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USMLE Step 1 > Neuro - Stuff Missed > Flashcards

Neuro - Stuff Missed Flashcards

1
Q

Tabes dorsalis

A

degeneration of dorsal spinal columns and nerve roots in patients with tertiary syphillis

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2
Q

JC virus

A

can cause chronic CNS demyelonation through infection of oligodendrocytes (e.g. progressive multifocal leukoencephalopathy)

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3
Q

Histo changes in brain 12-48 hours after infarct

A

“Red neurons” (Eosinophilic cytoplasm, pyknotic nuclei, loss of Nissl substance)

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4
Q

Histo changes in brain 24-72 hours after infarct

A

Necrosis and neutrophilic infiltration

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5
Q

Histo changes in brain 3-5 days after infarct

A

Macrophage infiltration and phagocytosis

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6
Q

Histo changes in brain 1-2 weeks after infarct

A

Microscopic: reactive gliosis and vascular proliferation around necrotic area

Macroscopic: Liquefactive necrosis: well-demarcated soft area (1 week - 1 month)

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7
Q

Histo changes in brain > 2 weeks after infarct

A

Microscropic changes: Glial scar

Macroscopic changes: Cystic area surrounded by gliosis (> 1 month)

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8
Q

Pupillary light reflex

A

assessed by shining light in eye and observing the response in that eye (direct) and opposite eye (consensual)

-

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9
Q

Nerves responsible for pupillary light reflect

A

Afferent limb: CN II (optic nerve)

Efferent limb: CN III (occulomotor nerve)

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10
Q

CN III

A

Somatic: innvervates and inferior, superior, medial rectus, inferior oblique, and levator palpebrae

Parasympathetic fibers: contract iris sphincter and ciliary muscle

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11
Q

Signs of CN III palsy

A
  • Ptosis (due to paralysis of levator palpebrae)
  • “Down and out” gaze - due to unopposed actions of LR and SO
  • Fixed dilated pupil and loss of accomodation - loss of PS fibers
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12
Q

Absence of corneal reflex can result from lesions involving which CN?

A 
CN V1 (afferent limb)
CV VII (efferent limb)
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13
Q

Inward deviation of left eye is caused by a lesion to what?

A

CN VI - result of unopposed action of CN III

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14
Q

Meningiomas

A

located to cerebral surface

- parasaggital meningomas can cause contralateral spastic paresis of leg due to compression of leg-foot motor area

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15
Q

Tinnitus and unilateral hearing loss are associated with which tumors?

A

Cerebellopontine angle tumor (e.g. acoustic neuroma)

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16
Q

Headache and anosmia associated with which tumors

A

Meningioma located in olfactory groove

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17
Q

Bitemporal heminopia associated with which tumors?

A

Pituitary adenomas and craniopharyngiomas

due to compression of central part of optic chiasm

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18
Q

Meningiococcal pilli

A

responsible for epithelial attachment to nasopharynx

- responsible for preventing invasion and disease

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19
Q

Common causes of Down’s Syndrome

A
  1. Trisomy 21 (95% of cases)
  2. Unbalanced Robertsonian translocations (usually 14 and 21)
  3. Mociaism: patients have two cell lines: one normal and one with trisomy 21
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20
Q

Uniparental disomy

A

when patient inherits two copies of a chromosome from one parent and no copies of a chromosome from the other.

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21
Q

Symptoms associated with pineal tumors

A
  1. Precocious puberty - caused by B-hcG production
  2. Parinaud syndrome
  3. Obstructive hydrocephalus
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22
Q

Precocious puberty

A

in males: enlarged genitalia with pubic and facial hair younger than 9
in females: appearance of breasts, pubic hair before age 7
– if associate with paralysis of upward gaze then that suggests hormone secreting tumor

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23
Q

Parinaud syndrome

A

paralysis of upward gaze and of convergence - these symptoms due to compression of tectal area of midbrain

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24
Q

Lateral medullary syndrome (Wallenberg(

A
  • due to lesions of lateral side of medulla

leads to contralateral loss of pain and temperature sensation along ipsilateral paralysis of CN V, IX, X, XI

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25
Q

Medially medullarysyndrome

A
  • due to lesions on medial side of medulla

causes contralateral spastic paralysis and ipsilateral paralysis of tongue (CN XII)

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26
Q

Wrist drop (inability to extend wrist) is associated with injury to which nerve?

A

Radial nerve

  • innervates the extensor compartment of the arm
  • innervates the dorsal portions of 1st half of 1st to 3rd fingers
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27
Q

Phenotyping mixing

A

refers to co-infection of a host cell by two viral strains resulting in progeny virions that contain nucleocapsid proteins from one strain and genome of another

  • since there is no change in the underlying genomes, the next generations of virions goes back to unmixed phenotypes
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28
Q

Reassortment

A

refers to changes in genomic composition that occur when host cells are co-infected with two SEGMENTED viruses that exchange whole genome segments
- can cause alterations in surface proteins (e.g. influenza)

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29
Q

Recombination

A

exchange of genes between two chromosomes by crossing over within homologous regions
- changes remain present in subsequent generations

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30
Q

Conversion disorder

A

unconscious manifestation of conversion symptoms (e.g. blindness, weakness, loss of sensation, paralysis) that don’t coincide with physical exam
- usually brought about by stress and resolve when stressor resolves

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31
Q

Malingering

A

consciously faking or claiming symptoms for secondary gain outside of medical attention (e.g financial gain)

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32
Q

Body dysmorphic disorder

A

patient believes body part is pathologically flawed

  • develops mostly in adolescence and affects men and women
  • high rate of depressive disorder and suicide attemps
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33
Q

Patient has history of atherosclerosis and upon autopsy presents wth cystic lesion on left side. The walls of lesions composed of what cells?

A

Astrocytes -
- after initial lesion is eaten by macrophages and necrotic area is resorbed, cystic cavity forms.
Around cyst, astrocytes undergo gliosis (proliferate and enlarge) to form a wall around cyst.

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34
Q

Which Vitamin deficiency resembles Friedrich’s ataxia?

A 
Vitamin E
Like Friedrich's Ataxia, Vitamin E deficiency leads to degeneration of:
- spinocerebellar tracts
- dorsal column of spinal cord, 
- peripheral nerves
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35
Q

Poliomyelitis

A
  • damage to anterior horn cells and leads to paralysis
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36
Q

Creutzfeldt- Jacob disease

A
  • prion disease
  • progressive dementia and myoclonic jerks of extremities
  • multiple vacuoles are seen in gray matter of brain (spongiform encephalopathy)
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37
Q

Thiamine deficiency signs

A
  • periperhal neuropathy
  • high output cardiac failure (due to AV shunts)
  • Wernicke encephalopathy
    • ataxia, confusion and abdominal pain
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38
Q

Nystatin

A
  • antifungal by binding to ergosterol in cell membrane to promote pore formation in cell membrane
  • drug of choice for oral candiasis in an immunosuppressant patient
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39
Q

Genomic imprinting

A

selective inactivation of genes in either maternal or paternal origin
- occurs in Prader-Willi and Angelman syndromes

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40
Q

Virulence factors for E.coli

A
  • K-1 capsule: associated with pneumonia and meningitis
  • fimbriae: virulence factor that allows bacteria to adhere to target tissue
  • Lipid A: septic shock from endotoxin in outer membrane
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41
Q

Sciatica

A
  • shooting pain down posterior thigh and leg that results from impingement of spinal nerves as it leaves spinal column
  • compression of S1 is associated with pain in posterior thigh and dimunition of ankle reflex
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42
Q

Damage to L4

A

L4 provides sensation ot posterior thigh or left

- damage to L4 would result in damage to knew reflex

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43
Q

Recombination

A
  • gene exchange that occurs through crossing over double stranded DNA molecules
  • two defective viruses co-infecting same cell can result in cytopathic wild type genome
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44
Q

Pseudomonas aeruginosa

A
  • NONLACTOSE-FERMENTING
  • Oxidase positive, motile gram negative rod
  • cause of external otitis media (esp. in elderly) - hich presents as LOTS of ear pain and draining and granulation tissue
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45
Q

Wallerian degeneration

A

occurs in segment of axon that lost connection with cell body

  • initially, swelling and irregularity noticed in distal axon
  • within week, axon is destroyed and fragments are digested by Schwann cells and macrophagees
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46
Q

Axonal reaction

A

changes in body of neuron after axon has been severed

  • increased protein synthesis that facilitates axonal repair
  • enlarged, rounded cells with peripherally located nuclei and dispered Nissl substance
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47
Q

Signs of compression of atrophy

A
  • result of increased intracranial pressure or mass lesion

- decrease in size and number of cells

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48
Q

Buccopharyngeal fascia

A

extends from carotid sheath to surround pharyngeal constrictor muscles
- space between buccopharyngeal and prevertebral fascia is retropharyngeal space

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49
Q

Deep cervical fascia

A

INVESTING- surrounds neck like a collar, investing deeper parts of neck
PRETRACHEAL - encloses viscera of neck (thyroid, parathyroid, larynx, esophagus, trachea)
PREVERTEBRAL - surrounds vertebral column and spinal muscles

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50
Q

Craniopharyngioma

A

calcified cystic tmors

  • arise from Rathke’s pouch
  • can cause headaches, growth failure and bitemporal heminopsia
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51
Q

Coagulative necoris

A

occurs following hypoxic death in all tissues EXCEPT CNS

- acute denaturation of cellular proteins following irreversible cell injury

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52
Q

Fibrinoid necrosis

A

pattern of injury seen in walls of blood vessels affected by immune complex vasculitis and related processes

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53
Q

Liquefactive necoris

A

irreversible ichemic injury to BRAIN

- infarcted tissue eventually replaced with cystic astroglial scar

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54
Q

Caseous necrosis (in brain)

A

results from tuberculosis

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55
Q

Nonenzymatic fat necrosis

A

describes necrosis of fat tissue after trauma

- female breast is common site of trauma

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56
Q

Facial flushing and mydriasis after taking medication to cure asthma

A
  • due to muscarinic blockade

1st generation antihistamines (e.g. diphenhydramine, neuroleptics, and antiparkisoninan drugs often have muscarinic blockade)

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57
Q

Pilocytic astrocytomas

A
  • usually arise in cerebellum, brainste
  • well differentiated neoplasms comprised of hair-like glial processes associated with microcysts
  • show mixed Rosenthal fibers and granular eosinophilic bodies
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58
Q

Medulloblastomas

A
  • 2nd most common posterior fossa tumor in children
  • cells are small and poorly differentiated with scant cytoplasm and little stroma
  • high mitotic index
  • Classic Homer-Wright rosettes
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59
Q

Neuroblastomas

A
  • common extracranial solid tumors in children
  • composed of round blue-cell tumors
  • neuropil, neuritic process, is pathognomonic feature of neuroblastoma ecells
  • neuroendocrine markers (synaptophysin, NSE, chromagranin, S100 +_
  • have elevated HVA and VMA levels
  • N-MYC
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60
Q

Ependymomas

A
  • 10% of posterior fossa tumors in children
  • often occur in roof of 4th ventricle in children vs. spine in adults
  • ependymal pseudorosettes
  • GFAP + processes tapering toward blood vessels
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61
Q

Fracture to pterion hits what artery?

A

Pterion - where frontal, parietal, temporal, and sphenoid bones meet
- thin in this region and can hit middle meningeal artery which can cause EPIDURAL HEMATOMA

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62
Q

Occipital artery

A

serves posterior scalp and sternocleidomastoids

- runs posteriorly

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63
Q

Ophthalmic artery

A

first branch of internal carotid

- serves eye, orbital contents, and eyelids

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64
Q

Middle cerebral artery

A
  • branch of internal carotid
  • supplies parietal and temporal regions of brain
  • injury causes subarachnoid and intercerebral hemorrhage
65
Q

Transtentorial (uncal) herniation

A
  • complication of ipsilateral mass lesion (e.g. hemorrhage or brain tumor)
  • associated with ipsilateral FIXED AND DILATED pupil
  • ipsilateral paralysis of occulomotor muscles, contralateral
  • ipsilateral hemiparesis and contralateral homonymous hemiaopsia with macula sparing may occur
66
Q

Signs of uncal herniation

A
  • Ipsilateral fixed and dilated pupil (due to compression of CN III)
  • Contralateral homonymous hemianopsia with macula sparing (due to compression of ipsilateral PCA
  • Ipsilateral hemiparesis due to compression of contralateral corticospinal tract
67
Q

Fragile X Syndrome

A
  • trinucleotide repeats within FMR1 gene on X chromosome

- signs include mental retardation, facial deformities, and macroorchidism

68
Q

C. neoformans

A
  • fungus associated with CNS infection (meningitis) in immunocompromised individuals
  • found in soil and pigeon droppings
  • transmitted via respiratory route with lungs primary site of entry
  • found with Indian ink stain, Methanmine silver, Methacarmine
69
Q

Tabes dorsalis

A
  • manifestation of neurosyphillis
  • affects dorsal columns - causing loss of proprioception and vibration
  • affects dorsal sensory routes - loss of pain and sensation
  • Argyll-Robertson pupil (involvement of periaqueductal gray matter of brain) -
70
Q

Argyll-Robertson pupil

A

loss of response to light, but still accomodates

71
Q

Progressive multifocal Leukoencephalopathy

A
  • results of JC virus infection
  • demyelination of CNS due to oligodendrocyte destruction
  • rapidly progressive and atal
72
Q

Multiple scleoris

A
  • self-limiting neurological symptoms in patients 20-30 yeears old
  • associated with optic neuritis
  • internuclar opthalmoplegia
  • sensory deficits
73
Q

HIV fenome

A
  • structural gene (gag, pol, env) poduces nucleocapsid p24 and p7
  • envelope glycoproteins (e.g. gp120 and gp41)
  • viral replicaiton (tat and rev)
74
Q

Defects in first branchial arch can affect which structures

A
  • Mandible
  • Maxila
  • Malleus
  • Incus
  • Masseter
  • associated with trigeminal nerve (CN V)
75
Q

Mechanisms of diabetic neuropathy

A
  1. Non-enzymatic glycosylation of proteins - leads to increased thickness, hyalinization and narrowing arteriolar walls
  2. Intracellular hyperglycemia occurs in peripheral nerves - accumulated glucose is converted into sorbitol and fructose by aldose reductase. Sorbitol inc. cell osmolarity and increases water influx which causes osmotic damage to nerves
76
Q

Liquefactive necrosis

A
  • characterized by complete digestion and removal of necrotic tissue by cystic cavity
  • Hypoxic CNS injury followed by liquefactive necrosis
  • Abscess formation due to this type of injury is due to this type of necross
77
Q

Oselatamivir

A

neuraminidase inhibitor usedful for treatment of both influenza A and B viruses

  • impairs release of newly formed virions from infected host cells
  • impairs viral penetration of mucous secretions that overlie respiratory epithelium
  • best if taken after 48 hours
78
Q

Amantadine

A

impairs uncoating or dissembly of influenza A after host cell endocytosis

79
Q

Niemann-Pick disease

A

deficiency of sphingomyelinase

  • causes abnormal accumulations of ceramide phospholipid sphingomyelin and neurologic deterioriation within 1st year of life
  • foamy appearing, sphingomyelin histocytes accumulate in liver and spleen –> hepatosplenomegay
80
Q

Niemann-Pick disease

A
  • deficiency in sphingomyelinase
  • progressive neurodegeneration
  • hepatosplenomegaly
  • cherry red macula
  • foamy macrophages filled with sphingomyelin
81
Q

Interferons alpha and B

A

produced by eukaryotic cells in response to viral infectios

- act on neighboring cells to stimulate production of antiviral proteins that would impair viral protein synthesis

82
Q

Non-pathogenic corynebacterium

A
  • can cause severe pseudomembranous pharyngitis after acquiring Tox gene via lysogenization by temperate bacteriophage
83
Q

Bacteria that can acquire bacterial toxins via lysogenic phase

A 
"ABCDE"
A= ShigA-like toxin
B = Botilinium toxin
C = Cholera toxin
D = Diptheria
E = Erythrogenic toxin of Group B Strep
84
Q

Virulence factors in N. meningitidis that’s responsible for meningitis and meningococecemia

A
  • LOS (Meningococcal lipoligosaccharide)

- it’s analgous to the LPS seen in many gram negative bacteri

85
Q

Drugs associated with the redistribution of fat from extremities to trunk

A
  • Medication induced body fat redistribution (fat from extremities to creation of buffalo hump) is usually done by:
  • Glucocorticoids - causes Cushing’s syndrome
  • HAART - causes lipodystrophy
86
Q

Huntington’s disease

A
  • AD
  • manifests with progressive dementia anc choreiform movements
  • loss of neurons in caudate nucleus and putamen is characteristis
  • decrease in GABA, ACh, and substance P
  • CAG repeats in chromosome 4
  • Anticipation is frequently seen
87
Q

Varicella Zoster Virus

A
  • typically infects children and causes “chickenpox”
  • present with fever, vescicular rash, and pruritic rash
  • vaccine recommended for children aged 12-18 months
88
Q

IgG antibodies

A

delayed response to antigen

  • most abundant isotupe
  • fixes complement
  • crosses the placenta anc provides infants with passive immunity
  • opsonizes bacteria
89
Q

IgM

A

produce in the first exposure to antigen

  • fixes complement but DOESN’T cross placenta
  • antigen receptor on surface of B cell
  • monomer of B cell and pentamer
  • pentamer allows it to efficiently trap free antigens out of tissue while humoral resopnse
90
Q

IgA

A

prevents attachment of bacteria and viruses to mucous membranes

  • does not fix complement
  • monomer in circulation or dimer when secreted
  • crosses epithelial cells via transctytosis
  • picks up secretory component from epithelial cell before secretion
91
Q

IgE

A

binds mast cells and basophils when exposed to allergen

  • mediated type I hypersensitivity through release of inflammatory mediators such as histamine
  • mediates immunity to worms by activating eosinophils
  • lowest concentration in serum
92
Q

IgD

A

unclear function

- found on surface of many B cells and in serum

93
Q

Synaptophysin

A

protein found on presynaptcic vesicles of neurons, neuroendocrine and neuroendocrine cells
- CNS tumors of neuronal origin stain for synaptophysin
-

94
Q

CNS tumors of glial origin

A
  • Astrocytomas
  • Ependymomas
  • Oligodendrogliomas
    • stain positively for GFAP
95
Q

Guillain Barrre syndrome

A
  • acute demyelinating peripheral neuropahy
  • affects young adults and is preceded by febrile illness
  • segmental demyelination of peripheral nerves
  • endoneural inflammatory infiltrate
96
Q

Subarachnoid hemorrahge

A
  • occurs due to rupture of saccular aneurysm and AV malformation
  • severe vasospasm 4 - 12 days after initial insult is major cause of morbidity and mortality in patients recovering from this
97
Q

Treatment of vasospasma associated with subarachnoid hemorrahge

A
  • Nimodipine - selective Ca channel blocker
98
Q

Corynebacterum diptheriae

A

Gram positive rod

  • found in clumps that look like Chinese letter
  • cytoplasm contain metachromatic granules that stain with aniline dyes like methylene blue
  • produces two subunit AB toxin
99
Q

Discuss toxins associated with C. diptheriae

A

toxin B - binds to heparin binding epidermal growth factors on cardiac and neural cells - explains affinity for heart and neural tissues
B subunit induces endocytosis of toxin
- A (Active subunit) - inhibits cell protein synthesis by catalyzing ADP- ribosylation of protein EF-2 which causes cell death

100
Q

Projection

A

transplanting one’s unacceptable impulses or affect to another person or situation
- immature defense mechanism

101
Q

Reaction formation

A

redirection of unacceptable impulse into its opposit

- ex. former alcoholic trying to ban alcohol sales

102
Q

Acting out

A

expressing unacceptable thoughts or impulses

e.x. throwing a tandrum

103
Q

Splitting

104
Q

Identification

A

modeling one’s behavior after someone who is perceived more powerful

  • may be admirable or non-admirable
  • classic example is child of an abusive father become a child abuser
105
Q

Common signs of Turner Syndrome

A
  • Lymphedema in hands/feet
  • Coarctation of aorta
  • Horseshow kidney
106
Q

Syringomyelia presentation

A

presents with chronic loss of upper extremity pain and temp sensation

  • upper extremity weakness and hyporeflexia
  • low extremity weakness and hyperreflexia
  • kyphoscloiosis
107
Q

Syringomyelia

A

caused by central cystic dulation in cervical spinal cord (syrinx) that slowly enlarges

  • damages anterior white commissure and anterior horns
  • injures lateral spinothalamic tract and ventral horns
  • most common at C8 - T1 levels
108
Q

C. diptheriae

A

Gram-positive, catalase +, club shaped ros

  • cultured in cysteine-tellurite agar in which colonies are black
  • produces metachromatic granules that can be detected with methylene blue staining
109
Q

Rabies encephalitis

A
  • caused by rhabdoviridae (rabies)
  • agitation, disorientation, pharyngospasm leading to coma and denth
  • initially flu-like prodrome that leads to acute neurologic syndrome
110
Q

Rhabdoviridae

A
  • single stranded RNA viruses enveloped by bullet-shaped capsule
  • studdded by glycoprotein spokes that bind to nicotinic ACh receptors
  • once inside women, virus can stay local for days to weeks before binding to ACh receptors on perpipheral nerves
111
Q

Cytomegalovirus

A
  • binds to cellular intergrins
112
Q

Epstein- Barr virus

A

binds to CD21

113
Q

HIV

A

binds to CD4 and CXCR4/CCR5

114
Q

Rhinovirus

A

binds to ICAM1 (CD54)

115
Q

Pathogenesis of Alzheimer’s disease

A
  • decreased ACH in nucleus basalis of Meynert and hippocampus
  • diminshed activity of choline acetyltransferase is that cause
116
Q

Symptoms of Alzheimers

A
  • slow progressive memory loss
  • mild to moderate brain atrophy
  • neurofibrillary tangles, senile plaques, and amyloid angiopathy
  • decreased ACh levels in basalis nucleus of Meynert and hippocampus
117
Q

Serotonin

A
  • formed in raphe nucleus

- loss leads to anorexia, depression, and sleep disorders

118
Q

Locus cereleus

A
  • site of NE production and located in pontine central

- implicated in panic attacks and panic disosorder

119
Q

Conductive hearing loss testing

A

Rinne test: (mastoid process test) - sounds louder in mastoid near affected ear (bone > air)
Webber test: sounds loudest in the affected ear

120
Q

Sensorial hearing loss testing

A

Rinner test: sounds normal - don’t hear sound in abnormal ear
Webber test: sounds loudest in unaffected ear

121
Q

Conductive hearing loss

A
  • due to obstruction of external sound vibrations to the inner ear
  • can be caused by cerumen impaction, tympanic membrane rupture, severe otitis meia
122
Q

Sensorineural hearing loss

A
  • due to involvement of inner ear, cochlea, and auditory nerve
  • can be caused by Meniere’s disease, acoustic neuromoa, ototoxic drugs (e.g. aminoglycosides0
123
Q

Duchenne muscle dystrophy

A
  • onset is between 3 -6 years old
  • affects proximal muscles of shoulder, lower back and pelvic girdl
  • waddling gait, may appear clumsy
  • Gower’s sign positive - to get up out of chair child must support weight with hands
  • Distal muscles of extremities enlarge due to PSEUDOHYPERTROPHY
  • Asymmetric weakening of muscles leads to kyphoscoliosis
124
Q

Mitochondrial myopathies

A

associated with ragged red fibers (muscle fibers with irregular contours and blotchy red appearance)

125
Q

Multiple sclerosis

A

autoimmune demyelinating disease

  • within plaques, loss of myelin sheaths adn depletion of oligodendrocytes
  • oligoclonal bands of IgG may be seen in CSF fluid
126
Q

Common peroneal nerve injury

A
  • most common injury of leg
  • trauma to head of fibula
  • presents with plantarflexted and inverted posture of affected foot
  • loss of sensation to anterolateral leg
  • associated with “foot drop” - affected foot slaps the ground with each step
127
Q

Tibial nerve injury

A

causes dorsiflexion and eversion of the foot with sensory loss on sole of foot

128
Q

Dorsal column

A
  • affects pressure, vibration, proprioception, fine touch

- medial leminiscal pathway

129
Q

DC-ML Pathway (neurons and synapses)

A

1st order neurons: Sensory nerve ending to DRG –> enters spinal cord and ascends ipsilaterally
Synapse 1: ipsilateral nucleus cunneatus or ipsilateral fasisculus
2nd order neurons: Decussates in medulla ascends CONTRALATERALLY in ML
Synapse 2: VPL of thalamus
3rd order neurons: Sensory cortex

130
Q

Spinothalamic tract
Lateral: pain and temperature
Anterior: crude touch and pressure

A

1st order neurons: sensory nerve ending (A-delta and C fibers) - cell body in DRG –> enter spinal cord
Synapse 1: Ispilateral gray matter
2nd order neurons: Decussates at anterior white commisure –> ascends CONTRALATERALLY
Synapse 2: VPL of thalamus
3rd order neurons: Sensory cortex

131
Q

Lateral corticospinal tract

- descending voluntary movements

A

1st order neuron: UMN -cell body in 1 motor cortex –> descends ipsilaterally (through internal capsule_ until decussating at caudal medulla (pyramidal decussation) –> descends CONTRALATERALLY
Synapse 1: Cell body of anterior horn (spinal horn)
2nd order neuron: LMN leaves spinal cord
Synapse 2: Neuromuscular Junction

132
Q

Primary CNS lymphomas

A
  • occur in immunocompromised patients
  • tumors arise from B cells and are associated with EBV
  • high grade tumors with poor prognosis
133
Q

Common causes of asceptic meningitis

A

Enteroviruses

  • Coxsackievirus
  • Echovirus
134
Q

Viral meningitis

A
  • commonly caused by enteroviruses
  • WBC count < 500 cells
  • lymphocytic predominance
  • Glucose levels are normal/ slightly reduced
  • Elevated protein but < 150 mg/dL
  • no organisms identified
135
Q

Bacterial meningitis

A
  • S. pneumonie and N. meningitidies - common in adults
  • Group B Strep and Gram-negative bacilli in kids
  • WBC count > 1000 cells
  • Neutrophil predomniance
  • Glucose levels < 70 mg/gL but may be lower
  • Elevated protein
  • Often positive for certain protein
136
Q

S. epidermidis

A
  • coagulase negative Staph species
  • associated with foreign bodies (e.g. catheters, procedures, IV lines)
  • can form biofilms
137
Q

Elderly patient with progressive memory loss.

Congo red staining shows patchy amyloid deposition in temporal cortex and hippocampus. Likely diagnosis

A

Alzheimer’s disease

  • associated with amyloid deposits (Congo red)
  • parenchymal, extracellular deposits in brain are senile plaques - composed of AB amyloid
  • amyloid angiopathy - amyloid deposition in media and adventitia of cerebral vessels and cause thickening of BM and vessel stenosis
138
Q

Paraneoplastic syndromes-

A
  • associated with systemic caner
  • tumors produce substances that induce AUTOIMMUNE reaction and cause damage and degeneration of health tissue
  • Paraneoplastic cerebellar degeneration are thought to be autoimmune
139
Q

Wernicke Encephalopathy

A
  • Confusion
  • Ataxia
  • Opthalmoplegia
140
Q

Medical treatments that can precipitate Wenicke’s encephalopathy

A
  • Infusion of glucose without thiamine in patient with chronic thiamine deficiency can precipitate encephalopathy
  • ** Thiamine needed for glucose metabolism
141
Q

Low frequency sounds are best heard where in ear?

A

At apex of cochlea near the helicotrema

142
Q

High frequency sounds are best heard where in ear?

A

At base of cochlea near round and oval windows

143
Q

General sensation from anterior 2/3 of tongue

A

Mandibular division of Trigeminal nerve

144
Q

Gustatory innervation of anterior 2/3

A

Chorda tympani branch of facial nerve

145
Q

Innervation of posterior 1/3 of tongue

A

Glossopharyngeal nerve - transmits pain, temperature and touch from posterior 1/3 of tongue

146
Q

Innervation of far posterior innervation of tongue root

A

Vagus nerve - transmits gustatory and general sensory stimuli

147
Q

Rabies encephalitis

A
  • restlessness, agitation, and dysphagia progressing 30 to 50 days following exposure to bats, rabid pets
  • manifests with flu-like prodrome and then subacute neuro symptoms (agitation, persistent fever, and painful spasms upon inspiration or with swallowing)
  • associated with rhabdoviridiae
148
Q

Merniere’s disease

A

triad of tinnitus, vertigo, and sensorineural hearing loss

- related to increase in volume and increase in endolymph in vestibular apparatus

149
Q

HSV-1

A
  • occurs often in children 1-3 years old
  • seen in Tzanck pereparation - ulcer scraping in Wright-Giemsa stain
  • presence of giant multi-nucleated cells
  • presents with ulcerative gingivitis and cervical lymphadenopathy
150
Q

Common clinical manifestation of primary infection of HSV-1

A

Herpetic gingivostomatitis

151
Q

Cause of anopia (no vision in one eye)

A
  • Injury to ipsilateral optic nerve

- seen in renal artery occlusions

152
Q

Cause of bitemporal hemianopia

A
  • lesion in optic chiasm

- seen in craniopharyngoma, pituitary tumors, ACA aneurysms

153
Q

Cause of (right) nasal hemianopis - no vision in inner right half of right eye

A
  • lesion in (right) -IPSILATERAL peri-chiasmal lesion

- calcificatino or aneurysm of internal carotid artery impinging on UNCROSSED lateral retinal fibers

154
Q

Cause of (left) homonymous hemianopia

A
  • lesion in (right) -CONTRALATERAL optic tract or optic radiation

Optic tract: occlusion of anterior choroidal artery
Optic radiation: occlusion of MCA or lesion in posterior limb of internal capsule

155
Q

Cause of left (homonymous) superior quandrantanopia (“pie in the sky”)

A
  • lesion in (right) CONTRALATERAL temporal lobe (Meyer’s loop)
  • lesion or stroke in
156
Q

Cause of left homonymous inferior quandrantaopia (“pie on the floor”)

A
  • Lesion in (right) CONTRALATERAL primary visual cortex

- Lesion in parietal lobe

157
Q

Cause of left homonymous heminanopia with macular sparing

A
  • Lesion in primary visual cortex (occipital lobe)

- Occlusion of PCA. Macula is spared due to colateral blood from MCA

158
Q

Which viruses can undergo reassortment

A

Viruses with segmented genomes (e.g. orthomyxoviruses and rotaviruses)

159
Q

Red neuron

A
  • signs of irreversible neuronal injury 12-24 hours after event
  • shrinkage of cell body
  • eosinophilia of cytoplasm
  • pyknosis of nucleus and loss of Nissl substance

USMLE Step 1 (34 decks)

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