Research news and notes
Article Outline
- 1. When less may be more
- 2. Hypothermia limitations?
- 3. Universal influenza vaccine
- 4. Shunts and valves
- References
- Copyright
1. When less may be more
Endoscopic thoracic sympathectomy is an effective procedure for palmar hyperhidrosis. It usually results in compensatory hyperhidrosis that may sometimes be severe and result in poor patient satisfaction. A recent article by Li et al [5] reports a randomized controlled study in which 232 patients were assigned to either T2-4 endoscopic ablation or T3 sympathectomy only. The authors reported similar results in both groups, with an outstanding 100% symptom resolution rate. Only 3% of the patients who had T3 ablation developed severe hyperhidrosis, as compared with 10% of the T2-4 group. The outcome sounds impressive. It is consistent with a smaller controlled study published in 2007 by Katara et al [4]. There, 25 patients received either T2 or combined T2-3 ablation. The smaller procedure had a similar rate of success and patient satisfaction. It looks like an isolated T2 or T3 ablation can be successful.
Endoscopic, particularly thoracoscopic, procedures are very useful for neurosurgeons. Endoscopy may be an alternative to throacotomy in some cases. Thoracoscopic sympathectomy is a good place to start a spinal endoscopic practice.
2. Hypothermia limitations?
Hypothermia has a long history in neuroprotection—it is used in open heart surgery, in cerebrovascular procedures, and has a solid theoretical and experimental basis for use in ischemia and brain injury. It was only logical to suppose that hypothermia can improve survival in traumatic brain injury. In the June 5 issue of the New England Journal of Medicine, Hutshison et al [3] report a multicenter international trial of hypothermia after traumatic brain injury (TBI) in children. The authors based the study on prior reports of benefit of hypothermia in cases of TBI, as well as the improvement of outcomes in animal models of TBI. This was a very complex multicenter international trial with 17 centers in 3 countries evaluating 1441 consecutive pediatric patients with TBI. After eliminating those who did not fit the criteria and those in whom consent could not be obtained, 225 patients remained. Hypothermia was moderate (33.1°C ± 1.2°C), was started within 8 hours of injury, and continued for 24 hours. The outcome at 6 months was the main outcome measure, and it was somewhat worse with hypothermia; 32 of 102 patients had a poor outcome with hypothermia, and 23 of 103 with normothermia. Various ways to analyze the data statistically yielded either no difference or worse outcomes with hypothermia. The subgroup of those older than 7 years, as well as patients without increased intracranial pressure, had a worse outcome with hypothermia. Why did hypothermia fail? The mean time to the initiation of hypothermia was 6.3 hours. The cascade of events that lead to increase brain damage after trauma may have started already. It is possible that cooling trauma patients in the field will be useful, and the authors of this study discussed this option but concluded that there could be a great logistical challenge in conducting such a study. I think that the multicenter prospective international study is also a great logistical challenge and a giant expense. The question is: What is the right thing to do? If the theoretical and animal experiment data show benefit to immediate cooling, then that is exactly what should be tried in humans. The field of medicine is full of expensive treatments used for causes less compelling than decreasing the neurologic sequelae of traumatic brain injury.
3. Universal influenza vaccine
The extreme virulence and worldwide spread of the H5N1 avian flu rekindled the fear of a pandemic. Current vaccination strategies are very inefficient because the vaccine is developed against the most common antigens on the surface of the influenza virus particles: hemagglutinin and neuraminidase. These are the antigens that vary among the strains, thus requiring a new vaccine every year. A universal vaccine has been a lofty yet elusive goal. The flu virus does have a protein that appears to be conserved in all strains, which is the M2 peptide that is associated with pores on the virion surface. This protein appears in very small quantities on the typical flu virus and is not immunogenic enough. In the June issue of the journal, Vaccine, Denis et al [1] present a method to create universal influenza immunization. They created virus-like particles based on a papaya mosaic virus (a plant pathogen). The papaya virus was engineered to express the universal M2e influenza epitope. A vaccine based on this idea provided full protection again infection in mice. The development of a universal influenza vaccine would be a historic event, well beyond the scope of specialists in infectious disease.
4. Shunts and valves
Shunts for the diversion of cerebrospinal fluid are performed very commonly by most neurosurgeons, and although almost 200 shunt systems [2] have been developed and tried, the perfect shunt system remains elusive. A recent report by Hertel et al brings to our attention a relatively uncommon valve system: the miethke dual switch valve. This valve has different opening pressures depending on the posture of the patient, and is therefore expected to prevent overdrainage. In this report, the authors describe their experience with 169 consecutive patients with this valve. Normal pressure hydrocephalus was the most common indication in 70 patients, with the rest distributed among a variety of diagnoses. They reported no valve obstructions and only 3.2% overdrainage, although overall shunt survival was 81% after 82 months, not exceptional in adults. This is an interesting report, mainly notable because there is little evidence for the superiority of any shunt system beyond such personal experiences. I am reminded of a 1995 study by Weiner et al [6] in which a retrospective comparison of flow-regulated and pressure-regulated valves failed to demonstrate a significant difference in outcomes. The selection of a shunt system remains highly subjective, like so many things in neurosurgery.
References
- . Development of a universal influenza A vaccine based on the M2e peptide fused to the papaya mosaic virus (PapMV) vaccine platform. Vaccine. 2008;26(27-28):3395–3403
- . The miethke dual switch valve: experience in 169 adult patients with different kinds of hydrocephalus: an open field study. Minim Invasive Neurosurg. 2008;51(3):147–153
- . Hypothermia Pediatric Head Injury Trial Investigators and the Canadian Critical Care Trials Group. Hypothermia therapy after traumatic brain injury in children. N Engl J Med. 2008;358(23):2447–2456
- . Comparing T2 and T2-T3 ablation in thoracoscopic sympathectomy for palmar hyperhidrosis: a randomized control trial. Surg Endosc. 2007;21(10):1768–1771
- . Endoscopic thoracic sympathectomy for palmar hyperhidrosis: a randomized control trial comparing T3 and T2-4 ablation. Ann Thorac Surg. 2008;85(5):1747–1751
- . Current treatment of normal-pressure hydrocephalus: comparison of flow-regulated and differential-pressure shunt valves. Neurosurgery. 1995;37(5):877–884
PII: S0090-3019(08)00652-6
doi:10.1016/j.surneu.2008.07.015
© 2008 Published by Elsevier Inc.
