Am. J. Respir. Crit. Care Med., Vol 153, No. 1, 01 1996, 422-425.
Sternomastoid muscle size and strength in patients with severe chronic obstructive pulmonary disease
R Peche, M Estenne, PA Gevenois, E Brassinne, JC Yernault and A De Troyer
Chest Service, Erasme University Hospital, Brussels School of Medicine, Belgium.
Chronic obstructive pulmonary disease (COPD) imposes a major strain on the
respiratory muscle pump, and it is conventionally thought that the
inspiratory muscles of the neck adapt to this chronic overload by
developing hypertrophy. Yet previous anthropometric studies have shown
atrophy of the sternomastoid muscles. To solve this discrepancy, we have
measured the cross-sectional area of these muscles by computed tomography.
Ten stable patients with severe airflow obstruction (FEV1 = 0.76 +/- 0.12
L) and hyperinflation (FRC = 210 +/- 29% of predicted) and 10 control
subjects matched for age, sex, and height were studied. The sternomastoid
cross-sectional area in the patients averaged (mean +/- SD) 4.29 +/- 1.48
cm2, and that in the control subjects was 3.96 +/- 0.82 cm2. This small
difference could be entirely accounted for by hyperinflation, and it was
not statistically significant. Sternomastoid muscle torque in patients was
also similar to that in the control subjects. In patients with severe COPD,
therefore, the sternomastoid muscles are essentially normal. As a
corollary, their frequent prominence on clinical examination is only
apparent.
