March 15 - Neurology Flashcards
Pathophysiology of diabetic neuropathy
Hyalinization of nerve arterioles leads to ischemic nerve injury.
Accumulation of sorbitol and fructose in nerve axons also contributes to damage.
CNS repair after ischemic injury
- 48 hours after can see red neurons - sign of irreversible damage
- then neutrophils come in
- 3-5 days after can see microglia which phagocytose damaged material
De novo purine synthesis pathway
Ribose-5-phosphate PRPP 5-phosphoribosylamine IMP (cnoversion requires tetrahydrofolate) GMP and AMP
Regulation of cerebral blood flow
1) systemic BP: autoregulation works within 60-140mmHg
2) arterial blood gases: decreased pCO2 such as in hyperventilation results in vasoconstriction and decreased cerebral blood flow
Ventilator management of increased ICP
Increase RR to decrease pCO2, causing vasoconstriction in the brain and decreased cerebral blood flow.
BH4
Cofactor in synthesis of serotonin, tyrosine, and DOPA. Produced by dihydropteridine reductase which reduces BH2 to BH4
PKU: two causes
Most cases due to phenylalanine hydroxylase deficiency
Also can be dihydropteridine reductase deficiency resulting in BH4 deficiency, impairing synthesis of both catecholamines and serotonin
Nerve conduction: length and time constants and effect of myelin
Length constant: how far along axon electric impulse propagates; increased by myelin
Time constant: how long it takes membrane potential to change; decreased by myelin
Birth defect associated with valproate
neural tube defects
Sympathetic pathway to eye
First order neuron: hypothalamus; axons go through brainstem to spinal cord
Second order neuron: intermediolateral cell column (pre-ganglionic fibers)
Third order neuron: superior cervical ganglion (post ganglionic fibers)
Pancoast tumor: presentation
Non-small cell lung cancer near superior sulcus in lung apex. Can compress/invade brachial plexus resulting in parasthesias, weakness, areflexia. Can invade superior cervical sympathetic ganglia resulting in Horner syndrome
POMC
precursor to endorphins, ACTH, and MSH
Dandy-Walker malformation: three findings
Hypoplasia/absence of cerebellar vermis
Cystic dilation of 4th ventricle
Posterior fossa enlargement
Early symptom of uncal herniation
Oculomotor nerve palsy
N-acetylglutamate
activator of carbamoyl phosphate synthetase I
Friedreich ataxia: neuro and non-neuro manifestations
Neuro: progressive gait ataxia, impaired joint position and vibration sense due to spinal tract damage
Non-neuro: hypertrophic cardiomyopathy, skeletal abnormalities, diabetes
Craniopharyngioma: gross pathology and pathophys
Suprasellar tumor seen in kids. Cystic, filled with brown-yellow fluid with protein and cholesterol. Remnant of rathke’s pouch which is oral ectoderm that gives rse to the anterior pituitary
COMT inhibitors
Entacapone: inhibits peripheral methylation of L-dopa
Tolcapone: inhibits both peripheral and central methylation of L-dopa
Atropine MOA
anti muscarinic
Branched chain amino acids
isoleucine, valine, leucine
Thiamine: three enzymes its a cofactor for
- Pyruvate dehydrogenase (glycolysis)
- Alpha-ketoglutarate dehydrogenase (TCA cycle)
- Transketolase (HMP shunt)
Inhaled anesthetics effect on blood flow
- decrease CO resulting in systemic hypotension
- decrease cerebral vascular resistance which can increase ICP
- decrease flow to kidney and liver
positioning in coma
Decerebrate: extensors predominate, lesion below red nucleus
Decorbitate: flexors predominate, lesion above red nucleus
Pineal gland mass presentation
Obstructive hydrocephalus, impaired upward gaze
Lamotrigine toxicity
Skin rash (10%). Can be very severe rarely with SJS or toxic epidermal necrolysis
Trapezius: innervation and function
CNXI
Elevates scapula, rotates scapula up, stabilizes shouldr
Accessory nerve damage: cause and presentation
Caused by trauma to posterior triangle of neck
Presentation: drooped shoulder, winged scapula, impaired abduction of shoulder above horizontal
Sympathetic innervation of eccrine sweat glands
ACh is the NT at both pre and post synaptic nerve terminals
Vitamin A toxicity: acute and chronic
Acute: N/V, vertigo, blurred vision
Chronic: alopecia, dry skin, hyperlipidemia, hepatoxociity and HSM, vision problems, pseudotumor cerebri with increased ICP
Lateral horns
Carry pre ganglionic symp fibers. T1-L2 spinal level
Oculomotor nerve palsy: two types
Ischemia: extraocular efferents on the inside effected more, down and out eye
Compression: parasympathetics on outside affected more, APD
Phenytoin: MOA and side effects
MOA: blocks VG Na+ channels
Side effects: narrow therapeutic index drugs with many ADRs. One is gingival hyperplasia. Also is a CYP450 inducer
Femoral nerve block: location
Inguinal crease, lateral to femoral artery. That way anesthatizes skin and muscles of anterior thigh, femur, and knee
Pramipexole
Nonergot dopamine agonist used to treat PD
Pathologic finding in CJD
Large intracytoplasmic vacuoles
Pathologic finding in brain in rabies
Negri bodies
Biochemical alteration in huntington disease
Loss of GABA-containing neurons results in decreased GABA levels in the brain
Cavernous hemangioma: what it is, presentation, and complication
Vascular malformation in brain parenchyma with clusters of dilated capillaries
Presentation: seizures, as progresses can see focal defects
Complication: can bleed and cause ICH
Barbiturates: kinetics
Plasma level rapidly decreases due to drug redistribution into tissue
Carbamazepine: MOA, Use, and ADRs
MOA: blocks Na+ channels in cortical nuerons
Use: complex partial seizures, mood stabilizer, trigeminal neuralgia
ADRs: bone marrow suppression, hepatotoxicity, SIADH, CYP450 inducer
Aneurysms: Charcot-Bouchard vs Berry
Charcot-Bouchard aneurysms: in basal ganglia, cerebellum, thalamus, pons. Rupture to cause ICH
Berry aneurysms: in circle of willis. Rupture to cause SAH.
Both associated with HTN. Berry also associated with ADPKD and ehlers danlos
Tabes dorsalis vs subacute combined degeneration
Tabes dorsalis: form of neurosyphilis. involves dorsal columns and dorsal roots (sensory only)
Subacute combined degeneration: B12 def, involves dorsal columns and lateral tracts (Sensory + UMN symptoms)
Treatment of restless leg syndrome
dopamine agonist
Intraventricular hemorrhage
Seen as complication of prematurity. Bleeding originates from germinal matrix
Isoniazid toxicity - neuropathy
Isoniazid is chemically similar to vitamin B6 and competes with B6 for neurotransmitter synthesis. Increase in urinary B6 excretion can cause person to become deficiency. Thus, supplemental B6 often given to prevent peripheral neuropathy from occurring.
Thiopental kinetics and MOA
Short acting barbiturate. Rapidly equilibrates with brain, knocking patient out in a minute following IV administration. Then redistributes to skeletal muscle and adipose tissue.
Basal ganglia: two pathways
1) Direct pathway
-sub niagra excites striatum via D1 receptors
-striatum inhibits GPi
-GPi inhibits thalamus
Net effect: disinhibition of thalamus
2) Indirect pathway
-sub niagra inhibits striatum via D2 receptors
-striatum inhibits GPe
-GPe inhibits subthalamic nucleus
-subthalamic nucleus excites GPi
-GPi inhibits thalamus
Net effect: also disinhibition of thalamus
Subacute cerebellar degeneration
Paraneoplasic syndrome associated with small cell lung cancer
Geniculate nuclei
Medial: auditory information
Lateral: vision information
ALS vs poliomyelitis
ALS: affects anterior horn, descending spinal tracts (mixed upper and lower motor neuron)
Polio: affects anterior horn only (pure LMN)
Vitamin E deficiency
Neurologic symptoms mimicking Friedreich’s ataxia: ataxia, loss of position/vibration sense, loss of DTRs.
Hemolysis
