Quantitative Muscle MRI to Monitor Disease Progression in Hypokalemic Period Paralysis

Area of Science:

• Neurology
• Muscle Channelopathies
• Medical Imaging

Background:

• Primary hypokalemic periodic paralysis (HypoPP) is a muscle channelopathy.
• HypoPP can lead to periodic paralysis and permanent muscle weakness.
• The progressive nature of HypoPP is not well understood.

Purpose of the Study:

• To describe the natural history of HypoPP.
• To assess quantitative fat imaging as a biomarker for HypoPP progression.
• To evaluate muscle strength changes over time.

Main Methods:

• Prospective follow-up study.
• Dixon MRI used to quantify muscle fat replacement.
• Stationary dynamometry used to measure muscle strength.

Main Results:

• 37 individuals with HypoPP-causing variants in CACNA1S were included.
• Median follow-up was 20 months.
• Fat fraction increased in examined muscles across symptomatic phenotypes, while muscle strength showed no significant change.

Conclusions:

• Quantitative muscle MRI is a valuable biomarker for monitoring subclinical disease progression in HypoPP.
• Fat replacement in muscles indicates disease progression.
• MRI can track HypoPP progression in patients with or without paralysis attacks.