Category Archives: Head

Abstracts, Head

Best of EAST #8: Reversing Antithrombotic Drugs After Severe TBI

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Falls are the most common mechanism of injury at a majority of trauma centers these days. And due to the escalating number of comorbidities in our older population, more and more are taking some kind of anticoagulant or antiplatelet medication. And as all trauma professionals know, falling down and failure to clot do not mix well.

A variety of reversal regimens have been developed, including Vitamin K, plasma or platelet infusion, prothrombin complex concentrate, andexxanet, or idarucizumab depending on the agent. But when it comes to evaluating the efficacy of these agents, there are two important questions that need to be answered:

  1. Does the regimen reverse or neutralize the offending agent?
    and more importantly
  2. Does the regimen have a positive effect, i.e. reduce mortality and/or complications?

This last question has been problematic, especially for the direct oral anticoagulant drugs (DOACs). They are very expensive, but there has been little, if any, evidence that they improve mortality.

A study from the University of Florida at Jacksonville, and sponsored by EAST was performed last year. It was a multi-center, prospective, observational study of data provided by 15 US trauma centers. They collected data on the agents used, reversal attempts, and comorbidities in injured patients taking these drugs, and analyzed for head injury severity and mortality.

Here are the factoids:

  • There were a total of 2913 patients in the study, 46% on aspirin (ASA), 13% taking ASA and a P2Y12 inhibitor (one of the -grels), 11% on warfarin, 4% on ASA + warfarin, 13.5% on a Factor Xa inhibitor, and 6% on a Xa inhibitor + ASA
  • Patients on platelet blockers (P2Y12 inhibitor) had the highest mean ISS at 9
  • Warfarin was associated with a higher abbreviated injury score (AIS) for head, 1.2
  • Controlling for ISS, comorbidities, ISS, and initial SBP, warfarin + ASA had the highest head ISS with an odds ratio of 2.1 (with the lower confidence interval value of 1.19)
  • Reversal of antiplatelet therapy with DDAVP was not successful, with no change in mortality (87% with reversal and 93% without)
  • Reversal of Xa inhibitors with plasma or PCC was also unsuccessful with a mortality of 100% with reversal and 95% without

The authors concluded that reversal attempts for antiplatelet therapy or Factor Xa inhibitors did not decrease mortality, and shared the observation that combination therapies posed the most risk for severity of head injury.

My comments: Remember, the first thing to do is look at the study group. The authors did not share the inclusion or exclusion criteria for the study in the abstract, so we are a little in the dark here.

The next item that makes this study difficult to interpret (and perform) is the fact that nearly a quarter are on combination therapy for their anticoagulation. So even though nearly 3,000 patients were studied, many of the medication subgroups had only a few hundred subjects. The aspirin group was the largest, with 1,338. This makes me wonder if the overall study had the statistical power to find subtle differences in their outcome measures and support the conclusions.

Now have a look at one of the results tables:

In reviewing the demographic data, the concept of statistical significance vs clinical significance quickly comes to mind. Somehow, age, ISS, head AIS, mortality, and SBP are significantly different between some of the groups. Yet if you examine the specific values across most of the rows, there is little difference (e.g SBP ranges from 137 to 147, ISS from 7-9, mortality from 2-7%). These are all clinically identical. The only row that means much to me is the top one telling how many patients are in a group.

Here are my questions for the authors and presenter:

  1. Tell us about the study design, especially the inclusion and exclusion criteria. Were there any? How might this have influenced the study group?
  2. Please comment on your perception of the statistical power of the study, especially with seven groups of patients, each with relatively small numbers.
  3. Do you have information on the variety of reversal agents used? Were there any standards? Could this have contributed to the mortality in some of the groups?
  4. Do you have any clinical recommendations based on your findings? If not, what is the next step in examining this group of patients?

My bottom line is that I’m not sure that this study has the power to show us any significant differences. And looking at the information table and logistic regression results (odds ratio confidence intervals close to 1), I’m not really able to learn anything new from it. I’m hoping to learn a lot from the live presentation!

Reference: EAST MCT: comparison of pre-injury antithrombotic use and reversal strategies among severe TBI patients. EAST 2021, Paper 19.

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Head

Everything You Wanted To Know About: Cranial Bone Flaps

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Patients with severe TBI frequently undergo surgical procedures to remove clot or decompress the brain. Most of the time, they undergo a craniotomy, in which a bone flap is raised temporarily and then replaced at the end of the procedure.

But in decompressive surgery, the bone flap cannot be replaced because doing so may increase intracranial pressure. What to do with it?

There are four options:

  1. The piece of bone can buried in the subcutaneous tissue of the abdominal wall. The advantage is that it can’t get lost. Cosmetically, it looks odd, but so does having a bone flap missing from the side of your head. And this technique can’t be used as easily if the patient has had prior abdominal surgery.

2. Some centers have buried the flap in the subgaleal tissues of the scalp on the opposite side of the skull. The few papers on this technique demonstrated a low infection rate. The advantage is that only one surgical field is necessary at the time the flap is replaced. However, the cosmetic disadvantage before the flap is replaced is much more pronounced.

3. Most commonly, the flap is frozen and “banked” for later replacement. There are reports of some mineral loss from the flap after replacement, and occasional infection. And occasionally the entire piece is misplaced. Another disadvantage is that if the patient moves away or presents to another hospital for flap replacement, the logistics of transferring a frozen piece of bone are very challenging.

4. Some centers just throw the bone flap away. This necessitates replacing it with some other material like metal or plastic. This tends to be more complicated and expensive, since the replacement needs to be sculpted to fit the existing gap.

So which flap management technique is best? Unfortunately, we don’t know yet, and probably never will. Your neurosurgeons will have their favorite technique, and that will ultimately be the option of choice.

Reference: Bone flap management in neurosurgery. Rev Neuroscience 17(2):133-137, 2009.

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Abstracts, Head

Best Of AAST #4: TBI and Antiplatelet / Antithrombotic Agents

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More and more people are taking antiplatelet or antithrombotic agents for a variety of medical conditions. One of the dreaded side effects of these medications is undesirable bleeding, particularly after injury. This is especially true if the bleeding occurs inside the skull after any kind of head trauma.

Which agents, if any, lead to worse outcomes? The literature has been a bit inconsistent over the past 10 years. A group from HCA Healthcare reviewed the trauma registries from 90 hospitals, which I presume are in the HCA system. They included patients patients who suffered a ground level fall and were 65 years or older. They excluded those who had a significant injury to regions other than the head.

Here are the factoids:

  • Over, 33,000 patient records were reviewed, with an average age of 81
  • Nearly half were on single or multiple anti-thrombotic therapy (!)
  • The proportion of patients sustaining a “TBI” was roughly the same (21%) whether they were not on anti-thrombotic therapy or not
  • Apixaban and rivaroxiban were associated with lower rates of “TBI” (13-16%)
  • Clopidogrel was associated with a higher “TBI” rate (23%)
  • Patients requiring brain surgery  were more common in patients taking aspirin plus clopidogrel (2.9%) vs all the others (2%) and this was statistically significant
  • None of the treatment regimens were associated with higher mortality (roughly 2-3%)

The authors conclude that anti-thrombotic use in the elderly who suffer a ground level fall are not at risk for increased mortality and that they may have negligible impact on management.

My comments: The one thing that makes this abstract difficult to read is their use of the term TBI, which is why I put it in quotes above. I think that the authors are conflating this acronym with intracranial hemorrhage. It’s a bit confusing, because I think of TBI as a term that means the head was struck and either left a physical mark (bump on the outside or blood on the inside) or there was known or suspected loss of consciousness. They are apparently using  it to describe intracranial bleeding seen on CT.

And because this is a registry study, many of the patient-specific outcome details cannot be analyzed. Mortality and operative rates are very crude outcomes. What about some of the softer ones? Although the average GCS was stated to be 14.5, it would be interesting to know how many of these patients were able to return to their previous living situation, and how many were significantly impaired even though they didn’t die or need an operation.

Here are my questions for the presenter and authors:

  • How do you define a TBI in this study? Could it be just a concussion? Does it require some type of blood in the head? Assuming that there are lots of TBIs that occur without intracranial bleeding, including such patients in your analyses will skew the data toward lower incidence and will dilute out the patients with hemorrhage.
  • What was the length of your study? If it includes data that is older than six years or so, it may under-represent the use of some of the direct oral anticoagulant drugs (DOACs).
  • Are half of your elderly falls patients really on anti-thrombotic therapy? This is a shocking number, and seems to be high in my experience. Since your study was distributed across a large number of hospitals, it brings up the question of whether so many of our elders really need this medication.
  • Do you have any sense for how your various subgroups fared in terms of their discharge disposition? You conclude that the use of anti-thrombotic agents isn’t so bad, really. At least when it comes to needing brain surgery or dying. But are there other cognitive issues that are common that might encourage trauma professionals to continue to look at these drugs with a wary eye?

This is important work, and I am anticipating a great discussion after your presentation.

Reference: Antiplatelet and antiplatelet agents, alone and in combination, have minimal impact on traumatic brain injury (TBI) incidence, need for surgery, and mortality in ground level falls (GLFs): a multi-institutional analysis of 33,710 patients. AAST 2020 Oral Abstract # 7.

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Head

More On CSF Rhinorrhea/Otorrhea

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Trauma professionals worry about stuff. Like just about everything, really. Sometimes we have good guidance (research) to help us decide what to do. Many times, we don’t. Management of rhinorrhea and otorrhea from CSF leak after trauma is definitely one of those things.

I’ve seen a variety of treatments used in these patients over the years. Is it really a CSF leak? Let’s get a beta-2 transferrin test (see below). Can’t the patient get meningitis? Their may be concomitant sinus fracture and bacterial contamination, so why not give antibiotics? Or vaccinate them?

The Cochrane library contains a vast number of reviews of common clinical questions. One of those questions just happens to be the utility of giving prophylactic antibiotics in patients with basilar skull fracture. Interestingly, they’ve been reviewing and re-reviewing this question about every 5 years, since 2006. During the three reviews done, there have been no additional research papers published on the topic.

Here are the factoids:

  • Studies that specifically examined the use of prophylactic antibiotics in patients with basilar skull fracture were reviewed. All included meningitis as one of the outcome parameters.
  • There were only 5 high quality (randomized, controlled) trials, with a total of 208 participants
  • There were an additional 17 lower quality trials published, but no conclusions could be reached from them due to methodology problems
  • In the high quality trials, there were no differences in the incidence of meningitis, mortality, or meningitis-related mortality
  • There were no specific adverse effects related to antibiotic administration. But one of the high quality studies did note a shift to higher counts of pathologic bacteria in the posterior nasopharynx in the antibiotic group.
  • No studies on the use of meningitis vaccinations exist. A survey of UK physicians showed that 35% recommend at least one vaccine, typically for Strep Pneumo.

Bottom line: There is still no good evidence to support the use of prophylactic antibiotics or meningitis vaccination in patients with CSF leak from uncomplicated basilar skull fracture. When you see surveys that show some physicians promoting a treatment and others doing nothing, it means there is most likely no significant benefit. If there were a big difference, we would have seen it by now! And giving drugs (antibiotics, vaccines) that have no proven use is expensive and can always lead to unexpected complications. 

References:

  • Immunisations and antibiotics in patients with anterior skull base cerebrospinal fluid leaks. J Laryngol Otol 128(7):626-629, 2014.
  • Antibiotic prophylaxis for preventing meningitis in patients with basilar skull fractures. Cochrane Database Syst Rev April 28, 2015.
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Head

Tips For Taking Care Of CSF Leaks

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The management of CSF leaks after trauma remains somewhat controversial. The literature is sparse, and generally consists of observational studies. However, some general guidelines are supported by large numbers of retrospectively reviewed patients.

  • Ensure that the patient actually has a CSF leak. In most patients, this is obvious because they have clear fluid leaking from ear or nose that was not present preinjury. Here are the options when the diagnosis is less obvious (i.e. serosanguinous drainage):
    • The “halo” or “double ring sign” is a form of pillow chromatography. The blood components separate from the CSF as they move through the pillow fabric, creating a clear ring or halo surrounding a bloody spot. This is the cheapest, fastest test and is actually fairly reliable.
    • High resolution images of the temporal bones and skull base. If an obvious breach is noted, especially if fluid is seen in the adjacent sinuses, then a CSF leak is extremely likely.
    • Glucose testing. CSF glucose is low compared to serum glucose.
    • Beta 2 transferrin assay. Don’t do it!! This marker is very specific to CSF. However, the test is expensive and results may take several days to a few weeks to receive. Most leaks will have closed before the results are available, making this a poor test.
  • Place the patient at bed rest with the head elevated. The basic concept is to decrease intracranial pressure, which in turn should decrease the rate of leakage. This same technique is used for management of mild ICP increases after head injury.
  • Consider prophylactic antibiotics carefully. The clinician must balance the likelihood of meningitis with the possibility of selecting resistant bacteria. If the likelihood of contamination is low and the patient is immunocompetent, antibiotics may not be needed.
  • Ear drops are probably not necessary. They may confuse the picture when gauging resolution of the CSF leak.
  • Wait. Most tramatic leaks will close spontaneously within 7-10 days. If it does not, a neurosurgeon or ENT surgeon should be consulted to consider surgical closure.

References:

  1. Brodie HA, Thompson TC. Management of complications from 820 temporal bone fractures. Am J Otol, 1997;18:188-197.
  2. Brodie HA. Prophylactic antibiotics for posttraumatic cerebrospinal fluid fistulas. Arch Otolaryngol Head, Neck Surg. 123:749-752.
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