Electrical impedance myography in the assessment of disuse atrophy.

UNLABELLED Tarulli AW, Duggal N, Esper GJ, Garmirian LP, Fogerson PM, Lin CH, Rutkove SB. Electrical impedance myography in the assessment of disuse atrophy. OBJECTIVE To quantify disuse atrophy using electrical impedance myography (EIM), a noninvasive technique that we have used successfully to study neurogenic and myopathic atrophy. DESIGN We performed EIM of the tibialis anterior of subjects with disuse atrophy secondary to cast immobilization and in their contralateral normal leg. Subjects were studied shortly after cast removal and again several weeks to months after the cast was removed and normal mobility was restored. SETTING Outpatient neurology and orthopedic practices at a tertiary care medical center. PARTICIPANTS Otherwise healthy subjects (N=10) with unilateral leg fracture. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Resistance, reactance, and phase measured at 50kHz. RESULTS The main EIM outcome parameter, phase at 50kHz, was lower in the immobilized leg in 9 of 10 cases. Additionally, when normal mobility was restored, the phase of the casted leg increased relative to its initial measurement in all 10 cases, while it increased inconsistently in the contralateral leg. CONCLUSIONS EIM may be a powerful tool for the assessment of disuse atrophy.