@phdthesis{Aster2023,
  author    = {Aster, Hans-Christoph},
  title     = {Characterization of subgroups in fibromyalgia syndrome},
  doi       = {10.25972/OPUS-31304},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313049},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {The present cumulative dissertation summarizes three clinical studies, which examine subgroups of patients within the fibromyalgia syndrome (FMS). FMS entails chronic pain and associated symptoms, and its pathophysiology is incompletely understood (1). Previous studies show that there is a subgroup of patients with FMS with objective histological pathology of the small nerve fibers of the peripheral nervous system (PNS). Another subgroup of FMS patients does not show any signs of pathological changes of the small nerve fibers. The aim of this dissertation was to compare FMS patients with healthy controls, and these two FMS subgroups for differences in the central nervous system (CNS) in order to explore possible interactions between PNS and the CNS. Regarding the CNS, differences of FMS patients with healthy controls have already been found in studies with small sample sizes, but no subgroups have yet been identified. Another aim of this thesis was to test whether the subgroups show a different response to different classes of pain medication. The methods used in this thesis are structural and functional magnetic resonance imaging (MRI), magnetic resonance diffusion imaging and magnetic resonance spectroscopy. For the evaluation of clinical symptoms, we used standardized questionnaires. The subgroups with and without pathologies of the PNS were determined by skin biopsies of the right thigh and lower leg based on the intraepidermal nerve fiber density (IENFD) of the small nerve fibers. 1) In the first MRI study, 43 female patients with the diagnosis of FMS and 40 healthy control subjects, matched in age and body mass index, were examined with different MRI sequences. Cortical thickness was investigated by structural T1 imaging, white matter integrity by diffusion tensor imaging and functional connectivity within neuronal networks by functional resting state MRI. Compared to the controls, FMS patients had a lower cortical volume in bilateral frontotemporoparietal regions and the left insula, but a higher cortical volume in the left pericalcarine cortex. Compared to the subgroup without PNS pathology, the subgroup with PNS pathology had lower cortical volume in both pericalcarine cortices. Diffusion tensor imaging revealed an increased fractional anisotropy (FA) of FMS patients in corticospinal pathways such as the corona radiata, but also in regions of the limbic systems such as the fornix and cingulum. Subgroup comparison again revealed lower mean FA values of the posterior thalamic radiation and the posterior limb of the left internal capsule in the subgroup with PNS pathology. In the functional connectivity analysis FMS patients, compared to controls, showed a hypoconnectivity between the right median frontal gyrus and the posterior cerebellum and the right crus cerebellum, respectively. In the subgroup comparisons, the subgroup with PNS pathology showed a hyperconnectivity between both inferior frontal gyri, the right posterior parietal cortex and the right angular gyrus. In summary, these results show that differences in brain morphology and functional connectivity exist between FMS patients with and without PNS pathology. These differences were not associated with symptom duration or severity and, in some cases, have not yet been described in the context of FMS. The differences in brain morphology and connectivity between subgroups could also lead to a differential response to treatment with centrally acting drugs. Further imaging studies with FMS patients should take into account this heterogeneity of FMS patient cohorts. 2) Following the results from the first MRI study, drug therapies of FMS patients and their treatment response were compared between PNS subgroups. As there is no licensed drug for FMS in Europe, the German S3 guideline recommends amitriptyline, duloxetine and pregabalin for temporary use. In order to examine the current drug use in FMS patients in Germany on a cross-sectional basis, 156 patients with FMS were systematically interviewed. The drugs most frequently used to treat pain in FMS were non-steroidal anti-inflammatory drugs (NSAIDs) (28.9\%), metamizole (15.4\%) and amitriptyline (8.8\%). Pain relief assessed by patients on a numerical rating scale from 0-10 averaged 2.2 points for NSAIDs, 2.0 for metamizole and 1.5 for amitriptyline. Drugs that were discontinued for lack of efficacy and not for side effects were acetaminophen (100\%), flupirtine (91.7\%), selective serotonin reuptake inhibitors (81.8\%), NSAIDs (83.7\%) and weak opioids (74.1\%). Patients were divided into subgroups with and without PNS pathology as determined by skin biopsies. We found no differences in drug use and effect between the subgroups. Taken together, these results show that many FMS patients take medication that is not in accordance with the guidelines. The reduction of symptoms was best achieved with metamizole and NSAIDs. Further longitudinal studies on medication in FMS are necessary to obtain clearer treatment recommendations. 3) Derived from previous pharmacological and imaging studies (with smaller case numbers), there is a hypothesis in the FMS literature that hyperreactivity of the insular cortex may have an impact on FMS. The hyperreactivity seems to be due to an increased concentration of the excitatory neurotransmitter glutamate in the insular cortex of FMS patients. The hypothesis is supported by magnetic resonance spectroscopy studies with small number of cases, as well as results from pharmacological studies with glutamate-inhibiting medication. Studies from animal models have also shown that an artificially induced increase in glutamate in the insular cortex can lead to reduced skin innervation. Therefore, the aim of this study was to compare glutamate and GABA concentrations in the insular cortex of FMS patients with those of healthy controls using magnetic resonance imaging. There was no significant difference of both neurotransmitters between the groups. In addition, there was no correlation between the neurotransmitter concentrations and the severity of clinical symptoms. There were also no differences in neurotransmitter concentrations between the subgroups with and without PNS pathology. In conclusion, our study could not show any evidence of a correlation of glutamate and GABA concentrations with the symptoms of FMS or the pathogenesis of subgroups with PNS pathologies.},
  subject      = {Fibromyalgie},
  language  = {en}
}
@phdthesis{Frank2019,
  author    = {Frank, Johanna},
  title     = {Untersuchung der Kleinfaserpathologie beim Fibromyalgie-Syndrom},
  publisher = {Annals of Neurology, The Journal of Rheumatology},
  doi       = {10.25972/OPUS-19265},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-192653},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Die Studienergebnisse st{\"u}tzen das Konzept, dass das periphere Nervensystem zu Schmerzen beim Fibromyalgie-Syndrom (FMS) beitr{\"a}gt. An der Neurologischen Universit{\"a}tsklinik W{\"u}rzburg wurden 53 FMS Patientinnen und 35 gesunde Kontrollen rekrutiert, ausf{\"u}hrlich anamnestiziert inklusive spezieller Schmerzfrageb{\"o}gen, neurologisch und mittels spezieller Tests auf eine St{\"o}rung der kleinkalibrigen A-delta- und C-Nervenfasern untersucht. Hierzu geh{\"o}rte eine quantitative sensorische Testung mit Pleasant touch Untersuchung und die schmerz-assoziierten elektrisch-evoziierten Potentiale f{\"u}r die Kleinfaserfunktion und die corneale confocale Mikroskopie, sowie die Analyse von Hautstanbiopsien f{\"u}r die Kleinfasermorphologie. Im Unterschied zu gesunden Kontrollen wiesen die FMS Patientinnen eine Reduktion, als auch eine Funktions{\"a}nderung der kleinkalibrigen Nervenfasern auf. Des Weiteren konnten wir aus der heterogenen Patientenpopulation anhand von unterschiedlichen Nervenfaserdichten der Haut eine Subgruppe mit generalisierter Reduktion der Hautinnervation identifizieren, die besonders schwer betroffen ist. Diese Subgruppenanalysen k{\"o}nnen k{\"u}nftig von großer Bedeutung f{\"u}r die Therapiewahl sein.},
  subject      = {Fibromyalgie},
  language  = {de}
}
@phdthesis{Kewenig2014,
  author    = {Kewenig, Susanne Katharina},
  title     = {Messung der zerebralen Aktivierung mittels funktioneller Nah-Infrarot-Spektroskopie bei Patienten mit Fibromyalgie-Syndrom},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-107515},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Wir untersuchten die zerebrale Aktivierung von Patienten mit Fibromyalgie-Syndrom (FMS) mittels funktioneller Nah-Infrarot-Spektroskopie (fNIRS). Das FMS ist ein Symptomenkomplex aus Schmerzen in mehreren K{\"o}rperregionen sowie weiteren k{\"o}rperlichen und seelischen Beschwerden, wie Schlafst{\"o}rungen, kognitiven Defiziten und Depressionen. Die fNIRS ist eine neue, nicht-invasive Technik, die eine indirekte Messung der regionalen kortikalen Hirnaktivierung erlaubt. Es wurden 25 FMS-Patienten, 10 MD-Patienten ohne Schmerzen und 35 gesunde Kontrollen in die Studie eingeschlossen. Alle Patienten wurden klinisch-neurologisch untersucht. Dar{\"u}ber hinaus f{\"u}llten alle Teilnehmer Frageb{\"o}gen zu Schmerzen (GCPS, NPSI), FMS-Symptomen (FIQ), Depressionen (BDI II, ADS) und Empathief{\"a}higkeit (SPF) aus. Die kortikale Aktivierung wurde unter drei Stimulations-Bedingungen mittels fNIRS gemessen: 1.) Anwendung mechanischer (Druck-) Schmerzreize auf den dorsalen Unterarm; 2.) Anwendung visuell-emotionaler Reize in Form von neutralen, negativen und Schmerz-assoziierten Bildern; 3.) Wortfl{\"u}ssigkeitstest. Erg{\"a}nzend wurden die unter 2.) pr{\"a}sentierten Bilder bewertet sowie ein Zahlenverbindungstest durchgef{\"u}hrt. FMS-Patienten hatten in den Schmerzfrageb{\"o}gen und im FIQ-Fragebogen deutlich h{\"o}here Werte als MD-Patienten und Kontrollen (p < 0,001). In den Depressionsfrageb{\"o}gen erreichten FMS-Patienten {\"a}hnlich hohe Werte wie MD-Patienten. Die Empathief{\"a}higkeit war bei FMS-Patienten tendenziell st{\"a}rker ausgepr{\"a}gt als bei MD-Patienten und Kontrollen. FMS-Patienten zeigten niedrigere Druckschmerzschwellen bei gleicher Schmerzintensit{\"a}t als MD-Patienten und Kontrollen (p < 0,001). Auf einen unilateralen schmerzhaften Druckreiz reagierten FMS-Patienten mit einer verst{\"a}rkten bilateralen kortikalen Aktivierung, die sich im Vergleich zu Kontrollen insbesondere im rechten pr{\"a}frontalen Kortex (p < 0,05) sowie zu MD-Patienten bilateral im Frontalkortex unterschied (p < 0,05). Auf einen Druckreiz der gleichen St{\"a}rke, der f{\"u}r FMS-Patienten schmerzhaft, aber f{\"u}r Zusatzkontrollen schmerzfrei war, zeigten FMS-Patienten im Vergleich zu diesen eine verst{\"a}rkte Aktivierung im linken dorsolateralen pr{\"a}frontalen Kortex (p < 0,05). Der kortikale Aktivierungsunterschied bei Schmerz-assoziierten versus neutralen Bildern war bei FMS-Patienten im linken pr{\"a}frontalen Kortex wesentlich ausgepr{\"a}gter als bei Kontrollen (p < 0,05), w{\"a}hrend die Schmerz-assoziierten Bilder von FMS-Patienten weniger unangenehm bewertet wurden als von Kontrollen. Der Aktivierungsunterschied bei negativen versus neutralen Bildern war bei MD-Patienten im linken Frontalkortex wesentlich geringer ausgepr{\"a}gt als bei FMS-Patienten und Kontrollen (p < 0,05). Im Wortfl{\"u}ssigkeitstest und im Zahlenverbindungstest konnten keine kognitiven Defizite bzw. Aktivierungsunterschiede zwischen FMS-Patienten und Kontrollen gefunden werden. Allerdings zeigten MD-Patienten in beiden Bedingungen des Wortfl{\"u}ssigkeitstests eine geringere frontale Aktivierung als FMS-Patienten und Kontrollen (p < 0,05). Diese Studie belegt die ver{\"a}nderte zentrale Schmerzverarbeitung bei FMS-Patienten und zeigt, dass diese mittels fNIRS messbar ist. FMS-Patienten zeigten st{\"a}rkere Aktivierungen Schmerz-assoziierter Hirnareale w{\"a}hrend mechanischer und visueller Schmerzstimuli im Vergleich zu gesunden Kontrollen. Zudem best{\"a}tigt diese Studie die Unterscheidung zwischen FMS und Depression.},
  subject      = {Fibromyalgie},
  language  = {de}
}
@phdthesis{Klitsch2021,
  author    = {Klitsch, Alexander},
  title     = {Corneal and cutaneous factors contributing to small fiber pathology in fibromyalgia syndrome},
  doi       = {10.25972/OPUS-22439},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224398},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {We examined 143 patients suffering from FMS, a syndrome characterized by chronic widespread pain, sleep disturbances, and fatigue. Etiology and pathophysiology of FMS are scarcely understood. In recent years abnormalities of small Aδ- and C-nerve fibers have been found in subgroups of FMS patients. It is yet unclear how such SFP is caused in FMS patients and how it contributes to FMS symptoms. We used CCM to analyze corneal small nerve fibers and associated LC, comparing FMS patients' results to those from 65 healthy controls and 41 disease controls suffering from SFN. We, further, assessed expression levels of mRNA and miRNA in keratinocytes taken from skin punch biopsies of FMS patients and healthy controls kept as monocellular cell cultures. A screening was performed using NGS in a small cohort of 12 FMS patients and 5 healthy controls. Results were validated in larger cohorts by qRT-PCR. As in previous studies IENFD and CNFD were reduced in a subgroup of FMS patients. We found identical LC densities in FMS patients, healthy controls, and SFN patients. The subpopulation of dLCfiber contact in FMS and SFN patients was lower than in healthy controls. Our RNA expression analysis revealed one mRNA that was expressed higher in FMS patients than in controls: PRSS21. We conclude that reduced neurotrophic signaling of LC may contribute to SFP in the cornea. Epidermal PRSS21 expression and dLCfiber contact density are promising biomarker candidates for FMS diagnosis.},
  subject      = {Fibromyalgie},
  language  = {en}
}
@article{UeceylerHaeuserSommer2011,
  author    = {{\"U}ceyler, Nurcan and H{\"a}user, Winfried and Sommer, Claudia},
  title     = {Systematic review with meta-analysis: Cytokines in fibromyalgia syndrome},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69189},
  year      = {2011},
  abstract  = {Background: To perform a systematic review and meta-analysis on cytokine levels in patients with fibromyalgia syndrome (FMS). Methods: Through December 2010 we systematically reviewed the databases PubMed, MEDLINE, and PsycINFO and screened the reference lists of 22 review articles for suitable original articles. Original articles investigating cytokines in patients with FMS were included. Data were extracted by two independent authors. Differences of the cytokine levels of FMS patients and controls were summarized by standardized mean differences (SMD) using a random effects model. Study quality was assessed applying methodological scores: modified Center of Evidence Based Medicine, Newcastle-Ottawa-Scale, and W{\"u}rzburg Methodological Quality Score. Results: Twenty-five articles were included investigating 1255 FMS patients and 800 healthy controls. Data of 13/25 studies entered meta-analysis. The overall methodological quality of studies was low. The results of the majority of studies were not comparable because methods, investigated material, and investigated target cytokines differed. Systematic review of the selected 25 articles revealed that FMS patients had higher serum levels of interleukin (IL)-1 receptor antagonist, IL-6, and IL-8, and higher plasma levels of IL-8. Meta-analysis of eligible studies showed that FMS patients had higher plasma IL-6 levels compared to controls (SMD = -0.34 [-0.64, -0.03] 95\% CI; p = 0.03). The majority of investigated cytokines were not different between patients and controls. Conclusions: The pathophysiological role of cytokines in FMS is still unclear. Studies of higher quality and with higher numbers of subjects are needed.},
  subject      = {Fibromyalgie},
  language  = {en}
}