Annette M. Stolle

Central processing of acute muscle pain in chronic low back pain patients: an EEG mapping study.

The presence of perceptual sensitization and related brain responses was examined in 14 chronic low back pain (CLBP) patients and 13 healthy controls comparable in age and sex. Multichannel EEG recordings and pain ratings were obtained during the presentation of 800 painful electrical intramuscular and intracutaneous stimuli each to the left m. erector spinae and the left m. extensor digitorum. Perception and pain thresholds were not significantly different between the two groups, though patients showed significantly more perceptual sensitization. Across all stimulation conditions, a larger EEG component 80 milliseconds after stimulation was observed in the CLBP group. No significant group differences were found for the N150. The component 260 milliseconds after stimulus onset was significantly smaller in the CLBP group. N80, N150, and perceptual sensitization were significantly positively correlated. These results indicate enhanced perceptual sensitization and enhanced processing of the sensory-discriminative aspect of pain, as expressed in the N80 component, in CLBP patients. This may be one neurophysiologic basis of sensitization and the chronicity process. The lower P260 component in the patients may be explained in terms of tonic pain inhibiting phasic pain or may be related to the affective distress observed in this patient group.

Spatiotemporal integration in somatosensory perception: effects of sensory saltation on pointing at perceived positions on the body surface.

In the past, sensory saltation phenomena (Geldard and Sherrick, 1972) have been used repeatedly to analyze the spatiotemporal integration capacity of somatosensory and other sensory mechanisms by means of their psychophysical characteristic. The core phenomenon consists in a systematic mislocalization of one tactile stimulus (the attractee) toward another successive tactile stimulus (the attractant) presented at another location, increasing with shorter intervals. In a series of four experiments, sensory saltation characteristics were studied at the forearm and the abdomen. Participants reported the perceived positions of attractees, attractants, and reference stimuli by pointing. In general, saltation characteristics compared well to those reported in previous studies, but we were able to gain several new insights regarding this phenomenon: (a) the attractee–attractant interval did not exclusively affect the perceived attractee position, but also the perceived attractant position; (b) saltation characteristics were very similar at different body sites and orientations, but did show differences suggesting anisotropy (direction-dependency) in the underlying integration processes; (c) sensory saltation could be elicited with stimulation patterns crossing the body midline on the abdomen. In addition to the saltation-specific results, our experiments demonstrate that pointing reports of perceived positions on the body surface generally show pronounced systematic biases compared to veridical positions, moderate intraindividual consistency, and a high degree of inter-individual variability. Finally, we address methodological and terminological controversies concerning the sensory saltation paradigm and discuss its possible neurophysiological basis.

Independent psychophysical measurement of experimental modulations in the somatotopy of cutaneous heat-pain stimuli

Distortions of the body image have been repeatedly reported for various clinical conditions, but direct experimental analyses of the perceptual changes involved are still scarce. In addition, most experimental studies rely on cerebral activation patterns to assess neuroplastic changes in central representation, although the relationship between cerebral topography and the topology of the perceptual space is not clear. This study examines whether the direct psychophysical mapping approach we introduced recently (Trojan et al., Brain Res 2006;1120:106–113) is capable of tracking perceptual distortions in the somatotopic representation of heat-pain stimuli. Eleven healthy participants indicated the perceived positions of CO2 laser stimuli, repetitively presented to the dorsal forearm, with a 3D tracking system in two consecutive sessions, separated by the topical application of capsaicin cream. In line with earlier reports, we expected that the resulting individual perceptual maps (i.e., one-dimensional projections of the perceived positions onto the forearm surface) would be subject to modulation through the altered sensory input, to be measured in terms of altered topological parameters. We found that the topology and metrics of the somatotopic representation were well preserved in the second session, but that the perceptual map was compressed to a smaller range in 9 out of 11 participants. By providing dimensional measures of perceptual representations, perceptual maps constitute an independent, genuinely psychological complement to the topography of cortical activations measured with neuroimaging methods. In addition, we expect them to be useful in diagnosing pathological changes in body perception accompanying chronic pain and other disorders.

Validation of the Ludwigshafen German Version of the Burn Specific Health Scale-Brief

The Burn Specific Health Scale-Brief (BSHS-B) is one of the most commonly used instruments to measure quality of life after burns. Our aim was to establish and to provide a German version of the BSHS-B for all German-speaking burn facilities. Translation and cross-cultural adaptation of the original English version into the German language was conducted. In a pilot study, 20 burn patients qualitatively validated the translated version concerning comprehensibility and content validity. The final version was then quantitatively validated by 364 patients who were treated in our burn center between 2011 and 2015. Internal consistency and test-retest reliability were assessed. Criterion validity was determined by correlating the subscales with relevant instruments (Short-Form Health Survey 36, Hospital Anxiety and Depression Scale, and Disabilities of the Arm, Shoulder and Hand Outcome Measure). The structure of the German version was investigated by principal component analysis. Confirmatory factor analysis was used to compare the structure with the original 9-factor structure and the second-order 3-factor structure. Qualitative testing revealed adequate comprehension and content validity. Cronbachs alphas ranged from α = 0.80 to α = 0.92. The test-retest reliability ranged from r = 0.72 to r = 0.97. The subscales correlated significantly with the measures of criterion validity (r = 0.30 to r = -0.77). The principal component analysis results showed a satisfactory overlap with the original data structure, except for the Affect and Sexuality domains, which were merged into 1 factor. The confirmatory factor analyses revealed the best model fit for the second-order 3-factor structure, excluding the Work domain. The Ludwigshafen German version of the BSHS-B shows good psychometric properties. It is well suited for clinical use, further research, and international comparison.