Deck VI Flashcards Preview

USMLE World Missed Questions > Deck VI > Flashcards

Flashcards in Deck VI Deck (30):

When does intraventricular hemorrhage in premature newborns most commonly occur?

Within the first 5 postnatal days.


How does IVH present in a newborn?

It can be clinically silent or present with an altered level of consciousness, hypotonia, decreased spontaneous movements or with symptoms of catastrophic bleeding (bulging anterior fontanells, hypotension, decerebate posturing, tonic-clonic seizures, irregular respirations, coma)


From where does IVH in preterm infants usually originate?

In the germinal matrix, a highly cellular and vascularized layer in the subventricular zone from which neurons and glial cells migrate out during brain development.


What fine motor skills are expected of an infant 3 years of age?

The child should be able to copy a circle and use utensils.


At age three, what are five milestones that a child should have met?

To play in parallel, speak in simple sentances, copy a circle, use utensils, ride a tricycle.


What visual defect is caused by lesions to the optic tract?

Contralateral homonymous hemianopia.


What is the preferred treatment for narcolepsy?

Agents that promote wakefullness- psychostimulants. Modafinil is a non-amphetamine psychostimulant that is first line; amphetamines are second line agents.


What is the pathophysiology of narcolepsy?

Low levels of the NT orexin (hypocretin).


What is the classic triad of symptoms in congenital toxoplasmosis?

Hydrocephalus, intracranial calcifications, chorioretinitis.


What is chorioretinitis?

Inflammation of the choroids and the retina that may leave cotton like white/yellow scars on the retina that are visible on funduscopy.


What should expectant mothers avoid to prevent exposure to Toxoplasma?

Cat feces.


How does tetrodotoxin (from pufferfish) cause toxicity?

By binding to voltage gated sodium channels in nerve and cardiac tissue to prevent sodium influx and depolarization.


Short acting benzodiazapines are preferred over long acting drugs in what patient population?

Patients with advanced liver dysfunction.


How does morphine interact with opioid pathways to modulate morphine tolerance?

Via the neurotransmitter glutamate.


How does the optic nerve respond to light when it is damaged?

Light to the damaged eye will cause neither pupil to constrict; light to the contralateral (undamaged) eye will cause both pupils to constrict.


What causes polyhydraminos?

Decreased fetal swallowing or increased fetal urination.


Which fetal anomalies may lead to decreased swallowing and polyhydraminos?

GI obstruction (duodenal, espohageal, intestinal atresia) and anencephaly


What fetal anomalies may lead to increased fetal urination?

High cardiac output due to anemai or twin-twin transfusion syndrome


What drugs are used to treat myasthenia gravis?

Cholinesterase inhibitors (physostigmine, neostigmine, pyridostigmine)


When does edrophonium produce improvement in patients with myasthenia gravis?

When the patient is undertreated (i.e. suboptimal doses of medication), not when patient is in cholinergic crisis (when too much acetylcholine causes muscles to be refractory to future impulses)


What symptoms indicate a urea cycle disorder?

Neurological damage with elevated serum ammonia levels.


What is the most common urea cycle disorder?

Ornithine transcarbamoylase deficiency.


What is increased in the urine of patients with an ornithine transcarbamoylase deficiency?

Increased urine orotic acid.


A positive Trendelenburg sign indicates damage to which nerve?

Superior Gluteal.


Defects in what type of reaction lead to development of methylmalonic acedemia (acudiura)?

Isomerization reaction of methymalonyl CoA to succinyl CoA, prior to succinyl CoA entering the TCA cycle.


What deficiency is present in Tay Sachs disease and what abnormal accumulation results?

Deficiency in b-hexosaminidase A; accumulation of GM2 Ganglioside


What is akathisia?

Subjective restlessness with inability to sit still; it typically presents days to weeks after initiating antipsychotic treatment.


What clinical features are associated with PCP abuse?

PCP is a hallucinogen causing violent behaviour, dissociation, hallucinations, amnesua, nystagmus, ataxia, memory loss.


What immature defense mechanism substitutes imaginary, less disturbing scenarios to avoid awareness of painful feelings?



What types of intracellular connections mediate the BBB between the endothelial cells of CNS capillaries?

Tight junctions (also known as zona occludens).