Bilateral somatosensory cortex disinhibition in complex regional pain syndrome type I.

OBJECTIVE: In a previous study, we found bilateral disinhibition in the motor cortex of patients with complex regional pain syndrome (CRPS). This finding suggests a complex dysfunction of central motor-sensory circuits. The aim of our present study was to assess possible bilateral excitability changes in the somatosensory system of patients with CRPS. METHODS: We measured paired-pulse suppression of somatosensory evoked potentials in 21 patients with unilateral CRPS I involving the hand. Eleven patients with upper limb pain of non-neuropathic origin and 21 healthy subjects served as controls. Innocuous paired-pulse stimulation of the median nerve was either performed at the affected and the unaffected hand, or at the dominant hand of healthy controls, respectively. RESULTS: We found a significant reduction of paired-pulse suppression in both sides of patients with CRPS, compared with control patients and healthy control subjects. CONCLUSION: These findings resemble our findings in the motor system and strongly support the hypothesis of a bilateral complex impairment of central motor-sensory circuits in CRPS I.

[Comparable disorder of the body schema in patients with complex regional pain syndrome (CRPS) and phantom pain]. / Vergleichbare Störung des Körperschemas bei Patienten mit komplexem regionalem Schmerzsyndrom (CRPS) oder Phantomschmerz.

In patients with complex regional pain syndrome (CRPS) a disruption of the body schema has been shown in an altered cortical representation of the hand and in delayed reaction times (RT) in the hand laterality recognition task. However, the role of attentional processes or the effect of isolated limb laterality training has not yet been clarified. The performance of healthy subjects (n = 38), CRPS patients (n = 12) and phantom limb pain (PLP) patients (n = 12) in a test battery of attentional performance (TAP) and in a limb laterality recognition task was compared and the effect of limb laterality training in CRPS patients and healthy subjects evaluated. The RTs of both CRPS and PLP patients were significantly slower than those of healthy subjects despite normal TAP values. The CRPS and PLP patients showed bilaterally delayed RTs. Through training RTs improved significantly but the RTs of CRPS patients remained slower than those of healthy subjects. In this study an equal disruption of the body schema was found in both CRPS and PLP patients which cannot be accounted for by attentional processes. For CRPS patients this disorder cannot be fully reversed by isolated limb laterality recognition training.

[Success of treatment in higher stages of pain chronification as well? An evaluation of the Mainz pain staging system based on the QUAST-analysis sample]. / Behandlungserfolg auch bei höherer Schmerzchronifizierung? Eine Auswertung des Mainzer Stadienmodells auf Basis der QUAST-Analysestichprobe.

BACKGROUND: More than 10 years ago Gerbershagen gave a pessimistic prognosis for treatment success in patients with higher stages of pain chronification. To date only few studies concerning this statement exist and the results are inconsistent. The objective of this study was to evaluate the prognostic validity of the Mainz pain staging system (MPSS) in a large multicenter sample. It was assessed whether effects of treatment in patients with higher stages of pain chronification are less than those in other patients. Of further interest was whether treatment success is related to different outcome measures. METHODS: A total of 1,461 patients with the pain syndromes headache, neuropathic pain, back pain or algiomuscular pain and arthralgia were enrolled in the analysis. They were selected from the QUAST analysis sample which includes patients from 19 cooperating pain clinics. All patients had completed the German pain questionnaire prior to pain treatment and these data were compared with the last available questionnaire during the course of treatment. Outcome measures were pain intensity, psychological disability scores and patient global impression of success (PGIS). RESULTS: Analysis showed a significant improvement of all outcome measures in every MPSS stage. The greatest improvement was noted for pain intensity whereas outcome variables regarding mental health revealed the lowest improvement. Compared with patients with low pain chronification, changes in pain intensity were smaller for patients with the highest MPSS stage III but even in these patients the strength of effect was more than 0.80. About 50% of all patients showed a reduction of pain intensity of 2 or more points on an 11 point numerical rating scale and 46.6% of patients with a MPSS stage III showed this improvement. Importantly, PGIS was independent of the stage of chronification. Nearly 45% of all patients evaluated the treatment success as good or very good. CONCLUSIONS: According to the view of the patients, treatment in specialized pain centres is successful even in the highest stage of pain chronification. This notwithstanding, success of treatment must not be confounded with the efficacy of an intervention. It has to be noted that the results of the current study do not allow conclusions regarding efficacy of treatment.

[Characterization of chronic pain patients in German pain centers : core data from more than 10,000 patients]. / Patientenkollektiv deutscher schmerztherapeutischer Einrichtungen : Kerndaten von mehr als 10.000 Patienten.

BACKGROUND: In 1998 the board of the DGSS introduced a computerized documentation system named QUAST (quality assurance in pain therapy) building the foundation for a large, anonymous database that served as a data source for the statistical characterization of clinically relevant profiles of patients in German pain clinics. METHODS: A total of 10,054 data files collected between 1998 and 2004, including socio-demographic as well as psychometric and pain parameters were analyzed. RESULTS: The main pain diagnoses found in the database sample were back pain (37%), neuropathic pain (21.4%), soft tissue or arthralgia pain (19.5%) and headache (10.6%). The average duration of illness upon presentation at pain clinics was 7 years, nearly 20% contacted it within the first year. Of the sample, 43.8% of the patients were in the second chronicity stage and 39.0% in the third stage of the Mainz Pain Staging System (MPSS). Psychological measurements concerning despression, pain disability and quality of life indicated a great amount of psychological distress. Pronounced differences between main diagnostic groups were observed not only for psychological factors but also for direct pain parameters. CONCLUSIONS: The documented data differ from other population-based data collections. In contrast to common belief there are a considerable number of patients who find access to specialized pain therapy institutions at an early stage of their illness. The hitherto regular use of generic, syndrome-overlapping diagnosis and treatment tools should be reconsidered taking into account the differences found between the main pain diagnosis groups. Lastly, this analysis provides current data on the psychological state of chronic pain patients showing a high degree of psychological distress and underlying the need of psychotherapeutic interventions in the treatment of chronic pain patients.

[Visual cortex in the Tolosa-Hunt syndrome. Functional imaging for the detection of a psychogenic disorder--a case report]. / Visusstörungen beim Tolosa-Hunt-Syndrom. Untersuchung mit der funktionellen Magnetresonanztomographie zur Abgrenzung psychogener Störungen--Ein Fallbericht.

Besides painful ophthalmoplegia, patients suffering from Tolosa-Hunt syndrome often present increasing loss of visual perception. The impairment of the optic nerve leads to a delay of the VEP (visual evoked potentials) responses. Using the method of magnetic resonance imaging (MRI), some patients present unspecific alterations in the vicinity of the optic nerve. However, both methods (VEP and MRI) are unsuitable to assess the effect of an impaired optic nerve function on neuronal processing in the visual cortex. We report one patient suffering from Tolosa-Hunt syndrome affecting the optic nerve. We used fMRI (functional magnetic resonance imaging) to show how this impairment of the optic nerve alters cortical processing of visual information. The activity of the unaffected visual cortex was bilaterally reduced when compared to healthy volunteers but greater that obtained from patients suffering from bilateral occipital infarction. Our results offer new opportunities to assess the efficiency of therapy in patients with increasing loss of visual perception due to the Tolosa-Hunt syndrome. Further studies are necessary to investigate, whether fMRI also provides the possibility to assess the efficiency of drug therapy on optic nerve function.

[Validation of the German Mainz Pain Staging System in different pain syndromes]. / Validität des Mainzer Stadienmodells der Schmerzchronifizierung bei unterschiedlichen Schmerzdiagnosen.

OBJECTIVE: Our study was carried out to clarify whether differences in pain intensity,pain-related disability,depression and quality of life change with respect to the stage of chronicity of the Mainz Pain Staging Study (MPSS) in different pain syndromes. Keywords. METHODS: All patients with an initial pain clinic consultation from July 2000 to July 2001 and suffering from four major pain syndromes ("headache", "neuropathic pain", "back pain" or "muscle and joint pain") were included. Indicators of validity were several self-rating scales from the German pain questionnaire of the German Chapter of the International Association for the Study of Pain (DGSS). Patient data were collected using QUAST, a database environment specifically developed for documentation and quality assurance in pain therapy. An assessment was made for each of the four major diagnoses to determine whether patients in the three chronicity stages differed in their psychometric test results. In addition,the four diagnosis groups were tested for differences from one another. RESULTS: A total of 862 patient charts with documented pain syndromes and MPSS were extracted and analyzed. The extent of the subjective psychosocial stress and disability increased in all diagnosis groups and was correlated with the chronicity stage. The proportion of patients with an indication of clinically relevant depression (ADS score >23) increased with chronicity regardless of the pain diagnosis. The four main diagnosis groups differed with respect to the chronicity stage according to MPSS (P<0.001), with headache patients being classified predominantly as stage I. Patients with an additional pain diagnosis had a higher chronicity stage (P<0.001). CONCLUSION: Our results underline the validity of the MPSS for the four diagnosis groups examined; however, pain diagnosis must be controlled in all studies using chronicity stage as an independent variable, e.g., therapy studies. For optimal results physicians must closely follow the test instructions of the MPSS.

Predicting subjective disability in chronic pain patients.

Subjective disability is considered as the variable that reflects the impact of chronic pain on a patient's life. This study examines the questions of which syndrome or patient characteristics determine subjective disability and whether there are differences between samples of patients with chronic headaches and low back pain. Direct pain variables and depression, pain coping strategies, and pain-related self-statements (including catastrophizing) are introduced into multivariate regression analyses as potential predictors of disability using a sample of 151 pain patients. Disability is not predicted by pain severity in patients with headaches or back pain. Psychological variables, especially coping strategies, are far more influential. Coping explains more variance in disability in the headache sample than in the chronic law hack pain group, whereas depression is more relevant for the degree of disability in the back pain sample. In this study, we present a critical analysis of possible interpretations of our results. We point to an overlap of concepts underlying some of the variables used: this overlap also considerably invalidates conclusions drawn from a multitude of studies done in this field, including the one presented. We strongly argue for a conceptual clarification, and consequently for the revision of assessment instruments, before further empirical work in this area is done.