Percutaneous cephalocaudal implantation of epidural stimulation electrodes over sacral nerve roots--a technical note on the importance of the lateral approach.

OBJECTIVE: Idiopathic overactive bladder, urgency-frequency syndromes, interstitial cystitis, pudendal neuralgia, vulvodynia, prostadynia, and coccygodynia have been effectively treated with sacral nerve root modulation. This is most commonly performed with placement of electrodes via a transforaminal approach, predominately to the S3 foramen. This approach is limited by a high lead migration rate and the limitations of stimulating a single nerve root. Beginning in the 1990s, some centers began pursuing retrograde percutaneous placement from the lumbar spine, but adoption of this technique was limited by the technical difficulty of the approach. METHODS AND MATERIALS: We developed a lateral approach to the epidural space for these procedures, which has improved the learning curve and facilitated the application of the retrograde technique. In this technical note, we describe the "laterograde" approach. RESULTS: A focused description of the technique is presented in this technical report. The epidural space is accessed from lateral to medial with the bevel facing up to keep the approach to the "shingled" lumbar laminae shallow. CONCLUSION: The "laterograde" modification of cephalocaudal approach appears to be technically less difficult method for accomplishing sacral nerve root stimulator electrode placement over multiple roots.

Percutaneous peripheral nerve stimulation.

Since its inception in the 1970s, peripheral neuromodulation has become an increasingly common procedure to treat chronic neuropathic disorders. Historically, peripheral nerve stimulation (PNS) originated with the placement of large surface cuff electrodes, which was refined by the introduction of functional nerve mapping with circumferential electrical stimulation. This substantially improved the targeting of sensory fascicles. Surgical placement of spinal cord stimulation (SCS) 'button type' paddle electrodes was replaced when the introduction of percutaneous cylindrical SCS electrodes expanded the spectrum of PNS applications and improved the ability to target afferent sensory fibers as well as reducing the complication rate. To further refine functional mapping for the placement of these percutaneous electrodes, radiofrequency needle probes have more recently been employed to elicit paresthesias in awake patients to map the pain generators and guide treatment. In this chapter, we provide a description of the development and basic mechanisms of peripheral nerve stimulation, as well as a more detailed description of the two most commonly employed forms of peripheral nerve stimulation: occipital nerve stimulation for occipital neuralgia, and subcutaneous peripheral nerve field stimulation to stimulate free nerve endings within the subcutaneous tissue when the pain is limited to a small, well-localized area. The closely related ideas of internal and external targeted subcutaneous stimulation are also discussed.

Percutaneous lumbar discectomy using the Dekompressor system under CT-control.

In recent years, new minimally invasive therapies for the treatment of radicular pain associated with contained disc herniation have been introduced. These techniques have changed the field of interventional pain management. In a prospective, nonrandomized case study, we treated patients using the Dekompressor system guided by computed tomography instead of fluoroscopy. Pain scores, analgesic usage, and activities of daily living were assessed via structured telephone interviews 6 and 12 months after the procedure. Sixty-four patients were treated at 76 lumbar levels. Follow-up data after 12 months were obtained for all patients. The average reported pain level as measured by visual analog scale was 7.3 before the procedure and 2.1 after 12 months. Before the procedure, 61 patients (95%) used opioid or nonopioid analgesics regularly; after 1 year, a reduction in analgesic use was seen in 51 patients (80%). None of the patients reported procedure-related complications. When standardized patient selection criteria are used, treatment of patients with radicular pain associated with contained disc herniation using the Dekompressor can be a safe and efficient procedure.

Peripheral neurostimulation for the treatment of chronic, disabling transformed migraine.

BACKGROUND: Up to 5% of the general population suffers from transformed migraine. This study analyzes clinical responses of transformed migraine to cervical peripheral nerve stimulation. METHODS: Headache frequency, severity, and disability (Migraine Disability Assessment [MIDAS] scores) were independently measured in an uncontrolled consecutive case series of 25 patients with transformed migraine implanted with C1 through C3 peripheral nerve stimulation. All patients met International Headache Society (IHS) criteria for episodic migraine, as well as suggested criteria for transformed migraine, and had been refractory to conventional treatment for at least 6 months. Responses to C1 through C3 peripheral nerve stimulation were recorded. RESULTS: Prior to stimulation, all patients experienced severe disability (grade IV on the MIDAS) with 75.56 headache days (average severity, 9.32; average MIDAS score, 121) over a 3-month period. Following stimulation, 15 patients reported little or no disability (grade I), 1 reported mild disability (grade II), 4 reported moderate disability (grade III), and 5 continued with severe disability (grade IV), with 37.45 headache days (average severity, 5.72; average MIDAS score, 15). The average improvement in the MIDAS score was 88.7%, with all patients reporting their headaches well controlled after stimulation. CONCLUSIONS: These results raise the possibility that C1 through C3 peripheral nerve stimulation can help improve transformed migraine symptoms and disability. A controlled study is required to confirm these results.

New trends in neuromodulation for the management of neuropathic pain.

Since its first application in 1967, the methodology and technology of spinal cord stimulation for the management of chronic, intractable pain have evolved continuously. Despite these developments and improved knowledge of the effects of spinal anatomy and epidural contact configuration on paresthesia coverage, the clinical results of spinal cord stimulation-particularly the long-term effects-are still unsatisfactory in many patients. This dissatisfaction has come primarily from the failure of single-electrode configurations to provide consistent paresthesia coverage of the entire painful area. Therefore, new approaches were developed during the late 1990s that attempted to selectively cover one or more dermatomes with paresthesia as well as to provide sequential stimulation of different anatomic sites. These approaches have been applied both intraspinally and extraspinally by stimulating either the spinal nerves or the dorsal columns. To target parts of the latter, different methods have been developed and tested using either two-dimensional contact configurations or electronic field steering. These developments hold promise for improving long-term outcomes as well as increasing the number of pain conditions that can be treated with neuromodulation therapy. In this review, the history, theoretical basis, and evolution of these methodologies, as well as the ways in which they represent new trends in neuromodulation, are discussed.

Four Year Follow-up of Dual Electrode Spinal Cord Stimulation for Chronic Pain.

This paper reports on 80 patients using dual electrode, spinal cord stimulation (SCS) over a four-year period Implant status, stimulation mode, anode-cathode configuration (array), cathode position, paresthesia overlap, explantation rates, complications, Visual Analog Scores (VAS), and overall satisfaction were examined in patients implanted with dual 8 contact, staggered, percutaneous electrodes. All patients had undergone implantation for chronic axial and extremity pain [e.g., Failed Back Surgery Syndrome (FBSS), Complex Regional Pain Syndrome (CRPS)]. Outcomes were evaluated in view of our previous reports in this same group at 24 and 30 months (1,2). Data was collected by a disinterested third party. At 48 months, 18 of the original 80 patients were lost to follow-up. Of the 62 patients contacted, 33 remained implanted and 29 (47%) had been explanted. After an average evaluation of 85 arrays (PainDoc, Advanced Neuromodulation Systems, Plano, Texas), 88% of patients reported using one or two "best" arrays (bipolar or guarded tripolar) to maintain favorable paresthesia overlap (89%), VAS reduction (8.1 to 4.9), and overall patient satisfaction (63%). These arrays were most commonly positioned about the physiologic midline of the COL3-4 vertebral segments for upper extremity pain, and the T9-10 vertebral segments for low back and lower extremity pain. In contrast to our initial reports where essentially all patients preferred more than two arrays to maintain "best" paresthesia overlap and outcome, only 12% of these same patients maintained this trend in this long-term follow-up study. The arrays most commonly selected long-term as the "best" ones (88% of all electrodes) were narrow (adjacent contact) bipoles and guarded cathode tripoles (< 8 contacts). Thirty-five percent of patients with thoracic implants achieved paresthesia in the low back at 48 months. Explantation rates and overall patient satisfaction were significantly affected by painful radio frequency (RF) antenna coupling. This data supports the efficacy of dual electrodes in optimizing long-term SCS paresthesia overlap and complex pain outcomes.

Selective Nerve Root Stimulation (SNRS) for the Treatment of Intractable Pelvic Pain and Motor Dysfunction: A Case Report.

Interstitial cystitis is the most disabling nonmalignant disorder seen by urologists. Chronic debilitating urinary bladder symptoms (severe pain and pelvic floor muscular dysfunction) often progress despite maximal medical attempts at management. Although the exact cause remains unknown, a neuropathic etiology has recently been suggested( 1,2). This case report describes the use of Selective Nerve Root Stimulation (SNRS) for the treatment of intractable pelvic pain and motor dysfunction in a patient with Interstitial cystitis (IC).