Noninvasive muscle test may measure Pompe disease severity: Study

Electrical impedance myography (EIM), a painless, noninvasive test that sends a small electrical current through a muscle, may help doctors measure the severity of Pompe disease, especially in children, because its results closely match what is seen in MRI and physical tests, according to a study.

“EIM may represent a functionally relevant, noninvasive tool to evaluate disease severity,” researchers wrote in “Evaluation of Electrical Impedance Myography as a Noninvasive Musculoskeletal Biomarker in Infantile- and Late-Onset Pompe Disease,” which was published in Genetics in Medicine. The study was funded by Sanofi.

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June 18, 2026 News by Andrea Lobo, PhD

Muscle MRI may detect early changes in late-onset Pompe disease

EIM measurements lower in patients than in healthy controls

Pompe disease is a genetic disease that causes muscles to become weaker over time. It can begin early in infancy (infantile-onset Pompe disease, or IOPD) or later in childhood or adulthood (late-onset Pompe disease, or LOPD). Doctors usually measure muscle health using MRI scans and physical tests. However, these can be difficult for young children or patients with severe muscle weakness.

This study looked at whether EIM could be a useful way to measure muscle health in Pompe disease. It included 64 participants: 11 with IOPD, 27 with LOPD, and 26 healthy children (ages 4 to 17) for comparison. EIM measurements were obtained for both upper and lower limbs. Of the 38 patients, 20 also had MRI scans of their lower limbs. Recruitment was carried out through specialized clinics at Boston Children’s Hospital, Massachusetts General Brigham, New York Medical College. and patient advocacy groups.

Compared with the healthy controls, patients with either of the two types of Pompe disease reported more problems with moving freely. In addition to poorer physical function and more physical stress, patients with LOPD, but not IOPD, reported more severe pain. Overall, patients also performed worse on motor tasks such as walking or keeping balance, with those with IOPD showing worse finger dexterity and weaker grip strength.

Given its noninvasive and accessible nature, EIM may be particularly well suited for tracking or predicting disease progression and treatment efficacy in individuals who may be unable to participate in traditional assessments.

EIM measurements were lower in patients than in healthy controls, especially in those with IOPD, suggesting poorer muscle health. Lower EIM measurements indicate changes in muscle structure. Indeed, they were linked to higher amounts of fat seen on MRI scans. As muscle tissue is damaged, it is gradually replaced by fat, making the muscles weaker. Fat built up more notably in some muscles than others.

Patients with lower EIM measurements tended to walk shorter distances, perform worse on hand function tests, and have weaker grip strength.

“These data support EIM as a promising tool for assessing muscle integrity and functional capacity in individuals with either IOPD or LOPD,” the researchers wrote.

Although larger studies are needed to confirm these data, “given its noninvasive and accessible nature, EIM may be particularly well suited for tracking or predicting disease progression and treatment efficacy in individuals who may be unable to participate in traditional assessments,” the researchers concluded.