Lateral Cord Stimulation Decreases Spastic Electromyographic Spreading: Responses in a Brain-Damaged Pig Preparation

Abstract

Objective. The aim of our work was to investigate whether lateral stimulation of the spinal cord, lateral cord stimulation (LCS), results in inhibition of the spastic phenomena of upper motor lesions in an animal model. Methods. This study was conducted using an animal model consisting of surgically brain damaged pigs subjected to unilateral cortical and subcortical brain lesions. A double laminectomy at cervical (C3-C4) and lumbar (L3-L6) was performed, and spastic thresholds of abnormal electromyographic responses, disseminated to adjacent segments, facilitated by spinal liberation, and produced by extradural electrical stimulation of the fourth lumbar root, were measured before and after cervical stimulation of the LCS. The variable studied was the minimal amount of current of LCS necessary to abolish electromyographic responses in the L7 myotome, away from the stimulated L4 nerve root. Results. Experiments in 12 animals showed a significant increase of threshold after LCS, with a marked posteffect, signaling a less abnormal threshold. Conclusions. This experiment demonstrated that LCS produces threshold increases to abolish abnormally propagated electromyographic evoked responses induced by the electrical stimulation of the fourth lumbar root in pigs with experimental cortical and subcortical brain lesions.