Dipole electrical stimulation employing direct current for recovery from spinal cord injury

Abstract

A system and method to treat neuromuscular conditions, including spinal cord injury, by what is characterized as dipole (two point) cortico-muscular stimulation. Two-point stimulation, with oppositely charged electrodes, allows pulsed, direct current to pass through the cortico-muscular pathway. The electrodes are placed on nerves, muscles, or a combination of both, that are on opposite sides of the spinal column, forming a current that passes across the spinal column. Further, an active electrode can be placed on the spinal column and a reference electrode can be placed outside the central nervous system. These methods improve functional recovery of the motor pathway.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority from U.S. Provisional Application Ser. No. 61 / 253,948, filed on Oct. 22, 2009 and U.S. Provisional Application Ser. No. 61 / 316,319, filed on Mar. 22, 2010, the entire contents of which are incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with support under New York State Department of Health (NYS / DOH) grant No. CO23684 and Professional Staff Congress at the City University of New York (PSCCUNY) grant No. 60027-37-39. The state of New York has certain rights in this invention.FIELD OF THE INVENTION[0003]The present invention generally relates to the field of providing stimulation of central nervous system tissue, muscles, nerves, or combinations thereof, and more particularly to a system and method for treating neuromuscular conditions through two-point electrical stimulation.BACKGROUND OF THE INVENTION[0004]The nerv...

AI Technical Summary

Benefits of technology

[0012]A system and method for treating neuromuscular conditions including spinal cord injury (SCI) are disclosed herein, which employ dipole (two point) cortico-muscular stimulation (“dCMS”). The system and method advantageously employ a discovery that utilizing a two point method of cortico-muscular stimulation dramatically improves the performance of the skeletal muscles after SCI. Two-point stimulation, with oppositely charged electrodes, allows pulsed, direct current to pass through the cortico-muscular pathway regardless of the extent of injury and number of spared neurons. These methods enable permanent functional recovery of the motor pathway.

[0013]The research leading to the present invention has demonstrated that dCMS substantially improved muscle twitch force and spinal cord responses in control and SCI animals, and that passage of pulsed direct current across the cortico-muscular pathway promotes stronger connections between spinal motor circuits and the motor cortex.

[0014]In one exemplary embodiment, the dCMS configuration involves an active electrode at a first point and a reference electrode at a second point, and is situated such that the current passes across the spinal cord. The first and second points may be the motor cortex, muscles, or a combination thereof. In one configuration, the active electrode can be situated at the motor cortex and the reference electrode is at a contralateral muscle (e.g., a partially isolated gastrocnemius muscle). The passage of pulsed direct current across the cortico-muscular pathway overcomes many of the excitability-confounding factors previously described. The advantage of using this method of stimulation is that the passage of such current will not be dependent on factors affected by lesion such as the degree of myelination, density of existing connections, synaptic strength and / or general excitability of the sensorimotor pathway. Instead, the current will passively flow along the core conductors of the target neuronal pathway leading to the activation of the entire pathway regardless of its morphological integrity. Dipolar cortico-muscular stimulation substantially improves muscle twitch force and spinal cord responses.

Problems solved by technology

Damage to the nervous system may result from a traumatic injury, such as penetrating trauma or blunt trauma, or a disease or disorder including, but not limited to Alzheimer's disease, multiple sclerosis, Huntington's disease, amyotrophic lateral sclerosis (ALS), diabetic neuropathy, senile dementia, stroke and ischemia.

After spinal cord injury (SCI), spared regions of the central nervous system are spontaneously capable of repairing the damaged pathway, although the process is very limited.

Moreover, despite the many promising treatment strategies to improve connections across the damaged spinal cord, the strength of connectivity and functional recovery of the impaired spinal cord are still unsatisfactory.

Therefore, one-point stimulation would be restricted in its efficacy and inclined toward stronger connections.

The loss of neuromuscular activity after SCI leads to inevitable abnormalities that limit the effectiveness of one-point stimulation by blocking excitatory responses from traveling across the sensorimotor pathway.

This maladaptive function will bias stimuli toward connections with better integrity, further limiting the effectiveness of localized stimulation.

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