Flashcards in Neuro Deck (304)
Amides are lidocaine, mepivacaine, bupivacaine. Esters are procain, cocaine, tetracaine.
Mech of local anesthetics
Block Na+ channels (inner portion) and preferentially bind to activated ones. Tertiary amines penetrate membrane uncharged, then after charge, bind ions.
Factors affecting the effectiveness of local anesthetics?
It's hard for charged, alkaline anesthetics to get into infected (acidic) tissue. Order of nerve blockade small diameter > large diameter. Then myelinated > unmyelinated. Lose pain, temp, touch, then pressure. Can give with vasoconstrictors like epi to enhance local action via dec bleeding and dec. systemic conc.
Local anesthetic toxicity
CNS excitation, CV tox (bupivacaine), HTN, hypotension, arrhythmias (cocaine)
Basic overview of paralytics
Used for surgery or mech ventilation. Selective for motor nicotinic receptors. Depolarizing vs. nondepolarizing = agonist vs. competetive antagonist
Strong ACh receptor agonist -> sustained depolarization and prevents muscle ctx. Complications - hyperCa, hyperK, malignant hyperthermia. Phase 1 block is prolonged depol. w/ no antidote. Phase 2 block is repolarized but AChR desensitized and req. cholinesterase inhibitors. Patients with hyperK (crush/burn, denervating injuries, myopathies) -> depolarizing agents
Ryanodine receptor. Prevents release of Ca2+ from SR in skeletal muscle. Used for malignant hyperthermia and NMS.
BALSA = Bromocriptine, Amantadine, Levodopa, Selegiline, Antimuscarinics.
MAO-B inhibitor that prevents DA breakdown (MAO-B prefers to breakdown DA > NE and 5-HT). Other DA breakdown inhibitors are COMT inhibitors (entacapone and tolcapone)
Curbs excess cholinergic activity in Parkinsons as an antimuscarinic.
Alzheimer's drug. NMDA receptor antagonist. Tox includes dizziness, confusion, hallucinations
AChE inhibitors for Alzheimer's
Donepezil, galantamine, rivastigmine.
Haloperidol (DA receptor antagonist). Inhibitors of vesicular monoamine transporter (VMAT) - tetrabenazine and reserpine.
5-Ht1b/1d agonist. Inhibits treigeminal n. activation and prevents vasoactive peptide release. t1/2 <2hrs. Used for acute migraines and cluster headaches. Tox = coronary vasospasm CONTRA = CAD or Prinzmetal angina
Myotonic muscular dystrophy
Myotonia = slow relaxation of muscles. Difficulty loosening one's grip. AD. CTG (myotonia-protein kinase). Anticipation. Cataracts. Atrophy of type 1> type 2.
Increased volume of endolymph. Tinnitus, vertigo, hearing loss is sensorineural (Weber will lateralize to HEALTHY side)
Fluorinated anesthetics effect on CV, Resp, Cerebral blood flow, Kidney, hepatic blood flow?
Myocardial depression leads to decreased CO. Hypotension. Respiratory depressant (dec. TV and minute ventilation -> hypercapnea and dec. mucociliary clearance). Halothane and sevolurane have bronchodilation prop's - asthma. Decreased vascular resistance -> increased cerebral blood flow -> ICP. Dec. GFR, increased renal vascular resistance, and decreased RPF. Decreased hepatic blood flow.
How does solubility of anesthetic in peripheral tissues effect anesthetic concentration?
If peripheral tissue solubility is high (AV gradient high), then it takes more anesthesia to saturate the blood and the brain.
How does pulmonary ventilation rate affect anesthetic concentration?
Rise of gas tension in alveoli is proportional to the rate AND depth of respiration.
How does the blood/gas partition coefficient affect the action of anesthetics?
Higher blood/gas partition coefficient means highly SOLUBLE --> blood saturates slowly leading to delayed rise in partial pressure -> increasing onset of time. (e.g. halothane)
Plaques. Demyelination w/ relative preservation of axons. Accumulation of lipid-laden macrophages. Astrocytosis. Infiltration by lymphocytes and mononuclear cells.
PNET tumor of chromatin cells of sympathetic nervous system (90% from adrenal medulla).
AD 100% penetrance. Loss of neurons in caudate nucleus and putamen (striatum). STN lesion = hemiballismus.
Side effects for 1st gen antipsychotics?
Generally, low-potency (Chlorpromazine and thioridazine) have more non-neuro SE's (sedation, Antichol, orthostatic hypotension). High-potency (haloperidol, fluphenazine) will have EPS - acute dystonia, akathisia, parkinsonism.
Etio - birth trauma or malposition of head in utero -> SCM injury and fibrosis. Develops by wk 2-4. Head tilted toward AFFECTED side with CHIN pointed AWAY. Good prognosis. Tx = conservative and stretching
Alcoholic cerebellar degeneration
Chronic thiamine deficiency. Gait ataxia, truncal instability, intention tremor. Atrophy of anterior lobes and cerebellar vermis.
Two ways that tumors increase ICP?
Blockage. Breakdown of the BBB.
How does NPH lead to urinary incontinence?
Disrupts paraventricular fibers from cortex which normally inhibit the SACRAL micturition center (responsible for bladder contraction and found in S2-S4 level)
Causes of exacerbations of myasthenia gravis?
(1) Myasthenic crisis 2/2 not enough Ach in cleft (e.g. not enough drug). Dx with edrophonium improvement. (2) Cholinergic crisis 2/2 TOO much Ach -> refractory muslce. Dx with no improvement with edrophonium.