ABSTRACT
Sacral nerve root stimulation (SNRS) is known to be effective in the treatment of pelvic motor dysfunction(1-4). Bladder and urethral motor disorders commonly treated include urinary urge incontinence, voiding/detrusor dysfunction, and urgency/frequency syndromes. To date, neurostimulation specific to bladder and urethral dysfunction has applied a unilateral, trans-sacral approach. (Interstim, Medtronic, Minneapolis, MN) Despite some success, this method has been associated with technical failures in maintaining electrode position(5,6). As an alternative, this case report describes the selective epidural application of a cephalocaudal ("retrograde") lead insertion method in a patient with severe detrusor dysfunction and urinary urge incontinence(7).
ABSTRACT
Background. Spinal cord stimulation (SCS) is being used with increasing frequency in the treatment of various chronic pain conditions. There is a paucity of reliable outcome data regarding changes in pain tolerance and peripheral sensory nerve function. The automated electrodiagnostic neuroselective sensory Nerve Conduction Threshold (sNCT) test measures painless current perception thresholds (CPTs) and atraumatic pain tolerance thresholds (PTTs). The ability of the sNCT test to independently evaluate small and large fiber function may have particular relevance for evaluating response to SCS. Methods/Results. Sixteen patients with implanted SCS systems and lower extremity neuropathic pain of greater than 6-months duration were tested using a standardized protocol, pre- and post-SCS. CPT and PTT measures (Neurometer, CPT/C Neurotron, Inc. Baltimore, MD) were obtained from the distal phalange of the most symptomatic extremity and at an ipsilateral asymptomatic control site. Only CPTs at the symptomatic site (2000 Hz only) and at the control site (5 Hz only) reached statistical significance. Changes in CPTs at other frequencies, and changes in PTTs at all frequencies (symptomatic and control sites) were not statistically significant. Conclusion. The results of this study appear to substantiate the postulates that both segmental and suprasegmental effects are involved in SCS-mediated analgesia. SCS modulates segmental large afferent fiber input as reflected by a statistically significant increase in large fiber CPTs (2000 Hz) at the symptomatic site post-SCS. A statistically significant increase in small fiber (5 Hz) CPTs at the control site suggests a central sensory (suprasegmental) modulating effect on nociceptive fiber activity. sNCT testing provided reliable outcome data for evaluating response to SCS.
ABSTRACT
Spinal cord stimulation (SCS) for the treatment of painful peripheral neuropathy (PN) has been met with mixed results. It has been suggested that early-stage symptoms that are sympathetically maintained (SMP) are more likely to respond to SCS, while progressive sympathetically independent symptoms (SIP) will not. Peripheral nerve stimulation (PNS), however, has successfully treated certain SIP presentations. With the advent of new selective nerve root stimulation (SNRS) strategies, the possibility of utilizing epidural, peripheral neurostimulation was investigated in a patient with endstage, diabetic, "dying back" peripheral SIP.
ABSTRACT
Objective. The conventional technique used to stimulate the lumbar dermatomes is by stimulation of the dorsal columns of the spinal cord. Until recently, stimulation of nerve roots had not been successfully accomplished. We had performed selective nerve root cannulations for the placement of temporary catheters at cervical, thoracic, lumbar, and sacral levels in chronic pain patients using a caudad rather than craniad approach. We hypothesized that by stimulating the nerve roots we could improve paresthesia coverage in areas which cannot be covered effectively by spinal cord stimulation (SCS). To test this hypothesis, we have performed trials of nerve root stimulation (NRS) in patients who had failed SCS, or who were not candidates for SCS because their pain was otherwise inaccessible to stimulation. Methods. Five patients who had been unresponsive to conservative treatment, surgery, or SCS underwent 7-day trials with NRS. The diagnoses included: ilioinguinal neuralgia, discogenic low back pain, failed back syndrome, vulvodynia, and interstitial cystitis. We collected paresthesia maps, pain maps, pain visual analog scale (VAS) scores, and patient satisfaction ratings. Results. Paresthesia coverage was above 75% in all patients. VAS scores declined from a mean of 9 ± 1.0 to 2.4 ± 2.1 (p < 0.05, n= 5), all 5 patients requested permanent implantation, and 4 have been implanted so far. Conclusions. Lumbar and sacral NRS trials resulted in adequate paresthesia coverage and effective pain relief in all 5 patients. Further clinical trials to evaluate long-term success rates and safety are indicated. Detailed mapping studies are needed to evaluate the relationship between electrode placement and paresthesia patterns as well as the optimal stimulation parameters.
ABSTRACT
Objective. To evaluate effectiveness of spinal cord stimulation (SCS) applied to complex regional pain syndrome I (CRPS I). To analyze trends to focus the design of a multicenter prospective study. Design. Retrospective multicenter series, 3 years. Outcome measures. We collected visual analog scales for pain and patient satisfaction data on n= 101 patients. Patients were divided into two groups: Group I had single-lead quadrapolar systems, Group II had dual-lead octapolar systems. Results. Mean pain scores decreased in both groups with a significantly greater decrease in Group II (p < 0.0001). 74.6% of Group II patients preferred multiple programming arrays with 15.5% requiring frequencies > 250Hz.; overall satisfaction scores were 70% in Group I and 91% in Group II (p < 0.05). Conclusions. SCS is an effective treatment of pain in CRPS I. Frequencies > 250Hz were necessary in some patients to maintain or re-establish pain control. Bilateral multielectrode leads appear superior with application of multiple arrays, permitting paresthesia steering without need for surgical revision. A multicenter, prospective design is needed applying dual-lead multichannel systems with high frequency capabilities in the treatment of CRPS I.
ABSTRACT
Objective. Since 1996 we have placed temporary catheters at the cervical nerve roots in chronic pain patients for the treatment of radiculopathy and complex regional pain syndrome. We investigated the possibility of placing electrodes both at the cervical spinal nerve and dorsal root ganglion for the purpose of neuromodulation. Methods. Anatomic and technical feasibility studies were performed on 4 human cadavers to examine the placement of electrodes at the cervical nerve roots. We proposed a novel trans-spinal approach to the cervical and upper thoracic nerve roots. We tested various approaches and insertion techniques. We collected radiographic images of the essential steps involved in this technique. Results. Successful placement was accomplished in 3 of the 4 cadavers at the C3, C4, C5, C6, C7, C8, T1, and T2 nerve roots. For placement at C5 to T2, we used a trans-spinal approach entering at the corresponding contralateral interlaminar space. However, due to the anatomy of the cervical nerve roots, vertebral artery, cervical plexus, and occiput, it was necessary to use a different technique for the upper cervical nerve roots. For placement at the C3 and C4 nerve roots, we made the initial insertion between the C1 and C2 lamina using curved needles which were advanced in a caudal direction transversing the median plane of the spine to arrive at the contralateral inter vertebral foramen of either C3 or C4. We were unable to cannulate either C1 or C2 in any of the cadavers. The required equipment included fluoroscopy, contrast dye, directable guide wires, electrodes, and curved needles. Conclusions. In human cadavers, a percutaneous technique was successful in the placement of neurostimulator electrodes at the cervical and upper thoracic nerve roots using a novel trans-spinal approach. New smaller electrode systems that can be placed in a transforaminal position safely may be needed.
ABSTRACT
Objective. Follow-up of 80 patients using multiple program spinal cord stimulation (SCS). Methods. For 30 months, we followed 80 chronic pain patients who had undergone SCS implantations at our center. Thirty-six patients had Failed Back Surgery Syndrome (FBSS). Patients were evaluated in patient-controlled stimulation mode (patients can select one of several specific programs in response to their activities and pain level). We collected visual analog pain scores, patient satisfaction scores, pain maps, and paresthesia maps. Results. We previously reported our preliminary findings (Neuromodulation 1998;1 :30-45). At 24 months all patients were using more than one program. At 30 months, 62 patients (76%) were using more than two programs as their preferred stimulation mode and three patients (4%) were satisfied with only one stimulation program. At 30 months all patients chose patient-controlled stimulation as their preferred mode of stimulation. A total of 18 patients (23%) were explanted. Mean pain scores declined from 8.2 at baseline to 4.8 (p < 0.05, n= 79). Paresthesia overlap was 91% (n= 79). Of the patients with FBSS, 81% reported that they were using their SCS daily. Conclusions. In spinal cord stimulation the use of multiple electrodes and multiple stimulation programs, together with advanced programmability, increases paresthesia overlap, reduces pain scores, and may improve patient satisfaction with SCS therapy. This study indicates a significant patient preference for multiple program SCS, if patients are given the option to choose between a single program SCS system or a multiple program SCS system.
ABSTRACT
Objective. To evaluate the effectiveness of spinal cord stimulation using multiple independent programmable electrode selections compared to simple continuous stimulation. Design. Prospective case series 2 years. Setting. Ambulatory care center. Patients. All chronic pain patients who underwent spinal cord stimulation treatment at our center from February 1995 until October 1996 entered the study as a consecutive sample (n = 80). Interventions. Patients were evaluated in continuous stimulation mode (single stimulation program) vs. multi-stimulation mode, (patients activate a series of stimulation programs simultaneously to cover all of their pain) and patient-controlled stimulation mode (patients can select a program in response to their activities and pain level). Outcome measures. We collected visual analog pain scores, patient satisfaction scores by stimulation mode, and paresthesia maps. Results. Mean pain scores declined from 8.1 at baseline to 4.6 with continuous stimulation, and to 3.1 with multi-stimulation and with patient-controlled stimulation (p<0.05). Paresthesia overlap improved from 74% with continuous stimulation to 91% with multi-stimulation, and to 89% with patient-controlled stimulation (p<0.05). None of the patients selected continuous stimulation. Thirty-two patients preferred multi-stimulation, and 48 patients preferred patient-controlled stimulation. Lead revision rates declined from 15% in our previous experience using continuous stimulation to 3.8%. Conclusions. Continuous stimulation was not selected by any patient in favor of multi-stimulation or patient-controlled stimulation. This study indicates that in spinal cord stimulation the use of multiple electrodes together with advanced programmability increases paresthesia overlap, reduces pain scores, reduces revision rates, and improves patient satisfaction with spinal cord stimulation therapy.
ABSTRACT
Objective. To examine the importance of posture on the efficacy of spinal cord stimulation in a population of chronic pain patients previously implanted with a spinal cord stimulator. Materials and Methods. Electrode leads (Octrode 2098, ANS) were placed percutaneously into the epidural space under fluoroscopic control (BV29, Phillips, Inc.) at either the cervical or thoracic vertebral level. Stimulation parameters were measured at least 24 h after initial Implantation, and as long as 3 y. All patients were asked to look forward and remain still in one of three positions: lying, sitting, and standing. At each posture, electrical stimulation was applied to the spinal cord. The voltages and pulse widths necessary to produce threshold paresthesia, therapeutic stimulation, and uncomfortable sensations were recorded. A stimulus frequency of 100 Hz was used for all subjects. Results. As previously described by Barolat(1), we found the thresholds for stimulation to be highest in the thoracic level. We also measured the largest usage range to be at this level. However, we found that this range varied greatly between patients and between postures. In 20 patients the threshold for paresthesia was lowest when lying, while in three patients it was lowest when sitting. The mean range and SD of stimulation required to achieve paresthesia at all three posture levels was found to be 0.113 ± 0.062 µC for leads in the cervical region (N = 11) and 0.494 ± 0.297 µC for leads in the thoracic region (N = 19). Conclusions. To provide adequate stimulation at all postures, multiple stimulation settings (programs) would be required.
