Flashcards in Neurology Deck (137):
What happens in neural development?
1. notochord induces overlying ectoderm to differentiate into neuroectoderm and form the neural plate
2. Neural plate gives rise to neural tube and neural crest cells
3. Notochord becomes nucleus pulposus of the intervertebral disc in adults
- Alar plate (dorsal) - sensory
- Basal plate (ventral) - motor
What are the 3 primary vesicles at week 4 for the brain?
1. forebrain = prosencephalon
2. midbrain = mesencephalon
3. hindbrain = rhombencephalon
What do the primary vesicles differentiate into at week 5 for the brain?
1. Pro becomes telencephalon and diencephalon
2. Mese stays mese
3. Rhombo becomes metencephalon and myelencephalon
What does the telencephalon become?
Ceberal hemispheres, basal ganglia, hippocampus, and amygdala. Forms lateral ventricles
What does the diencephalon become?
thalamus, hypothalamus, optic nerve and tracts. Forms 3rd ventricle
What does the mesencephalon become?
midbrain and forms aqueduct
What does the metencephalon become?
pons and cerebellum and forms upper part of 4th ventricle
What does the myelencephalon become?
medulla and forms the lower part of the 4th ventricle
What are neural tube defects caused by?
-neuropores fail to fuse (4th wk) --> persistent connection b/w amniotic cavity and spinal canal. Associated w/ low folic acid intake before conception and during pregnancy.
What is usually seen in labs for neural tube defects?
elevated AFP in amniotic fluid and maternal serum. Elevated AChEsterase in amniontic fluid
What is spina bifida occulta?
failure of bony spinal canal to close but NO structural herniation. Usually seen at lower vertebral levels. Dura is intact. Assocated w/ tuft of hair or skin dimple.
What is meningocele?
Meninges ( but not the spinal cord) herniate through spinal canal defect
What is meningomyelocele?
Meninges and spinal cord herniate through spinal canal defect
What is anencephaly?
- malformation of anterior neural tube = no forebrain, open calvarium (frog-like appearance)
What are the clinical findings for anencephaly?
increased AFP, polyhydraminos (no swallowing center in brain). Associated w/ maternal diabetes. Maternal folate supplement decreases risk.
What is holoprosenecephaly?
- failure of left and right hemispheres to separate. usually occurs during 5-6 weeks.
- may be related to Sonic hedgehog gene
- Patau syndrome (trisomy 13)
- Fetal alcohol syndrome
What is clinical presentation of holoprosenecephaly?
moderate form has cleft lip/palate. Most severe forms result in cyclopia
What are examples of forebrain anomalies?
anencephaly and holoproenecephaly
What are examples of posterior fossa malformations?
1. Chiarii II
2. Dandy- Walker
What is Chiarii II?
Significant cerebellar tonsillar and vermian herniation through foramen magnum w/ aqueductal stenosis and hydrocephalus. Often presents w/ thoraco-lumbar myelomeningocele and paralysis below the defect.
- syringomyelia can occur as well
What is Dandy-walker?
agenesis of cerebellar veins w/ cystic enlargement of 4th ventricle. Associated w/ hydrocephalus and spina bifida.
What is syringomyela?
- cystic enlargement of central canal of spinal cord.
- crossing fibers of spinothalamic tract are typically damaged first.
What is the clinical presentation of syringomyelia?
- bilateral loss of pain and temperature sensation in upper extremities (fine touch sensation is preserved)
- most common at C8-T1
What is involved w/ tongue development?
1. 1st branchial arch forms anterior 2/3 (sensation via CN V3, tase via CN 7)
2. 3rd/4th arches form posterior 2/3 (sensation and taste via CN 9, extreme posterior - CN 10)
Motor innervation via CN 12
Muscles of tongue are derived from occipital myotomes.
What are the cells of neurology and their embryologic derivatives?
1. neurons - neuroectoderm
2. astrocytes - neuroectoderm
3. microglia - mesoderm
4. oligodendria - neuroectoderm
5. Schwann cells - neural crest cells
What are neurons?
- signal transmitting cells of nervous system.
- permanent cells
What are components of a neuron?
1. dendrites - receive input; stained via Nissl substance
2. cell bodies
3. axons - send output. RER is NOT Present here.
What happens if the axon is injured?
undergoes Wallerian degeneration - degeneration distal to injury and axonal retraction proximally; allows for potential regenerations of axon if in PNS
What is the role of astrocytes?
physical support, repair, K metabolism, removal of excess NTs, maintenance of BBB
- Reactive gliosis in response to injury.
- marker = GFAP
What is the role of microglia?
CNS phagocytes. have small irregular nuclei and relatively little cytoplasm. Scavenger cells of CNS. Respond to tissue damage by differentiating into large phagocytic cells.
What does HIV do to infected microglia?
fuse to form multinucleated giant cells in the CNS
What is myelin?
used to increase conduction velocity of signals transmitted down axons. Results in saltatory conduction of AP btw nodes of Ranier where there are high concentrations of Na channels. Increase space constant as well.
What are oligodendrocytes?
myelinate multiple CNS axons.
- small nuclei w/ dark chromatin and little cytoplasm
- make up a lot of glial cell in white matter
What cells are destroyed in multiple sclerosis? and in Gulliain- Barre Syndrome?
MS - oligodendrocytes
GBS- Schwann cells
What is the role of Schwann cells?
- myelinate one PNS axon
- promotes axonal regeneration
- increases conduction velocity via saltatory conductions btw nodes of Ranvier where there are high concentrations of Na channel.
What is an acoustic neuroma?
type of schwannoma
- typically located in internal acoustic meatus ( CN 8 affected)
What makes up the BBB?
1. tight junctions btw nonfenestrated capillary endothelial cells
2. basement membrane
3. astrocyte foot processes
Where are the following NTs synthesized?
1. NE - locus ceruleus (pons), reticular formation, solitary tract
2. Dopamine - ventral tegmentum and SNc (midbrain)
3. 5HT - raphe nucleus (pons)
4. Ach - basal nucleus of meynert
5. GABA - nucleus accumbens
What effects are seen in anxiety when it comes to Nts?
What effects are seen in depression when it comes to Nts?
What effects are seen in schizophrenia when it comes to Nts?
What effects are seen in Parkinson's when it comes to Nts?
What effects are seen in Alzheimer's when it comes to Nts?
What effects are seen in Huntington's when it comes to Nts?
decreased Ach and decreased GABA
What is seen in REM sleep w/ nts?
What is GABA made from?
glutamate and need Vit B6 to make
How do glucose and aa cross the BBB?
slowly via carrier mediated transport mechanisms
What is reticular activating system?
mediates consciousness, attentiveness, and alertness.
- lesion in this place will cause coma
What are the 3 parts of the reticular activating system?
1. reticular formation
2. locus ceruleus
3. raphe nuclei
What are the 4 levels of the cerebrum?
1. neocortex - toolbox
2. limbic system - instincts
3. Prefrontal cortex- can inhibit limbic system, decision making, delayed gratification
4. Basal ganglia; thalamus; hypothalamus
What are all the roles of the Hypothalamus?
1. Thirst and water balance
2. Adenohypophysis control
3. Neurophyophysis releases hormones
5. Autonomic regulation
6. Temperature regulation
7. Sexual urge
What are all the nuclei of the hypothalamus?
What is the function of the lateral area of the hypothalamus?
- destruction of this area = anorexia, failure to thrive.
- inhibited by leptin
What is the function of the ventromedial area of the hypothalamus?
- destruction = hyperphagia
- stimulated by leptin
What is the function of the anterior hypothalamus and preoptic area?
Cooling via PNS, releases GnRH
- sweating, cutaneous VD, decrease HR/BP
-destruction = hyperthermia
What is the function of the posterior hypothalamus?
heating via SNS
- shivering, increase HR/BP
lesion = hypothermia
What is the function of the suprachiasmactic nucleus?
- receives input from retina and causes pineal gland to release melatonin ( inhibits FSH and LH = decreased libido)
What is the function of the dorsomedial hypothalamus?
stimulates GI system leading to savage behavior and obesity
What is the function of the Arcuate nucleus?
releases hormones that affect ant. pituitary, regulates hunger/satiety
What is the function of the posterior pituitary/neurohypophysis?
receives hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei
What is the 1st CN and it's function?
- Olfactory - purely sensory
Smell, no thalamic relay to cortex
What is the 2nd CN and it's function?
- Optic - purely sensory
What is the 3rd CN and it's function?
Oculomotor - purely motor
Eye movement (SR, IR, MR, OR), pupillary constriction (sphincter pupillae, Edinger Westphal nucleus, muscarinic receptors), accomodation, eyelid opening (levator palpebrae)
What is the 4th CN and its function?
Trochlear - purely motor
eye movement via SO
What is the 5th CN and its function?
Trigeminal - both motor/sensory
mastication, facial sensation (ophthalmic, maxillary, and mandibular divisions), somatosensation from anterior 2/3 of tongue
What is the 6th CN and its function?
Abducens - purely motor
Eye movement via LR
What is the 7th CN and its function?
Facial - both motor/sensory
Facial movement, taste from ant 2/3 of tongue, lacrimation, salivation (submandibular and sublingual), eyelid closing (orbicularis oculi), stapedius muscle in ear.
What is the 8th CN and its function?
Vestibulocochlear - sensory
What is the 9th CN and its function?
Glossopharyngeal - both motor/sensory
taste and somatosensation from posterior 1/3 of tongue, swallowing, salivation from parotid gland, monitoring carotid body and sinus chemo and baroreceptors, and stylopharyngeus (elevates pharynx and larynx)
what is the 10th CN and its function?
Vagus - both motor/sensory
taste from epiglottic region, swallowing, palate elevation, midline uvula, talking, coughing, thoracoabdominal viscera, monitoring aortic arch chemo and baroreceptors
What is the 11th CN and its function
Accessory - motor
head turning, should shrugging (SCM, trap)
What is the 12th CN and its function?
Where are the cranial nerve nuclei?
in the tegmentum portion of the brain stem (btw dorsal and ventral portions)
What CN nuclei are found in the midbrain?
CN 3 and 4
What CN nuclei are found in the pons?
What CN nuclei are found in the medulla?
What CN nuclei is found in the spinal cord
What CN is going to test the corneal reflex?
Afferent - V1 (nasociliary branch)
Efferent - 7 (temporal branch: orbicularis oculi)
What CN is going to test the lacrimation reflex?
Afferent - V1 (loss of reflex doesn't preclude emotional tears)
Efferent - 7
What CN is going to test Jaw jerk reflex?
First of all this reflex is normally absent. When present:
Afferent - V3 (sensory - muscle spindle from masseter)
Efferent - V3 (motor- masseter)
What CN is going to test the pupillary reflex?
Afferent - 2
Efferent - 3
What CN is going to test the gag reflex?
Afferent - 9
Efferent - 10
What are the 3 vagal nuclei?
1. nucleus solitarius
2. nucleus ambigus
3. Dorsal motor nucleus
What is received in the nucleus solitarisu?
visceral sensory information (taste, baroreceptors, gut distention) via 7, 9, and 10
What happens at the nucleus ambigus?
motor innervation of pharynx, larynx, and upper esophagus via 9 and 10
What happens at the dorsal motor nucleus?
sends autonomic (PS) fibers to heart, lungs, and upper GI via 10
Where does CN 1 come out of skull?
Where leaves through the middle cranial fossa through sphenoid bone?
CN 2 to 7
What comes out of the optic canal?
CN 2, ophthalmic artery, central retinal vein
What comes out of the superior orbital fissure?
CN 3, 4, V1, and 6, ophthalmic vein, sympathetic fibers
What comes out of the foramen rotundum?
What comes out of the foramen ovale?
What comes out of the foramen spinosum?
middle meningeal artery
What comes out of the posterior cranial fossa through temporal bone or occipital bone?
CN 7 to 12
What comes out of the internal auditory meatus?
CN 7 and 8
What comes out of the Jugular foramen?
CN 9, 10, 11, and jugular vein
What comes out of the hypoglossal canal?
What comes out of the foramen magnum?
spinal roots of Cn 11, brain stem, and vertebral arteries
What do KLM sounds test for?
1. Mi Mi Mi - facial nerve
2. La La La - hypoglossal
3. Kuh Kuh Kuh - vagus
What is the cavernous sinus?
a collection of venous sinuses on either side of the pituitary. Blood from eye and superficial cortex --> cavernous sinus --> internal jugular vein
What is found in the cavernous sinus?
1. CN 3, 4, V1, V2, and 6
2. Postganglionic sympathetic fibers en route to the orbit all pass through the cavernous sinus.
3. Internal carotid artery
What is the cavernous sinus syndrome?
due to mass effect, fistula, and thrombosis
- ophthalmoplegia, and decreased corneal and maxillary sensation w/ normal vision
What are some structures near the cavernous sinus?
sphenoid sinus, hypophysis, and optic chiasm
What happens when you have a CN 5 motor lesion?
Jaw deviates toward the side of the lesion due to unopposed force from the opposite pterygoid muscle
What happens when you have a CN 10 lesion?
uvula deviates AWAY from the side of the lesion. Weak side collapses and uvula points away.
What happens when you have a CN 11 lesion?
Weakness turning head to contralateral side of lesion (SCM). Shoulder droop on side of lesion (trap). The left SCM contracts to help turn the head to the right
What happens when you have a CN 12 lesion?
tongue deviates TOWARD side of lesion due to weakened tongue muscles on the affected side
How can you test for conduction hearing loss?
1. Rinne test - abnormal (bone> air)
2. Weber - localizes to affected ear
How can you test for sensorineual hearing loss?
1. Rinne test - normal (air > bone)
2. Weber - localizes to unaffected ear
How can you test for noise-induced hearing loss?
Damage to stereciliated cells in organ of Corti; loss of high frequency hearing first
- sudden extremely loud noises can produce hearing loss due to tympanic membrane rupture
What happens when you have an upper motor lesion of the facial nerve?
lesion of motor cortex or connection btw cortex and facial nucleus.
- Contralateral paralysis of lower face, forehead spared due to bilateral UMN innervation
What happens when you have lower motor lesion of the facial nerve?
ipsilateral paralysis of upper and lower face
What happens w/ facial nerve palsy?
complete destruction of facial nucleus itself or its branchial efferent fibers. Can occur idiopathically; gradual recovery in most cases
What is the clinical presentation of facial nerve palsy?
peripheral ipsilateral facial paralysis w/ inability to close eye on involved side
In what cases is facial nerve palsy seen?
2. Lyme Disease
3. Herpes simplex
4. herpes zoster
- called Bell's palsy when idiopathic
What are the muscles of mastication?
Masseter, temporalis, medial pterygoid - all close jaw
Lateral pterygoid - opens jaw.
- all innervated by V3
What are the different stages of sleep?
1. Awake - eye open, alert active mental concentration
2. Awake - eyes closed
3. Stage N1 - light sleep
4. Stage N2 - deeper sleep, bruxism (teeth grinding)
5. Stage N3/N4 - deepest, nonREM sleep (slow wave sleep) sleepwalking, night terrors, bedwetting
6. REM - dreaming, loss of motor tone, possibly a memory processing function, erections, increased brain 02 use
What are the different EEG waveforms during sleep?
1. Beta - awake eyes open, REM (25%)
2. Alpha - awake eyes closed
3. Theta - Stage N1
4. Sleep Spindles and K complexes - Stage N2 (45%)
5. Delta - stage N3/N4 - 25%
What NT initiates sleep?
Serotonin from raphe nucleus
What is sleep enuresis treated w/?
1. oral desmorpressin acetate - mimics ADH
What effects does alcohol, benzodiazepines, and barbiturates have on sleep?
they decrease REM and delta sleep - so no high quality sleep
What are benzodiazepines useful for when it comes to sleep?
for night terrors and sleepwalking b/c they decreased stage N3/4
What is REM sleep?
occurs every 90 minutes and duration increases through the night.
- Increased and variable pulse and BP
- Extraocular movements during REM sleep due to PPRF
- Penile/clitoral tumesence
What is the main NT for REM sleep?
What is associated w/ any sort of rapid horizontal eye movements?
PPRF - paramedian pontine reticular formation/conjugate gaze center
What happens to REM sleep as you age?
it decreases so older pts have less quality sleep
What is REM sleep termed paradoxical sleep and desynchronized sleep?
b/xc it has the same EEG patterns (beta waves) as wakefulness
What happens to the sleep patterns of depressed patients?
1. decreased slow wave sleep
2. decreased REM latency - get to REM sleep quickly
3. increased REM early in sleep cycle
4. increased total REM sleep
5. repeated nighttime awakenings
6. early morning awakening
What is the treatment for sleeping problems for depressed pts?
What happens in narcolepsy?
1. disordered regulation of sleep-wake cycles
2. excessive daytime sleeping
3. may have hypnagogic (just before sleep) or hypnopompib (just before awakening) halluncinations
4. start off w/ REM sleep
5. some pts have cataplexy - loss of all muscle tone following a strong emotional stimulus esp laughter
6. strong genetic component
What is the Rx for narcolepsy?
1. avoid drugs that cause sleep
2. scheduled naps
3. stimulants such as modafinil, amphetamines
4. Nighttime sodium oxybate
5. support groups
What is the circadian rhythm based upon?
driven by suprachiasmatic nucleus of hypothalamus. Controls ACTH, prolactin, melatonin, nocturnal NE release.
- SCN --> NE release --> pineal gland --> melatonin
SCN is regulated by light
What is sleep terror disorder?
periods of terror w/ screaming in middle of the night; occurs during slow wave sleep. No memory of arousal since it's during non-REM sleep.
When can nocturnal enuresis dxed?
at least 5 ( chronologic and developemental age)
What can nocturnal enuresis be Rxed?
What is the first line treatment for nocturnal enuresis?
1. start toilet training
2. motivational therapy
3. restrict fluids before daytime but not during the day to avoid dehydration
4. night time chaperone/scheduled wakening
5. enuresis alarm in bed for classic conditioning