Myotonia and Malignant Hypothermia

Question 1

What are symptoms of Myotonia?

Answer 1

Muscle stiffness, myotonic sierras which impacts balance

Question 2

What is the prevalence of Myotonia?

Answer 2

1:23000 to 1:50000

Question 3

What is Myotonia congenital caused by?

Answer 3

Loss of function CLCN1 only found on skeletal muscle

Question 4

What is Paramyotonia and Potassium aggravated myotonia caused by?

Answer 4

SCN4A (Nav1.4)- gain of function

Question 5

What is the Eion for k and Cl?

Answer 5

K- -90, Chloride- -70

Question 6

What is the structure of CLCN1 channel?

Answer 6

12 trans domains

Question 7

What does mutated CLCN1 cause?

Answer 7

Resting membrane potential lies closer to threshold

Question 8

What is treatment for Myotonia congenital?

Answer 8

Maxiltene- Sodium channel blocker

Question 9

What does mutation in SCN4A cause?

Answer 9

Issues with inactivation gate so channels do not close- more sodium entered muscle - depolarisation is prolonged

Question 10

What is the prevalence of Malignant Hypothermia?

Answer 10

1:10000 to 1:50000

Question 11

What is the change in amino acid in pig malignant hypothermia?

Answer 11

Argenine to cysteine

Question 12

What studies were done on Malignant Hypothermia?

Answer 12

Rabbit RyR1 614 mutation studies. using indo-1 fluorescence to measure calcium concentration

Question 13

What are treatments for Malignant Hypothermia?

Answer 13

Dantrolene (inhibits RyR1), take of GA, diuretic (stop kidney damage due to muscle breakdown products), NaHCO3, mechanical hyperventilation