March 28 - Neuro

Question 1

Pre and postcentral gyri

Answer 1

Pre: motor cortex, part of frontal lobe
Post: sensory cortex, part of parietal lobe

Question 2

Effect of botulinum toxin vs organophosphates vs tetrodotoxin

Answer 2

Botulinum toxin: Blockade at both nicotinic and muscarinic receptors

Organophosphates; AChEIs. Depolarizing NMJ blockade leading to weakness and paralysis. CNS symptoms (lethargy and seizures). Agonize muscarinic receptors by increasing ACh.

Tetrodotoxin: found in puffer fish. Inhibit Na+ channels causing paralysis

Question 3

MSUD: enzyme defect

Answer 3

branched chain alpha keto acid dehdrogenase

Question 4

POMC

Answer 4

Precursor molecule to endorphins, ACTH, and MSH

Question 5

Cingulate herniation

Answer 5

Also called subfalcine herniation. Cingulate gyrus herniates beneath faux cerebri. Compresses ACA leading to gait problems and coma

Question 6

Uncal herniation

Answer 6

Uncus herniates through tentorium cerebelli. Compresses midbrin - CNIII – leading to oculomotor palsy and dilated pupil. Can also cause duret hemorrhage and occipital lobe infarction due to PCA compression

Question 7

Tonsilar herniation

Answer 7

Herniation of cerebellar tonsils thorugh forament magnum. Can compress the midbrain cardiorespiratory center leading to death

Question 8

Pramipexole

Answer 8

Dopamine agonist used to treat PD

Question 9

Direct pathway in basal ganglia

Answer 9

Goal is to stimulate movement

Cortex activates striatum. Striatum inhibits GPi and pars reticulata resulting in disinhibition of the thalamus

Amplified by cortex stimulating substantia niagra pars compacta which stimulates striatum via D1 receptors

Question 10

Indirect pathway in basal ganlgia

Answer 10

Goal is to inhibit movement

Cortex actiavtes striatum. Sriatum inhibits GPe, which normally inhibits the subthalamic nucleus. Subthalamic nucleus freed to stimulate GPi resulting in increased inhibition of the thalamus.

Effect decreased by cortex stimulating substantia niagra which inhibits the striatum via D2 receptors

Question 11

Basal ganglia: ipsilateral/contralateral

Answer 11

Communicate with ipsilateral motor cortex so affect contralateral body.

Question 12

COMT inhibitors

Answer 12

Entacapone and tolcapone. Entacopone prevents peripheral breakdown of L-dopa, tolcapone stimualtes both peripheral and central breakdown. Hepatotoxicity

Question 13

Selegiline

Answer 13

MAO-b inhibitor - prevents breakdown of L-dopa centrally, increasing DA. Risk of serotonin syndrome when given with SSRI. Can cause tyramine reaction just like MAO-a inhibitors for depression

Question 14

Benztropine

Answer 14

centrally acting muscarinic antagonist used to treat PD

Question 15

Blood:gas partition coefficient

Answer 15

Used to describe the blood solubility of inhaled anesthetics. Inhaled anesthetics only have effect when NOT dissolved in blood and have a partial pressure in the blood. Thus, higher blood solubility means the drug takes LONGER to take effect and has slower offset.

Question 16

Oil:gas partiton coefficient

Answer 16

Describes lipid affinity of drug and correlates with potency (increased lipid solubility=increased potency). Inversely related to the MAC which is the minimum albeolar concentration that will prevent movement in 50%

Question 17

Halothane toxicity

Answer 17

Malignant hyperthermia, hepatotoxicity

Question 18

Enflurate toxicity

Answer 18

Seizure

Question 19

Global cerebral ischemia

Answer 19

Caused be decreased cerebral blood flow. Most vulnerable areas are pyramidal cells of hippocampus and cortex and purkinje cells of cerebellum. Hippocampus is first area to be damaged

Question 20

Cerebral amyloid angiopathy

Answer 20

Beta amyloid deposits in walls of small to medium cerebral arteries. Causes walls to be weak and predisposed to rupture, resulting in recurrent lobar hemorrhages.

Question 21

Heat sensitivity in MS

Answer 21

Heat such as from hot shower or strenuous exercise decreases axonal transmission resulting in worsened neuro symptoms and increased fatigue

Question 22

Optic neuritis

Answer 22

Visual disturbance + eye pain

Seen in MS

Question 23

Iliohypogastric nerve

Answer 23

Innervates anterolateral abdominal wall muscles. Can be damaged in appendectomy resulting in decreased sensation at suprapubic region

Question 24

Chemoreceptor trigger zone

Answer 24

Area postrema on posterior surface of MEDULLA

Question 25

HIV-associated dementia

Answer 25

Seen iwth CD4 less than 200. Subcortical dementia resulting in problems wth working memory, attention, executive function.

HIV infected monocytes cross BBB. Activated macropahges and microglial cells form microglial nodules around areas of necoris.

Question 26

Facial nerve parasympathetics

Answer 26

Innervate lacrimal, submandibular, and sublingual glands

Question 27

Benzos and barbs

Answer 27

Benzos increase Cl- channel opening frequency

Barbs increase Cl- channel opening duration

Question 28

Post-SAH complication

Answer 28

Vasospasm 4-12 days later. Presents as new onset confusion or focal deficit

Question 29

Urinary control

Answer 29

1) Sacral micturition center. S2-S4. Stimulates bladder wall
2) Pontine micturition center. In pontine reticular formation. Coordinates ext sphincter with bladder contraction
3) Cerebral cortex. Inhibits sacral micturition center. Damage is cause of incontinence in normal pressure hdyro

Question 30

Synaptophysin

Answer 30

Marker of neurons, neuroectodermal cells

Question 31

Precursro amino acid for serotonin

Answer 31

tryptophan

Question 32

Treatment for serotonin syndrome

Answer 32

Supportive care

cyproheptadine (serotonin receptor antagonist/1st gen antihistamine)

Question 33

Lacunar infarct

Answer 33

Ischemic stroke involving sm penetrating vessels. Affects basal galnglia, pons, internal capsule, corona radiata
Cansued by chronic HTN that leads to arteriolar sclerosis

Question 34

Chiari I: pathology and presentation

Answer 34

Low lying cerebellar tonsils that extend through foramen magnum
Typically doesn’t present until adolescence/adulthood. Paroxysmal occipital headache and cerebellar dysfunction

Question 35

Tensor tympani innervation

Answer 35

V3