UWorld-Neuro

Question 1

what are the inheritance pattern, etiology and symptoms of ataxia telangiectasia

Answer 1

ataxia telangiectasia is autosomal recessive disease caused by faulty nonhomologous end joining;
ataxia telangiectasia is characterized by cerebellar atrophy, oculocutaneous telangiectasias, repeated sinopulmonary infections and increased malignancy

Question 2

a patient with dilated pupils, piloerection, nausea, abdominal pain, muscle cramping, and yawning is likely suffering from what drug-related effect

Answer 2

heroin withdrawl

Question 3

a patient with hypersomnolence, malaise, severe psychological cravings and depression/suicidality is likely suffering from what kind of withdrawl

Answer 3

cocaine (similar to amphetamines)

Question 4

what two toxins found in sea creatures bind to Na+ channels and inhibit action potentials

Answer 4

tetrodotoxin (in pufferfish, Japanese delicacy)

saxitotoxin (in dinoflagellates)

Question 5

what two toxins found in sea creatures bind to Na+ channels and prevent their inactivation leading to persistent depolarization

Answer 5

ciguatoxin (in Moray eel)

batrachotoxin (in South American frog)

Question 6

what is the embryologic abnormality that leads to Hirschsprung’s disease

Answer 6

failure of neural crest cells to migrate to the intestinal wall leads to absence of myenteric and submucosal nervous plexi in intestines

Question 7

what kinds of defects occur when the posterior neural tube fails to close

Answer 7

spina bifida occulta, meningocele, myelomeningocele

Question 8

what is the genetic abnormality of Fragile X syndrome

Answer 8

CGG trinucleotide repeat in the FMR1 (fragile X mental retardation1 gene) that becomes greater than 200 repeats will cause hypermethylation and thereby silencing of the gene –>symptoms
(people with less than 200 repeats have “premutation” and are asymptomatic)

Question 9

what’s the function of glycine in the brain

Answer 9

co-agonist with glutamate for NMDA receptors

Question 10

how does ketamine help decrease morphine tolerance

Answer 10

blocking these NMDA-mediated processes:

• phosphorylation of opioid receptors
• increased adenylyl cyclase
• increases in nitric oxide

Question 11

what lesion would cause a left homonomous superior quadrantanopia (pie in the sky) and which lobe is it located in

Answer 11

lesion of the right Meyer’s loop (found in the temporal lobe)

Question 12

what would be the difference in terms of visual field deficits between a partial retinal, optic nerve or optic disc lesion and a lesion of the lateral portion of the optic chiasm (i.e. due to atherosclerosis or calcification of the internal carotids)

Answer 12

a partial lesion of the retina/ optic disc/ optic nerve would cause a central scotoma in one eye (not a fully diminished half of visual field of one eye), while a lesion of the lateral part of one side of the optic chiasm would cause a monocular nasal hemianopia

Question 13

name the common symptoms of Freidreich ataxia

Answer 13

1. ataxia (cerebellar and dorsal column lesions)
2. hypertrophic cardiomyopathy
3. kyphoscoliosis, pes cavus, hammertoes
4. 10% of patients get diabetes mellitus

Question 14

name the 4 epilepsy drugs that can cause Steven-Johnson Syndrome

Answer 14

lamotrigine, phenytoin, carbamazepine, and ethosuximide

Question 15

what is rachischisis

Answer 15

failure of the neural tube to close rostrally (at 4th week) leads to failure of the vertebrae to close around the spinal cord –> motor and sensory deficits, recurrent infections
often occurs with anencephaly

Question 16

conversion disorder vs. somatization

Answer 16

conversion disorder: sudden loss of sensation or muscle function occurring after a significant stressor

somatization: complaints of pain/ dysfunction of at least four varieties (two GI, one sexual, one pseudoneurologic), persisting for years and beginning before age 30

both are involuntary, but involve no apparent physical cause

Question 17

patients with what immune deficiency tend to get recurrent Neisseria infections

Answer 17

membrane attack complex (C5b-C9)

Question 18

Menetriere’s vs. Meniere’s disease

Answer 18

Menetiere’s: gastric hypertrophy of the stomach with increased parietal cells and mucous cells as well as protein loss

Meniere’s: increased endolymph due to malabsorption–> triad of tinnitus, vertigo, sensorineural hearing loss

Question 19

are all the cranial nerves covered by schwann cells

Answer 19

no, CN2 is covered by oligodendrocytes

Question 20

which vitamin deficiency mimics Freidrich’s ataxia and why

Answer 20

vitamin E: both involve posterior column and spinocerebellar tract demyelination as well as ataxia and dysarthria