Location
Advantages
Disadvantages
Ideal uses
Buttock
The generator is close to the implant site for the lumbar and thoracic spine
Patients with implants for back and leg pain do not require repositioning
The amount of adipose tissue is adequate in normal or obese patients
The generator can cause pain from irritation by the belt or clothing
In the immediate postoperative period, putting pressure on the tissue when sitting can open the wound (a greater concern for the obese patient)
Bending at the waist can place pressure on the wiring and may cause concern about migration
Sacral and caudal implants
Lumbar and thoracic spine implants
Abdomen
The generator is in an area with low pressure during sitting and lying
The generator is easily accessible for patient programming
The amount of wiring between the spine and the pocket may increase the risk of lead migration
In obese patients, the abdominal wall contour may lead to generator discomfort
When the leads are implanted simultaneously with the generator, the patient must be repositioned, reprepped, and redraped, a process that can increase the risk of infection
Patients who have discomfort from implants at other sites
Staged implant procedures, in which the trial leads are surgically implanted for the trial
Peripheral nerve implants of the pelvis, abdomen, or chest wall
Posterior flank
The ideal implant site for most implants
The location above the beltline has less stress on the tissue than the buttock
The area is less contaminated, owing to its distance from the anus and pelvis
Compared with the buttocks and abdomen, the stress on the leads is less when tunneling from the cervical spine and head and neck; this may reduce the risk of migration
Lumbar incisions are in close proximity to the flank, which may reduce the risk of migration
Sensitivity may result in pain at the generator site
Lumbar, thoracic, and cervical spine implants
Head and neck implants
Spine implant site, through same incision (possible for very small generator)
The distance between the spinal leads and the generator reduces the risk of migration
Single incision means fewer sites to become infected
Excessive wire length of the leads may make it difficult to place the generator into the pocket
Discomfort may occur with sitting or reclining
Patients with adequate tissue to support a generator in the paravertebral tissue
Chest
Chest wall position puts minimal stress on implants in the occiput, and facial nerves for peripheral implants
Area is sometimes difficult to reach by tunneling (When tunneling from the head and neck, it is important to be aware of the vessels of the neck and the lung position)
Tunneling must occur over the clavicle
Implants of the head and neck, including peripheral nerve and intracranial nerve implants
Subpectoral
May avoid the risk of skin erosion in children or patients with very low body fat
Technically difficult procedure requires additional training
Children or very thin patients without enough subcutaneous fat to support the metal under the dermis
Extremity (possible for small generator)
Not necessary to tunnel the wiring over joints, which can cause migration
The subcutaneous tissue of the limb may not support the device, because of pain or erosion
Site not possible with larger internal programmable generators
Peripheral nerve implants
Axillary line at T4
Reduced need for tunneling, compared with flank or buttock
Brassiere can be used to secure the antenna of a radiofrequency device
The tissue may be irritated by arm movement
Device may be difficult to reach with the opposite arm for programming
Cervical spine or head and neck implants
New devices are becoming smaller, and the choice of pocketing sites may continue to evolve, providing less impact on body contours and greater comfort. One factor affecting the selection of the surgical site is the direction of Langer’s lines, sometimes called cleavage lines, which correspond to the natural orientation of collagen fibers in the dermis (Fig. 12.1). Knowing the direction of Langer’s lines within a specific area of the skin is important for surgical operations, particularly cosmetic surgery. Given a choice about where and in what direction to place an incision, the surgeon may choose to cut in the direction of Langer’s lines. Incisions made parallel to Langer’s lines may heal better and produce less scarring than those that cut across. Incisions perpendicular to Langer’s lines have a tendency to scar and create an unsightly cosmetic outcome, although sometimes such incisions are unavoidable.
