Brain implants
 
 

A neuroprosthetic device uses electrical fields to activate neurons. It is used to replace sensory functions, motor functions, or used in the central nervous system to activate or suppress central structures that, due to a disease, are either inactive or hyperactive.


Cochlear implant

The clinically most successful neuroprosthetic device is the cochlear implant. It replaces the non-functional inner ear by direct electrical stimulation of the auditory nerve. So far it has been implanted in well over 400.000 subjects. As the rule they can undestand spoken language and even use the telephone. It‘s remarkable success has allowed to use it in „prelingually“ deaf children who then learn the mother language using this device. Some 100.000 children have been already implanted (read more...).


Deep brain stimulation

Devices for deep brain stimulation activate brain nuclei of the motor system to interrupt pathological activity or induce activation of the targeted structure. For this, the electrodes have to be implanted in a stereotactic approach deeply into the brain. It is used for therapy of some forms of Parkinson‘s disease, but treatment has been suggested also for other neurological disorders.


Brainstem implants

In the auditory system, use of central nervous prostheses has reached some success using brainstem implants. These are used if the auditory nerve is not available for stimulation with a cochlear implant (due to inborn agenesis, trauma or tumor removal). They are not as successfull as cochlear implants, but in some patients allow speech understanding.


Stimulation of spinal cord and peripheral nerves

Spinal cord stimulation has been used for controlling spinal function, including e.g. ,sacral modulation‘ for control of bladder functions. One important target of this stimulation is control of chronic pain. For this purpose, stimulators have been implanted in more than 100.000 patients.

Also after spinal cord injury, these devices could in the future allow stimulation of neurons controlling the limb muscles to secure standing, walking and sensory perceptions.


Retinal implants

Similarly as cochlear implants, retinal implants have been suggested for replacement of the non-functional eye. Due to anatomical differences compared to the ear and the resulting technical issues, this device is not yet broadly used and research on these prostheses is ongoing.

One application is also stimulation of the visual cortex (see video), nonetheless, at present this technology is in the research phase.

 

Links Cochlear Implant:

  1. Cochlear

  2. MedEl

  3. Advanced Bionics

  4. Neurelec

Links Deep Brain Stimulation:

  1. Medtronic

Links Cortical Stimulation:

  1. Utah electrode array

  2. Neuronexus probes

  3. Blackrock Microsystems