Field of the Invention
The present invention is directed generally to the field of medical electro-medical therapy devices, and more particularly to implantable stimulators and stimulator systems used in neurological rehabilitation for the treatment of traumatic and non-traumatic injury or illness.
Description of the Related Art
Prior art implantable neurostimulator devices have been used to deliver therapy to patients to treat a variety of symptoms or conditions such as chronic pain, epilepsy, and tremor associated with and without Parkinson's disease. The implantable stimulators deliver stimulation therapy to targeted areas of the nervous system. The applied therapy is usually in the form of electrical pulse at a set frequency. The current is produced by a generator. The generator and an associated control module may be constructed from a variety of mechanical and electrical components. The generator is typically housed in a casing made of biocompatible material such as titanium, allowing for surgical placement subcutaneously within the abdomen or chest wall of a patient by someone with ordinary skill in the art of orthopedic spine and neurosurgery.
The stimulator is attached via one or more leads to one or more electrodes that are placed in close proximity to one or more nerves, one or more parts of a nerve, one or more nerve roots, the spinal cord, the brain stem, or within the brain itself. The leads and electrode arrays may vary in length, and are also made of a biocompatible material.
Historically, implantable stimulators and their attached electrodes positioned outside of the brain around the spinal cord, nerve roots, spinal nerves, and peripheral nerves have been used to manage and treat chronic pain; none to date have been commercially used or approved to restore function. Further, none have been aimed at permanent remodeling of the nervous system. Attempts to restore function in neurologically impaired subjects have been limited to adjunctive modalities, such as physical and occupational therapy with emphasis on adaptation to disability. Little progress has been achieved in actually restoring normal functional capacity to damaged nerve tissue with the use of an implantable neurostimulator.
Impressive levels of standing and stepping recovery have been demonstrated in certain incomplete spinal cord injury (“SCI”) subjects with task specific physical rehabilitation training. A recent clinical trial demonstrated that 92% of the subjects regained stepping ability to almost a functional speed of walking three months after a severe yet incomplete injury. Dobkin et al. (2006) Neurology, 66(4): 484-93. Furthermore, improved coordination of motor pool activation can be achieved with training in patients with incomplete SCI. Field-Fote et al. (2002) Phys. Ther., 82 (7): 707-715.
On the other hand, there is no generally accepted evidence that an individual with a clinically complete SCI can be trained to the point where they can stand or locomote even with the aid of a “walker.” Wernig (2005) Arch Phys Med Rehabil., 86(12): 2385-238. Further, no one has shown the ability to regain voluntary movements, and/or to recover autonomic, sexual, vasomotor, and/or improved cognitive function after a motor complete SCI.
Therefore, a need exists for a neurostimulator device configured to deliver stimulation through an electrode array that will help a patient regain voluntary movements, and/or recover autonomic, sexual, vasomotor, and/or improved cognitive function after a motor incomplete SCI or motor complete SCI. The present application provides these and other advantages as will be apparent from the following detailed description and accompanying figures.