Periodic Paralysis
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Basics
Description
- Periodic paralysis (PP): Disorder of muscle metabolism, usually inherited, that leads to flaccid extremity weakness
- Primary: Familial autosomal dominate (AD) mutation in skeletal muscle calcium, sodium, or potassium channels
- Secondary: Due to thyrotoxicosis, hypokalemia, or hyperkalemia
Epidemiology
Incidence and Prevalence Estimates- Hypokalemic PP (HypoPP):
- Prevalence: 1:100,000
- 1/3 are new AD mutations
- Hyperkalemic PP (HyperPP):
- Prevalence: 1:200,000
- 90% of people with mutation will have clinical symptoms
- Thyrotoxic PP (ThyroPP):
- Incidence: 2% in patients with thyrotoxicosis
- Higher in Asians
- Subset of HypoPP, clinically identical
- Andersen–Tawil:
- Subset of HypoPP
- Rare
- Prevalence unknown
Etiology
- Mutation of skeletal muscle Na channel gene:
- SCN4A
- HypoPP, HyperPP:
- AD inheritance
- Spontaneous mutation
- Mutation of skeletal muscle calcium channel gene CACN1AS:
- HypoPP
- Mutation of KCNJ2 gene:
- Andersen–Tawil:
- AD inheritance
- 50% spontaneous
- Andersen–Tawil:
- M > F
- Age of onset:
- HypoPP:
- First or second decade
- HyperPP:
- First decade
- Andersen–Tawil:
- First or second decade
- ThyroPP:
- Second–fifth decade
- HypoPP:
-- To view the remaining sections of this topic, please log in or purchase a subscription --
Basics
Description
- Periodic paralysis (PP): Disorder of muscle metabolism, usually inherited, that leads to flaccid extremity weakness
- Primary: Familial autosomal dominate (AD) mutation in skeletal muscle calcium, sodium, or potassium channels
- Secondary: Due to thyrotoxicosis, hypokalemia, or hyperkalemia
Epidemiology
Incidence and Prevalence Estimates- Hypokalemic PP (HypoPP):
- Prevalence: 1:100,000
- 1/3 are new AD mutations
- Hyperkalemic PP (HyperPP):
- Prevalence: 1:200,000
- 90% of people with mutation will have clinical symptoms
- Thyrotoxic PP (ThyroPP):
- Incidence: 2% in patients with thyrotoxicosis
- Higher in Asians
- Subset of HypoPP, clinically identical
- Andersen–Tawil:
- Subset of HypoPP
- Rare
- Prevalence unknown
Etiology
- Mutation of skeletal muscle Na channel gene:
- SCN4A
- HypoPP, HyperPP:
- AD inheritance
- Spontaneous mutation
- Mutation of skeletal muscle calcium channel gene CACN1AS:
- HypoPP
- Mutation of KCNJ2 gene:
- Andersen–Tawil:
- AD inheritance
- 50% spontaneous
- Andersen–Tawil:
- M > F
- Age of onset:
- HypoPP:
- First or second decade
- HyperPP:
- First decade
- Andersen–Tawil:
- First or second decade
- ThyroPP:
- Second–fifth decade
- HypoPP:
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