3/15 - UWorld CNS

Question 1

Ataxia-telangiectasia (triad of symptoms, genetic defect)

Answer 1

Classic triad: Cerebellar ataxia, telangiectasias, increased risk of sinopulmonary infections (IgA deficiency)

Autosomal recessive Mutation of ATM gene (ATM - Ataxia Telangiectasia Mutated) -> failure to repair DNA double strand breaks

Think:

You sneeze (sinopulmonary infection), causing you to lose balance (ataxia), and knock something leading to telangiectasias on the skin

Question 2

Poisoning of pufferfish

Answer 2

Containt tetrodotoxin

Toxin binds to voltage-gated sodium channels in nerve and cardiac tissue

Prevention of sodium influx and depolarization

Symptoms: Dizziness, weakness, loss of reflexes, paresthesias of the face and extremities, nausea, vomiting, diarrhea Higher exposure leads to hypotension and paralysis

Death can occur from respiratory failure and hypotension

Treatment: Supportive care Intestinal decontamination Gut lavage and charcoal

Question 3

Transport proteins involved in recurrence of latent HSV

Answer 3

Reactivation: Anterograde axonal transport from ganglia to skin mediated via KINESIN (moves stuff away from nucleus toward nerve terminal)

Retrograde axonal transport (towards the nucleus) via DYNEIN Important in establishing the latent phase following primary infection

Question 4

Vomiting center

Answer 4

Chemoreceptor trigger zone (CTZ) located on dorsal surface of the medulla known as the area postrema

Question 5

Functions of the Midbrain

Answer 5

Control of eye movements, relay nuclei of the auditory and visual symstems

Question 6

Functions of the Pons

Answer 6

Balance and maintenance of posture; regulation of breathing; relays info from the cerebral hemisphere to the cerebellum

Question 7

Function of the Medulla

Answer 7

Contains autonomic centers that regulate breathing, blood pressure, swallowing, coughing, and vomiting reflexes

Question 8

Fragile X Syndrome (physical and neuro findings; genetic cause)

Answer 8

Most common inherited intellectual disability

Physical findings: macroorchidism (large testes) and dysmorphic facies (long and narrow face, prominent forehead and chin)

Neuropsychiatric disorders: developmental delay, ADHD, autism spectrum disorder

Trinucleotide repeat in FMRI gene (CGG) leads to hypermethylation

Question 9

Effects of botulinum toxin

Answer 9

Toxin causes disease by inhibition of ACh nerves

Enters the nerve terminals and prevents binding and fusion of ACh-containing vesicle (cleaves SNARE protein)

Presentation of botulism: descending paralysis that first manifests with cranial nerve abnormalities (diplopia, dysphagia, dysphonia)

Question 10

Review the Brachial Plexus

Answer 10

. . .

Question 11

Function of hypothalamic nuclei - ventromedial

Answer 11

Satiety Destruction leads to hyperphagia (excessive hunger)

Question 12

Function of hypothalamic nuclei - lateral

Answer 12

Mediates hunger Destruction leads to anorexia

Question 13

Function of hypothalamic nuclei - anterior

Answer 13

Mediates heat dissipation Destruction leads to hyperthermia

Question 14

Function of hypothalamic nuclei - posterior

Answer 14

Mediates heat conservation Destruction leads to hypothermia

Question 15

Function of hypothalamic nuclei - arcuate

Answer 15

Secretion of dopamine (inhibits prolactin), growth hormone-releasing hormone, gonadotropin-releasing hormone

Question 16

Function of hypothalamic nuclei - paraventricular

Answer 16

Primarily makes oxytocin

Antidiuretic hormone, corticotropin-releasing hormone, oxytocin, thyrotropin-releasing hormone

Question 17

Function of hypothalamic nuclei - supraoptic

Answer 17

Primarily makes ADH

Secretion of ADH and oxytocin

Question 18

Function of hypothalamic nuclei - suprachiasmatic

Answer 18

Circadian rhythm regulation and pineal gland function

Question 19

Swinging flashlight test

Answer 19

Due to lesion of the optic tract

Eye contralateral to the lesion will appear to dilate when light is shined in it after being shined in the other eye. This is because the nasal portion of the retina contributes more input.

E.g. The L optic tract is damaged. When light is shined in the L eye (nasal innervation from R, undamaged, optic tract) there will be normal constriction. When light is then quickly shone in to the R eye (nasal innervation from L optic tract), it appears to dilate even though it is really just constricting less

Question 20

Visual lesions

Answer 20

Question 21

Definition of scotoma

Answer 21

Any visual defect surrounded by relatively unimpaired field of vision

Occur due to pathology involving parts of the retina or optic nerve (e.g. macular degeneration)