The implantable neurostimulation system of today consists of four general subsystems--the pulse generator, the lead and electrode system, the physician programmer, and the patient controller (see Figure 3 in "Neurostimulation in the New Decade" [6]).
Pulse generator. This system is shaped much like a cardiac pacemaker, a device comprised of a thin titanium shell housing batteries and capacitors, microelectronics, and mechanical framework. Most neurostimulation products borrowed technology from pacemakers and defibrillators, which enabled neurostimulation pioneers to develop clinical therapies from already-established platform technology.
Lead and Electrodes. The lead is a thin, shielded wire that stems from the pulse generator’s header, which is a polyurethane molded connector on the device. An electrode is located on the distal tip of the lead. This system applies low-level electrical current from the pulse generator to a targeted nerve or a specific location in the brain.
Physician programmer. This nonimplanted handheld device communicates with the implanted pulse generator via telemetry. The physician uses the programmer to set the initial device parameters that drive therapy, such as signal output current, frequency, pulse width, and on-off time. The programmer is also used for follow-up visits as the physician optimizes the device parameters, tailoring therapy to the individual patient.
Patient controller. The patient interface, also a nonimplanted handheld device, allows patients to modulate their own therapy as needed. It can record and send data from the patient to a central database for an off-site physician to review.
In addition to these four subsystems, SCS devices specifically include an external power source to recharge the implanted pulse generator’s battery, necessitated by the continuous output of higher energy.
Return to article: Neurostimulation in the New Decade [6]