• Bitemporal hemianopsia ("tunnel vision") is a type partial blindness affecting the lateral halves of vision in both eyes (see attached diagram), and is usually associated with lesions or compression of the optic chiasm.
• Always assess visual fields in patients presenting with neurologic complaints, particularly when associated with visual abnormality, headache, focal deficit, and endocrine-related symptoms.
• One of the simplest ways of assessing visual fields is to (1) stand directly in front of the patient, (2) instruct them to stare straight at your nose, (3) laterally extend both your arms to 2/3 of full capacity (i.e. elbows slightly bent), and (4) ask them where they see your wiggling fingers (i.e. left or right).  
• Bitemporal hemianopsia commonly results from pituitary microadenomas (< 1 cm) and macroadenomas (> 1 cm), which are sometimes associated with acromegaly and Cushing's Disease.

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• 1004140823_Visual_Field_Abnormalities.jpg (44 Kb)

• Nonspecific brain atrophy is a common finding on Head CT's, sometimes without any clearly articulated clinical significance for the emergency physician.
• Generally speaking, brain atrophy is the manifestation of the effects of atherosclerosis.
• Radiographically, it typically presents as widened sulci and dilated ventricles.
• In patients with vague mental status abnormalities and limited access to medical history, consider the following brain atrophy clues in your management:

              --  Multiple areas of local cortical brain atrophy (wedge-shaped

                   appearance) suggests multi-infarct dementia.

              --  Disproportionate atrophy in the frontal and temporal lobes may be a 

                   sign of Alzheimer's Disease.

• The thalamus is a major relay center of the brain locaed between the cerebral cortex and the midbrain.
• It regulates motor and sensory function as well as sleeping and waking states. 
• It is supplied by 4 arterial systems (3 from the vertebrobasilar system; 1 from the posterior communicating system) such that strokes within these territories result in 4 distinct clinical syndromes, including syndromes consisting of pure sensory, arousal, and memory deficits.
• Thalamic strokes are thought to be more common in young people, associated with smoking and hypertension, and of poorer prognosis when presented with loss of consciousness.

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• Etiologic causes of hearing loss can be categorized into three groups:  (1) Sensorineural, (2) Conductive, and (3) Sensorineural and Conducitve.
• Sensorineural hearing loss results from problems with the vestibulocochlear nerve (cranial nerve VIII), inner ear, or central processing centers of the brain.
• When performing the Weber Test on patients with sensorineural hearing loss (tuning fork touched to midline of skull), sound localizes to the normal ear (i.e. sound conducts normally through bone, which measures sensorineural function, on the side without the abnormality).
• Examples of conditions that cause sensorineural hearing loss include:  Acoustic neuroma and other cerebellopontine angle tumors, perilymph fistula, noise trauma, and ototoxic medications.     

• The majority of epilepsies (60%) are partial-onset or focal, such that a single, isolated part of the body is affected.
• Seizures arising from the temporal lobe of the brain are the most common type of partial-onset epilepsy and have been associated with childhood febrile seizures.
• Simple temporal lobe seizures, which do not result in a loss of consciousness, typically present as a sensation such as: 

              -- Deja' vu (feeling of familiarity)     -- Jamais vu (feeling of unfamiliarity)

              -- Specific or single set of memories     --  Amnesia

             -- Auditory        --  Gustatory       --  Visual       --  Disphoric     -- Euphoric 

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•  Focal seizures, such as those due to frontal lobe epilepsy (FLE), are not always easy to recognize and may be erroneously attributed to peripheral or psychiatric sources.
• FLE seizures may present as abnormal body posturing, sensorimotor tics, and/or other abnormal motor skills, and rarely may be associated with uncontrollable laughing and/or crying.
• Post-seizure confusion >may occur, but typically does not last as long as the post-ictal states associated with other types of epilepsy.

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• Frontal Lobe Epilepsy (FLE) is characterized by recurrent, brief, focal seizures arising from the frontal lobe of the brain, often occuring during sleep.
• FLE is the second most common form of epilepsy, behind Temporal Lobe Epilepsy (TLE).
• FLE presents in 2 forms:  (1) simple partial (focal) seizures (no affect on awareness or memory), or (2) complex partial (focal) seizures (affects awareness and memory before, during, and/or after the seizure).
• FLE seizures are often misdiagnosed as psychiatric disorders, non-epileptic convulsions, or sleep disorders, due to the unusual symptoms that they often produce.

• The 7-day risk of completed ischemic stroke after TIA is 5%.
• The use of reliable stroke prediction tools are potentially invaluable in guiding the degree of urgency that one applies to the management of TIA patients.
• Accuracy of the ABCD² Score, considered to be the most-refined tool of its kind, was recently again evaluated.
• This 7-point scale assigns risk based on 5 factors: Age > 60 (1 pt.), BP > = 140/90 (1 pt), Clinical features - weakness (2 pts), speech impairment w/o weakness (1 pt); Duration  >=60 min (2 pts), 59 to 10 min (1 pt); Diabetes (1 pt).
• The study found that the discriminatory power of the ABCD² Score may best be applied when used in patients at low risk for an early, disabling ischemic stroke.     

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• For many years the recommendations for managing new-onset seizure (NOS) in the emergency department did not include any specific instruction for such patients with HIV/AIDS.
• A study done by Pesola and colleagues found that, infact, AIDS patients with NOS require additional vigilence in terms of their management.
• This study found that over 15% of AIDS patients with NOS would have erroneously been sent home without appropriate treatment had the standard recommendation for NOS management been followed; these patients were found to have intracranial lesions related to toxoplosmosis and lymphoma, and did not necessarily have focal neurologic deficits.
• It is therefore recommended that all AIDS patients with NOS undergo neuroimaging with lumbar puncture, as indicated.

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• 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.

---------------------------------------------------------------------------------------------------------------------------
 
Aisha T. Liferidge, MD, FACEP
---------------------------
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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