Features of motor control in patients with proximal childhood spinal muscle atrophy (pilot study)

The differences in the motor performance during different tasks between 19 subjects suffering from SMA and 10 healthy controls were observed. The simultaneous EMG activity of twelve lower limbs and lower trunk muscles was recorded with surface electrodes. EMG data were automatically reduced and compared with data evaluated from performed by physiotherapist manual testing of muscle strength. Results showed characteristic differences between healthy and spinal muscular atrophy (SMA) subjects: 1. SMA patients display generally more activity occurring in numerous muscle groups and more spinal levels are activated. 2. SMA patients reveal a disturbed functional relation between the posterior and anterior compartments of muscles. 3. EMG activity in SMA patients is spreading out also to the contralateral muscle groups even during slight, unilateral singlejoint movements. Oligosegmental, plurisegmental and brain sources are probably responsible for mentioned phenomena. The reciprocal influences between reduced number of motoneurons (in SMA) and function of central movement generators results in different mode of movement execution in SMA patients.