Clinical Applications of Intraspinal Microstimulation

Intraspinal microstimulation is a neuroprosthetic approach for activating specific spinal reflexes using penetrating electrodes chronically implanted into spinal cord. Artificial control of spinally mediated functions, such as arm and leg movement or bladder voiding, may be necessary in spinal cord injury, multiple sclerosis, cerebral palsy, amyotrophic lateral sclerosis, and spina bifida, when the brain becomes disconnected from spinal cord and a person loses control over these functions. Animal studies indicate the feasibility of efficient control of bladder voiding and limb movement. Development of novel microstimulation electrodes focuses on reduction of electrode dimensions for improved targeting efficiency, decreased tissue trauma, improved biocompatibility, and long-term safety and reliability of applied stimulation. Clinical usefulness of existing devices is limited by a lack of highly integrated and biocompatible neuroprosthetic systems, comprising high-density electrode arrays and integrated electronics for pulse generation and stimulation site addressing. Future developments will require a coordinated effort in the areas of neural prosthetic engineering, applied neurophysiology, neurosurgery, physical therapy, and rehabilitation. In the long term, clinical applications of intraspinal microstimulation may include treatments of such spinal cord-related disabilities, such as bladder and bowel emptying, sexual function, hand and arm control, and even walking. These treatments can address the long-standing needs of paralyzed patients aimed at improving their medical, psychological, social, and work-related conditions.