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Questions and Answers
What is the condition characterized by altered mental status, ataxia, stupor, and progression to coma if untreated?
What is the condition characterized by altered mental status, ataxia, stupor, and progression to coma if untreated?
High-altitude pulmonary edema is a cardiogenic edema.
High-altitude pulmonary edema is a cardiogenic edema.
False
What is the recommended treatment for acute mountain sickness?
What is the recommended treatment for acute mountain sickness?
Acetazolamide, dexamethasone, descent, and hyperbaric therapy
___________ is experienced only by mountain climbers and is accompanied by severe hypoxemia and hypocapnia.
___________ is experienced only by mountain climbers and is accompanied by severe hypoxemia and hypocapnia.
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Match the altitude ranges with their associated characteristics:
Match the altitude ranges with their associated characteristics:
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What is the term for a transient focal deficit following a simple or complex focal seizure?
What is the term for a transient focal deficit following a simple or complex focal seizure?
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Which of the following is a common precipitating factor for complex partial seizures?
Which of the following is a common precipitating factor for complex partial seizures?
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What is the term for the abnormalities in the structure of the central nervous system that can cause seizures?
What is the term for the abnormalities in the structure of the central nervous system that can cause seizures?
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Which of the following is NOT a common cause of provoked (secondary) seizures?
Which of the following is NOT a common cause of provoked (secondary) seizures?
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What is the term for the hallucinations and distorted perception that can occur during complex partial seizures?
What is the term for the hallucinations and distorted perception that can occur during complex partial seizures?
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Which of the following is a common feature of complex partial seizures?
Which of the following is a common feature of complex partial seizures?
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What is an important indication for obtaining CT imaging in a patient with a seizure?
What is an important indication for obtaining CT imaging in a patient with a seizure?
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What is the role of lumbar puncture in the evaluation of a patient with an acute seizure?
What is the role of lumbar puncture in the evaluation of a patient with an acute seizure?
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What is the primary indication for emergent EEG in the evaluation of a patient with a seizure?
What is the primary indication for emergent EEG in the evaluation of a patient with a seizure?
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What is the recommended treatment for an uncomplicated seizure?
What is the recommended treatment for an uncomplicated seizure?
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What is the primary laboratory test to consider in a patient with a well-documented seizure disorder who has had a single unprovoked seizure?
What is the primary laboratory test to consider in a patient with a well-documented seizure disorder who has had a single unprovoked seizure?
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What is the correlation between hyperventilation syndrome and seizures?
What is the correlation between hyperventilation syndrome and seizures?
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What is the role of imaging studies in the evaluation of a patient with a seizure?
What is the role of imaging studies in the evaluation of a patient with a seizure?
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What is the primary reason to consider lumbar puncture in the setting of an acute seizure?
What is the primary reason to consider lumbar puncture in the setting of an acute seizure?
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What is the primary concern when administering a supplemental or loading dose of anticonvulsant medication?
What is the primary concern when administering a supplemental or loading dose of anticonvulsant medication?
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What is the recommendation for patients with a first unprovoked seizure who have a normal neurologic examination and normal diagnostic testing?
What is the recommendation for patients with a first unprovoked seizure who have a normal neurologic examination and normal diagnostic testing?
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What is the most common cause of provoked (secondary) seizures in the developing world?
What is the most common cause of provoked (secondary) seizures in the developing world?
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What is the definition of status epilepticus?
What is the definition of status epilepticus?
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What is the pathophysiologic effect of the blood-brain barrier being compromised in status epilepticus?
What is the pathophysiologic effect of the blood-brain barrier being compromised in status epilepticus?
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What is a common association between seizures and alcohol use?
What is a common association between seizures and alcohol use?
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What is the recommended treatment for eclampsia?
What is the recommended treatment for eclampsia?
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What is the primary consideration when evaluating a patient with a seizure?
What is the primary consideration when evaluating a patient with a seizure?
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Study Notes
High-Altitude Disorders
- High altitude (>2440 m or >8000 ft) is a hypoxic environment with decreased partial pressure of oxygen (PO2) due to lower barometric pressure.
Altitude Staging
- Intermediate altitude (1520-2440 m or 5000-8000 ft): decreased exercise performance and increased alveolar ventilation without major impairment in arterial oxygen transport, with risk of Acute Mountain Sickness (AMS).
- High altitude (2440-4270 m or 8000-14,000 ft): decreased arterial oxygen saturation (SaO2), marked hypoxemia during exercise and sleep.
- Very high altitude (4270-5490 m or 14,000-18,000 ft): abrupt ascent can be dangerous, requires acclimatization to prevent illness, with SaO2 of 86-84%.
- Extreme altitude (>5490 m or >18,000 ft): severe hypoxemia and hypocapnia, progressive physiologic deterioration, and impossible sustained human habitation.
Adaptation Mechanisms
- Hyperventilation: hypoxic ventilatory response increases ventilation to compensate for low oxygen levels.
- Blood: increased serum erythropoietin levels within 2 hours of ascent, leading to increased red cell mass over days to weeks.
- Fluid balance: peripheral venous constriction increases central blood volume, suppressing secretion of antidiuretic hormone and aldosterone, and inducing diuresis.
High-Altitude Syndromes
- Acute Mountain Sickness (AMS): headache, GI disturbance, dizziness, fatigue, or sleep disturbance due to hypobaric hypoxia.
- Treatment: acetazolamide, dexamethasone, and hyperbaric therapy.
Treatment Principles
- Do not ascend to a higher sleeping altitude with symptoms.
- Descend if symptoms do not abate or become worse despite treatment.
- Descend and treat immediately if there is a change in consciousness, ataxia, or pulmonary edema.
High-Altitude Cerebral Edema
- Defined as progressive neurologic deterioration in someone with AMS or high-altitude pulmonary edema.
- Characterized by altered mental status, ataxia, stupor, and progression to coma if untreated.
- Treatment: oxygen supplementation, descent, and steroid therapy.
High-Altitude Pulmonary Edema
- Most lethal of altitude illnesses.
- Risk factors: heavy exertion, rapid ascent, cold, excessive salt ingestion, respiratory depressant use, previous history of susceptibility, and pulmonary hypertension.
- Early diagnosis critical, with decreased exercise performance and dry cough as early signs.
- Immediate descent is the treatment of choice.
Ultraviolet Keratitis (Snow Blindness)
- Increased UV radiation at high altitude due to less cloud cover, water vapor, and particulate matter.
- Radiation increases by 5% for every 300 m gained.
- Self-limited condition that heals within 24 hours, but warrants analgesic administration and cold compress application.
- Prevention crucial, with sunglasses that transmit <10% of UV radiation recommended.
Seizure Management
- Avoid unnecessary sedation as it can complicate evaluation and lead to a prolonged decrease in level of consciousness.
- Obtain serum anticonvulsant levels before administering supplemental or loading doses to prevent drug toxicity.
Patients with a First Unprovoked Seizure
- Guidelines do not recommend hospital admission or initiation of anticonvulsant therapy if the patient has returned to neurologic baseline.
- Patients with a normal neurologic examination, no acute or chronic medical comorbidities, normal diagnostic testing, and normal mental status can safely be discharged from the ED.
Neurocysticercosis
- Caused by CNS infection with the larval stage of the tapeworm Taenia solium.
- Most common cause of provoked (secondary) seizures in the developing world.
Pregnancy
- Eclampsia is defined as seizures in the setting of hypertension, edema, and proteinuria beyond 20 weeks of gestation.
- Magnesium sulfate has been used to treat eclampsia with good results.
Alcohol Abuse
- Seizures and alcohol use are associated through missed doses of medication, sleep deprivation, increased propensity for head injury, toxic co-ingestions, electrolyte abnormalities, and withdrawal seizures.
Status Epilepticus (SE)
- Defined as a single seizure ≥5 minutes in length or two or more seizures without recovery of consciousness between seizures.
- Pathophysiology of SE involves compromised blood-brain barrier, increased CNS penetration of potassium and albumin, metabolic disturbances, and toxins/drugs.
Paroxysmal Disorders: Differential Diagnosis
- Seizures
- Syncope
- Pseudoseizures or psychogenic seizures
- Hyperventilation syndrome
- Migraine headache
- Movement disorders
Laboratory Testing
- In patients with a well-documented seizure disorder, only tests needed may be glucose level and pertinent anticonvulsant medication levels.
Imaging
- CT imaging is indicated if there is concern for an acute intracranial process, even if there is a coexistent metabolic process.
Lumbar Puncture
- Indicated if the patient is febrile or immunocompromised or if subarachnoid hemorrhage is suspected and the noncontrast head CT is normal.
Emergent EEG
- Can be considered in the evaluation of a patient with persistent, unexplained altered mental status to evaluate for non-convulsive status epilepticus, subtle status epilepticus, paroxysmal attack, or ongoing status epilepticus after chemical paralysis for intubation.
Treatment of Uncomplicated Seizures
- IV anticonvulsant medications are not necessary during the course of an uncomplicated seizure, as most seizures will self-resolve within 5 minutes.
Clinical Features
- Presence of a preceding aura
- Abrupt or gradual onset
- Progression of motor activity
- Loss of bowel or bladder control
- Presence of oral injury
- Localization or generalization and symmetry or unilaterality of activity
Common Precipitating Factors
- Missed doses of antiepileptic medications
- Recent alterations in medication
- Sleep deprivation
- Increased strenuous activity
- Infection
- Electrolyte disturbances
- Alcohol or substance use or withdrawal
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Description
This quiz covers the effects of high altitude on the human body, including hypoxia and its treatment. It also discusses altitude staging and its impact on exercise performance and alveolar ventilation.
