Research news and notes

1. The effect of electrical stimulation on axon regeneration 

In experiments in rodents, electrical stimulation of cut peripheral nerves improves axon regeneration. A recent study in the Journal of Neurobiology [3] demonstrated this effect and shed some light on the possible mechanism. English et al [3] at Emory University demonstrated an increase in the number and length of regenerating axons in the cut fibular nerve of mice when 1 hour of electrical stimulation was administered during surgical repair. For the repair, they used allografts from littermates; they examined the regenerating nerves 1 to 2 weeks after the repair. The regenerating axons were immunoreactive for brain-derived neurotrophic factor. In the next phase, the experiment was performed with grafts that were made acellular through repeated freezing and thawing. Normally, the regeneration through these grafts is poor, but electrical stimulation resulted in normal regeneration. To elucidate the mechanism of action of the electrical stimulation, the authors used mice genetically engineered to lack neurotrophin 4/5. In these mice, electrical stimulation failed to produce enhanced regeneration. Probably, electrical stimulation enhanced neurotrophin production within the regeneration axons themselves and, thus, improves their growth even through acellular grafts.

For decades, peripheral nerve repair research was fairly stagnant—a variety of methods were evaluated to replace a live nerve autograft, but they were all very limited. Maybe, electrical stimulation at the time of repair can make alternatives to autograft more attractive.

2. Ventriculoperitoneal shunt or third ventriculostomy? 

The most common procedure in pediatric neurosurgery is the ventriculoperitoneal shunt (VPS). The device saved many lives, but well-known complications of shunt malfunction and infection of the permanent hardware resulted in increased popularity of a potential alternative for children with newly diagnosed obstructive hydrocephalus—endoscopic third ventriculostomy (ETV). Although no hardware is left behind, the procedure requires greater technical sophistication and the use of endoscopic equipment. The relative merit and risk/benefit ratio of the different procedure are not well known. A prospective population-based study could help. In the absence of such, a retrospective unselected review of an entire cohort can also be useful. In the January issue of Child's Nervous System, de Ribaupierre et al [2] presented just such a study. They reviewed the charts of all pediatric patients operated for newly diagnosed obstructive hydrocephalus in the French-speaking area of Switzerland since 1992. There were 24 ETVs and 31 VPSs. At 5 years of follow-up, there were 26% failures in the ETV group and 42% in the VPS group. The authors reviewed additional articles and found support for their conclusion that ETV should be the procedure of choice. Their data did not reach statistical significance, but it is very likely that ETV is at least not inferior to VPS when “failure rate” is measured. I believe the key study would be a prospective follow up with proper randomization and neurobehavioral and developmental testing. The ultimate goal of all procedures on the child's brain is to allow normal development. Optimal developmental results should also be the main outcome measure in hydrocephalus treatment research.

3. Can medical science tackle the malpractice litigation crisis? 

The cost of medical litigation can be high both for neurosurgeons and their patients. Medical malpractice is a common topic of conversation among neurosurgeons, a subject of advice columns and political activism. Medical research about medical malpractice has been limited. We are now aware of the practice of “defensive medicine” by physicians at risk—the excessive ordering of consultations, tests and imaging, voluntary practice limitation, avoidance of “high-risk” patients. A study about defensive medical practices in Pennsylvania was published in JAMA in June of 2005 [4] and revealed 93% prevalence of “defensive” practices among the 824 physicians surveyed. It appears to me that physicians and surgeons lack information about the type of errors or adverse outcomes that are most likely to lead to litigation. When objective data is limited, the natural response is a general hypervigilance by physicians at risk. This type of stress response takes its toll on the quality of patient care and physician-patient interaction.

I am not aware of any recent analysis of malpractice claims against neurosurgeons by cause of litigation. This is now occurring in other fields. A group of bariatric surgeons and a medical malpractice attorney reviewed 100 consecutive bariatric lawsuits [1]. They found that bowel anastomotic leaks and intra-abdominal abscess were the most common causes of complications that lead to litigation. Evidence of negligence was found in 28% of the cases—mostly delayed diagnosis and misinterpretation of vital signs.

A study of the most common causes of litigation in neurosurgery may be helpful in directing the quality improvement efforts for greatest impact. Such information may also help decrease the anxiety of neurosurgeons when involved in a situation less likely to lead to litigation.