Flashcards in Neuro Deck (304)
PNET. Highly malignant cerebellar. Compress 4th ventricle; Drop metastases into spinal cord. Path - Homer-Wright rosettes. Solid, small blue cells.
Usu. FOURTH ventricle. Hydrocephalus. Poor prognosis. Path - perivascular rosettes. Rod-shaped blepharoplasts (basal ciliary bodies) near nucleus.
Most common childhood supratentorial tumor derived from Rathke's pouch (evagination of ectoderm that lines fetal oral cavity -> adenohypophysis; neurohypophysis from neuroectoderm). Often calcified. CYSTS filled with yellow, viscous fluid rich in cholesterol crystals.
Ipsilateral CN III (blown and down and out), ipso PCA (contralateral homonymous hemianopsia), contralateral crus cerebra (ipsi paralysis)
Adrenergic glaucoma drugs
Epinephrine decreases aqueous humor synthesis via vasoconstriction (se of mydriasis so don't use in closed-angle). Brimonidine (alpha-2, decreases synthesis) w/ se of blurry vision, hyperemia, foreign body sensation, allergy, ocular. The beta-blockers are timlol, betaxolol, and carteolol.
Cholinomimetics used for glaucoma
Direct (pilocarpine, carbachol) and indirect (physostigmine, echotiophate). Contract ciliary muscle and open trabecular meshwork to increase outflow. SE include miosis and cyclospasm.
Prostaglandin used for glaucoma
Latanoprost (PDG2alpha) increases aqueous humor outflow and browns the iris.
Mechanism of opioid analgesics
Opioid receptors (mu = morphine, delta = enkephalin, kappa = dynorphin) to open K+ channels, close Ca2+ channels -> DECREASED synaptic transmission. Inhibit release of ACh, NE, 5-HT, glutamate, and substance P.
PARTIAL mu-opioid receptor agonist and kappa-opioid receptor agonist. Used for severe pain (migraine and labor) with LESS reparatory depression. H/e, withdrawal symptoms if patient on full opioid agonist. Overdose hard to reverse with naloxone.
VERY weak opioid agonist that also inhibits 5-HT and NE reuptake. Chronic pain. Similar tox profile as opioids, decreases sz threshold, serotonin syndrome.
Absence sz. Blocks t-type Ca2+ channels in thalamic neurons. SE's fatigue, GI, HA, Itching, Stevens-Johnson
1st line acute tx for status vs. 1st line ppx for status?
Benzos (diazepam, lorazepam) vs. Phenytoin
1st line tonic-clonic and ppx for status. Na+ channel inactivation. 0-order kinetics. Induces P450. Lots of SE (nystagmus, dipolpia, gingival hyperplasia, teraogeneis w/ fetal hydantoin syndrome, ale-like). Fosphenytoin is IV.
1st line for simple, complex, tonic-clonic sz, and trigeminal neuralgia. Na+ channel inactivation. SE diplopia, ataxia, blood dyscrasia, liver, teratogenesis, induces P-450, SIADH, Stevens
1st line for tonic clonic. Used for partial sz and absence. Na+ channel inactivation and inhibition of GABA transaminase to increase GABA. GI, hepatotoxicity (rare but fatal, Neural tube defects, tremor, wt gain. Myoclonic sz and bipolar.
Partial and tonic-clonic, peripheral neuropathy, postherpetic neuralgia, migraine ppx, bipolar. Inhibits high-voltage activated Ca2+ channels. SE - sedation and ataxia
Partial, tonic-clonic. Increases GABA action. 1st-line for neonates! sedation, tolerance, induce P-450, CV dep.
Partial and tonic-clonic. Blocks Na+ channels and increases GABA. Migraine prevention. Sedation, mental dulling, kidney stones, wt loss.
Partial, tonic-clonic, absence. Blocks voltage-gated Na+. Stevens-Johnson syndrome.
Partial, tonic-clonic. Unknown mech. No SE's noted.
Barbiturates - Mech and Tox
Increase DURATION of Cl- channel opening (GABA), decrease neuron firing. Contra'd in porphyria. Used for anxiety, sz, insomnia, induction of anesthesia (thiopental). Tox - CV depression, dependence, induces P450. Overdose tx is supportive. "Barbies are durable."
Benzos - Mech and Tox
Increase FREQUENCY of Cl- channel opening. Decreases REM sleep. Tox - dependence, CNS depression with alcohol, but less resp depression than barbiturates. Tx overdose w/ flumazenil. "Ppl that buy Benz's (and do benzos) are flippant."
Nonbenzo hypnotics - mech and tox
Zolpidem, Zaleplon, Eszopiclone. Act on BZ1 subtype of GABA receptor. Tox - ataxia,HA, confusion. Short duration b/c rapidly metabolized by LIVER. dec. dependence
What properties of anesthetics do we care about?
Solubility in lipids and blood. MAC - minimal alveolar concentration req. to prevent 50% from moving in response to noxious stimuli. Inc. solubility in lipids = greater potency (lower MAC). Inc. solubility to blood = slower cross to CNS = slower induction and recovery
Toxicities of inhaled anesthetics
Heptotoxicity (halothane), nephrotoxicity (methoxyflurance), proconvulsant (enflurane), expansion of trapped gas in body cavity (NO). All of these except NO and the addition of succinylcholine can cause malignant hyperthermia which is life-threatening HEREDITARY condition with fever and severe muscle contractions. Tx = dantrolene
Barbiturates, Benzos, Ketamine, Opioids, Propofol
Sedation in ICU, rapid anethesia induction, short procedures. Less postop nausea than thiopental. Potentiates GABA.
IV barbiturate of high potency and rapid entry into brain. Induction and short surgical procedures. Rapid redistribution into skeletal muscle and fat (recovery quick). Decreased cerebral blood flow
Commonly used for endoscopy. Used w/ gaseous anesthetics and narcotics. May cause severe post-op respiratory depression, decreased pressure, and anterograde amnesia