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Whole-Body Muscle MRI in Patients with Hyperkalemic Periodic Paralysis Carrying the SCN4A Mutation T704M: Evidence for Chronic Progressive Myopathy with Selective Muscle Involvement.

Lee YH, Lee HS, Lee HE, Hahn S, Nam TS, Shin HY, Choi YC, Kim SM - J Clin Neurol (2015)

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus

Pedigree of a family with hyperkalemic periodic paralysis and mutation of the SCN4A gene. A: Family pedigree with affected individuals shown as solid symbols. B: Genomic DNA sequence electropherogram of patient II:1 showing a heterozygous p.T704M SCN4A mutation arrow, which is present in all patients, but not in healthy family members.
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Figure 1: Pedigree of a family with hyperkalemic periodic paralysis and mutation of the SCN4A gene. A: Family pedigree with affected individuals shown as solid symbols. B: Genomic DNA sequence electropherogram of patient II:1 showing a heterozygous p.T704M SCN4A mutation arrow, which is present in all patients, but not in healthy family members.

Mentions: This study was approved by the Institutional Review Board at our institution (IRB no. 4-2013-0167). Written informed consent was obtained from all patients. Seven hyperKPP patients from one family were included in this study. Genetic analysis was performed, and all seven patients were found to have the T704M mutation in the SCN4A gene (Fig. 1). The clinical features of the patients are summarized in Table 1.


Whole-Body Muscle MRI in Patients with Hyperkalemic Periodic Paralysis Carrying the SCN4A Mutation T704M: Evidence for Chronic Progressive Myopathy with Selective Muscle Involvement.

Lee YH, Lee HS, Lee HE, Hahn S, Nam TS, Shin HY, Choi YC, Kim SM - J Clin Neurol (2015)

Pedigree of a family with hyperkalemic periodic paralysis and mutation of the SCN4A gene. A: Family pedigree with affected individuals shown as solid symbols. B: Genomic DNA sequence electropherogram of patient II:1 showing a heterozygous p.T704M SCN4A mutation arrow, which is present in all patients, but not in healthy family members.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596100&req=5

Figure 1: Pedigree of a family with hyperkalemic periodic paralysis and mutation of the SCN4A gene. A: Family pedigree with affected individuals shown as solid symbols. B: Genomic DNA sequence electropherogram of patient II:1 showing a heterozygous p.T704M SCN4A mutation arrow, which is present in all patients, but not in healthy family members.
Mentions: This study was approved by the Institutional Review Board at our institution (IRB no. 4-2013-0167). Written informed consent was obtained from all patients. Seven hyperKPP patients from one family were included in this study. Genetic analysis was performed, and all seven patients were found to have the T704M mutation in the SCN4A gene (Fig. 1). The clinical features of the patients are summarized in Table 1.

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus