Successful treatment of normokalemic periodic paralysis with hydrochlorothiazide.

Abstract

BACKGROUND:

Periodic paralysis (PP) is an autosomal dominant muscle disorder characterized by periodic muscle weakness attacks associated with serum potassium level variations. It is classified into hypokalemic (hypoKPP), hyperkalemic (hyperKPP), and normokalemic (normoKPP) forms based on the ictal serum potassium level. HyperKPP and normoKPP are caused by mutations of the same gene SCN4A, the gene encoding the skeletal muscle voltage-gated sodium channel. Prophylactic treatment with thiazide diuretics is highly effective in preventing attacks in hyperKPP. However, the efficacy and safety of such diuretics in normoKPP remain unclear.

CASE:

We describe a familial case of normoKPP wherein the affected individuals showed periodic muscle weakness attacks, with an early childhood onset, and a lack of serum potassium level variation during the paralytic attacks. Sequencing analysis of SCN4A gene revealed a heterozygous missense mutation (c. 2111C > T, p. Thr704Met) in all symptomatic family members. Oral administration of hydrochlorothiazide, a thiazide diuretic, markedly improved the paralytic attack frequency and duration in the affected individuals without adverse effects.

CONCLUSION:

Our case demonstrates the efficacy of hydrochlorothiazide in the prophylactic treatment of normoKPP caused by the SCN4A mutation of p.Thr704Met, the most frequent mutation of hyperKPP.

• Authors: Yuichi Akaba, Satoru Takahashi, Yoshiaki Sasaki, Hiroki Kajino
• Journal: Brain & development (Brain Dev) Vol. 40 Issue 9 Pg. 833-836 (Oct 2018) ISSN: 1872-7131 [Electronic] Netherlands
• PMID: 29907477 (Publication Type: Case Reports, Journal Article)
• Copyright: Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Chemical References

• NAV1.4 Voltage-Gated Sodium Channel
• SCN4A protein, human
• Sodium Chloride Symporter Inhibitors
• Hydrochlorothiazide

Topics

• Administration, Oral
• Child
• Diagnosis, Differential
• Family
• Female
• Humans
• Hydrochlorothiazide (therapeutic use)
• Mutation, Missense
• NAV1.4 Voltage-Gated Sodium Channel (genetics)
• Paralyses, Familial Periodic (diagnostic imaging, genetics, physiopathology)
• Sodium Chloride Symporter Inhibitors (therapeutic use)