Neurosurgeons' Armamentarium for the Management of Refractory Postherpetic Neuralgia: A Systematic Literature Review.

BACKGROUND/AIMS: Postherpetic neuralgia (PHN) can be refractory to both medical and minimally invasive treatments. Its complex pathophysiology explains the numerous neurosurgical procedures that have been implemented through the years. Our objective was to summarize all available neurosurgical strategies for the management of resistant PHN and evaluate their respective safety and efficacy outcomes. METHODS: A comprehensive systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: A total of 38 studies comprising 811 patients with refractory PHN were included. The safety and efficacy of the following procedures were investigated: spinal cord stimulation (SCS), dorsal root entry zone (DREZ) lesioning, intrathecal drug delivery, caudalis DREZ lesioning, dorsal root ganglion (DRG) radiofrequency lesioning, peripheral nerve stimulation, gamma knife surgery, deep brain stimulation, cordotomy, percutaneous radiofrequency rhizotomy and Gasserian ganglion stimulation. CONCLUSIONS: There are several available neurosurgical approaches for recalcitrant PHN including neuromodulatory and ablative procedures. It is suggested that patients with resistant PHN undergo minimally invasive procedures first, including SCS, peripheral nerve stimulation or DRG radiofrequency lesioning. More invasive procedures should be reserved for refractory cases. Comparative studies are needed in order to construct a PHN neurosurgical management algorithm.

Limited Midline Myelotomy for Intractable Visceral Pain: Surgical Techniques and Outcomes.

BACKGROUND: Limited midline myelotomy targets the midline nociceptive pathway for intractable visceral pain. Multiple techniques are available for limited midline myelotomy; however, outcome data for each technique are sparse. OBJECTIVE: To review our experience with open and percutaneous approaches for limited midline myelotomy for intractable visceral pain. METHODS: Patients who underwent limited midline myelotomy for intractable visceral pain were reviewed. Myelotomy was performed using 3 techniques: open limited myelotomy, percutaneous radiofrequency myelotomy, and percutaneous mechanical myelotomy. Demographic and perioperative clinical data were recorded. In addition to the visual analog scale and Karnofsy performance score, outcomes were categorized as excellent (no pain), good (considerable reduction in pain, not requiring opioids stronger than codeine), fair (minimal reduction in pain, but no change in opioid medication requirement), and poor (no reduction in pain). RESULTS: Eight patients (median age 56.5 yr, 6 females) underwent limited myelotomy. Four patients underwent open limited thoracic myelotomy with excellent pain outcomes. Three patients underwent percutaneous radiofrequency lesioning with fair (n = 1) and poor outcomes (n = 2). One patient underwent percutaneous mechanical lesioning with a good outcome (n = 1). The median duration of follow-up was 11 wk (2-54 wk). Two patients reported minor sensory complications after the procedure. CONCLUSION: In our preliminary experience, outcomes for open limited thoracic myelotomy were superior to percutaneous approaches. Given the limited utilization of this technique, multicenter registries are needed to further evaluate the best surgical technique for limited midline myelotomy.

The present role of percutaneous cervical cordotomy for the treatment of cancer pain.

The results obtained by percutaneous cervical cordotomy (PCC) were analysed in 43 terminally ill cancer patients treated in our institution from 1998 to 2001. We wished to determine whether there is still a place for PCC in the actual clinical situation with its wide choice of pain therapies. All patients had severe unilateral pain due to cancer, resistant to opioids and co-analgesics. Following PCC, mean pain intensity was reduced from Numeric Rating Scale (NRS) 7.2 to 1.1. At the end of life, pain had increased to NRS 2.9. Initially following PCC a good result (NRS<3) was obtained in 95% of patients. At the end of life, a good result was still present in 69% of patients. Mean duration of survival after the intervention was 118 days (2-1460). In general, complications were mild and mostly subsided within 3-4 days. There was one case of partial paresis of the ipsilateral leg. PCC remains a valuable treatment in patients with treatment-resistant cancer pain and still deserves a place in the treatment of terminal cancer patients with severe unilateral neuropathic or incidence pain.

Technology improvements for image-guided and minimally invasive spine procedures.

This paper reports on technology developments aimed at improving the state of the art for image-guided minimally invasive spine procedures. Back pain is a major health problem with serious economic consequences. Minimally invasive procedures to treat back pain are rapidly growing in popularity due to improvements in technique and the substantially reduced trauma to the patient versus open spinal surgery. Image guidance is an enabling technology for minimally invasive procedures, but technical problems remain that may limit the wider applicability of these techniques. The paper begins with a discussion of low back pain and the potential shortcomings of open back surgery. The advantages of minimally invasive procedures are enumerated, followed by a list of technical problems that must be overcome to enable the more widespread dissemination of these techniques. The technical problems include improved intraoperative imaging, fusion of images from multiple modalities, the visualization of oblique paths, percutaneous spine tracking, mechanical instrument guidance, and software architectures for technology integration. Technical developments to address some of these problems are discussed next. The discussion includes intraoperative computerized tomography (CT) imaging, magnetic resonance imaging (MRI)/CT image registration, three-dimensional (3-D) visualization, optical localization, and robotics for percutaneous instrument placement. Finally, the paper concludes by presenting several representative clinical applications: biopsy, vertebroplasty, nerve and facet blocks, and shunt placement. The program presented here is a first step to developing the physician-assist systems of the future, which will incorporate visualization, tracking, and robotics to enable the precision placement and manipulation of instruments with minimal trauma to the patient.

Myelotomy through the years.

Although myelotomy was first designed to treat somatic pain by interruption of the decussating fibers of the spinothalamic tract, it was soon recognized that pain relief may be obtained in a wider distribution than the dermatomes represented by the interrupted nerves. In 1970, Hitchcock described relief of pain throughout the body by stereotactic production of a single lesion in the middle of the spinal cord at the cervico-medullary junction, a procedure named extra-lemniscal myelotomy by Schvarcz several years later. This led me to the observation reported in 1984 that pelvic pain might be controlled by a non-stereotactic lesion at the thoraco-lumbar area, which appeared to be particularly effective against visceral pain of cancer, in a procedure termed limited myelotomy. In 2000, Kim recognized that thoracic pain might be treated by a similar lesion in the high thoracic area, and termed his procedure thoracic dorsal column midline myelotomy. Up to that time, all authors had considered that pain relief was the result of interruption of a multi-synaptic pathway just dorsal to or within the central canal, which had not yet been defined. However, Willis identified a new pathway in the ventromedial dorsal columns in the post mortem spinal cord provided to him by my coauthor, which he further documented by animal physiologic studies. Nauta, at that same institution, reintroduced limited myelotomy based on those anatomical findings, naming the procedure punctate myelotomy. It must be recognized that all of these procedures have involved interruption of the same pathway, even before it was defined anatomically, and all authors provided similar observations about relief of particularly visceral pain.