UWorld 2017 Flashcards
Innervation of the 2 skeletal muscles of the middle ear
Stapedius muscle: CN VII
Tensor tympani muscle: CN V3
Highly lipophylic drugs (Propofol, …)
Quickly accumulating in tissues of high blood flow (rapid onset of action)
Redistribution to organs of low blood flow (short duration of action)
2 drugs used as monotherapy to ttt spasticity secondary to brain or spinal cord disease
Baclofen (GABA-B receptor agonist)
Tizanidine (alpha2-adrenergic agonist)
1 drug indicated + 3 to avoid in ttt of insomnia in elderly
Ramelteon (melatonin agonist)
Antihistamines
Sedating antidepressants
Benzodiazepines
Gene mutations ass w/ familial Alzheimer ds
Early-onset familial AD: APP (ch 21), presenilin 1, presenilin 2
Late-onset familial AD: apolipoprotein E4 genotype
1 ttt for acute migraine + 3 ttts for prophylaxis
Serotonin agonist 5HT1B/5HT1D (postsynaptic S receptor ag)
Anticonvulsivants
Antidepressants
Beta blockers
1 drug for absence + 1 for absence and tonic-clonic seizures
Sodium valproate
Ethosuximide
4 clinical findings in Tabes dorsalis (late form of neurosyphilis)
Sensory ataxia
Lancinating pains
Neurogenic urinary incontinence
Ass w/ Argyll Robertson pupils
Onset of action of gas anesthetic
Depends on its solubility in blood (blood/gas partition coefficient)
High coeff, more soluble in blood, slower equilibration with brain, longer onset time
MOA of opiate analgesics
Activation of presynaptic mu recept: closure of voltage-gated Ca2+ ch + reduced excitatory neurotransm
Binding to postsynaptic mu recept: opening of K+ ch + membrane hyperpolarization
Treatment of severe atropine toxicity (anticholinergic)
Tertiary amine: physostigmine (reverse CNS + periph symptoms) is the ttt
Quartenary ammonium: neostigmine and edrophonium (anticholinesterase) limit CNS penetration
Adverse effects of Levodopa/carbidopa
Carbidopa reduces most of periph side eff of levodopa Behavioral changes (anxiety, agitation) can worsen
MOA of ethosuximide
Phenytoin, carbamazepine, valproic acid: reduce Na ch recovery from inactivation
Ethosuximide: block T-type Ca ch in thalamic neurons
Serotonin syndrome
Confusion, agitation, tremor, tachycardia, HTN, clonus, hyperreflexia, hyperthermia, diaphoresis
By overdose of SSRIs esp combined w/ MAOinh
Tryptophan: precursor for serotonin
Ttt: cyproheptadine (antihistamine+antiserotoninergic)
Topical capsaicin
For neuropathic pain
Causes defunctionalization of afferent pain fibers + depletion of substance P
Initially: burning + stinging sensation
Chronic use: reduces pain transmission
Treatment of status epilepticus
Initial: IV Lorazepam then Phenytoin
Lorazepam: enhance effect on GABA-A recept, increase Cl influx
Phenytoin (long-acting, reduces Na ch recovery from inactivation, inhibits neuronal high-frequency firing)
Solubility of anesthetics
Arteriovenous concentration gradient reflects overall tissue solubility
High solubility, large AV concentration gradient + slow onset of action
Broad-spectrum + narrow-spectrum anticonvulsants
Broad: (lamotrigine, levetiracetam, topiramate, valproic acid) for most seizure types (focal or generalized)
Narrow: (carbamazepine, gabapentin, phenobarbital, phenytoin) for focal seizures or focal secondarly generalized
Potency of inhaled anesthetic
Inversely proportional to MAC
MAC (minimal alveolar concentration) = conc. of anesth in alveoli that renders 50% of ptts unresp to pain
DRESS (Drug reaction + eosinophilia + systemic symptoms) syndrome
2-8 weeks after exposure to high-risk drugs
Phenytoin, carbamazepine, allopurinol, sulfasalazine, minocycline, vancomycin
Fever, generalized lymphadenopathy, facial edema, diffuse skin rash, eosinophilia, internal organ dysfunction
Vitamin E deficiency
Neuro symptoms (mimic Friedreich ataxia) Ataxia (degen of spinocerebellar T) Loss of position + vibration sense (degen of dorsal columns) Loss of deep tendon reflexes (periph nerve degen)
CN III palsy (anatomy + presentation)
Between post cerebral + superior cerebellar arteries
Compression from ipsilateral post communicating artery aneurysm
Injury: mydriasis (superf parasymp fiber) + diplopia, ptosis, down+out (somatic efferent fiber)
Alzheimer disease
Neurofibrillary tangles + amyloid-beta plaques
Trisomy 21: 3 copies of APP (Amyloid Precursor Protein) gene; increase amyloid-beta accumulation; high risk for Alzh
Mechanism of neurodegenerative disorders (Parkinson, Alzheimer)
Ubiquitin undergoes ATP-dep attachment to proteins labelling them for degradation
Modified proteins enter proteasome: degraded
Impaired ubiquitin-proteasome system: neurodegen disorders
Amyloid Precursor Protein processing (alpha+gamma secretases)
Inappropriate processing: beta+gamma secretase
Gives beta-amyloid
Insufficient clearance of beta-amyloid: extracellular accumulation, neurotoxic, Alzheimer dementia
Cavernous sinus thrombosis
Infection of medial face, sinuses (ethmo, spheno), teeth
Spread through valveless venous system into cavernous sinus: thrombosis
Headache, fever, proptosis, ipsilateral deficits in CN III,IV,VI,V1,V2
Von Recklinghausen (NF-1)
Peripheral nervous system tumor syndrome
Neurofibromas, optic nerve gliomas, Lisch nodules (iris), café-au-lait spots
NF-2
Nervous system tumor syndrome
Bilateral cranial nerve VIII schwannomas
Multiple meningiomas
Sturge-Weber syndrome (encephalotrigeminal angiomatosis)
Neurocutaneous disorder
Cutaneous facial angiomas (over CN V1, V2 distributions)
Leptomeningeal angiomas
Mental retardation, seizures, hemiplegia, skull radiopacities
Tuberous sclerosis
Kidney, liver, pancreatic cysts Cortical + subependymal hamartomas (not angiomas) - seizures Cutaneous angiofibromas Renal angiomyolipomas Cardiac rhabdomyomas
von Hippel-Lindau disease
Cerebellar hemangioblastoma
Congenital cysts of kidneys, liver, pancreas
Myotonic dystrophy
Increased number of trinucleotide repeat (CTG) on myotonia-protein kinase gene
Sustained muscle contraction (myotonia) + weakness + atrophy (type 1 fibers)
Cataracts, frontal balding, gonadal atrophy
# Duchenne (necrosis of muscle fibers + fibrofatty replacement)
Denervation muscle atrophy, inflammatory myopathy, ion channel myopathy
Denervation: axonal destruction (trauma, ischemia, ALS); paralysis+atrophy
Inflammatory: dermatomyositis, polymyositis
Ion channel: myotonia, hypotonic paralysis (w/ exercise); no atrophy; PAS-positive
Epidural hematoma
Rare complication of epidural anesthesia
After few hours to days
Sudden back pain or radicular pain
Progression to partial/complete paralysis of lower extremities
Ischemic injury in brain tissue vs other organs
Brain: liquefactive necrosis
Organs: coagulative necrosis
Activation of GABA-A receptors
Increase conductance of Cl- ions (enter)
Hyperpolarization of membrane potential
Chronic opioid use
Dev of tolerance to analgesic effects + most side effects
Exception of constipation + miosis
Prophylaxis ttt w/ fluid intake + laxatives
GFAP + Synaptophysin
Synaptophysin: presynaptic vesicles of neurons, neuroendocrine, neuroectodermal cells
GFAP: astrocytes, oligodendrocytes, ependymal cells (glial origin)
Lesions resp for decerebrate vs decorticate posturing
Decerebrate: damage to brainstem at/below red nucleus (midbrain tegmentum or pons)
Decorticate: damage to structures above red nucleus (hemispheres, internal capsule)
Vitamin B12 and folic acid deficiencies
Similar hemato symptoms
Neuro dysfunction only in vit B12 def
Neuro dysfunction worsen if vit B12 def is ttt w/ folate alone
Neurosyphilis
Different manif
Tabes dorsalis: degen of dorsal columns + dorsal roots of spinal cord (loss of proprioception + vibration, ataxia)
Argyll Robertson pupils
Dysfunction/obliteration of subarachnoid villi
Communicating hydrocephalus (symmetrical enlargement of ventriculi) Sequelae of meningeal inf (tuberculosis meningitis, ...) Sequelae of subarachnoid/intraventricular hge
Activation of muscarinic receptors
Endoth cells: NO + peripheral vasodilation; smooth muscle relaxation, hypotension
Other sites: smooth muscle contraction
Structures entering superior orbital fissure
CN III CN V1 CN IV CN VI Superior ophthalmic vein
Anatomy of area postrema
Dorsal medulla near 4th ventricle
Beta-endorphin
Endogenous opioid
Derived from POMC (like ACTH + MSH)
Wallerian degeneration
Axonal degen + breakdown of myelin sheath distal to injury
No axonal regen in CNS bcz persistence of myelin debris, secretion of neuronal inhib factors, dev of dense glial scarring
Creutzfeldt-Jacob ds
Rapidly progressive dementia + myoclonic jerks
Multiple vacuoles in gray matter
Neuroblastoma
Extracranial, from neural crest cells of adrenal medulla
Abdo mass
High catecholamine breakdown products
Paraneopl sd: opsoclonus-myoclonus
Wernicke encephalopathy + Korsakoff psychosis
Acute VitB1 def: Wernicke (mamillary body lesion, part of Papez circuit) = triad (confusion, ataxia, oculomotor dysfct)
Chronic VitB1 def: Korsakoff (permanent memory loss + confabulation)
Locus ceruleus
Brainstem nucleus in post rostral pons near lateral floor of 4th ventricle
Principle site of NE synthesis in brain
Projects to all CNS parts: control mood, arousal, sleep-wake states, cognition, autonomic fct
Pilocytic astrocytomas vs medulloblastomas
Both: in cerebellum
Piloc astr: cystic + solid components
Medullobl: solid component
MOA of normal pressure hydrocephalus
Distortion of periventricular white matter
Bladder control: influenced by descending cortical fibers (pass in distended paraventricular area) - urge incontinence
Most common causes of meningitis
Viral: enteroviruses, arboviruses, HSV-2
Bacterial - adults: Strep pneumo, N meningitidis
Bacterial - neonates: group B strep, G- bacilli
Epidural hematoma
Tear in middle meningeal artery
Ass w/ bone fracture
Between bone + dura mater
Lucid interval before clinical presentation, then loss of consciousness
Idiopathic intracranial HTN (pseudotumor cerebri)
Daily headache
Bilat symmetric papilledema
Transient visual disturbances
High intracranial pressure: optic N compression, impaired axoplasmic flow + optic disc edema
Fetal toxicity of Valproate
Decreases folic acid
Increases risk of neural tube def (meningoc, myelomeningoc)
Bell’s palsy
Unilateral facial paralysis
Decreased tearing
Hyperacusis
Loss of taste sensation over anterior 2/3
