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Flashcards in Neuro Deck (304)
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241

Medulloblastoma

PNET. Highly malignant cerebellar. Compress 4th ventricle; Drop metastases into spinal cord. Path - Homer-Wright rosettes. Solid, small blue cells.

242

Ependymoma

Usu. FOURTH ventricle. Hydrocephalus. Poor prognosis. Path - perivascular rosettes. Rod-shaped blepharoplasts (basal ciliary bodies) near nucleus.

243

Craniopharyngioma

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.

244

Uncal herniation

Ipsilateral CN III (blown and down and out), ipso PCA (contralateral homonymous hemianopsia), contralateral crus cerebra (ipsi paralysis)

245

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.

246

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.

247

Prostaglandin used for glaucoma

Latanoprost (PDG2alpha) increases aqueous humor outflow and browns the iris.

248

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.

249

Butorphanol

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.

250

Tramadol

VERY weak opioid agonist that also inhibits 5-HT and NE reuptake. Chronic pain. Similar tox profile as opioids, decreases sz threshold, serotonin syndrome.

251

Ethosuximide

Absence sz. Blocks t-type Ca2+ channels in thalamic neurons. SE's fatigue, GI, HA, Itching, Stevens-Johnson

252

1st line acute tx for status vs. 1st line ppx for status?

Benzos (diazepam, lorazepam) vs. Phenytoin

253

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.

254

Carbamazepine

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

255

Valproic acid

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.

256

Gabapentin

Partial and tonic-clonic, peripheral neuropathy, postherpetic neuralgia, migraine ppx, bipolar. Inhibits high-voltage activated Ca2+ channels. SE - sedation and ataxia

257

Phenobarbital

Partial, tonic-clonic. Increases GABA action. 1st-line for neonates! sedation, tolerance, induce P-450, CV dep.

258

Topiramate

Partial and tonic-clonic. Blocks Na+ channels and increases GABA. Migraine prevention. Sedation, mental dulling, kidney stones, wt loss.

259

Lamotrigine

Partial, tonic-clonic, absence. Blocks voltage-gated Na+. Stevens-Johnson syndrome.

260

Levetiracetam (Keppra)

Partial, tonic-clonic. Unknown mech. No SE's noted.

261

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."

262

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."

263

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

264

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

265

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

266

IV anesthetics

Barbiturates, Benzos, Ketamine, Opioids, Propofol

267

Propofol

Sedation in ICU, rapid anethesia induction, short procedures. Less postop nausea than thiopental. Potentiates GABA.

268

Thiopental

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

269

IV midazolam

Commonly used for endoscopy. Used w/ gaseous anesthetics and narcotics. May cause severe post-op respiratory depression, decreased pressure, and anterograde amnesia

270

Ketamine

PCP analog that blocks NMDA (dissociative anesthetic). CV stimulant. Disorientation, hallucination, bad dreams. Inc. cerebral blood flow.