Multi-target neurostimulation for adequate long-term relief of neuropathic and nociceptive chronic pain components
A 46-year-old male patient (MP) presented to our neurosurgical pain clinic in 1989, with complaints of extreme intractable chronic pain of the lower back and in both legs. MP's prior surgical history included 14 spinal surgical procedures, including decompressive procedures, fusions, scar tissue removal for postsurgical epidural fibrosis, facetectomies, and laminectomies at multiple levels. Prior to coming to our clinic, in an attempt to manage his chronic pain condition, MP had been tried on multiple block injections, transcutaneous electrical nerve stimulation (TENS), narcotics, antidepressant, antianxiety, and sedation medications, in addition to physical therapy and rehabilitation programs. Intradural morphine was trialed, but had to be discontinued because it failed to produce meaningful analgesia and furthermore MP developed urinary retention and pruritus with this intervention. Eventually, MP was placed in hospice care under heavy sedation by pain management physicians for an apparently hopeless intractable pain situation.\nOn examination, MP was found to be arreflexic with dermatomal hypoesthesia in legs and arms. Straight leg raise test was positive at 30°, bilaterally. There was mild weakness in dorsiflexion of both feet, and generalized mild weakness of both legs. However, the motor examination was limited due to suboptimal cooperation by the patient, secondary to severe pain. MP's worst complaints were of intractable lumbar and bilateral leg pain.\nThe lumbar pain in general was continuously relentless, and excruciating, and was further exacerbated by any activity, including sitting, standing, walking, and valsalva maneuver. The leg pain worsened with standing, walking, and showed claudication. Besides exhibiting dermatomal hypoesthsia, sensation in either leg showed areas of allodynia and hyperpathia. However, there was no evidence of sympathetically mediated pain, or of any trophic changes. Anal sphincter tone was good and there was no incontinence, although there was a history of urinary dribbling and a subjective sensation reported of incomplete bladder emptying after urinating.\nMP was diagnosed as having a mixed pain syndrome, composed of a neuropathic radicular component in both legs plus a nociceptive component in the lower back, secondary to FBSS.\nUnder our care, MP first underwent SCS, using a single Medtronic paddle “Resume” (Minneapolis, MN) stimulator placed epidurally at the midline at T10, T11, and T12 through laminectomies []. Excellent bilateral pain relief was achieved, however, axial lower back pain remained. Since the SCS provided no benefit for the back pain, a decision was subsequently made to implant a DBS of the PVG on the nondominant sphere. For the DBS, a single medtronic brain electrode(s) was stereotactically implanted in the PVG, utilizing a Leksell (Atlanta, GA) stereotactic frame with CT guidance [Figures and ]. The DBS procedure achieved excellent axial spinal pain relief. The current stimulation parameters are as shown in .\nOver these past 22 years, MP has been closely followed. Whenever both SCS and DBS neuromodulation systems were operating and utilized simultaneously, complete relief of back and leg pain has been maintained. However, electrode programming adjustments have been carried out as necessary, such as after accidental exposure to magnetic fields or after generator battery depletion. In addition, wire-connector revisions were twice required after motor vehicle accidents.\nDuring each reprogramming visit, the generators for each of the SCS and DBS were turned on or off separately and in combination. An independent programming technician would operate this alternating activation, while the patient and physician remained uninformed as to which system was on or off at the time. The testing was carried out in this fashion to protect against a possible placebo effect or other external factor that could bias observed analgesic effects. Additionally, at least twice a year, subthreshold stimulations were carried out by other physicians who were blinded to the optimal programming of the systems; independently and consistently, there was complete correlation among the various physicians, patient response, and visual analog pain scaling with each programming variation.\nThese tests showed specific and independent analgesic effects of the two implanted neuromodulation systems. The SCS induced analgesia specifically for the neuropathic bilateral leg pain, and produced no benefit on its own for the nociceptive axial spinal pain. Conversely, the PVG DBS stimulation was specific for the nociceptive lumbar pain and, on its own, had no effect at all on the leg pain. Whenever both systems were off, both nociceptive and neuropathic pains were excruciating, rated as 10/10 by the patient. Whenever both systems were on with optimized stimulation programming, the patient consistently reported pain as 0/10.\nAside from the intermittent stimulator adjustments that were required over the years, MP's chronic pain condition has been completely controlled with the neuromodulation intervention for the past 22 years. He has been able to return to living a normal life without interference by chronic pain in his activities. He no longer goes to physical therapy/rehabilitation, no longer takes any medication for chronic pain, and is no longer followed psychiatrically. MP's pain is currently controlled only with combined SCS/PVG-stimulation.