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BACKGROUND: This study examined whether chronic neuropathic pain, modulated by a local anesthetic block, is associated with cortical magnetic field changes. METHODS: In a group of 20 patients with pain caused by unilateral traumatic peripheral nerve injury, a local block with lidocaine 1% was administered and the cortical effects were measured and compared with a control group. The global field power (GFP), describing distribution of cortical activation after median and ulnar nerve stimulation, was plotted and calculated. The effects on the affected hemisphere and the unaffected hemisphere (UH) before and after a block of the injured nerve were statistically evaluated. RESULTS: Major differences based on the GFP curves, at a component between 50 ms - 90 ms (M70), were found in patients: in the affected hemisphere the M70 GFP peak values were statistically significantly larger in comparison with the UH, and the GFP curves differed morphologically. Interestingly, the mean UH responses were reduced in comparison with the control group, a finding suggesting that the UH is also part of the cortical changes. At M70, the GFP curves and values in the affected hemisphere were modulated by a local block of the median or the ulnar nerve. The most likely location of cortical adaptation is in the primary somatosensory cortex. CONCLUSIONS: Cortical activation is enhanced in the affected hemisphere compared with the UH and is modulated by a local block. The UH in neuropathic pain changes as well. Evoked fields may offer an opportunity to monitor the effectiveness of treatments of neuropathic pain in humans. [ABSTRACT FROM AUTHOR]

Motor dominance is well established, but sensory dominance is much less clear. We therefore studied the cortical evoked magnetic fields using magnetoencephalography (MEG) in a group of 20 healthy right handed subjects in order to examine whether standard electrical stimulation of the median and ulnar nerve demonstrated sensory lateralization. The global field power (GFP) curves, as an indication of cortical activation, did not depict sensory lateralization to the dominant left hemisphere. Comparison of the M20, M30, and M70 peak latencies and GFP values exhibited no statistical differences between the hemispheres, indicating no sensory hemispherical dominance at these latencies for each nerve. Field maps at these latencies presented a first and second polarity reversal for both median and ulnar stimulation. Spatial dipole position parameters did not reveal statistical left-right differences at the M20, M30 and M70 peaks for both nerves. Neither did the dipolar strengths at M20, M30 and M70 show a statistical left-right difference for both nerves. Finally, the Laterality Indices of the M20, M30 and M70 strengths did not indicate complete lateralization to one of the hemispheres. After electrical median and ulnar nerve stimulation no evidence was found for sensory hand dominance in brain responses of either hand, as measured by MEG. The results can provide a new assessment of patients with sensory dysfunctions or perceptual distortion when sensory dominance occurs way beyond the estimated norm.

Contralateral somatosensory evoked fields (SEF) by whole head MEG after unilateral median and ulnar nerve stimulation of both hands were studied in 10 healthy right-handed subjects. Major parameters describing cortical activity were examined to discriminate median and ulnar nerve evoked responses. Somatic sensitivity showed high similarity in the 4 study conditions for both hand and nerve. The brain SEFs consisted of 7-8 major peak stages with consistent responses in all subjects at M20, M30, M70 and M90. Comparable inter-hemispheric waveform profile but high inter-subject variability was found. Median nerve induced significantly shorter latencies in the early activities than those of the ulnar nerve. The 3D cortical maps in the post stimulus 450 ms timeframe showed for both nerves two polarity reversals, an early and a late one which is a new finding. Dipole characteristics showed differential sites for the M20 and M30 in the respective nerve. Higher dipole moments evoked by the median nerve were noticed when compared to the ulnar. Furthermore, the results of the dipole distances between both nerves for M20 were calculated to be at 11.17 mm +/- 4.93 (LH) and 16.73 mm +/- 5.66 (RH), respectively after right hand versus left hand stimulation. This study showed substantial differences in the cortical responses between median and ulnar nerve. Especially the dipole distance between median and ulnar nerve on the cortex was computed accurately for the first time in MEG. Little is known however of the cortical responses in chronic pain patients and the parameter(s) that may change in an individual patient or a group. These results provide precise basis for further evaluating cortical changes in functional disorders and disease sequelae related to median and ulnar nerves.

We examined the contralateral hemispheric cortical activity in MEG (151 ch) after unilateral median nerve stimulation of the right and left hand in twenty healthy right-handed subjects. The goal was to establish parameters to describe cortical activity of the hemispheric responses and to study the potential ability to assess differences in volunteers and patients. We focused on the within-subject similarity and differences between evoked fields in both hands. Cortical activity was characterized by the overlay display of waveforms (CWP), number of peak stages, loci of focal maxima and minima in each stage, 3D topographic maps and exemplified equivalent current dipole characteristics. The paired-wise test was used to analyze the hemispheric differences. The waveform morphology was unique across the subjects, similar CWPs were noted in both hemispheres of the individual. The contralateral hemispheric responses showed a well defined temporal-spatial activation of six to seven stages in the 500 ms window. Consistently (in over 80% of subjects), the six stages across the subjects were 20M, 30M, 50M, 70M, 90M, and 150M. A 240M was present in the left hemisphere (LH) in 15/20 subjects and in the right hemisphere (RH) in 10/20. Statistics of the latencies and amplitudes of these seven stages were calculated. Our results indicated that the latency was highly consistent and exhibited no statistical mean difference for all stages. Furthermore, no mean amplitude differences between both hemispheres at each stage were found. The patterns of magnetic fields in both hemispheres were consistent in 70% of the subjects. A laterality index (L.I.) was used for defining the magnetic field amplitude differences between two hemispheres for each individual. Overall, the absolute amplitude of the brain responses was larger in the left than in the right hemisphere in the majority of subjects (16/20), yet a significant portion (4/20) exhibited right dominance of the N20m activity. Each individual exhibited a unique CWP, there was reliable consistency of peak latencies and mean amplitudes in median nerve MEG. Nevertheless, this study indicates the limitations of using the intact hemisphere responses to compare with those from the affected (brain) side and suggests caution in assuming full homology in the cortical organization of both hemispheres. This study provides some results to address clinical issues like which parameter describes individual differences best. Whether a genuine difference is found or whether any difference may simply represent the variability encountered in a normal population.

This article describes a project in which a national continuous quality improvement system and a payment scheme were explicitly linked, while introducing an expensive treatment (Spinal Cord Stimulation (SCS)) in the social health insurance benefit package, in The Netherlands. By linking a national CQI system and a payment scheme in a conditional financing policy a steering instrument for future control of the quality of neuromodulation treatment through SCS is created.

We present here a descriptive article on the development of a national quality system for neuromodulatory techniques in the Netherlands. In 1994, due to reimbursement difficulties in the Netherlands, a Neuromodulation Working Group (WGN) undertook an initiative to develop a national quality system for neuromodulation. It was believed that with official recognition of neuromodulation as a therapy by the health authorities in the Netherlands, a quality system for monitoring would then follow. To that purpose an observational study was performed. Integration of this entire primary process (from intake to control phase) was based upon an inventory of the practices of the most experienced medical specialists practicing neuromodulation in the Netherlands. Based on the study data, nine quality indicators were identified that would allow monitoring of the quality of care to patients in the Netherlands. The study resulted in a positive feedback to the National Health Insurance Board and the Ministry of Health in the Netherlands. Neuromodulation for chronic pain and disabling spasticity is now recognized and fully reimbursed within the limits of the newly developed quality system. We therefore conclude that developed quality systems can provide a basis for medical specialists to cooperate around groups of patients or diseases. These quality systems can facilitate implementation and innovation within the health care system. The role of medical specialists and their will to cooperate is essential.

Baseline and 12-month follow-up data from a prospective controlled study on patients treated with SCS for neuropathic limb pain (NLP) are analyzed critically. The outcome on pain, use of medication, and quality of life are reported and compared with the literature. Patients enrolled from April 1999 to December 2001 were part of a quality system study by the Dutch Working Group on Neuromodulation. In two years, more than 400 patients were admitted for several indications of chronic neuropathic pain. Failed back surgery syndrome (FBSS) and complex regional pain syndrome (CRPS) were the largest cohorts. FBSS was defined as persistent limb pain with/or without concomitant minor back pain after prior surgery for a slipped lumbar disc or spinal instability. SCS was a last resort therapy. Two criteria were used for eligibility: a SCL-90 score below 225 and a mean visual analog score (VAS) of four days according to Jensen of ≥ 5. One hundred sixty nine patients were registered for FBSS. Thirty four did not fulfill the eligibility criteria, and 135 received several questionnaires for baseline evaluation. Thirty patients did not have successful trial stimulation (< 50% pain relief), leaving 105 patients for implantation. The mean scores of the baseline evaluation were: SCL 137 (SD 28.3) and VAS 7.3 (SD 1.2), McGill pain questionnaire (MPQ) total PRI: 22.4 (9.4), Sickness Impact Profile (SIP) total score: 19.4 (SD10.1), ROLAND disability (RD) 16.9 (SD 3.5) and EUROQOL (EQ-5D) 55.2 (SD 14.5) (simple linear index). Medication quantification scale at intake was 11.5 (SD 7.9). 56.2% of the patients used one or more narcotic drugs at intake. 82% of the patients did not have a paid job at the time of inclusion. 61% of the patients lost their job due to their medical problems. Scores at 12-m follow-up were VAS 3.0 (SD 2.4), MPQ 10.8 (SD 8), SIP 11.7 (SD 9.4), EQ-5D 38.2 (SD 19.2) and RD 12.4 (SD 4.8). The difference between baseline and 12-m follow-up is statistically significant for all measures. We conclude that the outcome measures indicate that SCS significantly reduces pain and enhances quality of life in patients having NLP not responding to other adjuvant therapy. Recommendations are proposed to make studies more comparable.

Background: Because neuromodulation was not included in the national health insurance system, the Dutch Neuromodulation Group (DNG) developed national standards and a continuous quality improvement (CQI) system for consistency in application of neuromodulation techniques and in the quality of outcomes., Developing the National Quality Improvement System: A stepwise approach was used in which the following ten steps were taken: (1) selected participating medical specialists and their centers, (2) described the treatment protocol, (3) collected data in a national database, (4) organized feedback sessions for the DNG, (5) formulated quality indicators, (6) adjusted the process of treatment, (7) formalized the structure of the DNG, (8) defined responsibilities, (9) established procedures for future development, and (10) made agreements with payers., Discussion: Making reimbursement for expensive health care interventions contingent on a national CQI system created a powerful financial incentive to continuously provide effective care in an efficient manner.

Somatosensory evoked magnetic fields and electrical potentials were measured in eight patients with unilateral neuropathic pain. After median nerve stimulation on the painful side, the amplitudes of the evoked responses were enhanced 2 to 3 times at a latency of about 100 ms compared to the responses of the contralateral, unaffected side. After posterior tibial nerve stimulation an enhancement was found at latencies around 110 ms and 150 ms. The scalp distribution of the magnetic field at the latencies of "abnormal" responses was dipolar and the responses could be ascribed to a current dipole. Three (of the eight) patients underwent spinal cord stimulation (SCS) for their pain. The enhancement of the evoked responses to stimulation of the painful side decreased after spinal cord stimulation. After a long period of spinal cord stimulation only (e.g., a year) during which the patient reported to be pain free, these "abnormal" responses were no longer observed.

Since 1982, 229 terminally ill cancer pain patients were treated by the administration of epidural opioids. An adequate level of aid was provided by the coordinated efforts of the patients' general practitioner, the district nurse, and the anesthesiologist. Based on 9 yr of experience with this model, a project on quality improvement and organization of cancer pain control by infusion techniques in the home situation was proposed. The purpose of the study is to create a nationwide organization for cancer pain control for terminal patients on a home-care basis. Specially trained ambulatory field teams will be set up to collect and process the information necessary to make protocols and instructions.