The effects of spinal reflexes and application of botulinum a toxin in post-stroke spasticity

The aim of this study is to investigate the spinal reflex changes in the spastic lower extremity of the patients having spasticity after stroke, and to compare spinal reflex changes in the spastic lower extremity of stroke patients with their own contralateral healthy lower extremity and with healthy control group. Another aim of the present study was to examine the effect of Botulinum A Toxin (BoNT) on the spinal reflex change in both the spastic and healthy lower extremities, thus, to investigate the central and peripheral effect of BoNT administration. Fourteen stroke patients with an average age of 56 (± 12) years, and age-sex matched 14 healthy individuals with an average age of 61 (± 16) years were included in the study. The socio-demographic characteristics of all participants in the study were recorded. Before and at the 1st and 3rd months of the BoNT injection, the Modified Rankin Scale (MRS) and Modified Ashwort Scale (MAS) values of all patients in the study group were recorded. Dysinaptic inhibition, presynaptic inhibition, and percent of post-activation depression were measured. In the control group, the percentage of dysinaptic inhibition, presynaptic inhibition and post-activation depression in the examined lower limb were measured only once. The percentage of dysinaptic inhibition, presynaptic inhibition and post-activation depression was decreased in the spastic lower limb of the study group, compared to the intact lower limb and the control group. While this decrease was espicially in 2 and 5 ms interstimulus interval for disinaptic inhibition, in 20, 80, 100, 150 ms interstimulus interval for presynaptic inhibition. In the examinations performed at the 1st and 3rd months after the BoNT injection, it was found that the disinaptic and presynaptic inhibition of the study group, which decreased in the spastic lower limb of the study group, increased and reached similar levels with the lower limb of the control group and the intact lower limb. The percentage of post-activation depression, which decreased in the spastic lower limb of the study group before the BoNT application, reached similar levels with the intact lower limb of the study group and the lower limb of the control group at the 1st month after BoNT application. The percentage of post-activation depression in the 3rd month after the BoNT application, the intact lower extremity of the study group and the lower extremity of the control group were found to be decreased. While the dysinaptic inhibition level of the control group and the intact lower extremity of the study group were within normal limits before the BoNT administration, it was found that the disinaptic inhibition decreased in the intact lower extremity of the study group after the first month of BoNT administration. In the present study, it was found that presynaptic inhibition, dysinaptic inhibition and the percentage of postactivation depression decreased in patients with spasticity. BoNT administration provides both clinically, MRS and MAS values, and electrophysiologically improvement, with the effect of increasing the percentage of presynaptic, dysinaptic and post-activation depression. The spinal reflex change in the intact extremity after BoNT administration supports the central mechanism of action of BoNT. Keywords:Botulinum A toxsin, dysinaptic inhibition, post-activation depression, presynaptic inhibition, spasticity