Diagnosing Primary Periodic Paralysis

The journey to a Primary Periodic Paralysis diagnosis can be a long one, often taking years and involving a multitude of diagnostic studies and misdiagnoses.1 Several symptoms, signs and test results can suggest alternative diagnoses.2 A significant number of these misdiagnoses are psychiatric conditions.1

82% of individuals who are diagnosed before the age of 20 are from families with a recognized history of periodic paralysis.4

There is an average of 26 years between age at onset and age at diagnosis.4

Genetic testing

Genetic testing is recommended as the first diagnostic step where there is a high clinical likelihood of a Primary Periodic Paralysis diagnosis.2

Remember that genetic testing only identifies an associated mutation in 60% to 70% of patients with Primary Periodic Paralysis. For the remaining 30% to 40% of patients with Primary Periodic Paralysis, diagnosis can be based upon clinical presentation, serum potassium levels during attacks and pattern abnormalities on long exercise testing.2

If genetic testing comes back negative, one or more of the following tests could be utilized to help reach a diagnosis or rule out Primary Periodic Paralysis:

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Compound muscle action potential


  1. Charles, B., et al  (2013). Characterization of hyperkalemic periodic paralysis: a survey of genetically diagnosed individuals. Journal of Neurology, [online] 260(10), pp.2606–2613. Available at: https://doi.org/10.1007/s00415-013-7025-9   [Accessed 1 Nov. 2023].
  2. Statland, J., et al (2017). Review of the Diagnosis and Treatment of Periodic Paralysis. Muscle & Nerve, [online] 57(4), pp.522–530. Available at: https://doi.org/10.1002/mus.26009 [Accessed 1 Nov. 2023].

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