This is a rare disorder which occurs in families.
A disorder characterised by periodic muscle weakness and alteration in serum potassium.
This is autosomal dominant. The disorder is of 3 types:
1. Hypokalaemic type:
Generalized weakness including speech and bulbar muscles usually starting after a heavy carbohydrate meal and on awakening and after exercise. Attacks last for several hours.
First seen in teenagers and may disappear after 35 years.
The condition may also be associated with hyperthyroidism and hypokalaemia due to diuretics.
2. Hyperkalaemic type:
Usually sudeen onset after exercise and last usually less an hour. Found in childhood and tend to disappear 20 years. There may be myotonia.
3. Normokalaemic type:
Extremely rare. Clinically same as hyperkalaemic.
A. Hypokalaemic type
1. mild cases:
Potassium chloride, 5-10g orally, then 5g 2-4 times daily as necessary.
2. severe cases:
In respiratory and pharyngeal muscle paralysis:
Potassium chloride, 1g in 50-60 ml of distilled water iv slowly.
The procedure is risky.
B. Hyperkalaemic type:
1. Calcium gluconate, 10-12 ml of 10 percent solution iv is given or,
2. Prusemide 20-40 mg. iv. Or,
3. Glucose and insulin
C. Normokalaemic type:
Acetazolamide.
D. For prevention:
1. potassium chloride, 3g daily at bed time.
2. acetazolamide, 250-750 mg daily has been found to be an effective prophylactic in
both hyperkalaemic and hypokalaemic paralysis.
Note :
(a). biochemical confirmation of hypokalaemia is extremely important before giving
potassium salts.
(b). fatigue and high carbohydrate diet specially in the evening should be avoided.
