Neurology

Question 1

When does development of the nervous system begin during gestation?

Answer 1

During week 3

Question 2

What are the three germ layers?

Answer 2

Ectoderm, mesoderm, endoderm

Question 3

Which part of the germ layer does neural tissue arise from?

Answer 3

Ectoderm

Question 4

How does the neural tube form?

Answer 4

Neural folds become elevated and grow towards the midline to fuse and form the neural tube. Begins in the cervical regin and progresses in the cephalic and caudal region

Question 5

When do you have full closure of the neural tube?

Answer 5

25-27 days

Question 6

What is the neural crest?

Answer 6

A population of cells separates from the tips of the neural folds to form neural crest. These cells migrate throughout the body to form cell types such as schwann cells, meninges, adrenal medulla and parafollicular cells

Question 7

What does the caudal end of the neural tube give rise to?

Answer 7

Composed of neuroepithelial cells which gives rise to neuroblasts which following maturation give rise to grey and white matter of the future spinal chord

Question 8

What does the cephalic end of the neural tube give rise to?

Answer 8

Hindbrain, midbrain, forebrain

Question 9

What does the neural tube and neural crest differentiate into?

Answer 9

Neural tube- central nervous system brain and spinal chord & neural crest- peripheral & autonomic nervous system

Question 10

What does the forebrain form? (prosencephalon)

Answer 10

Cerebral hemisphere, thalami & lateral ventricles

Question 11

What does the midbrain form? (mesencepahlon)

Answer 11

Midbrain & aqueduct

Question 12

What does the hindbrain form?

Answer 12

Pons, cerebellum, medulla and fourth ventricle

Question 13

What is anencephaly?

Answer 13

Failure of the neural tube to close at the cranial end. This is incompatible with life because you dont have brain development

Question 14

What is spina bifida?

Answer 14

Failure of the neural tube to close at the caudal end

Question 15

After having an affected child what is the risk for a second child or a third to have spina bifida?

Answer 15

Second child is 3-5% and third child is 5-10%

Question 16

What can cause spina bifida?

Answer 16

Folate deficiency, folate antagonists such as sodium valproate and genetic polymorphisms in genes that are needed for folate metabolism such as methylenetetrahydrofolate reductase MHTFR

Question 17

What are the spectrums for spina bifida?

Answer 17

Spina bifida occulta - developmental defect in the vertebral arch covered by intact skin and not involving the spinal chord. Lumbar spine is the most frequent location

Question 18

What are the two types of spina bifida cystica?

Answer 18

Meningocele - fluid filled meninges but not the spinal chord protrude through the defect

Myelomeningocoele- neural tissue is also involved and protrudes

Question 19

What is a chiari malformation?

Answer 19

Downward displacement of the cerebellar tonsils through the foramen magnum (into the spinal canal) squishing the outflow of CSF and causing hydrocephalus

Question 20

What do pluripotent neural stem cells differentiate into?

Answer 20

Neurons, astrocytes and oligodendrocytes

Question 21

What are neurons?

Answer 21

They have a cell body and dendrites and they are electrically excitable cells that rely on metabolically active ion channel pumps to maintain voltage gradients

Question 22

What are astrocytes?

Answer 22

Dominant cell line , star shaped and support the blood brain barrier. Can transform into neurons and provide nutrients to neural cells

Question 23

What is the function of oligodendrocytes?

Answer 23

Support and insulate the axon and permit the conduction of nerve impulses along myelinated axons

Question 24

When does synaptogenesis (creation of a synapse) happen?

Answer 24

Between 20 weeks gestation and continue to the first couple years after birth

Question 25

What protein stabilizes the synapse

Answer 25

N cadherin

Question 26

What is myelination and when does it happen?

Answer 26

Myelin is produced by glial cells and they insulate the axon so that it increases the speed and accuracy of transmission of info in the form of action potentials along a neuron. Between 36 weeks and term myelin increases from 1% to 5% total brain volume

Question 27

Name 4 conditions affected by ion channel malfunction

Answer 27

Generalized epilepsy with febrile seizures plus, dravet syndrome, familiam hemiplegic migraine and some of the ataxias

Question 28

Name three drugs that block sodium channels

Answer 28

Phenytoin, lidocaine and carbamazepine

Question 29

At resting potential is the inside of the neuron more negatively or positively charged than the outside?

Answer 29

AT REST- More negative inside than outside, resting potential -70mV

Question 30

What is depolarization?

Answer 30

Neurotransmitter molecules bind to receptors on the neurons dendrites and cause voltage gated ion channels to open and influx of positive ions to enter the target neuron.

Question 31

What is the threshold potential and what happens?

Answer 31

At the threshold potential (-55mV), Na channels open and Na enters the cell and the neuron completely depolarizes to a positive membrane potential of about +40mV. The action potential now travels dowm the neuron

Question 32

What happens when a action potential has been generated?

Answer 32

Na channels close and the cell is refractory to further stimulus. The voltage gated K+ channels open and K+ ions leave the cell making it negative again -70mv. The cells then rests itself by pumping out Na in exchange for K+

Question 33

Name a neurotrophin that is thought to have a role in pyschiatric and neurodevelopmental disorders and possible a therapeutic agent for neurodegenerative conditions and MS

Answer 33

hormone nerve growth factor

Question 34

What is the critical period of visual neuroplasticity in young children and up until when does the higher visual pathway continue to develop and differentiate?

Answer 34

3 months critical and continues to develop until 8 years

Question 35

When do you have the most maximum number of synpatic connections?

Answer 35

Early childhood- most receptive to learning

Question 36

How do neural cells migrate to their correct location?

Answer 36

Along specially created highway or glial cells

Question 37

What are some molecules that can cross the blood brain barrier?

Answer 37

water, gases and lipid soluble substances

Question 38

What is the pathophysiology of jaundice in the neonate?

Answer 38

unconjugated bilirubin is lipid soluble and able to pass reading through the BBB and into the brain which causes neurological damage

Question 39

Why does light therapy help in neonatal jaundice?

Answer 39

The light of a certain frequency is able to convert the lipid soluble unconjugated bilirubin into a water soluble stat which means it cannot cross the BBB

Question 40

What type of cell produces CSF ?

Answer 40

Ependymal cell mainly produced in the choroid plexus in the lateral ventricles of the brain

Question 41

Describe the flow of CSF

Answer 41

Lateral ventricle -> third ventricle via intraventricular foramne of munro Third ventricle-> Fourth ventricle via aqueduct of sylvisu Reabsorbed into circulation via arachnoid vila

Question 42

Name some causes of communicating hydrocephalus (no obstruction between the ventricles & subarachnoid space)

Answer 42

1) Excess CSF production - e.g. choroid plexus tumours 2) Impaired CSF re-absorption due to blockage of arachnoid granulations by debris after meningitis or haemorrhage

Question 43

Name some causes of non communicating hydrocephalus (physical obstruction between ventricles and subarachnoid space)

Answer 43

1) Congenital malformations such as arnold chiari malformation or aqueduct stenosis 2) Acquired obstruction such as brain tumour

Question 44

What are normal levels of glucose and protein in normal CSF?

Answer 44

The blood-brain barrier is effective against large molecules (e.g. protein) but allows the passage of smaller molecules (e.g. glucose). As such, normal CSF is generally a low-protein fluid with copious glucose.

Question 45

What can you see via cranial USS?

Answer 45

Intraventricular haemorrhage, ischemic cysts of periventricular leukomalacia, ventricular dilatation, cerebral malformations such as agenesis of corpus callosum

Question 46

What are oligoclonal bands?

Answer 46

Oligoclonal bands are visible as an increased concentration of restricted bands of IgG after isoelectric focusing and immunofixation of IgG. A serum sample is taken at the time of the lumbar puncture as oligoclonal bands may be present in CSF alone or CSF and blood. If present in both, they may represent systemic infection, autoimmune disease, sarcoidosis or neoplasia. Local CNS synthesis implies local CNS disease, especially multiple sclerosis

Question 47

What does the CSF look like in T2 vs T1 weighted MRI sequence?

Answer 47

CSF is bright white in T2 vs dark in T1 and T2 is good for assessing tissue fluid content such as oedema vs T1 which is better for assessing tissue anomalies

Question 48

When do you use Magnetic resonance angiography (MRA)?

Answer 48

Non-invasive assessment of the intracranial vascular system such as conditions like AVN malformations

Question 49

What is magnetic resonance spectroscopy?

Answer 49

MRS- Can detect metabolites or other target molecules within brain tissue

Question 50

What condition are infantile spasms associated with and what sign do you see on an EEG?

Answer 50

Tuberous scerlosis and EEG shoes hypsarrthymia

Question 51

What are the 4 EEG wave patterns and after 3 years what is the predominant pattern?

Answer 51

alpha, beta, theta and delta and after 3 years the prominent is alpha

Question 52

What is elcttomyography?

Answer 52

Needle electrode is directly inserted into the muscle. Can help detect myotonia and nerve injury

Question 53

What does nerve conduction studies look for?

Answer 53

Peripheral neuropathy and the classification of axonal vs demyelinating conditions. Axonal- conduction velocity is preserved and the amplitude is reduced. In demyelination the conduction velocity is reduced

Question 54

What doe the visual evoked potentials test help with?

Answer 54

Help detect lesions of the sensory visual pathways e.g. demyelination of the optic nerve in optic neuritis