Technique and technical problems associated with implantation of neuroaugmentive devices.

The effectiveness of implantation of depth electrodes for pain control in (a) the primary thalamic relay nuclei, and (b) the periventricular gray matter or periaqueductal gray matter is reviewed. In a series of 39 patients, 14 achieved relief with no further need for medication, 16 were able to reduce their drug intake and 9 experienced no relief. These results are compared to those for a series of 76 patients reported on by an international study group of neurological surgeons. 61 patients in this series were considered to have had a successful result immediately after implantation of the electrode, but at the time of follow-up only 42 were still in this category. The implantation of depth electrodes requires a technique that fulfills the following criteria: (1) the procedure must be performed in a fully awake, cooperative patient; (2) a precise stereotactic technique must be employed, and (3) the effects of stimulation must be evaluated before the implant is made permanent. The most common complication was infection at the implantation site; this can be reduced by the use of Teflon-insulated percutaneous leads. Other complications include erosion of the hardware through the scalp and internal migration of the electrodes.