Dynamic electromyography evaluation of spastic hemiplegia using a linear discriminator

Spastic hemiplegia (SH) is a type of cerebral palsy characterized by an uncontrolled increase of muscle tone on one side of the body. Superficial dynamic electromyography (SDEMG) signals, illustrate the contributions of the action potentials of motor units on the surface of muscle groups of the lower limbs during gait. This paper studies the SDEMG signals of patients with SH, acquired at the gait laboratory of the Hospital Ortopedico Infantil. Time and frequency domain indicators were determined in order to evaluate the kinematics classification of SH from the electromyographic point of view. The applied indicators were: accumulated energy, nonlinear accumulated energy, mean power frequency (MPF), spectral energy, bandwidth and wavelet decomposition. In order to identify the threshold and the error between each pair of types the following was used: one-way ANOVA with p value <0.05, a table of maximum significant differences was constructed from a student-t test of two tails with α=0.05 and Chernoff and Becker´s linear discriminator. Although it was not possible to discriminate between types I and III; a criteria was established that permits to differentiate among patients with SH (Type I, II or IV) with an error ≤1%.