Spinal cord injury often results in irreversible paralysis due to blocked communication between the brain and the spinal cord. While electrical stimulation of the spinal cord has been successfully applied to restore motor function in animal models, electrical stimulation in humans has been less effective for reasons not yet completely understood.

Impaired hearing affects the ability to communicate and often contributes to social isolation or diseases such as depression. It is most frequently caused by the loss of sensory hair cells which are involved in transmitting the audio signals to the cochlear nerve.