Chest
Volume 127, Issue 1, January 2005, Pages 143-148
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Clinical Investigations: Nerves and Muscle
Cardiac and Sternocleidomastoid Muscle Involvement in Duchenne Muscular Dystrophy: An MRI Study

https://doi.org/10.1378/chest.127.1.143Get rights and content

Objective

To examine the extent of cardiac muscle and sternocleidomastoid muscle (SCM) involvement detected by MRI measurement of T2 relaxation time in patients with Duchenne muscular dystrophy (DMD) and no cardiorespiratory symptoms.

Design

Prospective controlled study.

Setting

Teaching referral hospital and university hospital.

Subjects

Seventeen patients with DMD (age range, 7 to 25 years) and 17 age-matched control subjects. All patients were free of cardiac or respiratory complaints and had normal ECG, echocardiograph, and Holter monitor examination findings.

Methods

We assessed respiratory function by means of standard pulmonary function testing. MRI measurements included the T2 relaxation time of the myocardium and the SCM in patients and control subjects.

Results

The FVC and FEV1 values were lower in patients with DMD than in age-matched control subjects, whereas the FEV1/FVC ratio was normal in all subjects. Patients with DMD had lower T2 relaxation time of the heart (37.8 ± 6.1 ms vs 58.1 ± 7.1 ms, p < 0.001) and lower T2 relaxation time of the right SCM (24.5 ± 2.6 ms vs 42.2 ± 1.3 ms, p < 0.001) and left SCM (23.2 ± 3.2 ms vs 42.2 ± 1.6 ms, p < 0.001), compared to control subjects (± SD). In children (< 12 years of age), the T2 of the SCM was lower than that of the control subjects, but T2 of the heart did not differ between the two groups. In the patient group, T2 relaxation time of the heart decreased with age (r = − 0.80, p < 0.001). In patients with FVC < 80% of predicted, the T2 values of the heart were lower than the T2 values of patients with FVC ≥ 80% of predicted (35.6 ± 5.8 ms vs 41.8 ± 4.6 ms, p < 0.05).

Conclusions

MRI measurements of the T2 relaxation time in the myocardium and SCM of patients with DMD and no cardiorespiratory symptoms are abnormal, indicating altered tissue composition. These measurements may prove a clinically useful test for monitoring cardiac and respiratory muscle involvement in these patients.

Section snippets

Patients and Methods

Seventeen male patients with DMD (age range, 7 to 25 years) and 17 age-matched male control subjects were included in the study. Five of the patients and five control subjects were children (age range, 7 to 12 years). The diagnosis of DMD was initially based on the characteristic clinical history and neuromuscular findings, and was supported by electromyography, muscular biopsy with special dystrophin immunostaining, and DNA testing. All patients were free of cardiac or respiratory complaints

Results

Table 1 shows pulmonary function testing parameters in patients and age-matched control subjects. FVC and FEV1 values (both absolute and percentage of predicted) were lower in patients with DMD than in age-matched control subjects. Unlike the adults, children with DMD had FVC and FEV1 values similar to those of the age-matched control subjects. The FEV1/FVC ratio was normal in all subjects.

Figure 1 shows representative MRI images from which the data were derived in a patient with DMD. In

Discussion

In a group of patients with DMD, with no cardiorespiratory symptoms, MRI measurements of T2 relaxation time in the myocardium and the SCM were lower than in age-matched control subjects. Unlike the T2 values in the healthy volunteers, in the patient group the older the patient the lower the myocardial T2 relaxation time.

DMD is a myopathy characterized by a defect in the p21 band of the X chromosome that is responsible for dystrophin, a protein located on the inner surface of the sarcolemma. In

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