A digest of Dr. Herbert’s monthly audio CME series
edited by Chris Feier, MD

1. Aortic Dissection Pearls

Aortic dissection is a difficult diagnosis to make and has been dubbed the “Great Masquerader” due to the myriad of possible presentations including stroke, MI, abdominal pain, and lower extremity problems. D-dimer may be useful as a screening test for dissection because of reported sensitivities of >99% and negative predictive values >99% across multiple studies. D-dimer, like its use in pulmonary embolism, is useful in ruling out the diagnosis of dissection. Most unstable patients with an ascending dissection (Stanford A) should be transferred immediately to the OR, although some patients may benefit from medical anti-impulse therapy with β-blockers and afterload reducers. This includes patients with completed stroke, underlying malignancy, advanced age, and those refusing operation. Descending dissections (Stanford B) are usually managed medically with anti-impulse therapy and rarely require surgery.

Six Key Pitfalls in Diagnosis of Subarachnoid Hemorrhage
“But it wasn’t the worst HA of their life”
-Sentinel bleeds can present as mild headaches and not worst of their life
-Consider work-up for SAH in any patient whose headache is sudden onset, maximal within seconds, and different than previous headaches

“The neurologic examination was completely normal”
-If neuro exam is abnormal, then it may be too late
-Hunt-Hess Classification grades I and even II and III can have normal neurologic exams or slight deficits
-Grades IV and V SAH have obvious neurologic deficits because of devastating bleeds
-What to look for on examination: any neurological deficit and meningeal irritation (jolt test)

“The pain got better with…”
-SAH can improve with pain medication also

“The CT was negative”
-CT sensitivity is based on CT scanner, radiologist, time from headache onset, and selection bias
-Multiple studies show CT or MR alone are not sufficient to rule-out SAH

 “The RBC count decreased from tubes 1 to 3”
Misinterpreting the LP→what we were taught will rule-out SAH:
---25% decrease from tubes 1 to 4
---Less than 1,000 RBCs in tube 4
---No xanthochromia
The truth
---There is no number below which rules out SAH
---The RBC count must clear and approach zero to rule-out SAH
---Absence of xanthochromia does not rule out SAH

“I’ll skip the LP, we can always do an MRA”
-Lumbar puncture is the most sensitive test in medicine
-Angiographies have less sensitivity than LP
-Re-bleed incidence of ruptured aneurysm:
---24 hours_4%
---3 weeks_20%
---6 months_50%
-Bleeding incidence of UNruptured aneurysm <10mm (prevalence 2-3% of general population):
---6 months_0.025%
---20 years_1%
Conclusion: LP is needed at HA presentation to determine if aneurysm rupture is cause of HA (will need surgery) vs. unruptured aneurysm in a patient with a benign HA4 DO THE LP!
Source: Stuart Swadron, MD
2. Steroids are no longer recommended for spinal cord injury

There have been multiple studies in the past to evaluate the efficacy of steroids for acute traumatic spinal cord injury. The largest of these studies were the NASCIS (National Spinal Cord Injury Study) trials.

In the first study, NASCIS I (1979), a standard dose of methylprednisolone (100 mg) was compared with a megadose (1,000 mg) given intravenously once daily for 10 days. There was no difference between the two groups with respect to either modality at 6 weeks, 6 months, and 1 year.

NASCIS II (1985) compared the effect of placebo with a megadose of methylprednisolone. Patients who received methylprednisolone had better sensory function at 6 months as compared with the control group. However, this effect disappeared at 1 year. Improvement in motor function was statistically significant at 6 months and even after 1 year in the methylprednisolone group compared with the control group. Increased incidence of wound infection was seen with the high dose steroids.

The NASCIS III study (1991) randomized patients to either high dose steroids for 24 or 48 hours. Follow-up after 6 months revealed no significant difference between the groups with regard to any modality. Subgroup analysis showed a modest benefit in patients who received methylprednisolone between 3 to 8 hours after spinal cord injury for the full duration of 48 hours. This difference was observed at 6 weeks and 6 months, but was less apparent at 1 year (p=.053).

Conclusion: There is no convincing evidence to support the use of steroids in spinal cord injury and is no longer part of the recommendations of the American Association of Neurologic Surgeons or ATLS.
Source: Ali Salim, MD

3. Should I use Hypertonic Saline in Traumatic Brain Injury?

Hypertonic saline (HTS) has been shown to decrease intracranial pressure (ICP) and increase cerebral perfusion pressure (CPP) which is ideal in traumatic brain injury. Hypertonic saline has the added benefit over mannitol of increasing circulating blood volume which may be needed in the multi-system blunt trauma patient. When comparing HTS with mannitol, they both will lower ICP, but HTS may actually lower it more. In a study done by Cooper et al, (JAMA. 2004;291:1350-1357) pre-hospital HTS was compared to lactated ringers in comatose hypotensive trauma patients. Although there was no statistically significant improvement in outcomes with HTS, there was a modest trend toward improvement in mortality compared to Ringer’s lactate (55% vs. 47%). The Brain Trauma Foundation guidelines (www.braintrauma.org) currently recommend mannitol for decreasing ICP but caution against hypotension. Dr Salim concludes that more data will be needed in the future to fully evaluate hypertonic saline’s effectiveness on traumatic brain injury.
Source: Ali Salim, MD

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