UMEM Educational Pearls - Neurology

• The DAWN trial was a multicenter, randomized, open-label study comparing endovascular thrombectomy plus standard medical care with standard medical care alone for patients with:
  • Acute stroke symptoms
  • Last known well 6 to 24 hours earlier
  • Evidence of intracranial ICA or proximal MCA occlusion
  • Mismatch between clinical deficit and infarct volume on CTA or MRA
• The study found that patients receiving thrombectomy plus standard medical care had improved functional independence at 90 days as defined by modified Rankin Scale (mRS) of 0, 1, or 2 (49% vs 13%).
• The trial was stopped early based on prespecified interim analysis intended with the adaptive trial design.
• While the two treatment groups were similar, with median NIHSS score of 17, they had small infarct volumes and short time from symptom observation (4.8 vs 5.6 hours) compared to time of patient's last known well (12.2 vs 13.3 hours). 
• 88% of the patients had unwitnessed stroke onset (including wake-up strokes), thus it is possible that these patients had actual ischemia times closer to 6 hours, thereby reproducing similar results as prior thrombectomy trials.

Bottom Line: The use of neuroimaging to identify an ischemic penumbra that may benefit from thrombectomy may be considered even for patients with time of last known well beyond 6 hours.

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• A retrospective single center study reviewed 788 patients who presented to the ED with concern of stroke and found 21 (3%) patients had only aphasia symptoms by the NIHSS.
• None of these patients had evidence of infarct on neuroimaging.
• 3 of these patients were diagnosed with possible transient ischemic attack (TIA) though also had other possible diagnoses.
• Toxic/metabolic disturbances (39%), followed by seizure (11%), syncope (11%), and chronic medical problems (11%) were the most commonly diagnosed stroke mimics.

Take Home Point: This small but interesting study looked at the incidence of isolated aphasia presenting for concern of stroke. They found that none of their patients had evidence of an infarct, suggesting that strokes affecting language without motor or sensory deficits are uncommon.

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It's respiratory infection and flu vaccine season! Time to brush up on Guillain-Barré Syndrome..

- It is the most common cause of acute or subacute flaccid weakness worldwide

- 70% of cases are preceded by an infection in the past 10-14 days, but most are minimized or forgotten by the patient. 40% of these infections are by Campylobacter jejuni.

- 30% develop respiratory failure requiring intubation and ventilation

- Half of the patients will develop their maximum weakness by 2 weeks, most will develop it by 4 weeks.

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Traumatic brain injury (TBI) is associated with close to half of major trauma admissions in adults over age 65 in the U.K.

Falls accounted for 85% of all TBIs, while 45% of patients had subdural hematomas (SDH).

More than 3/4 of patients were treated conservatively, though outcomes were not significantly better than those who underwent neurosurgical intervention.

Higher age is associated with higher mortality and greater disability.

Bottom Line: Trauma in older adults is increasing and fall prevention is important in reducing significant injuries.

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IV vs. Non-IV Benzodiazepines for Cessation of Seizures

• A meta-analysis by Alshehri et al. included 11 studies with a total of 1633 patients, comparing IV vs. non-IV benzodiazepines from any route (buccal, intranasal, intramuscular) for seizure cessation in status epilepticus.
• They found that non-IV benzodiazepine is more effective than IV benzodiazepine in patients presenting without IV access.
• The largest and highest quality study included in the meta-analysis was the RAMPART study, which was also the only study to include adults.
• When considering pediatric studies only, there is no difference between IV vs. non-IV benzodiazepine in seizure cessation for status epilepticus.

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• CSF:blood glucose ratio is a useful characteristic in differentiating bacterial meningitis from viral meningitis. 
• Normal CSF glucose is at least 2/3 of serum glucose level.
• In bacterial meningitis, CSF:blood glucose ratio is usually <0.4
• Rousseau et al. conducted a study comparing CSF:blood glucose ratio obtained using a bedside glucometer with the laboratory.
• They found the optimal cutoff of CSF:blood glucose ratio using a bedside glucometer is 0.46 compared to 0.44 using the laboratory.
• This proof-of-concept study suggests that a point-of-care glucometer can be used for rapid diagnosis of abnormal CSF:blood glucose ratio in the evaluation of meningitis.

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• It most commonly occurs in patients with preexisting pituitary adenomas, but 3 out of 4 patients with pituitary adenomas are unaware of their diagnosis.
• Patients may acutely present with thunderclap headache, with or without visual field deficits or cranial nerve dysfunction. They may also have meningeal symptoms due to extravasation of blood into the subarachnoid space.
• Endocrine dysfunction is common but not readily diagnosed in the ED.
• Symptoms may be triggered by some hormonal treatments (e.g. GnRH agonists for prostate CA), head trauma, angiographic procedures, or anticoagulation therapy.
• CT is diagnostic in only one-third of cases, but can reveal the intrasellar mass in 80% of cases, and therefore should be the initial test. Blood may be missed in subacute cases.
• MRI is the test of choice, with a sensitivity of over 90%.  

Bottomline: Keep pituitary apoplexy in your differential when considering SAH or meningitis, especially in the presence of risk factors, and have a low threshold to order an MRI. 

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Question

50 YOF with acute onset of worst headache of life associated with nausea and vomiting.  Patient is somnolent, will rouse to noxious stimuli and complains of a headache as well as decreased vision.

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What is the role of EEG for first-time seizures in the ED?

• Wyman and colleagues performed a prospective trial on the use of 30-minute routine electroencephalogram (EEG) in the ED after a first-time seizure or recurrent seizure without performance of a previous EEG to guide decision making in the initiation of antiepileptic medication.
• A diagnosis of epilepsy based on EEG findings was made for 21% of patients (n=15/71).
• Antiepileptic medication was initiated in 24% of patients (n=17/71), including 2 patients with abnormal but not epileptic EEG findings.

Take Home Point:  A 30-minute routine EEG in the ED in adults with an uncomplicated first-time seizure revealed a substantial number of epilepsy diagnosis and can change ED management with immediate initiation of antiepileptic medication.

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Vasovagal syncope is a subtype of neurally mediated syncope, and it is distinctly different from orthostatic hypotension. 

Patients with orthostatic syncope have severe orthostatic hypotension that results in transient loss of consciousness immediately or within moments of standing up. This is different from neurally mediated syncope, which develops gradually under conditions of prolonged orthostatic stress such as standing for several minutes. Tilt table testing is useful for true orthostatic syncope, but not for neurally mediated syncope. In addition, checking for “orthostatic hypotension” may not capture patient with orthostatic syncope, because the hypotension occurs so quickly after standing up. Of note, patients may still have orthostatic tachycardia or intolerance with neurally mediated syncope. 

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• The Glasgow Coma Scale (GCS) is an instrument widely used to assess level of consciousness by EMS.
• The motor GCS (mGCS) and Simplified Motor Scale (SMS) have been proposed to simplify EMS triage.
• A number of retrospective studies have compared these scales.
• Chou et al. performed a systematic review and meta-analysis of 18 studies with a total number of 1.7 million patients to compare the predictive utility of these scales for identification of patients with severe traumatic injury.
• The total GCS was slightly better than the mGCS or SMS on predicting mortality, neurosurgical intervention, severe traumatic brain injury, and emergent intubation.

Bottom Line:  The motor GCS and Simplified Motor Scale (SMS) have similar discrimination when compared with the total GCS, and may be easier to use.

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• The incidence of stroke (both ischemic and hemorrhagic) in pregnant and peripartum women is three times age-matched controls. This increased risk is mostly in the 3rd trimester and up to 16 weeks postpartum. 

• Consider other causes of stroke:  posterior reversible encephalopathy syndrome (PRES), reversible cerebral vasoconstriction syndrome, cerebral venous sinus thrombosis and cardioembolic stroke from peripartum cardiomyopathy.

• CTs carry some risk due to the ionizing radiation, but with abdominal and pelvic shielding the exposure to the fetus is very low. MRIs do not carry that risk, but Gadolinium is absolutely contraindicated in pregnancy as it deposits in fetal tissue. 

• Pregnancy is a relative (not absolute) contraindication for tPA.

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