Neuro - First Aid Flashcards
The notochord induces…
overlying ectoderm to differentiate into neuroectoderm and form the neural plate.
The neural plate gives rise to…
the neural tube and neural crest cells.
The notochord becomes…
nucleus pulposus of the intervertebral disc in adults.
The alar plate is…
dorsal/sensory.
The basal plate is…
ventral/motor.
During development, forebrain/prosencephalon includes…
the telencephalon and diencephalon.
Adult derivatives of the telencephalon are…
the cerebral hemispheres and the lateral ventricles.
Adult deriatives of the diencephalon are..
the thalamus and third ventricle.
During development the midbrain/mesencephalon includes…
the mesencephalon.
Adult derivatives of the mesencephalon are…
the midbrain and aqueduct.
During development, the hindbrain/rhombencephalon includes..
the metencephalon and the myelencephalon.
Adult derivatives of the metencephalon are…
the pons, cerebellum and upper part of the 4th ventricle.
Adult derivatives of the myelencephalon are…
the medulla and lower part of the 4th ventricle.
Neuroectoderm derivatives (4)
- CNS neurons 2. ependymal cells 3. oligodendroglia 4. astrocytes
Neural crest derivatives (2)
- PNS neurons 2. Schwann cells
Mesoderm derivative (1)
Microglia (like Macrophages, derived from Mesoderm)
If neuroporses fail to fuse in the 4th week, there is….
persisten connection between the amniotic cavity and spinal canal. (neural tube defects)
Neural tube defects are associated with….
low folic acid intake before conception and during pregnancy.
Labs indicative of neural tube defects
-increased alpha-fetoprotein (AFP) -increased AChE in amniotic fluid
Spina bifida occulta is due to…
failure of the bony spinal canal to close but there is no structural herniation. The dura is intact.
Spina bifida occulta is associated with…
a tuft of hair or skin dimple at the level of bony defect. (usually lower vertebral levels)
Meningocele
Meninges (but not spinal cord) herniates through the spinal canal defect; normal AFP.
Meningomyelocele
Meninges and spinal cord herniate through spinal canal defect.
Anencephaly is…
malformation of the anterior neural tube resulting in no forebrain and an open calvarium (“frog-like” appearance).
Clinical findings of Anencephaly
increased AFP polyhydramnios (no swallowing center in brain)
Anencephaly is associated with…
maternal diabetes. Maternal folate supplementation decreases risk.
Holoprosencephaly is…
failure of the left and right hemispheres to separate usually during weeks 5-6.
Holoprosencephaly has a complex etiology that may be related to mutations in…
sonic hedgehog signaling pathway.
Moderate form of holoprosencephaly has…
cleft lip/palate and more severe form results in cyclopia.
Chiari II (Arnold-Chiari malformation) is…
significant herniation of cerebellar tonsils and vermis through the foramen magnum with aqueductal stenosis and hydrocephalus.
Chiari II often presents with…
lumbosacral myelomeningocele and paralysis below the defect.
Dandy-Walker is…
agenesis of the cerebellar vermis with cystic enlargement of the 4th ventricle.
Dandy-Walker is associated with…
hydrocephalus and spina bifida.
Syringomyelia is a…
cystic cavity within the spinal cord that typically damages the crossing anterior spinal commissural fibers.
Syringomyelia presents with a…
“cape-like” bilateral loss of pain and temperature sensation in the upper extremities.
Syringomyelia is most common at…
C8-T1.
Syringomyelia is associated with…
Chiari I malformation (> 3-5 mm cerebellar tonsillar ectopia; congenital and manifests with HAs and cerebellar symptoms)
The anterior 2/3 of the tongue are formed by…
1st and 2nd branchial arches (thus sensation via CN V3 and taste via CNVII).
The posterior 1/3 of the tongue is formed by…
the 3rd and 4th branchial arches (thus sensation and taste mainly from CN IX)
Motor innervation to the tongue is via…
CN XII.
Muscles of the tongue are derived from…
occipital myotomes.
Neurons are…
permanent cells; they do not divide in adulthood and generally do not have a progenitor stem cell population.
Cell bodies and dendrites of axons can be stained via…
Nissl substance (stains RER). RER is not present in the axon.
If an axon is injured, it undergoes…
Wallerian degeneration which is degeneration distal to the injury and axonal retraction proximally; this allows for potential regeneration.
Astrocyte Functions (6)
-physical support -repair -K+ metabolism -removal of excess NT -component of BBB -glycogen fuel reserve buffer
In response to neural injury, astrocytes cause…
reactive gliosis.
Astrocyte marker
GFAP
Microglia features
-CNS phagocytes (scavenger cells) -not readily discernible in Nissly stains -small, irregular nuclei and little cytoplasm
Microglia respond to tissue damage by…
differentiating into large phagocytic cells.
HIV-infected microglia will…
fuse to form multinucleated giant cells in the CNS.
Myelin in the CNS is formed by…
oligodendrocytes. And by Schwann cells in the PNS.
Myelin increases both…
space constant and conduction velocity.
Each oligodendrocyte can….
myelinate many axons. It is the predominant glial cell in white matter.
On H&E, oligodendroglia have a..
“fried egg” appearance.
Oligodendroglia are injured in…
MS, progressive multifocal leukoencephalopathy (PML) and leukodystrophies.
Each Schwann cell myelinates…
only 1 PNS axon and they promote axonal regeneration.
Scwhann cells are destroyed in…
Guillain-Barre.
Acoustic neuroma is a…
type of schwannoma typically located in the internal acoustic meaturs (CN VIII).
If acoustic neuroma is bilateral, it is strongly associated with…
neurofibromatosis type 2.
Freen nerve endings description
C fibers - slow, unmyelinated Adelta fibers - fast, myelinated
Free nerve endings are located in the…
skin, epidermis
Free nerve endings sense…
pain and temperature.
Meissner corpuscles are..
large, myelinated fibers that adapt quickly.
Meissner corpuscles are located in…
glabrous (hairless) skin.
Meissner corpuscles sense…
dynamic, fine/light touch; position sense
Pacinian corpuscles are…
large, myelinated fibers that adapt quickly
Pacinian corpuscles are in the…
deep skin layers, ligaments and joints.
Pacinian corpuscles sens..
vibration and pressure.
Merkel discs are…
large, myelinated fibers that adapt slowly.
Merkel discs are located in..
the basal epidermal layer and hair follicles.
Merkel discs sense…
pressure, deep static touch; position sense
The endoneurim surrounds…
a single nerve fiber layers. This is the inflammatory infiltrate in Guillain barre.
The perineurium surrounds…
a fascicle of nerve fibers; must be rejoined in microsurgery for limb reattachment; permeability barrier.
The epineurium is a…
dense CT that surrounds the entire nerve (fascicles and blood vessels).
NE is synthesized in…
the locus ceruleus (pons).
Dopamine is synthesized in…
the ventral tegmentum and SNc (midbrain).
5-HT is synthesized in…
the raphe nucleus (pons, medulla, midbrain)
ACh is synthesized in…
the basal nucleus of Myenert.
GABA is synthesized in…
the nucleus accumbens.
NE change in disease (2)
increased in anxiety decreased in depression
Dopamin change in disease (3)
increased in Huntington decreased in Parkinson decreased in depression
Serotonin change in disease (3)
increased in Parkinson decreased in anxiety decreased in depression
ACh change in disease (3)
increased in Parkinson decreased in Alzheimer decreased in Huntington
GABA change in disease (2)
decreased in anxiety decreased in Huntington
The BBB is formed by 3 structures:
- tight junctions between nonfenestrated capillary endothelial cells 2. basement membrane 3. astrocyte foot processes
Glucose and amino acids cross the BBB via…
slow, carrier-mediated transport.
Nonpolar/lipid-soluble substances cross the BBB via…
rapid diffusion.
Areas of the brain w/o BBB allow for special brain functioning (3):
- area postrema (vomiting after chemo) 2. OVLT (osmotic sensing) 3. neurohypophysis (ADH release)
In regards to the BBB, infarction or neoplasm can destroy…
endothelial cell tight junctions leading to vasogenic edema.
Functions of the Hypothalamus (7)
TAN HATS 1. Thirst and water balance 2. Adenohypophysis control 3. Neurohypophysis regulates hormones produced in the hypothalamus 4. Hunger 5. Autonomic regulation 6. Temperature regulation 7. Sexual urges
ADH is made in the…
supraoptic nucleus.
Oxytocin is made in the…
paraventricular nucleus.
ADH and oxytocin are both made by…
the hypothalamus but stored and released by the posterior pituitary.
Lateral area of the Hypothalamus
Hunger (destruction leads to anorexia and FTT) inhibited by leptin
Ventromedial area of the hypothalamus
Satiety (destruction leads to hyperphagia) stimulated by letin
Anterior hypothalmus
cooling, parasympathetic
Posterior hypothalamus
heating, sympathetic
Suprachiasmatic nucleus
circadian rhythm
Circadian rhythm controls the nocturnal release of…
ACTH, prolactin, melatonin, and NE.
The SCN releases…
NE to the pineal gland which releases melatonin.
SCN is regulated by…
the environment (light).
Extraocular movements during REM sleep are due to…
activity of PPRF (paramedian pontine reticular formation).
Alcohol, benzodiazapenines, and barbituates are associated with…
decreased REM sleep and delta wave sleep.
Bedwetting should be treated with…
oral desmopressin (DDAVP) which mimics ADH.
Treat night terrors and sleepwalking with…
benzodiazepines.
Awake (eyes open) EEG
beta waves (high frequency, low amplitude)
Awake (eyes closed) EEG
alpha
Stage 1 NREM is…
light sleep with theta waves.
Stage 2 NREM is…
deeper sleep with sleep spindles and K complexes that makes up 45% of sleep.
Bruxism occurs during…
Stage 2 sleep.
Stage 3 NREM is…
deepest slow-wave sleep with delta waves (low frequency, high amplitude).
Sleepwalking, night terrors and bedwetting occur during…
stage 3 sleep.
REM sleep features
-loss of motor tone -increased brain O2 use -increased pulse/bp -memory processing function? -Beta waves
Dreaming and clitoral/penile tumescence occurs during…
REM.
The posterior pituitary (neurohypophysis) receives…
hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei.
The thalamus is the major relay for…
all ascending sensory info except olfaction.
VPL input
spinothalamic and dorsal columns/medial lemniscus
VPL info
pain/temp, pressure, touch, vibration and proprioception
VPL destination
primary somatosensory cortex
VPM input
trigeminal and gustatory pathway
VPM info
face sensation and taste
VPM destination
primary somatosensory cortex
LGN input
CN II
LGN info
vision
LGN destination
calcarine sulcus
MGN input
superior olive and inferior colliculus of tectum
MGN info
hearing
MGN destination
auditory cortex of the temporal lobe
VL input
basal ganglia and cerebellum
VL info
motor
VL destination
motor cortex
Cerebellum input
- contralateral cortex via middle cerebellar peduncle 2. ipsilateral proprioceptive info via inferior cerebellar peduncle from the spinal cord
Cerebellum outputs information to the contralateral cortex to…
modulate movement. It starts at the purkinje cells then to the deep nuclei then to the contralateral cortex via the superior cerebellar peduncle.
Deep nuclei (from lateral to medial)
Dentate, Emboliform, Globose, Fastigial
Lateral lesions of the cerebellum affect…
voluntary movement of the extremities; when injured, there is a propensity to fall toward the injured side
Medial lesions of the cerebellum involve…
vermal cortex, fastigial nuclei and flocculonodular lobe resulting intruncal ataxia, nystagmus and head tilting.
Pts with medial lesions of the cerebellum may present with…
a wide-based gait and deficits in truncal coordination.
The basal ganglia is important in…
voluntary movements and making postural adjustments.
Basal ganglia receives…
cortical input and provides negative feedback to the cortex to modulate movement.
The exicatory pathway receives cortical inputs that…
stimulate the striatum to release GABA which disinhibits the thalamus via the GPi/SNr (leading to increased motion).
The inhibitory pathway receives cortion inputs that..
stimulate the striatum which disinhibits STN via GPe and then STN stimulates GPi/SNr to inhibit the thalamus (decreased motion).
In the excitatory pathway, dopamine binds to…
D1 stimulating the excitatory pathway. (increases motion)
In the inhibitory pathway, dopamine binds to…
D2 inhibiting the inhibitory pathway (increased motion).
Parkinson is a degenerative disorder of the CNS associated with…
Lewy bodies and loss of dopaminergic neurons in the substantia nigra pars compacta.
Lewy bodies are composed of..
alpha-synuclein - intracellular eosinophilic inclusions.
Clinical findings of Parkinson (5)
- tremor (pill-rolling) 2. cogwheel rigidity 3. Akinesia 4. postural instability 5. shuffling gait
Huntington Disease features
-autosomal dominant -trinucleotide repeat of CAG on chr 4 -20-50 yrs old
Huntington is characterized by…
choreiform movements, aggression, depression and dementia.
Huntington pathology is due to…
decreased levels of ACh and GABA in the caudate. (atrophy of caudate on imaging)
In Huntington, neuronal death is via…
NMDA-R binding and glutamate toxicity.
Hemiballismus presentation
sudden, wild flailing of 1 arm +/- ipsilateral leg
Characteristic lesion of hemiballismus
contralateral subthalamic nucleus (ex. lacunar stroke)
Chorea presentation
sudden, jerky, purposeless movements
Characteristic lesion of chorea and athetosis
basal ganglia
Athetosis presentation
slow, writhing movements (esp in fingers)
Myoclonus (sudden, brief, uncotrolled muscle contraction) is common in…
metaboic abnormalities such as renal and liver failure.
Dystonia is…
sustained, involuntary muscle contractions. Ex. writer’s cramp, blepharospasm
Essential tremor (postural tremor) is an..
action tremor; exacerbated by holding posture/limb position
Treatment for essential tremor
beta-blockers primidone
Resting tremor is an…
uncontrolled movement of distal appendages; tremor is alleviated by intentional movement
Intetion tremor is a…
slow, zigzag motion when pointing/extending toward a target.
Characteristic lesion of intention tremor…
cerebellar dysfunction.
Lesion to the bilateral amygdala causes…
Kluver-Bucy syndrome (hyperorality, hypersexuality, disinhibited behavior); associated with HSV-1.
Lesions to the frontal lobe cause…
disinhibition and deficits in concentration, orientation and judgement; may have reemergence of primitive reflexes.
Lesions to the right parietal-temporal cortex cause…
spatial neglect syndrome (agnosia of the contralateral side of the world)
Lesions to the left parietal-temporal cortex cause…
agraphia, acalculia, finger agnosia and left-right diorientation (aka Gerstmann syndrome)
Lesion to the reticular activating system (midbrain) causes…
reduced levels of arousal and wakefulness
Lesion to the mamillary bodies causes…
Wernicke-Korsakoff syndrome (confusion, ophthalmoplegia, ataxia, memory loss, confabulation and personality changes.
Mamillary body lesions are associated with…
thiamine deficiency and excessive EtOH use; can be precipitated by giving glucose w/o B1 to a B1 deficient pt.
Basal ganglia lesion may result in…
tremor at rest, chorea or athetosis.
Cerebellar hemisphere lesions lead to..
intention tremor, ataxia and loss of balance
Cerebellar vermis lesions lead to…
truncal ataxia and dysarthria.
Lesions in the subthalamic nucleus lead to…
contralateral hemiballismus.
Lesions to the hippocampus cause..
anterograde amnesia.
Lesions to the paramedian pontine reticular formation lead to…
eyes looking away from the side of the lesion.
Lesions to the frontal eye fields lead to…
eyes looking toward the lesion.
Central pontine myelinolysis causes…
acute paralysis, dysarthria, dysphagia, diploplia and loss of consiousness. Can cause “locked-in syndrome”.
Central pontine myelinolysis pathology is due to…
massive axonal demyelination in pontine white matter tracts secondary to osmotic forces and edema.
Central pontine myelinolysis is commonly iatrogenic caused by…
overly rapid correction of hyponatremia.
Broca’s aphasia
nonfluent aphasia with intact comprehension
Broca’s area is located in the…
inferior frontal gyrus of the frontal lobe.
Wernicke’s aphasia is…
fluent aphasia with impaired comprehension and repetition.
Wernicke’s area is located in the…
superior temporal gyrus of the temporal lobe.
Global aphasia is…
nonfluent aphasia with impaired comprehension; both broca and wernicke areas are affected.
Conduction aphasia
poor repetition but fluent speech; intact comprehension
Conduction aphasia can be caused by damage to..
left superior temporal lobe and/or left supramarginal gyrus.
Transcortical motor aphasia
nonfluent aphasia with good comprehension and repetition
Transcortical sensory aphasia
poor comprehension with fluent speech and repetition
Mixed transcortical aphasia
nonfluent speech, poor comprehension, and good repetition
Watershed zones of the brain are damaged in severe…
hypotension leading to upper leg/arm weakness and defects in higher-order visual processing.
Cerebral perfusion is primarily driven by…
PCO2 (PO2 can help in severe hypoxia).
Therapeutic hyperventilation (decreases PCO2) helps to decrease…
intracranial pressure in cases of acute cerebral edema via decreased cerebral perfusion by vasoconstriction.
If there is a lesion in the MCA supply to the motor cortex, this causes…
contralateral paralysis of the upper limb and face.
If there is a lesion in the MCA supply to the sensory cortex, this causes….
contralateral sensation of the upper and lower limbs and face.
If there is a lesion in the MCA supply to Wernicke’s or Broca’s area regions, this causes…
aphasia if in the dominant hemisphere (usually left) and hemineglect if it affects the nondominant side.
If there is a lesion in the ACA supply to the motor cortex, this causes…
contralateral paralysis in the lower limb.
If there is a lesion in the ACA supply to the sensory cortex, this causes…
contralateral loss of sensation in the lower limb.
If there is a lesion in the lenticulostriate artery to the striatum and internal capsule, this causes…
contralateral hemiparesis/hemiplegia.
A lesion in the ASA to the lateral corticospinal tract will cause…
contralateral hemiparesis (arms and legs).
A lesion of the ASA to the medial lemniscus will cause…
decreased contralateral proprioception.
A lesion of the ASA to the caudal medulla will cause…
ipsilateral hypoglossal dysfunction (causing the tongue to deviate ipsilaterally).
Medial Medullary syndrome is caused by…
infarct of paramedian branches of ASA and vertebral arteries.
A lesion to the PICA will affect the…
lateral medulla (vestibular nuclei, lateral spinothalamic tract, spinal trigeminal nucleus, nucleus ambiguus, sympathetic fibers, and inferior cerebellar peduncle).
Symptoms of a PICA lesion include…
vomiting, vertigo, nystagmus decreased pain and temp sensation from ipsilateral face and contralateral body dysphagia hoarseness decreased gag reflex ipsilateral Horner ataxia dysmetria (Lateral Medullary Syndrome - Wallenberg)
AICA lesion affects the…
lateral pons (cranial nerve nuclei, vestibular nuclei, facial nucleus, spinal trigeminal nucleus, cochlear nuclei, sympathetic fibers). (Lateral Pontine Syndrome)
AICA lesion affecting the lateral pons causes…
vomiting, vertigo, nystagmus paralysis of the face decreased lacrimation and salivation decreased taste from 2/3 anterior tongue decreased corneal reflex decreased pain/temp in face ipsilateral decreased hearing and Horner
AICA lesions can also affect the middle and inferior cerebellar peduncles leading to…
ataxia and dysmetria.
PCA lesion affects the…
occipital cortex and visual cortex causing contralateral hemianopia with macular sparing.
Lesion to the basilar artery affects…
the pons, medulla, lower midbrain, corticospinal and corticobulbar tracts, ocular crainal nerve nuclei, and PPRF.
Basilar artery lesion causes…
“locked in syndrome”: quadriplegia, loss of voluntary facial, mouth and tongue movements. (preserved consciousness and blinking)
Most common lesion of the anterior communicating artery is…
an aneurysm which can lead to visual field defects and stroke.
Saccular aneurysms can cause…
cranial nerve impingment.
The posterior communicating artery is a common location of…
saccular aneurysms where they cause CNIII palsy (pupil is down/out with ptosis and dilation).
Aneurysms are…
abnormal dilation of the artery due to weakening of the vessel wall.
Berry aneurysms occur at…
the birfucations of the circle of willis, most commonly the junction of the ACA and anterior communicting a.
Rupture of berry aneurysms leads to…
subarachnoid hemorrhage (worst HA of life) or hemorrhagic stroke. Can also cause
Berry aneurysms can also cause bitemporal hemianopia due to..
compression of the optic chiasm.
Berry aneurysms are associated with…
ADPKD Ehlers-Danos Marfan
Risk factors of Berry aneurysms include…
advanced age HTN smoking race (AA)
Charcot-Bouchard microaneurysms are associated with..
chronic HTN and they affect small vessels (in basal ganglia, thalamus).
Central post-stroke pain syndrome is…
neuropathic pain due to thalamic lesions. Initial sense of numbness and tingling followed by allodynia and dysaesthesia.
Epidural hematoma is ususally due to..
rupture of the middle meningeal artery secondary to fracture of the temporal bone.
Rapid expansion is seen in epidural hematoma leading to…
transtentorial herniation and CN III palsy.
CT of an epidural hematoma shows…
convex (lentiform), hyperdense blood collection.
Epidural hematoma does not cross…
suture lines. It can cross falx and tentorium.
Subdural hematomas are usually due to…
rupture of bridging veins casuing slow venous bleeding.
Subdural hematomas are seen in…
elderly individuals, alcoholics, blunt trauma, shaken baby.
CT of a subdural hematoma shows…
crescent-shaped hemorrhage that crosses suture lines. Cannot cross falx, tentorium.
Time course of a subarachnoid hemorrhage is…
rapid and pts complain of worst HA of life. Due to rupture of aneurysm.
Spinal tap of subarachnoid hemorrhage shows…
bloody or yellow (xanthochromic) spinal tap.
2-3 days after a subarachnoid hemorrhage, there is risk of..
vasospasm due to blood breakdown (not visible on CT, treat with nimodipine) and rebleed (visible on CT).
Intraparenchymal (hypertensive) hemorrhage is most commonly caused by…
systemic HTN. Also seen with amyloid angiopathy, vasculitis and neoplasm.
Intraprenchymal hemorrhages typically occur in…
basal ganglia and internal capusle but can be lobar.
Irreversible damage from stroke begins after…
5 minutes of hypoxia.
Most vulnerable brain regions to stroke (ischemia) are:
-hippocampus -neocortex -cerebellum -watershed areas
Histology 12-48 hrs after ischemic event
red neurons
Histology 24-72 hrs after ischemic event
necrosis + neurtrophils
Histology 3-5 days after ischemic event
macrophages