The electrodes should be implanted at the time of muscle mobilisation. Deferred electrode implantation after graciloplasty is quite difficult to perform although possible.
Different types of electrodes have been used for stimulating the muscle:
A four-plate electrode (Resume quod, mod. 3587A Medtronic Inc., Minneapolis, MN, USA) or a two-plate electrode (Nice Implant®, Ft Lauderdale, FL, USA) were originally used by Williams et al. . This lead is fixed with non-absorbable sutures directly on the main trunk of the gracilis nerve, where it lies on the abductor magnus muscle far from the gracilis; the rationale for this solution is to achieve simultaneous activation of the motor units with the minimum impulse voltage, thus lengthening the life of the battery.
Baeten et al.'s  and Cavina et al.'s  prefer the use of a couple of intramuscular flexible coil platinum iridium electrode wires (model 4300 Medtronic Inc., Minneapolis) (cathode) passed perpendicularly through the muscle very close to the entry of the main branch of the nerve and another electrode (anode) positioned similarly about 4 cm distally and sutured to the epimysium. This is the technique now generally preferred because it is easier to perform and poses less risk of electrode dislocation. Furthermore the theoretical advantages of the four plates over the wire electrodes have not been demonstrated in a retrospective comparative study .
The plate or wire electrodes are then passed sub-cutaneously and connected to the IPG. The interposition of an extension set (mod 7495-51 Medtronic Inc., Minneapolis) was necessary using the four-plate lead, which was originally designed not for this purpose but for spinal stimulation.
Was this article helpful?