Community EM rejoice- CT within 6 hours safe for SAH rule out.

There is yet another paper to further elucidate who should get the CT / LP work up for subarachnoids. The authors looked at six EDs over 5 years, and encompassed 2,248 patients – of which 1898 had suitable LPs for analysis (insufficient sample, exposed to light [?], blood contamination, incorrect storage or transport [?], or they just plain lost the sample). CT reads were done by on-call radiologists in training (I imagine that means residents), or by board-certified radiologists. Images were then reviewed by a board-certified neuro-radiologist OR by a board-certified general radiologist for a final report. There was no “time limit” from onset of headache for exclusion (ie, patients did not need to be scanned within six hours).

92 patients of the 1898 patients were positive for blood via spectrophotometry – 4.8%. Nine of these positives ended up having a subarachnoid hemorrhage (9.8% of their LPs, or 0.47% of patients). What do these nine patients generally have in common? Six of them had a headache for a week or longer. One had a previously coiled embolism. One had a negative CT performed within 3 hours of onset.  All of these nine patients got coiled or clipped.

So, what do we make of these? If you present within 6 hours with a negative CT (or, dare I say, less than a week!), you have a 0.053% of having a subarachnoid. If you still do the LP in those <6hours from onset (or, <1 week from onset), the baseline risk of a false positive is 10% vs 1.1% chance of true SAH.

Time for some well-informed shared decision making, and perhaps a higher threshold for those that present with a prolonged headache.  Further good news to take away from this study- it does not seem as neuro-radiologists need to make the call and that the <6 hour proposal can be safely extended to the community setting at this point.

 

(First link is to free text of article.  Pubmed did not have a working link to the paper at time of post.  If the first link does not work, try here)

Patient Backstabbing in the Age of SDM

11 non-academic hospitals reviewed 760 consecutive patients who had a brain CT for an acute headache that was followed by an LP 12 hrs from the onset of headache from January 2007 to January 2013.  These 11 centers diagnosis roughly 250 subarachnoid bleeds annually.  In this study, the patients presented within 6 hours from onset of the headache, and all had a negative CT read by staff radiologists, and were independently reviewed by two neuroradiologists and one stroke neurologist.  At these 11 centers, of the 760 patients with a negative CT read by staff radiologists, 52 patients had CSF positive for bilirubin (7%).  Of these 52 patients, there was one patient identified to have a non-aneurysmal perimesencephalic SAH on repeat review of the images.  This one patient had a benign outcome.  There were 8 others who had an aneurysm on CTA, DSA, or MRA  (3 of which had been previously coiled).  All of them were deemed as having rupture unlikely for various reasons (RBC <100, no bilirubin on spectrophotometry, etc).

So, with a negative CT read at a non-academic center by non-neuro radiologists, at the high end, we have a 1 in 760 miss rate if we *only* miss perimesencephalic bleeds on CT.  These types of bleeds account for about 5% of SAH, so, potentially, at the low end, we are looking at a miss rate of 1 in 15,200.  Essentially, the lumbar puncture is not a very useful test to diagnose SAH – with a posttest probability of 1.9% in cases with a positive CSF spectrophotometric result (a previous study reported about 8% PPV for xanthochromia)

Unfortunately, it is not mentioned how SAH was diagnosed throughout the study period.  It would be nice to know if they were made via CT in the ED, as that would help solidify the author’s suggestion that CT/LP is a dinosaur in the age of shared decision making.  Speaking of which…

I’ve had a few colleagues who have said, “show them the needle” as a somewhat subversive way to have patients either sign AMA or a refusal to consent for an LP for a subarachnoid hemorrhage.  Few, if any, have actually said, “tell them the evidence.”

What sounds better to you for well informed shared decision making?

A) “You could die from this. You need a spinal tap. If you don’t do it, you could die.”

B) “Ultimately, I think your risk of a bleed is low, but I want you to understand that there is significant consequences to a subarachnoid and over half of those diagnosed may die.  With that said, studies show that with a normal CT scan, your risk of having this condition is well below 2%.  “Normal” spinal tap results performed 12 hours from the onset of your headache helps to further reduce your risk, but also comes with a significant number of false positives.  While an abnormal spinal tap is concerning for a subarachnoid, it is not specific, and you will likely require admission for further testing if your spinal tap is abnormal.”

 

more reading on this:

http://stroke.ahajournals.org/content/43/8/2031.long

Day Two of Christmas – ‘Lytes off for Seizures?

Welcome to the Twelve Trials of Christmas series on EMinFocus!  This is the second of twelve posts in a series where I ramble on various topics for which I would love to see an EM study done.  I’ve taken morsels of prior studies (case series, small trials, etc) and highlight reasons on why I believe this study would benefit EM.  Some may pan out, some may not.  All of them I would be highly interested in assisting with in any way possible to continue to advance our fine specialty.

The ACEP clinical policy for seizures states to check electrolytes in new onset seizures, in patients with status epilepticus, and in those who are not back to baseline. They do not comment on patients with recurrent seizures who are back to baseline and do not have a compelling story (ie, fever, have not felt well recently, possible withdrawal, etc). Infrequently, if ever, have I seen a patient with clinically relevant hyponatremia that looked and felt well, let alone a patient with a hyponatremia-induced seizure that went back to their baseline and felt and looked fine. I have, however, frequently and instinctively ordered electrolytes “just to check” in a patient with a known seizure disorder with a normal exam and unconcerning history. Sometimes these patients wait well over an hour or two for labs to be drawn and resulted. I would love to see a multicenter retrospective study that looks at the rate of electrolyte abnormalities for which a patient with a known seizure disorder with a recurrent seizure required hospitalization due to said electrolyte disturbances. This could save a significant amount of time and resources likely without significant detriment to the patient. However, there is something about being able to document that you observed the patient for several hours without recurrence or a decline in their status. Then again, this could easily become a secondary outcome in the study I’d love to see (& do!) – is there a recurrence rate over a 1-2 hour observation period? Is there a 24 hour bounceback rate if an electrolyte panel is not drawn? How about outcomes at 1 month? Shockingly, there is scant, if any, literature on the need for labs to be drawn from a patient with a known seizure disorder having a breakthrough seizure.  I really think we could be turning off the ‘lytes for these patients if they are back at baseline and look & feel well.

Treat and Street Headaches.

Wouldn’t it be great if you could take care of the photophobia, nausea, and headaches (of dealing with another night shift) of a patient with a migraine in under 20 minutes?

The Study:

417 headache patients given a lower cervical paraspinous intramuscular injection with bupivacaine.  Total relief in 65% and partial relief in 20% of patients.  No relief in 14%, and worsening symptoms in 1%. Relief of headache as well as associated symptoms were typically noted within 5 to 10 minutes.

YouTube:

http://www.youtube.com/watch?v=0to5wzftpnM

http://www.youtube.com/watch?v=Ut_vXrDD2hU

http://www.youtube.com/watch?v=2OtDXLUBDLo

My Own Story

I have had good success, probably similar to the 80 – 85% published rate.  I have used it for toothaches, primary headache disorders, and the migraineurs.  I usually use an insulin syringe with lidocaine and use 0.25cc for pretreatment on either side as our shop does not have the spray coolant seen in the above videos.  I order meds, do the block, and by the time the nurse steps in for meds, we can figure out if they need anything additional.  Often, they do not, or can take PO meds.

With that said, the only randomized trials for myofascial pain are with spheno-palatine ganglion blocks and show they are not better than placebo. (one looks at chronic myofascial pain & uses lidocaine, the other looks at endoscopic sinus surgery with bupivacaine) Thats not to say that all nerve blocks are a sham – femoral blocks for hip fractures have shown good results over placebo.

Regardless, at an 80 % improvement rate, even if it is placebo effect, I am ok at 80% improvement rate! Next time, instead of waiting an hour for meds to be given, offer it to your patients.  Over 60% of the time they can take discharge papers instead of Compazine.

Special thanks to the SOCMOB blog (socmob.org) who showed up on the #foamed RSS feed with this a few months ago and gave me the inspiration to begin doing these.

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Sphenopalatine ganglion block for the treatment of myofascial pain of the head, neck, and shoulders. PMID: 9552776

The effectiveness of preemptive sphenopalatine ganglion block on postoperative pain and functional outcomes after functional endoscopic sinus surgery. PMID :22287376

A comparison of pre-operative nerve stimulator-guided femoral nerve block and fascia iliaca compartment block in patients with a femoral neck fracture. PMID: 23789738

Treatment of headaches in the ED with lower cervical intramuscular bupivacaine injections: a 1-year retrospective review of 417 patients. PMID: 17040341

http://www.epmonthly.com/clinical-skills/emrap/how-to-use-paraspinous-injections-for-complex-headaches/

http://socmob.org/2014/01/paraspinous-cervical-block-headache/