Distribution and progression of muscle weakness in two cases of polymyositis

The strength profile of two patients suffering from polymyositis is presented. In the first patient, 6 muscle actions (shoulder abduction, elbow flexion, grip, hip flexion, knee extension, ankle dorsiflexion) were measured bilaterally in 3 ways including a modification of the Stroke Impact Scale, manual muscle testing and hand-held dynamometry. All methods indicated considerable weakness, including that of the distal muscles. In the second patient, concentric and eccentric strength of the quadriceps was measured 6 times over a period of 13 years. The findings strongly demonstrated a progressive increase in knee extension weakness. The results support the notion that polymyositis affects distal as well as proximal muscles and that the weakness is fully appreciated when the strength of the muscles involved is quantitatively measured using dynamometry.