Chapter 15 - Episodic flaccid muscle weakness (Periodic paralysis)

Abstract

Episodic flaccid muscle weakness can occur with altered serum potassium levels. Causes may be genetic (primary periodic paralysis) or secondary to a systemic condition that alters serum potassium. It is important to discern the difference. Treating the systemic problem in secondary causes prevents further episodes of muscle weakness. Primary periodic paralyses may have no cure, but there are many effective and readily available symptomatic treatments that can significantly reduce the number and severity of episodes of muscle weakness. Diagnostic indication that symptoms are due to a primary periodic paralysis can require a combination of investigations which may parallel excluding secondary causes. Next-generation sequencing and gene panels have helped to simplify genetic analysis. New clinical presentations of periodic paralysis in combination with other neurological comorbidities, e.g., neuropathy, and expanding genetic diagnoses are emerging.