to transfer modern surgical skills to local neurosurgeons. A selection criteria and structure for targeted missions is a derivative of logistical and pedagogical lessons ascertained from previous missions by our teams in Peru and Ukraine. Results: Outreach programs should be applied to hospitals in capital cities to serve as a central referral center for maximal impact with fiscal efficiency. The host country should fulfill several criteria, including demonstration of geopolitical stability in combination with lack of modern neurosurgical care and equipment. The mission strategy is outlined as three to four 1-week visits with an initial site evaluation to establish a relationship with the hospital administration and host surgeons. Each visit should be characterized by collaboration between visiting and host surgeons on increasingly complex cases, with progressive transfer of skills over time. Conclusion: A strategic approach for surgical outreach missions should be built on collaboration and camaraderie between visiting and local neurosurgeons, with the mutual objective of cost-effective targeted renovation of their surgical equipment and skill repertoire.

Stem cells and the origin of gliomas: A historical reappraisal with molecular advancements.

The biology of both normal and tumor development clearly possesses overlapping and parallel features. Oncogenes and tumor suppressors are relevant not only in tumor biology, but also in physiological developmental regulators of growth and differentiation. Conversely, genes identified as regulators of developmental biology are relevant to tumor biology. This is particularly relevant in the context of brain tumors, where recent evidence is mounting that the origin of brain tumors, specifically gliomas, may represent dysfunctional developmental neurobiology. Neural stem cells are increasingly being investigated as the cell type that originally undergoes malignant transformation – the cell of origin – and the evidence for this is discussed.

Transforaminal Lumbar Interbody Fusion (TLIF)

Methods of spinal arthrodesis continue to evolve in efforts to treat back pain. The latest techniques include approaching from the anterior, posterior, lateral, and posterolateral. The transforaminal interbody lumbar fusion (TLIF) developed by Harms [1] is a modification of the posterior lumbar interbody fusion (PLIF). The procedure varies primarily in the access to the spine, being a unilateral, posterolateral approach to the spine [2]. Simultaneous pedicle screw fixation can be used to achieve anterior column stability. The TLIF has been shown to be a valuable alternative to the traditional PLIF [3–7]. Advantages of the TLIF over the PLIF are fewer complications [4], the elimination of epidural scarring [1], less intraoperative bleeding [4], and the avoidance of dura and nerve roots [2, 4]. Further, given its unilateral approach, the TLIF offers better preservation of the lumbar spine musculoligamentous complex. Current approaches to lumbar discectomy and techniques in interbody fusion have been greatly influenced by recent advances in minimally invasive spine surgery [8–15]. One minimally invasive tubular system in existence is the METRx system (Sofamor Danek). Another minimally invasive system is the Atavi (Endius). One nontubular system which we describe further in this chapter is called MaXcess (NuVasive). A variation on the standard TLIF, it allows rapid, unilateral access to the lumbar spine via a percutaneous route while minimizing the amount of operative soft tissue trauma. The MaXcess system is designed to maximize surgical access while minimizing disruption of the musculature. It enables the use of standard instruments to perform conventional surgery and allows direct visualization without requiring special equipment. Additionally, an illuminated operative corridor aids in providing direct visualization with superior lighting.