Neuroscience Flashcards

(96 cards)

1
Q

Intramedullary lesions

A

produce burning or tingling pain in extremities

May spare sensation in perineal and sacral areas (located on periphery of cord)

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2
Q

Intradural lesions

A

Commonly benign masses (schwannomas of spinal

Usually painless, present w/ gradual symptoms

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3
Q

Extradural lesions

A

Tend to be more malignant processes (infections or cancer)

Associated w/ severe pain- bone destruction

Symptoms can progress rapidly

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4
Q

Cauda Equina Compression

Signs and Symptoms

A

□ Numbness in genitals, buttocks, and anus due to compression of sacral nerve roots (Saddle anesthesia)
□ Lower extremity weakness, often asymmetrical
□ Decreased knee reflexes
□ Bowel and bladder retention (often a later finding)
□ Pain if a disc herniation is the case

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5
Q

Cause of Cauda Equina Compression

A

herniated disk at L4,L5 or L5-S1

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6
Q

Conus medullaris Compression

Signs and Symptoms

A

□ Knee reflexes preserved, ankle reflexes gone

□ Bowel/bladder incontinence develop early, as does impotence

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7
Q

Lhermitte’s Sign

A

electrical sensation

® Runs down back into limbs
® Caused by neck flexion
® Most commonly occurs in MS

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8
Q

Posterior cord syndrome

A

□ Loss of proprioception due to involvement of dorsal columns:
® Underrated syndrome
® Abnormal sensations, parethesias- burning, tingling, buzzing
® Can make patients miserable
® Central pain- originates in CNS

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9
Q

Anterior cord syndrome

A

□ Motor deficits- below lesion (corticospinal)
□ Loss of pain and temperature sensation (spinothalamic)
® Proprioception intact- sparing of dorsal columns
□ Bowel and bladder dysfunction, impairment of sexual function
□ Occlusion of anterior spinal artery (most common)
® Supplies anterior 2/3 of cord

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10
Q

Central cord syndrome

A

□ Loss of pain and temperature in arms, hands, and around shoulders and torso (shawl distribution)
® - disruption of spinothalamic tract as it crosses
® Lower extremities can be affected, not to same extent
□ Weakness of arms and hands- involvement of anterior horn cells w/in gray metter

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11
Q

Hemicord syndrome

A

□ Weakness on same side of lesion- injury of corticospinal tract (ipslateral)
□ Loss of proprioception on same side- injury to dorsal columns (ipslateral)
□ Loss of pain and temperature sensation on opposite side of lesion- injury to spinothalamic tract (contralateral)
□ Stabbed in the back

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12
Q

Transverse lesions

A

□ Complete motor or weakness loss below the lesions
® Paraparesis- weakness of the legs
® Quadraparesis- weakness of the arms and legs
® Paraplegia- paralysis of the legs
® Quadraplegia- paralysis of the arms and legs
□ Loss of sensation- damage to spinothalamic tract and dorsal columns
□ Bowel and bladder dysfunction, impairment of sexual function
□ i.e. transverse myelitis

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13
Q

Spinothalamic tract

A

pain and temperature from the opposite side of the body

ascending

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14
Q

Upper motor neuron signs

A

® Weakness, increased tone/spasticity, increased reflexes
® Pathological reflexes (Babinski, Hoffman’s signs)
® Lack of atrophy

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15
Q

Clonus

A

Continuous involuntary muscle contraction, relaxation

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16
Q

Lower motor neuron signs

A

® Damage to anterior horn cells or peripheral nerves
® Decreased tone, decreased reflexes, atrophy, fasciculations
® Flaccid, atrophy…

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17
Q

Corticospinal tract

A

motor to same side of the body

descending

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18
Q

Dorsal columns/Medial Lemniscus tract

A

proprioception and vibration from same side of body

ascending

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19
Q

Adrenoleukodystrophy

A

Disorder of peroxisomal function

By gross pathology: disorder of adrenal and white matter

By EM: disorder of peroxisomal storage
Biochem: disorder of deficient activity of VLCFA

Eufibers, deep white matter completely gone

Enlarged cortical adrenal cells w/ prominent striations

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20
Q

Krabbe’s disease

A

□ Autosomal recessive
□ Deficiecny of enzyme galactosyl ceramidase
□ Chromosome 14q31
□ Globoid cells w/ galactocerebroside shunting of galactocerebroside to phychosine
□ Very destructive, kills brain cells
□ Deteriorating around 4/5 months
□ Dense gliosis of the brain
□ Globoid cells- macrophages accumulating substance that isn’t being properly digested

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21
Q

Differential Diagnoses for Leukodystrophy

A

□ Infantile Krabbe Disease- begins w/in first year of life
□ Metachromatic LD: 2nd year of life
□ Spongy degeneration: megalencephaly
□ Pelizaeus- Merzbacher: abnormal eye movements, microcephaly
□ Neonatal adrenoleukodystrophy- affects brain, liver, retina

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22
Q

Leukodystrophy

A
§ Hereditary
§ Normal early development
§ Affect brain myelin and causes regression
§ Commonly fatal
§ Progressive
	□ Cognitive deterioration
	□ Neuropsychiatric difficulties
	□ Pyramidal and cerebellar abnormalities
	□ Visual abnormalities
      □ Deafness
§ Dementia and death within a few years
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23
Q

Gaucher disease

A

Lysosomal storage disorder
§ Autosomal recessive
§ Most prevalent lysosomal storage disease
§ Deficiency of enzyme, accumulation of glucocerebroside
§ Rare cases- deficiency of…
§ Non-neruonopathic form
□ Adult onset (Type 1)- hepatosplenomegaly, pancytopenia, skin
□ Bond- deformities of distal femur (Erlenmeyer)
§ Neuronopathic forms
□ Infantile (Type II)- rapidly progressive
□ Juvenile (Type III)- slowly progressive

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24
Q

Disorders of gray matter

A

§ Alpers-Huttenlocher syndrome
§ Pantothenate-kinase associated neurodegeneration
§ Menke’s disease
§ Leigh’s disease

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25
Disorders of white matter
leukodystrophes
26
Metabolic diseases
associated with genetic defects involving specific cellular organelles: lysosomes, peroxisomes, mitochondria unable to handle metabolism of neurons to execute their function, defect in myelination
27
Germinal matrix hemorrhage
○ Precise factors are unknown ○ Prematurity is commonest association ○ Not necessarily associated w/ stressed-out fetus ○ Hemorrhage may be localized or spread into ventricles and beyond § Can expand ventricle or explode into germinal matrix back into the brain (Grade IV) ○ Lower incidence when mom's were given K+ early on in fetal distress Stabilizes germinal matrix
28
Dandy-walker malformation
§ Triad of 4th ventricle cystic dilatation, vermal agenesis, and enlargement of posterior fossa □ Vermis between R and L cerebellar hemispheres □ Cyst expands, full of fluid § Patency of foramina of Lushka and Magendie variable □ Closed- fluid obstruction, hydrocephalus § Aplasia of the entire cerebellar vermis in 1/4 of patients □ Can almost always find small remnants microscopically
29
Arnold-chiari malformation (Chiari Type II)
§ Small posterior fossa with downward displacement of cerebellar tissue (vermis) through foramen magnum □ Malformation of skull? § Caudal displacement of medulla § Associated with hydrocephalus and lumbar meningomyelocele § Pathogenesis uncertain § Hydrocephalus
30
Hydranencephaly
§ Cerebral hemispheres largely absent § Fluid filled cavity instead § Fetal hypoxia, maternal intoxication, twinning § Skull present, often externally normal Secondary destruction - brain tissue killed by hypoxic ischemic insults
31
Agenesis of corpus callosum
§ Brain won't learn how L and R talk to each other § Absence of white matter bundle connecting both hemispheres § Sporadic or inherited § Associated conditions: holoprosencephaly, midline tumors (lipoma, meningioma, etc.)
32
Microcephaly (micrencephaly)
``` § Small brain § Numerous genetic syndromes, alcohol, drugs, viruses § In late stage of development § Very non-specific § Look at the family** small/large head? ```
33
Double cortex
§ Neurons made it half-way § Mutations in double cortin § Not connected appropriately, can be a cause of seizures
34
Nodular ventricular heterotopia
§ Nodular and laminar heterotopia § Neurons mature in wrong spot § Normal looking neurons, but not connected to anything else
35
Polymicrogyria
§ Small, irregularly formed, numerous individually thin gyri § Cobblestone appearance § Loss of external contours of the convolutions of the brain § Many genetic syndromes associated § Twinning, VZV, CMV, Toxo, syphillis….
36
Pachygyria (macrogyria)
§ Reduced number of broadened convolutions (gyri) § Reduction in number of neurons reaching neocortex § Results in simplification of gyral foldings
37
Agyria (lissencephaly)
§ Small brain with smooth cerebral surface § Absence of gyri and sulci § Neuroblasts migrated into subarachnoid space Defect in border preventing neurons from getting out
38
Arrhinencephaly
olfactory aplasia Agenesis of olfactory bulbs and tracts and related structures Mildest form of craniofacial anomalies Incidental, or with holoprosencephaly
39
Holoprocencephaly
Failure in outgrowth/cleavage of pros encephalic vesicle Incomplete separation of cerebral hemispheres Single ventricle and fused basal ganglia (holosphere) Associated w/ Trisomy 13, maternal diabetes, rubella, toxo, fetal-alcohol syndrome □ Severe facial malformation (cyclopia) □ Severe mental retardation and reduced lifespan
40
Myelomeningocele
Failure of posterior end of NT closure Both meninges and deformed spinal cord herniate through defect in vertebrae Covered by skin membrane or skin Mostly in lumbosacral region (motor and sensory deficits in LE) Defect limited to spine (spina bifida occulta)
41
Encephalocele
Hernia of brain tissue through midline defect in cranial cavity (mesodermal defect) Mostly located in occipital or posterior fossa regions, can be frontal Mostly female There may be associated abnormalities- hydrocephalus
42
Anencephaly
Failure of anterior end of neural tube closure Complete loss of brain- leakage of fluid into brain 1-5/1000 live births, mostly females 28 days of gestation □ Detected early in gestation by US Absence of brain and calvarium Small disc shaped brain (area cerebrovasculosa) Rarely survives more than a few hours Raised alpha-fetoprotein level Protuberant eyes, short neck, low set ears Incidence high in Ireland, Wales, France (10X)
43
completion of neurulation
4 weeks
44
completion of segmentation and cleavage
8 weeks
45
proliferation and migration
8 weeks --> birth
46
etiology of CNS abnormalities
genetic, sporadic, familial infectious: VZV, CMV, toxo metabolic: maternal diabetes, folate deficiency toxic: alcohol
47
etiology of CNS structural malformations
Genetic factors (most cases have no link) Intrauterine infections, particularly viral Systemic factors: hypoxia, hypoglycemia, alcoholism, drugs, CO-poisoning Physical factors: ionizing radiation Idiopathic: often the specific cause is unknown
48
lower motor neuron lesion
``` Loss of volitional control Weakness Hyporeflexia Flaccidity Fasciculations Atrophy ```
49
upper motor neuron lesion
® Initial flaccidity and loss of reflexes due Hyperreflexia Spasticity Weaknss Loss of volitional control (particularly the digits) No atrophy (except for disuse)
50
reflex (definition)
a reflex is relatively predictable, involuntary, and stereotyped response to a particular stimulus
51
components of reflex
□ Afferent limb (Ia, Ib, II, FRAs) □ Central component (ITNs) □ Efferent limb (motor neurons)
52
membrane potential
voltage (electrical potential) between the inside of a neuron and the surrounding liquid
53
neuron resting potential
resting potential of between -90 and -40mV
54
depolarization
increase in membrane potential
55
hyperpolarization
decrease in membrane potential
56
ions inside of cell at rest
K+, Cl-
57
ions outside of the cell at rest
Na+, Ca++, Cl-
58
Action potential
rapid electrical event that allows a neuron to signal over a long distance (e.g. from the brain to a distant muscle).
59
Hodgkin-Huxley Model
mathematical framework for understanding the action potential and the electrical behavior of neurons in general. This model describes the cell as an electrical circuit, in which different currents are carried by different ions
60
3 variables for Hodgkin-Huxley model
peak conductance gating variables driving force
61
synaptic potentials
are mediated by ligand-gated ion channels, ion channels that are activated by neurotransmitters rather than by voltage. Synaptic potentials are graded, rather than all-or- none like action potentials.
62
what do Neurons use to store energy and facilitate rapid signaling
active transport
63
what allows for the generation of rapid signals
ion channels
64
how can ion channels be activated
voltage, chemical ligands, sensory stimuli
65
use of electrical circuit model
can be used to understand how ion channels interact to produce cellular behavior.
66
Tetrodotoxin poisoning
Na+ channel blocker can't generate AP's doesn't cross BBB?- stay conscious
67
Charybdotoxin
K+ channel blocker prevent depolarization, hyperactive-state, convulsions Scorpion bite
68
Saxitoxin
paralytic shellfish poisoning Na+ channel blocker can't generate AP
69
cause of MG
Auto-antibodies directed against neuromuscular junction proteins 85%: Ab against postsynaptic Ach receptors 10%: Ab against MuSK (less ocular symptoms) Rare and of unknown pathogenicity: Abs against LRP4 and agrin POSTsynaptic abnormality
70
Symptoms of MG
Diplopia (double vision) or ptosis (eyelid drooping) – initial symptom in 2/3 of patients Bulbar dysfunction – difficulty chewing, swallowing, talking Limb weakness – hip flexors, neck extensors, ankle dorsiflexors
71
Course of MG
Symptoms fluctuate, fatigue-able, worse later in day and with prolonged use Weakness limited to ocular muscles -10% Most cases progress with weakness within 2 years of onset Spontaneous improvement with symptom free intervals can occur early in disease
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Aggravating factors in MG
``` Systemic illness Thyroid dysfunction Pregnancy / menstrual cycle Increased body temperature Emotional distress Drugs: aminoglycosides, fluoroquinolones, macrolides, magnesium, quinidine, procainimide ```
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tensilon test
diagnosis of MG Acetylcholinesterase inhibitor Most reliable if ptosis present, + in 90% of MG patients Incremental injections of tensilon, monitor every 60 seconds for improvement in lid ptosis Can cause bradyarrhythmias and syncope
74
nerve conduction study purpose
Helps distinguish myelin from axon problem on the nerve
75
EMG purpose
Helps distinguish neuropathic from myopathic disorders
76
treatment of MG
Initial therapy- acetylcholinesterase inhibitors (AchE inhibitors) Pyridostigmine (most common) or neostigmine If ocular symptoms become debilitating or weakness of oropharyngeal/limb muscles: Prednisone (can use azathioprine if want to spare steroids) IVIG or plasma exchange + azathioprine Thymectomy- in all patients with thymoma, optional in patients without one
77
LEMS- cause
Autoimmune attack against the voltage gated calcium channels on motor nerve terminal PREsynaptic abnormality of Ach release Half have underlying malignancy Usually small cell lung cancer
78
Symptoms of LEMS
Difficulty walking- most common initial symptom Bulbar and ocular muscles typically spared or mildly affected Dry mouth Postural hypotension, erectile dysfunction
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course of LEMS
Strength improves after exercise in most patients Weakness is rarely life threatening May be aggravated by agents that also worsen MG
80
PE in LEMS
Symptoms typically out of proportion to degree of weakness found on exam Tendon reflexes absent or reduced Can be increased by brief activation of appropriate muscles or by tapping the tendon repeatedly
81
treatment of LEMS
Treat any malignancy present- weakness may improve without any further treatment AchE inhibitors may help dry mouth but rarely weakness in LEMS Amifampridine (3,4-Diaminopyridine) Increases Ach from autonomic and motor nerve terminal Prednisone, azathioprine– modest benefit IVIG, plasma exchange – for rapid, temporary improvement (like in MG)
82
tick paralysis
Blocks Na ion influx, inhibits presynaptic depolarization
83
snake venom
Can affect pre- or postsynaptic junction
84
organophosphates and carbamates
Inhibit acetylcholinesterase abundance of Ach Sx: miosis, bradycardia, salivation, bronchospasm, diarrhea, urination, vomiting Tx: atropine, pralidoxime
85
hypermagnesemia
IV administration in women with eclampsia | blocks Ca channels weakness, absent DTRs
86
hypocalcemia
Increases permeability to Na ions  progressive depolarization  sustained contractions = tetany
87
anesthetic agents
Succinylcholine – binds AchR, does not allow muscle to repolarize Curare – blocks Ach R
88
What major ions and neurotransmitters play a role in neural transmission at the NMJ?
Ca, Na, K, Ach
89
Which enzyme is responsible for stopping neural transmission?
Acetylcholinesterase
90
Which part of the synaptic membrane does myasthenia gravis affect?
Postsynaptic
91
Which part of the synaptic membrane does LEMS affect?
Presynaptic
92
Most common presenting symptom in MG?
Diplopia
93
Most common presenting symptom in LEMs?
Falls, difficulty walking
94
How can you diagnose MG and LEMS?
Serum antibodies, RNS
95
When should a thymectomy be done?
Definitely if there is a thymoma, optional otherwise
96
What are key features of botulism
Cranial nerve palsies, descending weakness