Effect of muscle weakness distribution on balance in neuromuscular disease

To assess balance and identify the effects of muscle weakness distribution on balance in children with different neuromuscular diseases.

Forty ambulant, pediatric patients with neuromuscular disease were enrolled in the study. Patients were separated into two groups according to muscle weakness distribution as group 1 (proximal) and group 2 (distal). Demographic data were recorded. Functional level (Brooke lower extremity functional classification), muscular strength (manual muscle testing), balance (pediatric functional reach test [PFRT], timed up-and-go test [TUGT], stabilometric platform) and functional performance (6 min walk test [6MWT]) were assessed.

Group 1 consisted of 20 Duchenne muscular dystrophy patients, and group 2, of 20 neuropathy patients. The total lower, upper limbs and trunk muscles muscle strength (P < 0.05); forward and right side reach subsections of the sitting position, and PFRT total score (P < 0.01) were significantly different between the groups. TUGT results were 7.79 ± 1.54 s and 10.13 ± 2.63 s, respectively, in group 1 and 2 (z = -2950; P < 0.01). No statistically significant difference between groups in any performance parameters of the 6MWT was found (P ≥ 0.05). Anterior body balance was found to be dominant in group 1, while posterior body balance was dominant in group 2 (P ≤ 0.05) measured by stabilometric platform.

The distal group was particularly affected regarding dynamic balance, and the proximal group regarding static balance. Muscle strength was important for providing dynamic stability in the distal group, and for maintaining proximal stabilization during dynamic activities in the proximal group.