UMEM Educational Pearls - Neurology

• Given the recent extremely cold winter weather experienced in some parts of the country, we will likely be expected to recognize and treat true frostbite and its sequelae at an increasing rate.
• Frostbite is the result of focal injury that follows the crystallization of water within subcutaneous tissue when exposed to low temperatures. 
• Sequelae such as chronic neuropathic pain syndromes can results in up to 25% of patients with frostbite due to microvascular damage.
• Hyperbaric oxygen has been shown to effectively treat this sequelae, even if administered in a delayed fashion, and should be considered as a viable therapeutic option.

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• In states without mandatory physician reporting of patients with seizures, the decision of whether to breach confidentiality and report a poorly controlled epileptic patient who continues to drive an automobile becomes an ethical dilemma.
• In making this decision, one must consider the probability and magnitude of the potential harm.
• If the probability and magnitude are both low, or the probability of harm is high but the associated magnitude is low, there is generally no moral obligation to breach confidentiality and report.
• If the probability of harm is low but the potential magnitude of the harm is high, one should strongly consider reporting the case.
• Each case should be handled on an individual basis, take into consideration the risks and benefits to the patient and society if reporting is ensued, and perhaps elicit the advice of risk management.

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• Apart from time and rehabilitation, there is currently no effective treatment for reversing brain damage caused by stroke.

• Clinical recovery after a stroke results from neuro-restorative processes such as neurogenesis, angiogenesis, synaptic plasticity, and/or re-modeled and strengthened connections between neurons. 

• Stem cell therapy for stroke is a novel, but progressive area of research which would potentially facilitate the neuro-restorative processes required for recovery. 

• Despite the extremely complex nature of brain function and central nervous system networks, successful stem cell therapy for brain infarct could become the wave of the future for optimal stroke management.

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-- While we typically associate seizures within the context of alcoholism with physiologic withdrawal, studies have shown that there is a dose-dependent relationship between the consumed amount of alcohol and the onset of seizure activity, independent of alcohol withdrawal.

-- Specifically, Ng and colleagues found a 3-fold increase in seizure occurance with 50 to 100 grams of ethanol per day, compared to an 8-fold increase with 101 to 200 grams of ethanol per day.

-- This study further found that ex-drinkers (abstention for >= 1 yr.) were not at any increased risk of seizure and that drinkers who had seizures did so well outside of the conventional window of withdrawal.  

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• While seizure is rarely associated with stroke during its hyperacute phase, Arboix found that the development of epileptic strokes within the first 48 hours post-stroke occurs about 2.4% of the time and portends a higher degree of in-patient mortality.
• Seizure activity in the setting of acute stroke is more commonly associated with hemorrhagic types (4.3 % of cases), compared to just 2% with ischemic strokes.
• Younger age, acute confusional states, hemorrhagic strokes, cortical strokes, and strokes affecting the frontal, parietal, occipital, and temporal lobes were found to be risk factors for stroke-related seizures.
• The use of prophylactic anti-epileptic medication in the acute phase of stroke varies and, some say, requires further research; such treatment is more commonly reserved for use in hemorrhagic stroke patients, however, if at all.

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Cortical versus Subcortical Strokes

• Gray matter (neuronal cell bodies) of the brain forms a rim over the cerebral hemispheres, forming the cerebral cortex.
• White matter (neuronal axons coated in myelin) is located below the cortex and makes up the "subcortical" regions of the brain.
• Strokes affecting the cerebral cortex (i.e. cortical strokes) classically present with deficits such as neglect, aphasia, and hemianopia.
• Subcortical strokes affect the small vessels deep in the brain, and typically present with purely motor hemiparesis affecting the face, arm, and leg.
• Nearly 30% of all ischemic strokes are subcortical in nature, and includes lacunar infarcts which have the best prognosis.

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Aisha T. Liferidge, MD, FACEP
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Assistant Professor, Attending Physician
University of Maryland School of Medicine
Department of Emergency Medicine
Baltimore, MD 21201
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MPH Candidate, Columbia University 2011

• Non-enhanced Brain CT (NECT) offers low yield in terms of its diagnostic utility for acute ischemic stroke (AIS), with sensitivities less than 67% at 3 hours out from symptom onset.

• A hyperdense middle cerebral artery (MCA) sign may represent acute thrombus and predicts impending large territorial infarct of poor prognosis (*see images of MCA Sign (left) and subsequent territorial edema representing infarct (right) below).

• While MCA Signs occur somewhat rarely, this finding is one of the earliest and most useful indicators of probable (clinical) stroke on NECT, and should be a recognizable hallmark for the emergency physician.

• Note that hyperdense MCA's can mimic a thrombus and actually represent atherosclerotic calcifications.

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• Elevated intracranial pressure (ICP) can sometimes be associated with focal symptoms related to mass lesions or herniation syndromes.

• Herniation is the result of pressure gradients between two regions of the cranial vault, such as that related to cerebral edema from an acute stroke.

• The following list describes areas most commonly affected by herniation syndromes: 

          --- subfalcine

          --- central transtentorial

          --- uncal transtentorial

          --- upward cerebellar

          --- cerebellar tonsillar/foramen magnum

          --- transcalvarial

• Frank hypointensity (i.e. dark hue) on CT of the brain, particularly if involving greater than one-third of the middle cerebral artery (MCA) territory, is a contraindication to treating acute ischemic stroke with tPA.

• Early signs of infarct on brain CT, regardless of extent, are NOT contraindications to treatment.

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The following is a differential diagnosis for unilateral headaches with typical associated features:

• Migraine headache ->  throbbing pain preceded by aura; nausea; photophobia; chronicity.
• Cluster headache ->  piercing eye pain; ipsilateral lacrimation and rhinorrhea; group of headaches come periodically in waves.
• Temporal arteritis ->  dull ache over temporal artery; associated with arthralgia, myalgia, and anemia; typically in older populations.
• Glaucoma ->  eye pain with cloudy appearing cornea; eyeball feels hard; pupillary dilitation may worsen pain.
• Sinusitis ->  associated with sinus congestion; tenderness over sinus with or without swelling; typically only relieved with decongestants and/or antibiotics.
• Subarachnoid hemorrhage ->  pain may be diffuse or unilateral; sudden onset of severe pain; may be associated with a stiff neck.

Optimal brain imaging for diagnosing and managing acute ischemic stroke should address the presence of 4 essential issues:

• hemorrhage
• intravascular thrombus
• core irreversibly infarcted tissue and its size, and
• hypoperfused tissue at risk for subsequent infarction if not rescued.

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Optimal brain imaging for diagnosing and managing acute ischemic stroke should address the presence of 4 essential issues:

• hemorrhage
• intravascular thrombus
• core irreversibly infarcted tissue and its size, and
• hypoperfused tissue at risk for subsequent infarction if not rescued.

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• Neuroleptic Malignant Syndrome (NMS) is a rare, but true neurological emergency which is today associated with much lower mortality given heightened awareness about the condition.

• It typically initially begins with muscle rigidity resulting in rhabdomyolysis, followed by high fever, and delirium.

• Always check creatinine phosphokinase (CPK) and white blood cell levels when concerned about NMS, as these typically elevate in response to muscle breakdown.

• The following mnemonic (FEVER) serves as a reminder of the signs and symptoms associated with NMS:

           F - Fever (anything over 100.4 F counts)

            E - Encephalopathy

           V - Vital signs instability

           E - Enzymes elevation (i.e. CPK)

            R - Rigidity of muscles

Global symptoms of elevated intracranial pressure (ICP) include:

• Headache (likely mediated via the pain fibers of cranial nerve V in the dura and blood vessels)
• Depressed consciousness (likely due to either the local effect of mass lesions or pressure on the midbrain reticular formation)
• Vomiting

• Guillain-Barre’ syndrome can be associated with marked neuropathic pain which is best described as having “burning” skin.

• Additionally, these patient may develop hemodynamic instability and adynamic ileus, both related to autonomic dysfunction.

• Classically, GB patients present with a foot drop several days after an episode of food poisoning, most commonly from Campylobacter jejuni.

• Infections induce activated T cells and antibodies, which within the context of an influenza syndrome, are thought to cross react with axonal antigens and macrophages, resulting in demyelination.  This process likely triggers a subsequent Guillain-Barre’ syndrome (GBS).

• Presumably, influenza vaccine induces a similar response in susceptible individuals.

• Juurlink and colleagues found there to be a 1.45 relative risk, which equals a 1.7-fold adjusted relative risk for contracting GBS, associated with influenza vaccination.

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• In 1976, vaccination with the swine flu vaccine was associated with a small risk of developing Guillain Barre Syndrome (GBS), approximately 1 additional case per 100,000 people who received the swine flu vaccine, which was slightly higher than the background rate for GBS.

• Since then, numerous studies have been done to evaluate if other flu vaccines were associated with GBS. In most studies, no association was found, but two studies suggested that approximately 1 additional person out of 1 million vaccinated people may be at risk for GBS associated with the seasonal influenza vaccine.

• It is important to keep in mind that severe illness and possible death can be associated with influenza, and that vaccination is the best way to prevent influenza infection and its complications.

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• Guillain-Barre’ Syndrome (GBS) is a group of immune mediated processes characterized by motor, sensory, and autonomic dysfunction of peripheral nerves.

• Classically, GBS is an acute inflammatory demyelinating polyneuropathy (AIDP) consisting of progressive, symmetric, ascending muscle weakness and paralysis, associated with diminished deep tendon reflexes.

• This rare condition, affecting 3,000 to 6,000 Americans annually (1 to 2 out of 100,00 per year), can lead to respiratory failure in severe cases, requiring vigilance in pro-actively administering mechanical ventilation as needed.

• Pregnant patients presenting with their first seizure, should essentially be managed in the same way as any other adult patient (i.e. Is the source of the seizure due to a reversible systemic condition, and if not, is the patient at risk for recurrent unprovoked seizures; specialist follow-up arrangement).

• Additional pregnancy-related conditions that can be associated with seizure, such as eclampsia and cerebral venous thrombosis, should be considered.

• While the safety of all anti-epileptic drugs in pregnancy is questionable, the use of valproate (Depakote) should definitely be avoided, given its compelling association with fetal malformations.

• Strokes resulting from embolic or thrombic insult to the middle cerebral artery (MCA) are common.

• These patients tend to present with contralateral motor deficit which is most pronounced in the upper extremity (and face), compared to the lower extremity.

• If motor weakness is more pronounced in the lower extremity, consider an anterior cerebral artery (ACA) infarct as the source.