Whole-Body Muscle MRI in Patients with Hyperkalemic Periodic Paralysis Carrying the SCN4A Mutation T704M: Evidence for Chronic Progressive Myopathy with Selective Muscle Involvement.
10.3988/jcn.2015.11.4.331
- Author:
Young Han LEE
1
;
Hyung Soo LEE
;
Hyo Eun LEE
;
Seok HAHN
;
Tai Seung NAM
;
Ha Young SHIN
;
Young Chul CHOI
;
Seung Min KIM
Author Information
1. Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
- Publication Type:Original Article
- Keywords:
hyperkalemic periodic paralysis;
chronic progressive myopathy;
muscle MRI;
fat quantification;
two-point Dixon technique
- MeSH:
Channelopathies;
Humans;
Leg;
Magnetic Resonance Imaging*;
Muscles;
Muscular Atrophy;
Muscular Diseases*;
Paralysis, Hyperkalemic Periodic*;
Pathology;
Thigh
- From:Journal of Clinical Neurology
2015;11(4):331-338
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND AND PURPOSE: Hyperkalemic periodic paralysis (hyperKPP) is a muscle sodium-ion channelopathy characterized by recurrent paralytic attacks. A proportion of affected individuals develop fixed or chronic progressive weakness that results in significant disability. However, little is known about the pathology of hyperKPP-induced fixed weakness, including the pattern of muscle involvement. The aim of this study was to characterize the patterns of muscle involvement in hyperKPP by whole-body magnetic resonance imaging (MRI). METHODS: We performed whole-body muscle MRI in seven hyperKPP patients carrying the T704M mutation in the SCN4A skeletal sodium-channel gene. Muscle fat infiltration, suggestive of chronic progressive myopathy, was analyzed qualitatively using a grading system and was quantified by the two-point Dixon technique. RESULTS: Whole-body muscle MRI analysis revealed muscle atrophy and fatty infiltration in hyperKPP patients, especially in older individuals. Muscle involvement followed a selective pattern, primarily affecting the posterior compartment of the lower leg and anterior thigh muscles. The muscle fat fraction increased with patient age in the anterior thigh (r=0.669, p=0.009), in the deep posterior compartment of the lower leg (r=0.617, p=0.019), and in the superficial posterior compartment of the lower leg (r=0.777, p=0.001). CONCLUSIONS: Our whole-body muscle MRI findings provide evidence for chronic progressive myopathy in hyperKPP patients. The reported data suggest that a selective pattern of muscle involvement-affecting the posterior compartment of the lower leg and the anterior thigh-is characteristic of chronic progressive myopathy in hyperKPP.
