Week 3- randoms- genetics, muscular conditions etc

Question 1

What is myasthenia gravis?

Answer 1

Autoimmune disorder of the neuromuscular junction where antibodies are targeted against the acetyl choline receptors.

Question 2

What does a reduced number of functioning receptors in myasthenia gravis lead too?

Answer 2

Muscle weakness and fatiguability

Question 3

What do the antibodies in myasthenia gravis do?

Answer 3

Block the binding of acetylcholine and trigger inflammatory cascades that damage the folds of the post-synaptic membrane.

Question 4

Who gets myasthenia gravis?

Answer 4

Young women and older men.

Question 5

Clinical features of myasthenia gravis?

Answer 5

Weakness- typically fluctuating
Most commonly- extra ocular weakness, facial and bulbar weakness.
Limb weakness is typically proximal.

Question 6

What is the treatment for myasthenia gravis?

Answer 6

Acetylcholinesterase inhibitor- means AcH is left in the synaptic cleft for longer- pyridostigmine.
Also immunomodulating
Steroids- good for younger people, bad for older people.

Question 7

What is the emergency treatment for myasthenia gravis?

Answer 7

Immunoglobulin or plasma exchange.

Question 8

What is myotonia?

Answer 8

Failure of muscle contraction after use.

Question 9

What is rhabdomyolysis?

Answer 9

Damage to skeletal muscle leads to leakage of large quantities of toxic intracellular contents into the plasma.

Question 10

Triad of rhabdomyolysis

Answer 10

Myalgia (muscle pain)
Muscle weakness
Myoglobinuria

Question 11

How is Duchenne’s muscular dystrophy inherited?

Answer 11

X linked recessive

Question 12

What clinical signs indicate Duschenne’s muscular dystrophy?

Answer 12

Delay in motor development

Onset of weakness at 3-4 years. Occurs in the pelvic and shoulder girdles.

Question 13

On examination of a patient with Duschenne’s muscular dystrophy, what might you expect to find?

Answer 13

Calf hypertrophy.

Shoulders back, stomach stuck out posture.

Question 14

What might Duchenne’s muscular dystrophy be linked too?

Answer 14

Dystrophin deficiency- large scale deletions in 70% of the boys affected. Other mutations involving it in the other 30%.

Question 15

How would you go about diagnosing Duchenne’s muscular dystrophy?

Answer 15

Look for:
Developmental delay in boys
Muscle weakness- toe walking and Gowers sign
Raised serum CK

Question 16

What investigations would you do into Duschennes muscular dystrophy?

Answer 16

Serum CK
Electromyography
Muscle biopsy
Molecular genetic testing (carrier testing)

Question 17

Only boys can be affected if its X linked recessive. True or false?

Answer 17

True- a girl will be a carrier but wont show the disease unlike the boy.

Question 18

How is Huntington’s disease inherited?

Answer 18

Autosomal dominantly.

Question 19

Huntingtons disease can only manifest in males. True or false?

Answer 19

False, due to it being autosomal dominant- it affects females too.

Question 20

Onset of Huntington’s disease?

Answer 20

Usually 30-50 years old.

Question 21

Symptoms of huntingtons disease

Answer 21

Dementia
Involuntary movement
Progression to severe dependency and death.

Question 22

Early clinical signs of Huntington’s?

Answer 22

Clumsiness
Agitation
Irritability 
Apathy
Anxiety
Disinhibition
Delusions/hallucinations
Abnormal eye movements
Depression

Question 23

Later clinical signs of Huntington’s

Answer 23

Dystonia
Involuntary movements
Trouble with balance and walking
Trouble with activities that require manual dexterity 
Slow voluntary movements
Difficulty initiating movements
Inability to control speed and force of movement
weight loss
speech difficulties
stubborness

Question 24

What are senile plaques and what are they associated with?

Answer 24

Associated with Alzheimers disease

They are extracellular protein deposits containing amyloid beta protein (fragment of the APP gene)

Question 25

What mutations can cause Alzheimers?

Answer 25

APP
Presenilin 1
Presenilin 2

Question 26

NOTE ON CT SCANS

Answer 26

You are looking at the density of electrons within the structure. The contrast is determined by electron density. Things that are dense in electrons e.g. bone are white on the scanner. Things like gas which are not electron dense are black.

Question 27

What colour does CSF show up on CT scan?

Answer 27

Dark- not electron dense.

Question 28

What colour does clotted blood show up?

Answer 28

Its denser than brain so shows up whiter.

Question 29

Why would you use iodine as a contrast agent on CT scan?

Answer 29

Its electron dense. Allows you to do CT angiography where you look at the blood vessels.

Question 30

When is it a CT angiogram and when is it a CT venogram?

Answer 30

During and into 30 seconds its a CT angiogram because you are looking at the arteries. After that it is a CT venogram.

Question 31

NOTE ON MRI

Answer 31

Mechanism- about the interactions with nuclei. If you put giant magnets together- the nuclei will line up either vertically or horizontally. They accept energy and do this. They then give back out that energy when they return to their previous position which allows you to record an image.
To do with proton density.

Question 32

When is an MRI contraindicated?

Answer 32

Implanted foreign material (e.g. pacemaker)

Question 33

What most often causes subarachnoid haemorrhage?

Answer 33

Rupture of aneurysms (85%)

Bleed from AVM (10%)

Question 34

What is a saccular aneurysm?

Answer 34

A true aneurysm with involvement of all layers of the blood vessel. The tunica media becomes interrupted but the tunica intima is generally normal.

Question 35

How do aneurysms present?

Answer 35

Generally asymptomatic until rupture.

Uncommonly can produce cranial nerve palsies.

Question 36

How would you diagnose a subarachnoid haemorrhage?

Answer 36

CT scan- however you get false negatives in about 5% of cases and therefore you need to do a lumbar puncture to exclude a subarachnoid haemorrhage.

Question 37

How would you determine which treatment is best in a subarachnoid haemorrhage?

Answer 37

Could do a CT angiography or an MR angiography to see size of bleed etc.

Question 38

Treatment of aneurysms

Answer 38

Could do craniotomy and clipping

or endovascular treatment