Saturday, June 18, 2011

Sensitivity of CT Angiography for Aneurysms

Not exactly the article I was expecting when I pulled it, but mildly interesting nonetheless.  The real applicability of this article is towards those folks who say the LP for SAH is outdated, and we should just proceed with CTA to identify the culprit aneurysm.

As opponents say, many aneurysms identified by CTA are asymptomatic and unrelated to the acute headache in the Emergency Department, and, without the LP, you don't know their clinical relevance.  This study lets them also say that CTA doesn't even necessarily perform well enough at this task to warrant use - it will miss 5% of aneurysms and overcall 3.8%.

However, it must be said, this meta-analysis uses data from a number of old studies that have older CT scanners that were very poor at detecting <4mm aneurysms.  Once you get to 16 and 64 row CT, your sensitivity is closer to 98-99% - and then you have to fall back to the asymptomatic/clinical relevance argument.

"Diagnosing cerebral aneurysms by computed tomographic angiography: meta-analysis"
http://www.ncbi.nlm.nih.gov/pubmed/21391230

Thursday, June 16, 2011

Neurothrombectomy Devices - Still Not The Answer

Catheter-based endovascular treatment of acute ischemic stroke has been around for several years - this is a nice, concise review of the published literature regarding their use.

The abstract sounds a little more favorably skewed than the actual content of the article - their discussion is appropriately skeptical regarding the efficacy and applicability of this particular treatment modality.  It is certainly true that restoring flow to affected regions in stroke is advantageous, and the theory behind the use of these devices is to mechanically ensure open vessels in situations where systemic thrombolysis may not be efficacious and the disability is likely to be profound.

The problem is, there really isn't any "evidence" in this article.  The published literature on this topic is primarily retrospective cohort/case-reports by industry-affiliated inventors of these devices and, even despite this bias, that literature tends to report unacceptable levels of procedural complications while trying desperately to show benefit.

Regardless, as the authors mention, there are many studies of MERCI and Penumbra ongoing - slowly chasing that inexorable statistical probability of finally performing enough studies that, by chance, one of them will be favorable enough upon which to base widespread marketing efforts.

"Neurothrombectomy devices for the treatment of acute ischemic stroke: state of the evidence"
http://www.ncbi.nlm.nih.gov/pubmed/21242342

Wednesday, June 15, 2011

Patients With Brugada May Have Normal EKGs ...and Then Drop Dead

The sodium-channelopathy that went many years before being described, now increasingly well-known.  More interestingly, the phenotype is apparently autosomal dominant in inheritance.  These investigators use this inheritance to retroactively diagnose deceased family members with a Brugada cause to their sudden cardiac death.

They found, unfortunately, that not only were most individuals who died of Brugada young, most were asymptomatic - and of the five patients for whom they could find an antemortem EKG, only one of them had a typical Type I Brugada pattern, and one had a single lead with a Type III pattern.

I think my take-home point from this article is that, in the young patients presenting with syncope, it's important not just to do the EKG, but also to enquire regarding family history of sudden cardiac death - and then hope whatever cardiologist you refer them to is insightful enough to order a amajaline provocation test if needed.

http://www.ncbi.nlm.nih.gov/pubmed/21636035

Tuesday, June 14, 2011

Significant Populations Have No Timely Access to Stroke, Pediatric Trauma Care

These are a couple studies from a family of publications that use population data, GIS mapping tools, and travel times by air and ground to estimate what percentage of the population has access to a certain healthcare resource.  In these two papers, the resources in question are Primary Stroke Centers and Pediatric Trauma Centers.  They estimate that 71% of the pediatric population is within 60 minutes of a pediatric trauma center by ground or air - which is appropriate, because trauma systems are set up to use aeromedical transport.  However - and, depending on what direction the TPA pendulum swings - only 55.4% of the population has access to a stroke center within 60 minutes - by ground, which is typical.  They say this could be increased to 79% within 60 minutes if aeromedical resources were involved, but I think we should wait to establish a greater treatment effect for acute stroke treatment before we go nuts with air travel.

I like maps; I worked with one of the authors (Dr. Branas) on previous iterations of descriptive articles similar to these.  The problem with these articles is the statistic they describe - timeliness of care - may or may not have significant effects on patient outcomes.  And, in theory, the solutions - moving trauma center designations, establishing new stroke centers, increasing aeromedical use, etc., have significant costs and unintended consequences.

http://www.ncbi.nlm.nih.gov/pubmed/20937948
http://www.ncbi.nlm.nih.gov/pubmed/19487606

Monday, June 13, 2011

Shoulder Reduction - Spanish-Style

Another interesting article regarding shoulder reduction techniques.

Essentially, what I read into shoulder reduction is that - if there many usually successful ways to do something, pretty much anything works.  And, what seems to be the generally accepted way to do it - excepting the scapular manipulation technique - is pulling on it.  What is different between methods seems to be how exactly you apply the traction.

This is a single-operator method with direct axial traction on the distal humerus with one hand and counter-traction on the acromium with the other hand.  The trouble I foresee with this method is that you're fighting a lot of large muscles on the patient with your own, smaller, rotator cuff and shoulder abductors.  I think you'd end up fatiguing before a lot of your patients.

The variation I might suggest is the snowbird technique, where you use the weight of your leg to provide downward traction via stockinette around the forearm.  You can sometimes get away from having to do full procedural sedation if you can perform a technique like this where the patient fatigues before you do.

http://www.ncbi.nlm.nih.gov/pubmed/21620607