Nervous System Flashcards
Neural Crest Cell derivatives
- ANS
- Celiac Ganglia
- Adrenal chromaffin cells
- Dorsal root ganglion
- Schwann cells
- Pia
- Arachnoid
- Bones (skull)
- Odontoblasts
- melanocytes
- C-cells of thyroid
- thyroid and laryngeal cartilage
- Aorticopulmonary septum
Neuro Cell components
- Neurons are permanent cells that do not divide in adulthood
- Nissl Substance = found in the cell body and dendrites of neuron
- GFAP = found in astrocytes used as a marker
- HIV infected microglia fuse to form multinucleated giant cells in the CNS
- microglia are derived from mesoderm
- Schwann cells are damaged in Guillain Barre Syndrome
- Schwannoma = acoustic neuroma located in the internal acoustic meats CN8; if bilateral = NF2
- Oligodendrocytes are damaged in MS, Progressive multifocal leukencepholapthy, and leukodystrophies
Embryo logic Origin
Neuro ectoderm
- neurons
- ependymal cells that line ventricle of brain
- Oligodendrocytes and Astrocytes
- neural crest cells
Mesoderm
- microglia
BBB
- nonfenestrated endothelial cells with tight junctions
- basement membrane of capillary
- astrocytes foot processes
Areas of brain with fenestrated capillaries
- hypothalamus
Mannitol diuretic is given to decrease ICP for short term
Highly lipophilic drugs are able to pass through the BBB
Infarction or neoplasm may destroy endothelial cell tight junction –> vasogenic edema
The Hypothalamus, Stages of Sleep
454-455
Treat bed wetting = Desmopressin > imipramine
Treat night terrors and sleepwalking = Benzodiazepene
Insomnia Drugs
See Picture
Cranial Nerves
Pg 474-476
AFP
Increased AFP = neural tube defects
Decreased AFP = Down Syndrome
Embryology of Branchial Arches
564-566
Teratogens
- Ace inhibitors
- Valproate
- Phenytoin
- Lithium
- Tetracycline
- Warfarin
- Excessive vitamin A
Arcuate Fasciculus
- connects brocas and wernickes area
Carotid Arteries
Come from the aortic arch
- found in the carotid sheath with the internal jugular vein and vagus nerve
Superior Gluteal Nerve Injury
- the patient will lean toward the affected side to compensate for the hip drop
Aneurysms
Ruptured berry aneurysm = worst headache of life
Pg 465-466
Subarrachnoid Hemorrohage
- MCC of a non traumatic = ruptured aneurysm
- MCC of SAH overall = trauma
- 2nd MCC of a non-traumatic SAH = Ruptured AVM
- CT scan of brain
- if no evidence of blood do Lumbar puncture to examine CSF for blood
- Yellow CSF = xanthochromia = hemoglobin in CSF is broken down into bilirubin
- Treatment = surgical clip of aneurysm and give Nimodipine
Lumbar Puncture = SEE picture
- epidural anesthesia = go into the epidural space
- spinal anesthesia = goes to subarachnoid space
- in adults = go between L3 & L5 in order to not hit the spinal cord
- in children = go between L4&5 or L5&S1
Epidural hematoma
Can cause compression of brain and then herniation of brain
- causing CN3 palsy
- lucid interval
- lens shape biconvex
Subdural Hematoma
- between dura and arachnoid
- venous bleed that is slow
- crescent shaped
Intra ventricular hemorrhage in the newborn
- Hemorrhage into the ventricular system
- most common in premature/very low weight infants within the first 72 hours of life
- originates from the germinal matrix in the sub ependymal, subventricular zone that gives rise to neurons and glia during development
- all infants born at 30-32 weeks should be screened with ultrasound to make sure the child doesn’t have it
Stroke
Pg 467
First thing you do is get a Non-contrast CT scan to see if it’s a hemorrhagic or ischemic stroke
- don’t give anticoagulants to a hemorrhagic stroke patient only give to ischemic stroke
Ischemic Stroke Definitions
- Symptoms resolve within 24 hours ==> Transient ischemic attack
- Symptoms last beyond 24 hours ==> STROKE
Contraindications for thrombolytics for Ischemic Strokes
- Active bleeding
- history of intracranial bleeding
- recent surgery
- known bleeding diathesis = hemophilia
- severe hypertension
Give TPA if within 3-4.5 hrs of onset symptoms (if person fell asleep and woke up with stroke more than 4.5 hours later do NOT give TPA)
Parts of the brain that are most susceptible to ischemic damage
- Cerebellum
- Neocortex
- Hippocampus
- Watershed areas
You’ll know if it’s an embolic stroke if it affects multiple areas
CSF
467-468
Pseudo tumor cerebri
- occurs in young obese females
- Headaches - daily (worse in the morning) pulsatile, possible nausea/vomiting, possible retro ocular pain worsened by eye movement (pain behind the eye)
- papilledema
- vision loss is most worrisome sequelae
- CT scan: absence of ventricular dilation, no tumor or mass
- on lumbar puncture = CSF pressure elevated >200 in non obese and >250 in obese = make sure patient is lying down when measuring CSF pressure
Treatment options
- CT and MRI to rule out any other pathology
- Discontinue any inciting agents (vitamin A, tetracyclines, corticosteroid withdrawal
- weight loss is helpful if patient is obese
- First line treatment = Acetozolamide
- invasive treatment options = serial lumbar puncture (removes any excess fluid), optic nerve sheath decompression, and limbo peritoneal shunting
Damage to the orbital floor
- causes damage to the infra orbital nerve which is a branch of the maxillary nerve
- also the inferior rectus muscle can become entrapped, limiting superior gaze
- numbness and parenthesia of the upper cheek, upper lip, and upper gingiva
Thiamine
Is needed for erythrocytes transketolase activity
Chronic thiamine deficiency impairs glucose utilization in the CNS due to it being a cofactors in multiple enzymes
Beta Endorphin
- opioid peptide derived from POMC
- POMC is cleaved to produce beta endorphins (bind to mu and alpha receptors), MSH, and ACTH
Important
- Lowering PCO2 is one of the measures used to reduce ICP in mechanically ventilated patients with cerebral edema = a drop in PCO2 due to hyperventilation causes vasoconstriction, increasing vascular resistance and reducing cerebral blood flow
Liquefactive Necrosis
- caused by a release of lysosomal enzymes from ischemic neurons that result in degradation of the tissue in the ischemic region
- Phagocytic cells migrate into the area and remove the necrotic tissue leaving a cavity, and astrocytes proliferate around the necrotic area with the formation of a scar (gliosis)
- hypoxic injury to the brain
Forebrain anomalies
Anencephaly = maternal type 1 diabetes and decreased folate
Holoprosencephaly = Patau syndrome and fetal alcohol syndrome
Chiari 2 = presents with lumbosacral meningomyelocele paralysis below the defect
Sleep Pattern in the Depressed
decreased slow wave sleep
increased REM and increased REM latency
Diabetic Meningitis
Most likely to be due to Mucor
HIV/AIDS meningitis
most likely to be due to
- Toxoplasma gondii
- Cryptococcus
- JC virus
Cauda Equina
dorsal and ventral roots of lumbar, sacral, and coccygeal spinal nerves
Spinal Cord
- gray matter in the center
- White matter surrounds
Dorsal ramus = supplies skin of back and neck and deep intrinsic back muscles (erector spinae)
Ventral ramus = everywhere else
Ventral Horn
- extensors are ventral
- flexors are dorsal
Wernickes Encephalopathy
must give thiamine before given glucose in order to prevent wernicke korsakoff syndrome
Common Brain lesions
- Hippocampus bilateral = inability to make new memories
- PPRF - eyes will look away from side of lesion
- FEF = eyes will look towards side of lesion
- Superior colliculi damage = paralysis of upward gaze = parinauds syndrome = cant look up
Random Treatments
Subarachnoid Hemorrhage = nimodipine
ALS = raluzole treatment modestly increases survival by decreasing presynaptic glutamate release
Wet macular degeneration = Ranbizumab (Anti-Vegf)
Multiple Sclerosis = B-interferon and natalizumab
Midbrain Lesions
Above midbrain = Decorticate rigidity
- postural flexion of arms and extension of legs
Below midbrain = Decerebrate ridgidity
- postural extension of arms and legs
Auditory Pathway
Basal cochlea = high frequency sounds
Apex of cochlea = low frequency sounds
Presbycusis
- bilateral high frequency loss and difficulty with speech discrimination
- epithelial atrophy with loss of hair cells and supportive organ of Corti cells
- begins in basal cochlea and progresses to apex
Any lesion after the cochlear nucleus in the brainstem = bilateral sensorineural hearing loss
Vestibular System
- Utricle and Saccule = respond to linear acceleration and gravitational pull ==> via macula (detects head positional changes with gravity)
- Semicircular canals = rotation ==> respond to angular head acceleration and deceleration
Vestibulo-ocular reflex
- horizontal head turning –> horizontal eye movement in opposite direction
Nystagmus
- rhythmic oscillation of eyes slowly to one side follwed by a fast reflexive movement to opposite side
- named by fast phase
- slow phase is in response to path
COWS
- based on the fast phase of the nystagmus
Subacute combined degeneration
demyelination of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts
pg 472
Reflexes
L1-L2 = testicles move (cremaster reflex) S3-S4 = winks galore (anal wink reflex)
Vagal Nuclei
476
Guillain Barre
increased CSF protein with normal cell count
increased protein may cause papilledema
Adrenoleukodystrophy
X-linked genetic disorder typically affecting males
- disrupts metabolism of very long chain fatty acids
- excessive buildup in nervous system, adrenal gland, testes
- Progressive disease that can lead to long term coma/death and adrenal gland crisis
Neurocutaneous Disorders
pg 491
