Periodic paralysis with cardiac arrhythmia.

Area of Science:

• Neurology
• Cardiology
• Genetics

Background:

• Periodic paralysis is a group of rare genetic disorders characterized by episodes of muscle weakness.
• Normokalemic periodic paralysis typically presents with normal serum potassium levels during attacks.
• Cardiac arrhythmias can occur in patients with periodic paralysis, posing significant health risks.

Observation:

• A 15-year-old female presented with cardiac arrhythmia, normokalemia, and symptoms overlapping with hyperkalemic periodic paralysis.
• Clinical examination revealed a waddling gait, Gower's sign, proximal muscle atrophy, and reduced deep tendon reflexes.
• Electrocardiogram (ECG) showed bigeminy with multifocal premature ventricular contractions.

Findings:

• Serum potassium levels increased from 3.1 to 4.4 mEq/l at the onset of muscle weakness.
• Intravenous glucose and insulin administration did not provoke muscle weakness.
• Ingestion of potassium chloride (4 g) successfully evoked muscle weakness, with temporary normalization of ECG during the episode.

Implications:

• This case highlights a unique variant of periodic paralysis with normokalemia and cardiac involvement.
• The findings suggest a potential potassium-gated channel dysfunction contributing to both muscle weakness and cardiac arrhythmias.
• Further research is needed to understand the specific mechanisms and genetic basis of this rare condition.