Botulinum Toxin as a Neuro-Relearning Drug Tool in Motor Paralytic Disorders

R.   Venkata   Krishnan

Abstract

The clinical use of Botulinum toxin (BoTx) in motor paralytic disorders until now is limited to spasticity relief in isolated spastic muscle/s. This paper advocates that BoTx should be used as a neuro-relearning tool that can significantly improve recovery in motor paralytic disorders. BoTx generates redundant numbers of synapses at motor endplates and at spinal motoneuron-interneurons. It facilitates muscle activity-dependent synapse competition at these two sites. Redundancy and competition-based selection of synaptic connections are naturally occurring learning- related plasticity events during infant motor learning- now familiarly known as competitive-learning. Thus when injected in small doses to multiple muscles of a paralyzed limb, BoTx can recreate and replay those competitive-learning processes in the learningresistant paralyzed brain centers. Computational modeling, humanoid robot, and animal studies reveal that motor re) learning can be significantly faster if competitive-learning mechanisms are employed in the paralyzed system. A treatment protocol is presented that aims to keep the paralyzing effects of BoTx minimized while prolonging relearning duration. Recent clinical studies strongly attest that small-dose; multi-muscle, repeat regimens improve function. The principal objective of the present paper is that future multi-muscle clinical studies will take note of the relearning properties of BoTx and make full utilization of this therapeutic effect.

Keywords: Botulinum toxin, cerebral palsy, motor paralysis, spinal cord injury, stroke, traumatic brain injury (TBI)