40 - Myopathies

Question 1

What is Duchenne’s muscular dystrophy?

Answer 1

• Present at birth ***
• APPARENT AT 3-5 YEARS OLD ***
• Frequent falls, can’t keep up with friends ***

Question 2

What sign do with see in Duchenne MD?

Answer 2

• GOWERS SIGN ***

- Patient uses hands to climb up himself when getting up from floor ***

Question 3

How do you diagnose Duchenne MD?

Answer 3

Definitive diagnosis with dystrophin deficiency in a biopsy or with a mutation analysis of leukocytes.

DYSTROPHIN DEFICIENCY ***

Question 4

What is dystrophin?

Answer 4

• Dystrophin is a large protein that is part of a large complex of muscle proteins and stablilizes the sarcolemma.
• Subsequently, the protein complex is weakened, the muscle cell membrane tears and a cascade of events leads to muscle fiber necrosis.

Question 5

What is Becker muscular dystrophy?

Answer 5

• Less severe X-linked recessive MD
• 10 times less frequent than Duchenne
• Similar pattern of muscle wasting
• Difficulties are first seen AT AGE 5-15 *****

Question 6

Describe dystrophin in Becker MD

Answer 6

SOME DYSTROPHIN IS PRODUCED ***

- You will see altered, but not absent dystrophin on a western blot

Question 7

What are acquired myopathies?

Answer 7

Inflammatory myopathies

• Dermatomyositis and polymyositis
• Inclusion body myositis

Question 8

What do you need to know about dermatomyositis?

Answer 8

• Increased association with malignancy
• Common: Ovarian cancer, breast cancer, melanoma, colon cancer, and non-hodgkin lymphoma
• IMPORTANT TO GET ALL SCREENING EXAMS FOR CANCER ***

Question 9

What will you see with dermatomyositis?

Answer 9

• Subacute progressive proximal muscle weakness with a skin rash (rash may precede weakness)
• You WILL have a rash

Question 10

Describe the risks associated with prescribing statins and fibrates

Answer 10

• Myalgia, malaise, and muscle tenderness
• May be related to exercise
• Muscle necrosis
• Severe reactions have rhabdomyolysis and myoglobinuria
• Elevated CK is indication of toxicity
• Stop the drug

Appropriate plan of action is to STOP the drug and monitor closely ***

Question 11

TEST QUESTION: If you have a 50 year old man, discharged from the hospital with simvastatin (most side effects) for hyperlipidemia, comes in complaining of muscle weakness with elevated CK, what is the appropriate course of action?

Answer 11

Most appropriate would be to STOP the med, monitor improvement and decrease of CK

Question 12

What do you NEED to know about dermatomyositis?

Answer 12

Association with malignancy ***