Neuro Flashcards
Forebrain derivatives
- telencephalon (cerebral hemispheres)
- diencephalon (thalamus)
midbrain derivatives
- mesencephalon (midbrain)
Hindbrain derivatives
- metencephalon (pons, cerebellum)
- myelencephalon (medulla)
Neural tube defect findings
- increased AFP and AchE (confirmatory test)
spina bifida
- failure of bony spinal canal to close, no herniation
- tuft of hair overlying defect
- dura is intact
meningocele
- meninges (but not the spinal cord) herniate through spinal canal defect
- normal AFP
meningomyelocele
- meninges and spinal cord herniate through spinal cord defect
anencephaly
- malformation of anterior neural tube
- increased AFP, polyhydramnios (no swallow center)
- associated with type I DM and decreased folate
Arnold Chiari I malformation
- cerebellar tonsillar ectopia (congenital malformation that is usually asyptomatic, but can manifest with headache and cerebellar symtpoms)
- associated with syringomyelia
Arnold Chiari II malformation
- signficant herniation of cerebellar tonsils and vermis through foramen magnum with aqueductal stenosis and hydrocephalus
- often presents with lumbosacral myelomeningocele and paralysis below the defect
Dandy-Walker malformation
- agenesis of vermis, with cystic enlargement of 4th ventricle
- associated with hydrocephalus and spina bifida
syringomyelia
- cystic cavity within the spinal cord
- crossing anterior spinal commissural fibers are typically damaged first
- results in “cape-like” bilateral loss of P/T sensation
- late stage can progress to lower extremity weakness and hyperreflexia
tongue innervation
- ant 2/3 - V3 sensation and VII taste
- post 1/3 - IX sensation and taste
- XII movement
neurons
- if the axon is injured, undergoes Wallerian degeneration
- neuronal marker is synaptophysin
astrocytes
- supporting cell that is a component of the BBB
- responsible for reactive gliosis in response to neuronal injury
- marker - GFAP
- derived from neuroectoderm
microglia
- CNS phagocytes
- mesodermal origin
- respond to tissue damage by differentiating into large phagocytic cells
myelin
- CNS - oligodendrocytes
- PNS - schwann cells
- increase space constant (length constant) and conduction velocity
oligodendroglia
- derived from neuroectoderm
- “fried egg” appearance
- myelinate many different axons in the CNS
- damaged in MS, PML and leukodystrophies
schwann cells
- each cell myelinates only one PNS axon
- derived from neural crest
- destroyed in GBS
- acoustic neuromas are schwannomas
free nerve endings
- C - slow, unmyelinated fibers
- Ad - fast, myelinated fibers
- located in all skin, epidermis and some viscera
- senses pain and temp
meissner corpuscles
- large, myelinated fibers
- adapt quickly
- located in glabrous (hairless) skin
- senses dynamic, fine/light touch, position sense
pacinian corpuscles
- large, myelinated fibers
- adapt quickly
- located in deep skin layers, and joints
- sense vibration, pressure
merkel discs
- large, myelinated fibers
- adapt slowly
- located in basal epidermal layer, hair follicles
- sense pressure, deep static touch, and position sense
TTX and Saxitoxin effect
- blocks Na channels, inhibiting influx and preventing AP conduction
Norepinephrine
- locus ceruleus (pons)
- increased in anxiety, decreased in depression
dopamine
- ventral tegmentus and SNc
- increased in Huntingtons, decreased in parkinsons and depression
5HT
- raphe nucleus
- plays a role in sleep/wake cycle - lesions lead to insomnia and depression
- increased in parkinsons, decreased in axiety and depression
Ach
- basal nucleus of Meynert
- increased in parkinsons, decreased in Alzheimers, decreased in HD
GABA
- nucleus acumbens
- decreased in anxiety, decreased in Huntington disease
Hypothalamus functions
TAN HATS
- Thirst/water balance
- Adenohypophysis control
- Neurohypophysis releases hormones made in the hypothalamus
- Hunger
- Autonomic regulation
- Temp regulation
- Sexual urges
supraoptic nucleus of the hypothalamus
makes ADH
paraventricular nucleus of the hypothalamus
makes oxytocin
lateral area of the hypothalamus
mediates hunger
- lesions –> anorexia, inhibited by leptin
- if you zap your lateral nucleus, you shrink laterally
ventromedial area of the hypothalamus
medaties satiety
- lesions –> hyperphagia, stimulated by leptin
- if you zap your ventromedial nucleus, you grow ventrally and medially
anterior hypothalamus
- cooling, parasympathetic
- lesions lead to hyperthermia
- Anterior is the A/C
posterior hypothalamus
- heating, sympathetic
- lesions lead to hypothermia
- if you zap the posterior, you become a poikilotherm
suprachiasmatic nucleus of the hypothalamus
- circadian rhythm
- you need to sleep so you can be charismatic
waves of sleep phases
BATS Drink Blood awake (eyes open) - beta awake (eyes closed) - alpha Stage 1 - Theta Stage 2 - Sleep spindles and K complexes Stage 3 - Delta REM - beta
VPL thalamus
- input from spinothalamic tract and dorsal columns
- pain and temp, pressure, touch, vibration and proprioception
- transmits to the primary somatosensory cortex
VPM thalamus
- input from trigeminal and gustatory pathway
- face sensation and taste
- transmits to primary somatosensory cortex
- vpM - Makeup goes on the face
LGN thalamus
- input from CN II
- vision
- goes to calcarine sulcus
- Lateral = Light
MGN thalamus
- input from superior olive and inferior colliculus of the tectum
- hearing
- goes to auditory cortex of temporal lobe
- Medial = Music
VL thalamus
- input from basal ganglia, cerebellum
- receives motor information
- destination – motor cortex
basal ganglia
- Direct pathway - via D1 receptors - stimulates movement
- indirect pathway - via D2 receptors - inhibits movement
- SNc inputs on D1/D2 receptors in putamen, then to GP and on to thalamus
Parkinson disease
- degenerative disease of Lewy bodies
- loss of dopaminergic neurons in the SN pars compacta
- TRAPS - tremor, rigidity, akinesia, postural instability, shuffling gait
Huntington disease
- CAG repeat on chromosome 4
- huntington protein deacetylates histones - silencing genes that are needed for neuronal survival – neuronal death via NMDA-R binding and glutamate toxicity
- decreased levels of GABA and Ach in the brain
CAG repeats - Caudate loses Ach and GABA
hemiballisumus
sudden, wide flailing of 1 arm +/- ipsilateral leg
- lesion: contralateral subthalamic nucleus (lacunar stroke)
chorea
sudden, jerky, purposeless movements
- lesion: basal ganglia (HD)
amygdala lesion
Kluver Bucy syndrome - hyperorality, hypersexuality, disinhibited behavior
right parietal-temporal cortex lesion
spatial neglect syndrome (agnosia of contralateral world)
left parietal-temporal cortex lesion
agraphia, acalculia, finger agnosia, and L/R disorientation
subthalamic nucleus lesion
contralateral hemiballismus (lacunar stroke)
paramedian pontine reticular formation
eyes look away from the side of the lesion
frontal eye fields
eyes look toward the side of the lesion
brocas area
inferior frontal gyrus of frontal lobe
wernickes area
superior temporal gyrus of temporal lobe
conduction aphasia
- poor repetition but fluent speech and intact comprehension
- due to lesions of the left superior temporal lobe or left supramarginal gyrus
ACA stroke
- affects the motor and sensory cortices of the contralateral lower limb
lenticulostriate artery stroke
- affects the striatum, internal capsule
- contralateral hemiparesis, hemiplegia
- common location of lacunar infarcts 2/2 uncontrolled hypertension
ASA stroke
- affects the lateral corticospinal tract, medial lemniscus and caudal medulla - hypoglossal nerve
- causes contralateral hemoparesis, upper and lower limbs
- decreased contralateral proprioception
- ipsilateral hypoglossal dysfunction
PICA stroke
- lateral medulla
- vomiting, vertigo, nystagmus, decreased pain and temp sensation from ipsilateral face and contralateral body
- dysphagia, hoarseness, decreased gag reflex, ipsilateral Horner syndrome, ataxia, dysmetria
AICA stroke
- lateral pons and medial/inferior cerebellar peduncles
- vomiting, vertigo, nystagmus, paralysis of the face, decreased lacrimation, salivation, taste and corneal reflex
- face - decreased pain and temp, ipsilateral decreased in hearing and Horners
- ataxia, dysmetria
- “facial droop means the AICA’s pooped”
PCA stroke
- occipital cortex, visual cortex
- contralateral hemianopia with macular sparing
basilar artery stroke
- post, medulla, lower midbrain, etc
- “locked in syndrome” - preserved cognition and blinking with quadraplegia
PCOM aneurysm
CN III palsy - down and out eye with ptosis and pupil dilation
berry aneurysms
- most commonly at the ACA and ACOM junction
- associated with ADPKD, Ehlers Danlos and Marfans
Charcot-Bouchard aneurysm
- associated with chronic HTN, affects small vessels (basal ganglia, thalamus)
first area to be damaged in global cerebral hypoperfusion
hippocampus
central post-stroke pain syndrome
neuropathic pain due to thalamic lesions (starts as numbness, progresses to allodynia)
intraparenchymal hemorrhage
- most commonly caused by systemic HTN, also amyloid angiopathy, vasculitis and neoplasm
- typically happens in the basal ganglia and internal capsule, but can be lobar
12-48 hours after brain ischemia
red neurons (eosinophilic cytoplasm, pynknotic nuclei, decreased Nissl)
24-72 hours after brain ischemia
necrosis and neutrophils
3-5 days after brain ischemia
macrophages
1-2 weeks after brain ischemia
reactive gliosis and vascular proliferation
> 2 weeks after brain ischemia
glial scar
