Biomedical Engineering Reference
In-Depth Information
When applications require leads to traverse a relatively long distance, an
extension lead is inserted in the circuit. This extension may have a more robust
design than the lead in order to address the design requirements. For example,
DBS applications often make use of an INS implanted in a subcutaneous pocket
inferior to the clavicle. Here, an extension lead traverses the neck, making
connection to the main lead at a location behind the ear on the skull. This
configuration allows the main lead to be designed for implanting in the brain,
while the extension lead can be designed for the significant mechanical demands
of traversing the neck region.
The leads used in neurostimulation are specifically designed for the particular
anatomical target being stimulated. Most important is the configuration of
electrodes on the lead. An electrode array design is used to optimize the ability
of the clinician to couple the stimulation voltage to the appropriate nervous
tissue (Figs 4.13 and 4.14). The wide variety of anatomical locations targeted for
neurostimulation can be grouped into two broad categories: those outside the
blood±brain barrier (SCS and peripheral nerve stimulation), and those that
4.13 Two versions of electrode spacing inDBS leads. Individual electrodes can
be programmed to be positive, negative, or off. The Model 3389 lead, on the
right, has electrodes more closely spaced together. This feature allows more
alternatives for stimulation within a smaller space, compared with the Model
3387 lead seen on the left (courtesy of Medtronic, Inc.).
